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Posted to dev@chemistry.apache.org by David Caruana <da...@alfresco.com> on 2010/11/08 12:51:01 UTC
Re: Proposal to clarify CmisObject caching behaviour
Have we reached a conclusion on this issue? It's been a while since we last discussed.
Regards,
Dave
On 22 Oct 2010, at 15:06, Florian Müller wrote:
> Oh, right, there is yet another option. :)
>
> I support all your arguments against b), c) and d). But there are also two issues with e).
> 1. Which value wins if a property is changed in the transient object _and_ present in the map?
> 2. save() stores the whole object. If we make ACLs and Policies transient too (do we want that?) than updateProperties() has the side effect of storing those as well.
>
> Which leaves us with a) which is pretty strong. And in this case I prefer two interfaces because it much is easier to understand and provides more compile checks and less runtime surprises.
>
>
> - Florian
>
>
> On 22/10/2010 14:44, Florent Guillaume wrote:
>> On Fri, Oct 22, 2010 at 3:33 PM, Florian Müller
>> <fl...@alfresco.com> wrote:
>>> So your proposal is to add a method getTransientObject() (or something like that) to CmisObject. And that method would return a transient, not thread-safe version of the object but with setProperty(), save(), etc. enabled?
>>> Is that correct?
>>
>> Yes.
>>
>>> In this case we should also add a method isTransient() to CmisObject. There should be a way to discover the state of the CmisObject.
>>
>> Yes that would be useful.
>>
>>> I suggest that if the object is not transient, the transient methods should throw an IllegalStateException.
>>
>> Ok.
>>
>>> I agree that keeping the number of interfaces and classes low helps to learn and understand an API. But blending two semantics in one class could be even more confusing.
>>> For example, what should happen if updateProperties(Map) is called on a transient object? There are multiple options:
>>> a) updateProperties(Map) throws an exception because it only works for non-transient objects.
>>> b) updateProperties(Map) writes instantly to the repository and the transient object is refreshed.
>> (which btw means that transient changes are lost)
>>> c) updateProperties(Map) writes instantly to the repository and but object keep its (now outdated) state.
>>> d) The property map is merged with the transient properties and written when save() is called.
>>
>> And also:
>> e) The property map is merged with the transient properties and then
>> save() is automatically called.
>>
>>> It is not obvious. All semantics would be right and wrong at the same time.
>>
>> Agreed, we have to make a choice. But we would make a similar choice
>> when deciding what methods would be available on the TransientDocument
>> interface and what they would do.
>>
>> But anyway my choices in order of preference would be e) then a).
>> I don't like b) because it loses changes.
>> I don't like c) because there's an issue with not keeping the changes in order.
>> I don't like d) because if you didn't do any transient operation it
>> doesn't behave like its non-transient counterpart.
>>
>> Florent
>>
>>>
>>>
>>> On 22/10/2010 13:43, Florent Guillaume wrote:
>>>> Hi,
>>>>
>>>> Looking back at your example:
>>>>
>>>> Document doc = (Document) session.getObject(id);
>>>> TransientDocument transDoc = doc.createTransientDocument():
>>>> transDoc.setProperty("prop1", "value1");
>>>> transDoc.setProperty("prop2", "value2");
>>>> transDoc.save();
>>>>
>>>> I agree with the need to explicitly getting a transient object if you
>>>> need different semantics.
>>>> One thing that will be painful though is having different classes:
>>>> TransientCmisObject, TransientDocument, TransientFolder, etc.
>>>> Couldn't we simply have all the methods available on the CmisObject,
>>>> Document, Folder, etc. and make them throw
>>>> UnsupportedOperationException when called on a non-transient object?
>>>> This would tremendously help learning about the API and avoid juggling
>>>> with many different interfaces for the users.
>>>>
>>>> Florent
>>>>
>>>>
>>>>
>>>>
>>>> On Mon, Oct 18, 2010 at 10:43 PM, Florian Müller
>>>> <fl...@alfresco.com> wrote:
>>>>> Hi Florent,
>>>>>
>>>>> Well, no, there would be no CmisObject.save() method. The save() method
>>>>> would only be on the transient object.
>>>>>
>>>>> CmisObject would have updateProperties(Map), applyAcl(List<Ace>, List<Ace>,
>>>>> AclPropagation), applyPolicy(ObjectId), etc. And all of them would write
>>>>> instantly to the repository and refresh the object.
>>>>>
>>>>>
>>>>> Florian
>>>>>
>>>>>
>>>>> On 18/10/2010 17:49, Florent Guillaume wrote:
>>>>>>
>>>>>> Ok understood and agreed. There would be a new CmisObject.save() to
>>>>>> replace updateProperties() then? That works for me as it's a less
>>>>>> restrictive name that allows for different implementations of the
>>>>>> transient space that don't deal with just properties.
>>>>>>
>>>>>> Regarding your examples I don't need to do all that, because in the
>>>>>> Nuxeo use cases I described the client Session I'm providing to the
>>>>>> user of the API is not a PersistentSessionImpl but a completely new
>>>>>> Nuxeo class that does all the wrapping it needs around native Nuxeo
>>>>>> objects. So I'm not constrained by the semantics of the current
>>>>>> PersistentSessionImpl. It's just that I need a save()-like API to
>>>>>> exist on the CmisObject. And of course I want to have semantics that
>>>>>> are not too far to what's available when you use an actual remote
>>>>>> connection using pure OpenCMIS PersistentSessionImpl.
>>>>>>
>>>>>> Florent
>>>>>>
>>>>>>
>>>>>> On Mon, Oct 18, 2010 at 6:06 PM, Florian Müller
>>>>>> <fl...@alfresco.com> wrote:
>>>>>>>
>>>>>>> Hi Florent,
>>>>>>>
>>>>>>> We don't want to remove the transient space entirely. The proposal is to
>>>>>>> detach the transient from the non-transient part. We would have two
>>>>>>> separate
>>>>>>> objects.
>>>>>>>
>>>>>>> The non-transient object is always consistent, can be shared across
>>>>>>> threads
>>>>>>> and is cached. Changes are directly written to the repository. This
>>>>>>> object
>>>>>>> would have an updateProperties(Map) method that immediately refreshes the
>>>>>>> object after the update.
>>>>>>>
>>>>>>> The transient object is owned by one thread and not thread safe. That
>>>>>>> should
>>>>>>> prevent inconsistent views on the object. This object would have
>>>>>>> setProperty() and save() methods. Internally it would use the
>>>>>>> non-transient
>>>>>>> object to access all unchanged data. It's a wrapper around the
>>>>>>> non-transient
>>>>>>> object that holds the transient data.
>>>>>>>
>>>>>>> So you still could use the pattern that you are using today. The only
>>>>>>> difference would be that you have to create a transient wrapper object.
>>>>>>>
>>>>>>>
>>>>>>> That could look like this:
>>>>>>>
>>>>>>> Document doc = (Document) session.getObject(id);
>>>>>>> TransientDocument transDoc = new TransientDocument(doc);
>>>>>>>
>>>>>>> transDoc.setProperty("prop1", "value1");
>>>>>>> transDoc.setProperty("prop2", "value2");
>>>>>>> transDoc.save(); // that also refreshes the underlying non-transient
>>>>>>> object
>>>>>>>
>>>>>>>
>>>>>>> Or maybe we do something like this:
>>>>>>>
>>>>>>> Document doc = (Document) session.getObject(id);
>>>>>>> TransientDocument transDoc = doc.createTransientDocument():
>>>>>>>
>>>>>>> transDoc.setProperty("prop1", "value1");
>>>>>>> transDoc.setProperty("prop2", "value2");
>>>>>>> transDoc.save();
>>>>>>>
>>>>>>>
>>>>>>> Florian
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> On 18/10/2010 16:07, Florent Guillaume wrote:
>>>>>>>>
>>>>>>>> Hi,
>>>>>>>>
>>>>>>>> In Nuxeo the OpenCMIS client API is made available locally as another
>>>>>>>> API to manipulate documents, in addition to the Nuxeo native APIs.
>>>>>>>>
>>>>>>>> I have a problem with removing CmisObject.updateProperties() and the
>>>>>>>> mini transient space because for me it's quite useful. The Nuxeo
>>>>>>>> internal non-CMIS session has a notion of a property-only transient
>>>>>>>> space, so in Nuxeo you update several properties and do some kind of
>>>>>>>> object save() to flush them. Without a similar flushing concept on the
>>>>>>>> OpenCMIS client API, I'm obliged to make a flush on every property
>>>>>>>> write, which leads to severely degraded performance.
>>>>>>>>
>>>>>>>> If all method calls on a CmisObject immediately write everything
>>>>>>>> through the network and potentially refetch a full object there will
>>>>>>>> be many people that aren't happy with CMIS performance once they get
>>>>>>>> to use OpenCMIS. The client API is supposed to provide some
>>>>>>>> convenience to the user, and having a mini transient space for
>>>>>>>> properties is IMHO the very first step of convenience. There may be
>>>>>>>> problems with the semantics of interactions between this transient
>>>>>>>> space and caching / refetches, but let's solve them rather than remove
>>>>>>>> them.
>>>>>>>>
>>>>>>>> Dave wrote:
>>>>>>>>>
>>>>>>>>> For example, with a transient space, what is the behaviour when
>>>>>>>>> setProperty has been called and an "update" method is then called prior
>>>>>>>>> to
>>>>>>>>> updateProperties. Are the transient changes discarded, flushed, or just
>>>>>>>>> left
>>>>>>>>> as is?
>>>>>>>>
>>>>>>>> So if I understand correctly you're talking about the case:
>>>>>>>> 1. doc.setPropertyValue("foo", ...);
>>>>>>>> 2. doc.updateProperties(map);
>>>>>>>> 3. doc.setPropertyValue("bar", ...);
>>>>>>>> 4. doc.updateProperties();
>>>>>>>>
>>>>>>>> And you're asking if the "foo" change is sent with 2. or with 4. or
>>>>>>>> discarded? I'd say let's keep this undefined, as I feel that it's a
>>>>>>>> use pattern that's not natural. If we really want to specify this then
>>>>>>>> I have no problem mandating that the "foo" change should be sent with
>>>>>>>> 2. by saying that updateProperties(map) is the same as
>>>>>>>> setPropertyValue() on all the properties of the map then calling
>>>>>>>> updateProperties() with the transient map.
>>>>>>>>
>>>>>>>> Florent
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>> On Mon, Oct 18, 2010 at 4:05 PM, Klevenz, Stephan
>>>>>>>> <st...@sap.com> wrote:
>>>>>>>>>
>>>>>>>>> Hi,
>>>>>>>>>
>>>>>>>>> Coming back to the cache discussion. I would like to support this
>>>>>>>>> proposal by Dave/Florian and think we can also delete Methods on
>>>>>>>>> Session
>>>>>>>>> class like cancel() and save() which are currently not implemented.
>>>>>>>>>
>>>>>>>>> +1 for this:
>>>>>>>>>
>>>>>>>>>> - All write operations provided by CmisObject should automatically do
>>>>>>>>>> an
>>>>>>>>>> object
>>>>>>>>>> refresh after the update. That guarantees that the object is always
>>>>>>>>>> consistent.
>>>>>>>>>> The cost for this consistency is an additional call to the repository.
>>>>>>>>>
>>>>>>>>>> - Is some cases you don't need or want this addition cost. Lets say
>>>>>>>>>> you
>>>>>>>>>> just
>>>>>>>>>> want to update a bunch of objects but you don't work with them
>>>>>>>>>> afterwards.
>>>>>>>>>> That's what the operations provided by Session are good for. They just
>>>>>>>>>> do
>>>>>>>>>> that and nothing else.
>>>>>>>>>
>>>>>>>>> About the transient support we can design this as an optional add on
>>>>>>>>> with
>>>>>>>>> additional interfaces and additional implementations. With a clear
>>>>>>>>> separation the API become easier to use.
>>>>>>>>>
>>>>>>>>> Regards,
>>>>>>>>> Stephan
>>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>
>>>>>
>>>>
>>>>
>>>>
>>>
>>>
>>
>>
>>
>
Re: Proposal to clarify CmisObject caching behaviour
Posted by Florian Müller <fl...@alfresco.com>.
Yes, sounds reasonable. I will create a branch.
- Florian
On 10/11/2010 19:41, Florent Guillaume wrote:
> Could you do it in a branch for a few days?
> I have a fix to do for the AtomPub bindings (they generate bad atom
> alternate links for renditions), and I'll need it for the Nuxeo server
> bindings shortly. I'd rather not change the updateProperties / save
> that I may be using right now in our connector's code. In a 1-2 days
> I'll commit and make a private snapshot and we can merge your branch.
> Is that ok?
>
> Florent
>
> On Wed, Nov 10, 2010 at 8:35 PM, Florian Müller
> <fl...@alfresco.com> wrote:
>> Got it. Thanks.
>>
>> Would somebody object if I would start the refactoring?
>> If we don't like it, we can roll it back.
>>
>> I would also remove the "persistent" and "transient" notion from the session
>> implementation including renaming those classes.
>>
>>
>> - Florian
>>
>>
>>
>> On 10/11/2010 17:43, Florent Guillaume wrote:
>>>
>>> It would be an interface.
>>>
>>> I agree that it's not obvious in this case that transient behavior can
>>> be obtained using an adapter (and autocompletion doc.get... does not
>>> immediately provide it). But this can be solved by simple
>>> documentation I think. Yes if we think transient documents are
>>> fundamental we can make createTransientDocument a synonym to get this
>>> adapter. It's not mandatory though.
>>>
>>> Florent
>>>
>>> On Wed, Nov 10, 2010 at 3:16 PM, Florian Müller
>>> <fl...@alfresco.com> wrote:
>>>>
>>>> Hi Florent,
>>>>
>>>> Could you elaborate a bit more on that proposal?
>>>> Would TransientDocument.class be an Interface or a Class?
>>>>
>>>> I like the idea of adapters. But it is not intuitive that there is an
>>>> adapter the provides a transient paradigm. Would it make sense to add
>>>> another method that provides a shortcut to the "transient adapter"?
>>>>
>>>>
>>>> Thanks,
>>>>
>>>> Florian
>>>>
>>>>
>>>> On 10/11/2010 13:27, Florent Guillaume wrote:
>>>>>
>>>>> I've come around to agreeing that 2. is probably better.
>>>>>
>>>>> I can see either:
>>>>> TransientDocument transDoc = doc.createTransientDocument():
>>>>> or
>>>>> TransientDocument transDoc = doc.getAdapter(TransientDocument.class);
>>>>>
>>>>> The latter is more extensible for other uses besides transience
>>>>> (protocol extensions, application-specific adapters).
>>>>>
>>>>> WDYT?
>>>>>
>>>>> Florent
>>>>>
>>>>>
>>>>> On Wed, Nov 10, 2010 at 10:41 AM, Florian Müller
>>>>> <fl...@alfresco.com> wrote:
>>>>>>
>>>>>> I would like to see that sorted out soon. There are more and more users
>>>>>> of OpenCMIS and API changes are usually painful for them. We should
>>>>>> also
>>>>>> consider a new release (0.2.0) when this is done.
>>>>>>
>>>>>> So, where are we?
>>>>>>
>>>>>> The main question is where we want to handle transient data. We have
>>>>>> two
>>>>>> opinions:
>>>>>> 1. Transient and non-transient data access should be covered by the
>>>>>> CmisObject interface. (Florent)
>>>>>> 2. Transient data access should be covered by a new interface and
>>>>>> non-transient data access should be covered by the CmisObject
>>>>>> interface.
>>>>>> (Florian)
>>>>>>
>>>>>> Personally, I still want to go for option 2 since it provides cleaner
>>>>>> semantics -- especially in multi-threaded environments.
>>>>>>
>>>>>> Other opinions?
>>>>>>
>>>>>>
>>>>>> - Florian
>>>>>>
>>>>>>
>>>>>> On 08/11/2010 11:51, David Caruana wrote:
>>>>>>>
>>>>>>> Have we reached a conclusion on this issue? It's been a while since we
>>>>>>> last discussed.
>>>>>>>
>>>>>>> Regards,
>>>>>>> Dave
>>>>>>>
>>>>>>> On 22 Oct 2010, at 15:06, Florian Müller wrote:
>>>>>>>
>>>>>>>> Oh, right, there is yet another option. :)
>>>>>>>>
>>>>>>>> I support all your arguments against b), c) and d). But there are
>>>>>>>> also
>>>>>>>> two issues with e).
>>>>>>>> 1. Which value wins if a property is changed in the transient object
>>>>>>>> _and_ present in the map?
>>>>>>>> 2. save() stores the whole object. If we make ACLs and Policies
>>>>>>>> transient too (do we want that?) than updateProperties() has the side
>>>>>>>> effect
>>>>>>>> of storing those as well.
>>>>>>>>
>>>>>>>> Which leaves us with a) which is pretty strong. And in this case I
>>>>>>>> prefer two interfaces because it much is easier to understand and
>>>>>>>> provides
>>>>>>>> more compile checks and less runtime surprises.
>>>>>>>>
>>>>>>>>
>>>>>>>> - Florian
>>>>>>>>
>>>>>>>>
>>>>>>>> On 22/10/2010 14:44, Florent Guillaume wrote:
>>>>>>>>>
>>>>>>>>> On Fri, Oct 22, 2010 at 3:33 PM, Florian Müller
>>>>>>>>> <fl...@alfresco.com> wrote:
>>>>>>>>>>
>>>>>>>>>> So your proposal is to add a method getTransientObject() (or
>>>>>>>>>> something like that) to CmisObject. And that method would return a
>>>>>>>>>> transient, not thread-safe version of the object but with
>>>>>>>>>> setProperty(),
>>>>>>>>>> save(), etc. enabled?
>>>>>>>>>> Is that correct?
>>>>>>>>>
>>>>>>>>> Yes.
>>>>>>>>>
>>>>>>>>>> In this case we should also add a method isTransient() to
>>>>>>>>>> CmisObject.
>>>>>>>>>> There should be a way to discover the state of the CmisObject.
>>>>>>>>>
>>>>>>>>> Yes that would be useful.
>>>>>>>>>
>>>>>>>>>> I suggest that if the object is not transient, the transient
>>>>>>>>>> methods
>>>>>>>>>> should throw an IllegalStateException.
>>>>>>>>>
>>>>>>>>> Ok.
>>>>>>>>>
>>>>>>>>>> I agree that keeping the number of interfaces and classes low helps
>>>>>>>>>> to learn and understand an API. But blending two semantics in one
>>>>>>>>>> class
>>>>>>>>>> could be even more confusing.
>>>>>>>>>> For example, what should happen if updateProperties(Map) is called
>>>>>>>>>> on
>>>>>>>>>> a transient object? There are multiple options:
>>>>>>>>>> a) updateProperties(Map) throws an exception because it only
>>>>>>>>>> works
>>>>>>>>>> for non-transient objects.
>>>>>>>>>> b) updateProperties(Map) writes instantly to the repository and
>>>>>>>>>> the transient object is refreshed.
>>>>>>>>>
>>>>>>>>> (which btw means that transient changes are lost)
>>>>>>>>>>
>>>>>>>>>> c) updateProperties(Map) writes instantly to the repository and
>>>>>>>>>> but object keep its (now outdated) state.
>>>>>>>>>> d) The property map is merged with the transient properties and
>>>>>>>>>> written when save() is called.
>>>>>>>>>
>>>>>>>>> And also:
>>>>>>>>> e) The property map is merged with the transient properties and then
>>>>>>>>> save() is automatically called.
>>>>>>>>>
>>>>>>>>>> It is not obvious. All semantics would be right and wrong at the
>>>>>>>>>> same
>>>>>>>>>> time.
>>>>>>>>>
>>>>>>>>> Agreed, we have to make a choice. But we would make a similar choice
>>>>>>>>> when deciding what methods would be available on the
>>>>>>>>> TransientDocument
>>>>>>>>> interface and what they would do.
>>>>>>>>>
>>>>>>>>> But anyway my choices in order of preference would be e) then a).
>>>>>>>>> I don't like b) because it loses changes.
>>>>>>>>> I don't like c) because there's an issue with not keeping the
>>>>>>>>> changes
>>>>>>>>> in order.
>>>>>>>>> I don't like d) because if you didn't do any transient operation it
>>>>>>>>> doesn't behave like its non-transient counterpart.
>>>>>>>>>
>>>>>>>>> Florent
>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> On 22/10/2010 13:43, Florent Guillaume wrote:
>>>>>>>>>>>
>>>>>>>>>>> Hi,
>>>>>>>>>>>
>>>>>>>>>>> Looking back at your example:
>>>>>>>>>>>
>>>>>>>>>>> Document doc = (Document) session.getObject(id);
>>>>>>>>>>> TransientDocument transDoc = doc.createTransientDocument():
>>>>>>>>>>> transDoc.setProperty("prop1", "value1");
>>>>>>>>>>> transDoc.setProperty("prop2", "value2");
>>>>>>>>>>> transDoc.save();
>>>>>>>>>>>
>>>>>>>>>>> I agree with the need to explicitly getting a transient object if
>>>>>>>>>>> you
>>>>>>>>>>> need different semantics.
>>>>>>>>>>> One thing that will be painful though is having different classes:
>>>>>>>>>>> TransientCmisObject, TransientDocument, TransientFolder, etc.
>>>>>>>>>>> Couldn't we simply have all the methods available on the
>>>>>>>>>>> CmisObject,
>>>>>>>>>>> Document, Folder, etc. and make them throw
>>>>>>>>>>> UnsupportedOperationException when called on a non-transient
>>>>>>>>>>> object?
>>>>>>>>>>> This would tremendously help learning about the API and avoid
>>>>>>>>>>> juggling
>>>>>>>>>>> with many different interfaces for the users.
>>>>>>>>>>>
>>>>>>>>>>> Florent
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>> On Mon, Oct 18, 2010 at 10:43 PM, Florian Müller
>>>>>>>>>>> <fl...@alfresco.com> wrote:
>>>>>>>>>>>>
>>>>>>>>>>>> Hi Florent,
>>>>>>>>>>>>
>>>>>>>>>>>> Well, no, there would be no CmisObject.save() method. The save()
>>>>>>>>>>>> method
>>>>>>>>>>>> would only be on the transient object.
>>>>>>>>>>>>
>>>>>>>>>>>> CmisObject would have updateProperties(Map), applyAcl(List<Ace>,
>>>>>>>>>>>> List<Ace>,
>>>>>>>>>>>> AclPropagation), applyPolicy(ObjectId), etc. And all of them
>>>>>>>>>>>> would
>>>>>>>>>>>> write
>>>>>>>>>>>> instantly to the repository and refresh the object.
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>> Florian
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>> On 18/10/2010 17:49, Florent Guillaume wrote:
>>>>>>>>>>>>>
>>>>>>>>>>>>> Ok understood and agreed. There would be a new CmisObject.save()
>>>>>>>>>>>>> to
>>>>>>>>>>>>> replace updateProperties() then? That works for me as it's a
>>>>>>>>>>>>> less
>>>>>>>>>>>>> restrictive name that allows for different implementations of
>>>>>>>>>>>>> the
>>>>>>>>>>>>> transient space that don't deal with just properties.
>>>>>>>>>>>>>
>>>>>>>>>>>>> Regarding your examples I don't need to do all that, because in
>>>>>>>>>>>>> the
>>>>>>>>>>>>> Nuxeo use cases I described the client Session I'm providing to
>>>>>>>>>>>>> the
>>>>>>>>>>>>> user of the API is not a PersistentSessionImpl but a completely
>>>>>>>>>>>>> new
>>>>>>>>>>>>> Nuxeo class that does all the wrapping it needs around native
>>>>>>>>>>>>> Nuxeo
>>>>>>>>>>>>> objects. So I'm not constrained by the semantics of the current
>>>>>>>>>>>>> PersistentSessionImpl. It's just that I need a save()-like API
>>>>>>>>>>>>> to
>>>>>>>>>>>>> exist on the CmisObject. And of course I want to have semantics
>>>>>>>>>>>>> that
>>>>>>>>>>>>> are not too far to what's available when you use an actual
>>>>>>>>>>>>> remote
>>>>>>>>>>>>> connection using pure OpenCMIS PersistentSessionImpl.
>>>>>>>>>>>>>
>>>>>>>>>>>>> Florent
>>>>>>>>>>>>>
>>>>>>>>>>>>>
>>>>>>>>>>>>> On Mon, Oct 18, 2010 at 6:06 PM, Florian Müller
>>>>>>>>>>>>> <fl...@alfresco.com> wrote:
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> Hi Florent,
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> We don't want to remove the transient space entirely. The
>>>>>>>>>>>>>> proposal is to
>>>>>>>>>>>>>> detach the transient from the non-transient part. We would have
>>>>>>>>>>>>>> two
>>>>>>>>>>>>>> separate
>>>>>>>>>>>>>> objects.
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> The non-transient object is always consistent, can be shared
>>>>>>>>>>>>>> across
>>>>>>>>>>>>>> threads
>>>>>>>>>>>>>> and is cached. Changes are directly written to the repository.
>>>>>>>>>>>>>> This
>>>>>>>>>>>>>> object
>>>>>>>>>>>>>> would have an updateProperties(Map) method that immediately
>>>>>>>>>>>>>> refreshes the
>>>>>>>>>>>>>> object after the update.
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> The transient object is owned by one thread and not thread
>>>>>>>>>>>>>> safe.
>>>>>>>>>>>>>> That
>>>>>>>>>>>>>> should
>>>>>>>>>>>>>> prevent inconsistent views on the object. This object would
>>>>>>>>>>>>>> have
>>>>>>>>>>>>>> setProperty() and save() methods. Internally it would use the
>>>>>>>>>>>>>> non-transient
>>>>>>>>>>>>>> object to access all unchanged data. It's a wrapper around the
>>>>>>>>>>>>>> non-transient
>>>>>>>>>>>>>> object that holds the transient data.
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> So you still could use the pattern that you are using today.
>>>>>>>>>>>>>> The
>>>>>>>>>>>>>> only
>>>>>>>>>>>>>> difference would be that you have to create a transient wrapper
>>>>>>>>>>>>>> object.
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> That could look like this:
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> Document doc = (Document) session.getObject(id);
>>>>>>>>>>>>>> TransientDocument transDoc = new TransientDocument(doc);
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> transDoc.setProperty("prop1", "value1");
>>>>>>>>>>>>>> transDoc.setProperty("prop2", "value2");
>>>>>>>>>>>>>> transDoc.save(); // that also refreshes the underlying
>>>>>>>>>>>>>> non-transient
>>>>>>>>>>>>>> object
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> Or maybe we do something like this:
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> Document doc = (Document) session.getObject(id);
>>>>>>>>>>>>>> TransientDocument transDoc = doc.createTransientDocument():
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> transDoc.setProperty("prop1", "value1");
>>>>>>>>>>>>>> transDoc.setProperty("prop2", "value2");
>>>>>>>>>>>>>> transDoc.save();
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> Florian
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> On 18/10/2010 16:07, Florent Guillaume wrote:
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> Hi,
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> In Nuxeo the OpenCMIS client API is made available locally as
>>>>>>>>>>>>>>> another
>>>>>>>>>>>>>>> API to manipulate documents, in addition to the Nuxeo native
>>>>>>>>>>>>>>> APIs.
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> I have a problem with removing CmisObject.updateProperties()
>>>>>>>>>>>>>>> and
>>>>>>>>>>>>>>> the
>>>>>>>>>>>>>>> mini transient space because for me it's quite useful. The
>>>>>>>>>>>>>>> Nuxeo
>>>>>>>>>>>>>>> internal non-CMIS session has a notion of a property-only
>>>>>>>>>>>>>>> transient
>>>>>>>>>>>>>>> space, so in Nuxeo you update several properties and do some
>>>>>>>>>>>>>>> kind of
>>>>>>>>>>>>>>> object save() to flush them. Without a similar flushing
>>>>>>>>>>>>>>> concept
>>>>>>>>>>>>>>> on the
>>>>>>>>>>>>>>> OpenCMIS client API, I'm obliged to make a flush on every
>>>>>>>>>>>>>>> property
>>>>>>>>>>>>>>> write, which leads to severely degraded performance.
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> If all method calls on a CmisObject immediately write
>>>>>>>>>>>>>>> everything
>>>>>>>>>>>>>>> through the network and potentially refetch a full object
>>>>>>>>>>>>>>> there
>>>>>>>>>>>>>>> will
>>>>>>>>>>>>>>> be many people that aren't happy with CMIS performance once
>>>>>>>>>>>>>>> they
>>>>>>>>>>>>>>> get
>>>>>>>>>>>>>>> to use OpenCMIS. The client API is supposed to provide some
>>>>>>>>>>>>>>> convenience to the user, and having a mini transient space for
>>>>>>>>>>>>>>> properties is IMHO the very first step of convenience. There
>>>>>>>>>>>>>>> may
>>>>>>>>>>>>>>> be
>>>>>>>>>>>>>>> problems with the semantics of interactions between this
>>>>>>>>>>>>>>> transient
>>>>>>>>>>>>>>> space and caching / refetches, but let's solve them rather
>>>>>>>>>>>>>>> than
>>>>>>>>>>>>>>> remove
>>>>>>>>>>>>>>> them.
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> Dave wrote:
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> For example, with a transient space, what is the behaviour
>>>>>>>>>>>>>>>> when
>>>>>>>>>>>>>>>> setProperty has been called and an "update" method is then
>>>>>>>>>>>>>>>> called prior
>>>>>>>>>>>>>>>> to
>>>>>>>>>>>>>>>> updateProperties. Are the transient changes discarded,
>>>>>>>>>>>>>>>> flushed,
>>>>>>>>>>>>>>>> or just
>>>>>>>>>>>>>>>> left
>>>>>>>>>>>>>>>> as is?
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> So if I understand correctly you're talking about the case:
>>>>>>>>>>>>>>> 1. doc.setPropertyValue("foo", ...);
>>>>>>>>>>>>>>> 2. doc.updateProperties(map);
>>>>>>>>>>>>>>> 3. doc.setPropertyValue("bar", ...);
>>>>>>>>>>>>>>> 4. doc.updateProperties();
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> And you're asking if the "foo" change is sent with 2. or with
>>>>>>>>>>>>>>> 4.
>>>>>>>>>>>>>>> or
>>>>>>>>>>>>>>> discarded? I'd say let's keep this undefined, as I feel that
>>>>>>>>>>>>>>> it's a
>>>>>>>>>>>>>>> use pattern that's not natural. If we really want to specify
>>>>>>>>>>>>>>> this then
>>>>>>>>>>>>>>> I have no problem mandating that the "foo" change should be
>>>>>>>>>>>>>>> sent
>>>>>>>>>>>>>>> with
>>>>>>>>>>>>>>> 2. by saying that updateProperties(map) is the same as
>>>>>>>>>>>>>>> setPropertyValue() on all the properties of the map then
>>>>>>>>>>>>>>> calling
>>>>>>>>>>>>>>> updateProperties() with the transient map.
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> Florent
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> On Mon, Oct 18, 2010 at 4:05 PM, Klevenz, Stephan
>>>>>>>>>>>>>>> <st...@sap.com> wrote:
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> Hi,
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> Coming back to the cache discussion. I would like to support
>>>>>>>>>>>>>>>> this
>>>>>>>>>>>>>>>> proposal by Dave/Florian and think we can also delete Methods
>>>>>>>>>>>>>>>> on
>>>>>>>>>>>>>>>> Session
>>>>>>>>>>>>>>>> class like cancel() and save() which are currently not
>>>>>>>>>>>>>>>> implemented.
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> +1 for this:
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> - All write operations provided by CmisObject should
>>>>>>>>>>>>>>>>> automatically do
>>>>>>>>>>>>>>>>> an
>>>>>>>>>>>>>>>>> object
>>>>>>>>>>>>>>>>> refresh after the update. That guarantees that the object is
>>>>>>>>>>>>>>>>> always
>>>>>>>>>>>>>>>>> consistent.
>>>>>>>>>>>>>>>>> The cost for this consistency is an additional call to the
>>>>>>>>>>>>>>>>> repository.
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>> - Is some cases you don't need or want this addition cost.
>>>>>>>>>>>>>>>>> Lets say
>>>>>>>>>>>>>>>>> you
>>>>>>>>>>>>>>>>> just
>>>>>>>>>>>>>>>>> want to update a bunch of objects but you don't work with
>>>>>>>>>>>>>>>>> them
>>>>>>>>>>>>>>>>> afterwards.
>>>>>>>>>>>>>>>>> That's what the operations provided by Session are good for.
>>>>>>>>>>>>>>>>> They just
>>>>>>>>>>>>>>>>> do
>>>>>>>>>>>>>>>>> that and nothing else.
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> About the transient support we can design this as an optional
>>>>>>>>>>>>>>>> add on
>>>>>>>>>>>>>>>> with
>>>>>>>>>>>>>>>> additional interfaces and additional implementations. With a
>>>>>>>>>>>>>>>> clear
>>>>>>>>>>>>>>>> separation the API become easier to use.
>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> Regards,
>>>>>>>>>>>>>>>> Stephan
>>>>>>
>>>>>
>>>>>
>>>>>
>>>>
>>>>
>>>
>>>
>>>
>>
>>
>
>
>
Re: Proposal to clarify CmisObject caching behaviour
Posted by Florent Guillaume <fg...@nuxeo.com>.
Could you do it in a branch for a few days?
I have a fix to do for the AtomPub bindings (they generate bad atom
alternate links for renditions), and I'll need it for the Nuxeo server
bindings shortly. I'd rather not change the updateProperties / save
that I may be using right now in our connector's code. In a 1-2 days
I'll commit and make a private snapshot and we can merge your branch.
Is that ok?
Florent
On Wed, Nov 10, 2010 at 8:35 PM, Florian Müller
<fl...@alfresco.com> wrote:
> Got it. Thanks.
>
> Would somebody object if I would start the refactoring?
> If we don't like it, we can roll it back.
>
> I would also remove the "persistent" and "transient" notion from the session
> implementation including renaming those classes.
>
>
> - Florian
>
>
>
> On 10/11/2010 17:43, Florent Guillaume wrote:
>>
>> It would be an interface.
>>
>> I agree that it's not obvious in this case that transient behavior can
>> be obtained using an adapter (and autocompletion doc.get... does not
>> immediately provide it). But this can be solved by simple
>> documentation I think. Yes if we think transient documents are
>> fundamental we can make createTransientDocument a synonym to get this
>> adapter. It's not mandatory though.
>>
>> Florent
>>
>> On Wed, Nov 10, 2010 at 3:16 PM, Florian Müller
>> <fl...@alfresco.com> wrote:
>>>
>>> Hi Florent,
>>>
>>> Could you elaborate a bit more on that proposal?
>>> Would TransientDocument.class be an Interface or a Class?
>>>
>>> I like the idea of adapters. But it is not intuitive that there is an
>>> adapter the provides a transient paradigm. Would it make sense to add
>>> another method that provides a shortcut to the "transient adapter"?
>>>
>>>
>>> Thanks,
>>>
>>> Florian
>>>
>>>
>>> On 10/11/2010 13:27, Florent Guillaume wrote:
>>>>
>>>> I've come around to agreeing that 2. is probably better.
>>>>
>>>> I can see either:
>>>> TransientDocument transDoc = doc.createTransientDocument():
>>>> or
>>>> TransientDocument transDoc = doc.getAdapter(TransientDocument.class);
>>>>
>>>> The latter is more extensible for other uses besides transience
>>>> (protocol extensions, application-specific adapters).
>>>>
>>>> WDYT?
>>>>
>>>> Florent
>>>>
>>>>
>>>> On Wed, Nov 10, 2010 at 10:41 AM, Florian Müller
>>>> <fl...@alfresco.com> wrote:
>>>>>
>>>>> I would like to see that sorted out soon. There are more and more users
>>>>> of OpenCMIS and API changes are usually painful for them. We should
>>>>> also
>>>>> consider a new release (0.2.0) when this is done.
>>>>>
>>>>> So, where are we?
>>>>>
>>>>> The main question is where we want to handle transient data. We have
>>>>> two
>>>>> opinions:
>>>>> 1. Transient and non-transient data access should be covered by the
>>>>> CmisObject interface. (Florent)
>>>>> 2. Transient data access should be covered by a new interface and
>>>>> non-transient data access should be covered by the CmisObject
>>>>> interface.
>>>>> (Florian)
>>>>>
>>>>> Personally, I still want to go for option 2 since it provides cleaner
>>>>> semantics -- especially in multi-threaded environments.
>>>>>
>>>>> Other opinions?
>>>>>
>>>>>
>>>>> - Florian
>>>>>
>>>>>
>>>>> On 08/11/2010 11:51, David Caruana wrote:
>>>>>>
>>>>>> Have we reached a conclusion on this issue? It's been a while since we
>>>>>> last discussed.
>>>>>>
>>>>>> Regards,
>>>>>> Dave
>>>>>>
>>>>>> On 22 Oct 2010, at 15:06, Florian Müller wrote:
>>>>>>
>>>>>>> Oh, right, there is yet another option. :)
>>>>>>>
>>>>>>> I support all your arguments against b), c) and d). But there are
>>>>>>> also
>>>>>>> two issues with e).
>>>>>>> 1. Which value wins if a property is changed in the transient object
>>>>>>> _and_ present in the map?
>>>>>>> 2. save() stores the whole object. If we make ACLs and Policies
>>>>>>> transient too (do we want that?) than updateProperties() has the side
>>>>>>> effect
>>>>>>> of storing those as well.
>>>>>>>
>>>>>>> Which leaves us with a) which is pretty strong. And in this case I
>>>>>>> prefer two interfaces because it much is easier to understand and
>>>>>>> provides
>>>>>>> more compile checks and less runtime surprises.
>>>>>>>
>>>>>>>
>>>>>>> - Florian
>>>>>>>
>>>>>>>
>>>>>>> On 22/10/2010 14:44, Florent Guillaume wrote:
>>>>>>>>
>>>>>>>> On Fri, Oct 22, 2010 at 3:33 PM, Florian Müller
>>>>>>>> <fl...@alfresco.com> wrote:
>>>>>>>>>
>>>>>>>>> So your proposal is to add a method getTransientObject() (or
>>>>>>>>> something like that) to CmisObject. And that method would return a
>>>>>>>>> transient, not thread-safe version of the object but with
>>>>>>>>> setProperty(),
>>>>>>>>> save(), etc. enabled?
>>>>>>>>> Is that correct?
>>>>>>>>
>>>>>>>> Yes.
>>>>>>>>
>>>>>>>>> In this case we should also add a method isTransient() to
>>>>>>>>> CmisObject.
>>>>>>>>> There should be a way to discover the state of the CmisObject.
>>>>>>>>
>>>>>>>> Yes that would be useful.
>>>>>>>>
>>>>>>>>> I suggest that if the object is not transient, the transient
>>>>>>>>> methods
>>>>>>>>> should throw an IllegalStateException.
>>>>>>>>
>>>>>>>> Ok.
>>>>>>>>
>>>>>>>>> I agree that keeping the number of interfaces and classes low helps
>>>>>>>>> to learn and understand an API. But blending two semantics in one
>>>>>>>>> class
>>>>>>>>> could be even more confusing.
>>>>>>>>> For example, what should happen if updateProperties(Map) is called
>>>>>>>>> on
>>>>>>>>> a transient object? There are multiple options:
>>>>>>>>> a) updateProperties(Map) throws an exception because it only
>>>>>>>>> works
>>>>>>>>> for non-transient objects.
>>>>>>>>> b) updateProperties(Map) writes instantly to the repository and
>>>>>>>>> the transient object is refreshed.
>>>>>>>>
>>>>>>>> (which btw means that transient changes are lost)
>>>>>>>>>
>>>>>>>>> c) updateProperties(Map) writes instantly to the repository and
>>>>>>>>> but object keep its (now outdated) state.
>>>>>>>>> d) The property map is merged with the transient properties and
>>>>>>>>> written when save() is called.
>>>>>>>>
>>>>>>>> And also:
>>>>>>>> e) The property map is merged with the transient properties and then
>>>>>>>> save() is automatically called.
>>>>>>>>
>>>>>>>>> It is not obvious. All semantics would be right and wrong at the
>>>>>>>>> same
>>>>>>>>> time.
>>>>>>>>
>>>>>>>> Agreed, we have to make a choice. But we would make a similar choice
>>>>>>>> when deciding what methods would be available on the
>>>>>>>> TransientDocument
>>>>>>>> interface and what they would do.
>>>>>>>>
>>>>>>>> But anyway my choices in order of preference would be e) then a).
>>>>>>>> I don't like b) because it loses changes.
>>>>>>>> I don't like c) because there's an issue with not keeping the
>>>>>>>> changes
>>>>>>>> in order.
>>>>>>>> I don't like d) because if you didn't do any transient operation it
>>>>>>>> doesn't behave like its non-transient counterpart.
>>>>>>>>
>>>>>>>> Florent
>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> On 22/10/2010 13:43, Florent Guillaume wrote:
>>>>>>>>>>
>>>>>>>>>> Hi,
>>>>>>>>>>
>>>>>>>>>> Looking back at your example:
>>>>>>>>>>
>>>>>>>>>> Document doc = (Document) session.getObject(id);
>>>>>>>>>> TransientDocument transDoc = doc.createTransientDocument():
>>>>>>>>>> transDoc.setProperty("prop1", "value1");
>>>>>>>>>> transDoc.setProperty("prop2", "value2");
>>>>>>>>>> transDoc.save();
>>>>>>>>>>
>>>>>>>>>> I agree with the need to explicitly getting a transient object if
>>>>>>>>>> you
>>>>>>>>>> need different semantics.
>>>>>>>>>> One thing that will be painful though is having different classes:
>>>>>>>>>> TransientCmisObject, TransientDocument, TransientFolder, etc.
>>>>>>>>>> Couldn't we simply have all the methods available on the
>>>>>>>>>> CmisObject,
>>>>>>>>>> Document, Folder, etc. and make them throw
>>>>>>>>>> UnsupportedOperationException when called on a non-transient
>>>>>>>>>> object?
>>>>>>>>>> This would tremendously help learning about the API and avoid
>>>>>>>>>> juggling
>>>>>>>>>> with many different interfaces for the users.
>>>>>>>>>>
>>>>>>>>>> Florent
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> On Mon, Oct 18, 2010 at 10:43 PM, Florian Müller
>>>>>>>>>> <fl...@alfresco.com> wrote:
>>>>>>>>>>>
>>>>>>>>>>> Hi Florent,
>>>>>>>>>>>
>>>>>>>>>>> Well, no, there would be no CmisObject.save() method. The save()
>>>>>>>>>>> method
>>>>>>>>>>> would only be on the transient object.
>>>>>>>>>>>
>>>>>>>>>>> CmisObject would have updateProperties(Map), applyAcl(List<Ace>,
>>>>>>>>>>> List<Ace>,
>>>>>>>>>>> AclPropagation), applyPolicy(ObjectId), etc. And all of them
>>>>>>>>>>> would
>>>>>>>>>>> write
>>>>>>>>>>> instantly to the repository and refresh the object.
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>> Florian
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>> On 18/10/2010 17:49, Florent Guillaume wrote:
>>>>>>>>>>>>
>>>>>>>>>>>> Ok understood and agreed. There would be a new CmisObject.save()
>>>>>>>>>>>> to
>>>>>>>>>>>> replace updateProperties() then? That works for me as it's a
>>>>>>>>>>>> less
>>>>>>>>>>>> restrictive name that allows for different implementations of
>>>>>>>>>>>> the
>>>>>>>>>>>> transient space that don't deal with just properties.
>>>>>>>>>>>>
>>>>>>>>>>>> Regarding your examples I don't need to do all that, because in
>>>>>>>>>>>> the
>>>>>>>>>>>> Nuxeo use cases I described the client Session I'm providing to
>>>>>>>>>>>> the
>>>>>>>>>>>> user of the API is not a PersistentSessionImpl but a completely
>>>>>>>>>>>> new
>>>>>>>>>>>> Nuxeo class that does all the wrapping it needs around native
>>>>>>>>>>>> Nuxeo
>>>>>>>>>>>> objects. So I'm not constrained by the semantics of the current
>>>>>>>>>>>> PersistentSessionImpl. It's just that I need a save()-like API
>>>>>>>>>>>> to
>>>>>>>>>>>> exist on the CmisObject. And of course I want to have semantics
>>>>>>>>>>>> that
>>>>>>>>>>>> are not too far to what's available when you use an actual
>>>>>>>>>>>> remote
>>>>>>>>>>>> connection using pure OpenCMIS PersistentSessionImpl.
>>>>>>>>>>>>
>>>>>>>>>>>> Florent
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>> On Mon, Oct 18, 2010 at 6:06 PM, Florian Müller
>>>>>>>>>>>> <fl...@alfresco.com> wrote:
>>>>>>>>>>>>>
>>>>>>>>>>>>> Hi Florent,
>>>>>>>>>>>>>
>>>>>>>>>>>>> We don't want to remove the transient space entirely. The
>>>>>>>>>>>>> proposal is to
>>>>>>>>>>>>> detach the transient from the non-transient part. We would have
>>>>>>>>>>>>> two
>>>>>>>>>>>>> separate
>>>>>>>>>>>>> objects.
>>>>>>>>>>>>>
>>>>>>>>>>>>> The non-transient object is always consistent, can be shared
>>>>>>>>>>>>> across
>>>>>>>>>>>>> threads
>>>>>>>>>>>>> and is cached. Changes are directly written to the repository.
>>>>>>>>>>>>> This
>>>>>>>>>>>>> object
>>>>>>>>>>>>> would have an updateProperties(Map) method that immediately
>>>>>>>>>>>>> refreshes the
>>>>>>>>>>>>> object after the update.
>>>>>>>>>>>>>
>>>>>>>>>>>>> The transient object is owned by one thread and not thread
>>>>>>>>>>>>> safe.
>>>>>>>>>>>>> That
>>>>>>>>>>>>> should
>>>>>>>>>>>>> prevent inconsistent views on the object. This object would
>>>>>>>>>>>>> have
>>>>>>>>>>>>> setProperty() and save() methods. Internally it would use the
>>>>>>>>>>>>> non-transient
>>>>>>>>>>>>> object to access all unchanged data. It's a wrapper around the
>>>>>>>>>>>>> non-transient
>>>>>>>>>>>>> object that holds the transient data.
>>>>>>>>>>>>>
>>>>>>>>>>>>> So you still could use the pattern that you are using today.
>>>>>>>>>>>>> The
>>>>>>>>>>>>> only
>>>>>>>>>>>>> difference would be that you have to create a transient wrapper
>>>>>>>>>>>>> object.
>>>>>>>>>>>>>
>>>>>>>>>>>>>
>>>>>>>>>>>>> That could look like this:
>>>>>>>>>>>>>
>>>>>>>>>>>>> Document doc = (Document) session.getObject(id);
>>>>>>>>>>>>> TransientDocument transDoc = new TransientDocument(doc);
>>>>>>>>>>>>>
>>>>>>>>>>>>> transDoc.setProperty("prop1", "value1");
>>>>>>>>>>>>> transDoc.setProperty("prop2", "value2");
>>>>>>>>>>>>> transDoc.save(); // that also refreshes the underlying
>>>>>>>>>>>>> non-transient
>>>>>>>>>>>>> object
>>>>>>>>>>>>>
>>>>>>>>>>>>>
>>>>>>>>>>>>> Or maybe we do something like this:
>>>>>>>>>>>>>
>>>>>>>>>>>>> Document doc = (Document) session.getObject(id);
>>>>>>>>>>>>> TransientDocument transDoc = doc.createTransientDocument():
>>>>>>>>>>>>>
>>>>>>>>>>>>> transDoc.setProperty("prop1", "value1");
>>>>>>>>>>>>> transDoc.setProperty("prop2", "value2");
>>>>>>>>>>>>> transDoc.save();
>>>>>>>>>>>>>
>>>>>>>>>>>>>
>>>>>>>>>>>>> Florian
>>>>>>>>>>>>>
>>>>>>>>>>>>>
>>>>>>>>>>>>>
>>>>>>>>>>>>>
>>>>>>>>>>>>> On 18/10/2010 16:07, Florent Guillaume wrote:
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> Hi,
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> In Nuxeo the OpenCMIS client API is made available locally as
>>>>>>>>>>>>>> another
>>>>>>>>>>>>>> API to manipulate documents, in addition to the Nuxeo native
>>>>>>>>>>>>>> APIs.
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> I have a problem with removing CmisObject.updateProperties()
>>>>>>>>>>>>>> and
>>>>>>>>>>>>>> the
>>>>>>>>>>>>>> mini transient space because for me it's quite useful. The
>>>>>>>>>>>>>> Nuxeo
>>>>>>>>>>>>>> internal non-CMIS session has a notion of a property-only
>>>>>>>>>>>>>> transient
>>>>>>>>>>>>>> space, so in Nuxeo you update several properties and do some
>>>>>>>>>>>>>> kind of
>>>>>>>>>>>>>> object save() to flush them. Without a similar flushing
>>>>>>>>>>>>>> concept
>>>>>>>>>>>>>> on the
>>>>>>>>>>>>>> OpenCMIS client API, I'm obliged to make a flush on every
>>>>>>>>>>>>>> property
>>>>>>>>>>>>>> write, which leads to severely degraded performance.
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> If all method calls on a CmisObject immediately write
>>>>>>>>>>>>>> everything
>>>>>>>>>>>>>> through the network and potentially refetch a full object
>>>>>>>>>>>>>> there
>>>>>>>>>>>>>> will
>>>>>>>>>>>>>> be many people that aren't happy with CMIS performance once
>>>>>>>>>>>>>> they
>>>>>>>>>>>>>> get
>>>>>>>>>>>>>> to use OpenCMIS. The client API is supposed to provide some
>>>>>>>>>>>>>> convenience to the user, and having a mini transient space for
>>>>>>>>>>>>>> properties is IMHO the very first step of convenience. There
>>>>>>>>>>>>>> may
>>>>>>>>>>>>>> be
>>>>>>>>>>>>>> problems with the semantics of interactions between this
>>>>>>>>>>>>>> transient
>>>>>>>>>>>>>> space and caching / refetches, but let's solve them rather
>>>>>>>>>>>>>> than
>>>>>>>>>>>>>> remove
>>>>>>>>>>>>>> them.
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> Dave wrote:
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> For example, with a transient space, what is the behaviour
>>>>>>>>>>>>>>> when
>>>>>>>>>>>>>>> setProperty has been called and an "update" method is then
>>>>>>>>>>>>>>> called prior
>>>>>>>>>>>>>>> to
>>>>>>>>>>>>>>> updateProperties. Are the transient changes discarded,
>>>>>>>>>>>>>>> flushed,
>>>>>>>>>>>>>>> or just
>>>>>>>>>>>>>>> left
>>>>>>>>>>>>>>> as is?
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> So if I understand correctly you're talking about the case:
>>>>>>>>>>>>>> 1. doc.setPropertyValue("foo", ...);
>>>>>>>>>>>>>> 2. doc.updateProperties(map);
>>>>>>>>>>>>>> 3. doc.setPropertyValue("bar", ...);
>>>>>>>>>>>>>> 4. doc.updateProperties();
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> And you're asking if the "foo" change is sent with 2. or with
>>>>>>>>>>>>>> 4.
>>>>>>>>>>>>>> or
>>>>>>>>>>>>>> discarded? I'd say let's keep this undefined, as I feel that
>>>>>>>>>>>>>> it's a
>>>>>>>>>>>>>> use pattern that's not natural. If we really want to specify
>>>>>>>>>>>>>> this then
>>>>>>>>>>>>>> I have no problem mandating that the "foo" change should be
>>>>>>>>>>>>>> sent
>>>>>>>>>>>>>> with
>>>>>>>>>>>>>> 2. by saying that updateProperties(map) is the same as
>>>>>>>>>>>>>> setPropertyValue() on all the properties of the map then
>>>>>>>>>>>>>> calling
>>>>>>>>>>>>>> updateProperties() with the transient map.
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> Florent
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> On Mon, Oct 18, 2010 at 4:05 PM, Klevenz, Stephan
>>>>>>>>>>>>>> <st...@sap.com> wrote:
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> Hi,
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> Coming back to the cache discussion. I would like to support
>>>>>>>>>>>>>>> this
>>>>>>>>>>>>>>> proposal by Dave/Florian and think we can also delete Methods
>>>>>>>>>>>>>>> on
>>>>>>>>>>>>>>> Session
>>>>>>>>>>>>>>> class like cancel() and save() which are currently not
>>>>>>>>>>>>>>> implemented.
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> +1 for this:
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> - All write operations provided by CmisObject should
>>>>>>>>>>>>>>>> automatically do
>>>>>>>>>>>>>>>> an
>>>>>>>>>>>>>>>> object
>>>>>>>>>>>>>>>> refresh after the update. That guarantees that the object is
>>>>>>>>>>>>>>>> always
>>>>>>>>>>>>>>>> consistent.
>>>>>>>>>>>>>>>> The cost for this consistency is an additional call to the
>>>>>>>>>>>>>>>> repository.
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>> - Is some cases you don't need or want this addition cost.
>>>>>>>>>>>>>>>> Lets say
>>>>>>>>>>>>>>>> you
>>>>>>>>>>>>>>>> just
>>>>>>>>>>>>>>>> want to update a bunch of objects but you don't work with
>>>>>>>>>>>>>>>> them
>>>>>>>>>>>>>>>> afterwards.
>>>>>>>>>>>>>>>> That's what the operations provided by Session are good for.
>>>>>>>>>>>>>>>> They just
>>>>>>>>>>>>>>>> do
>>>>>>>>>>>>>>>> that and nothing else.
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> About the transient support we can design this as an optional
>>>>>>>>>>>>>>> add on
>>>>>>>>>>>>>>> with
>>>>>>>>>>>>>>> additional interfaces and additional implementations. With a
>>>>>>>>>>>>>>> clear
>>>>>>>>>>>>>>> separation the API become easier to use.
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> Regards,
>>>>>>>>>>>>>>> Stephan
>>>>>
>>>>
>>>>
>>>>
>>>
>>>
>>
>>
>>
>
>
--
Florent Guillaume, Director of R&D, Nuxeo
Open Source, Java EE based, Enterprise Content Management (ECM)
http://www.nuxeo.com http://www.nuxeo.org +33 1 40 33 79 87
Re: Proposal to clarify CmisObject caching behaviour
Posted by Florian Müller <fl...@alfresco.com>.
Got it. Thanks.
Would somebody object if I would start the refactoring?
If we don't like it, we can roll it back.
I would also remove the "persistent" and "transient" notion from the
session implementation including renaming those classes.
- Florian
On 10/11/2010 17:43, Florent Guillaume wrote:
> It would be an interface.
>
> I agree that it's not obvious in this case that transient behavior can
> be obtained using an adapter (and autocompletion doc.get... does not
> immediately provide it). But this can be solved by simple
> documentation I think. Yes if we think transient documents are
> fundamental we can make createTransientDocument a synonym to get this
> adapter. It's not mandatory though.
>
> Florent
>
> On Wed, Nov 10, 2010 at 3:16 PM, Florian Müller
> <fl...@alfresco.com> wrote:
>> Hi Florent,
>>
>> Could you elaborate a bit more on that proposal?
>> Would TransientDocument.class be an Interface or a Class?
>>
>> I like the idea of adapters. But it is not intuitive that there is an
>> adapter the provides a transient paradigm. Would it make sense to add
>> another method that provides a shortcut to the "transient adapter"?
>>
>>
>> Thanks,
>>
>> Florian
>>
>>
>> On 10/11/2010 13:27, Florent Guillaume wrote:
>>>
>>> I've come around to agreeing that 2. is probably better.
>>>
>>> I can see either:
>>> TransientDocument transDoc = doc.createTransientDocument():
>>> or
>>> TransientDocument transDoc = doc.getAdapter(TransientDocument.class);
>>>
>>> The latter is more extensible for other uses besides transience
>>> (protocol extensions, application-specific adapters).
>>>
>>> WDYT?
>>>
>>> Florent
>>>
>>>
>>> On Wed, Nov 10, 2010 at 10:41 AM, Florian Müller
>>> <fl...@alfresco.com> wrote:
>>>>
>>>> I would like to see that sorted out soon. There are more and more users
>>>> of OpenCMIS and API changes are usually painful for them. We should also
>>>> consider a new release (0.2.0) when this is done.
>>>>
>>>> So, where are we?
>>>>
>>>> The main question is where we want to handle transient data. We have two
>>>> opinions:
>>>> 1. Transient and non-transient data access should be covered by the
>>>> CmisObject interface. (Florent)
>>>> 2. Transient data access should be covered by a new interface and
>>>> non-transient data access should be covered by the CmisObject interface.
>>>> (Florian)
>>>>
>>>> Personally, I still want to go for option 2 since it provides cleaner
>>>> semantics -- especially in multi-threaded environments.
>>>>
>>>> Other opinions?
>>>>
>>>>
>>>> - Florian
>>>>
>>>>
>>>> On 08/11/2010 11:51, David Caruana wrote:
>>>>>
>>>>> Have we reached a conclusion on this issue? It's been a while since we
>>>>> last discussed.
>>>>>
>>>>> Regards,
>>>>> Dave
>>>>>
>>>>> On 22 Oct 2010, at 15:06, Florian Müller wrote:
>>>>>
>>>>>> Oh, right, there is yet another option. :)
>>>>>>
>>>>>> I support all your arguments against b), c) and d). But there are also
>>>>>> two issues with e).
>>>>>> 1. Which value wins if a property is changed in the transient object
>>>>>> _and_ present in the map?
>>>>>> 2. save() stores the whole object. If we make ACLs and Policies
>>>>>> transient too (do we want that?) than updateProperties() has the side effect
>>>>>> of storing those as well.
>>>>>>
>>>>>> Which leaves us with a) which is pretty strong. And in this case I
>>>>>> prefer two interfaces because it much is easier to understand and provides
>>>>>> more compile checks and less runtime surprises.
>>>>>>
>>>>>>
>>>>>> - Florian
>>>>>>
>>>>>>
>>>>>> On 22/10/2010 14:44, Florent Guillaume wrote:
>>>>>>>
>>>>>>> On Fri, Oct 22, 2010 at 3:33 PM, Florian Müller
>>>>>>> <fl...@alfresco.com> wrote:
>>>>>>>>
>>>>>>>> So your proposal is to add a method getTransientObject() (or
>>>>>>>> something like that) to CmisObject. And that method would return a
>>>>>>>> transient, not thread-safe version of the object but with setProperty(),
>>>>>>>> save(), etc. enabled?
>>>>>>>> Is that correct?
>>>>>>>
>>>>>>> Yes.
>>>>>>>
>>>>>>>> In this case we should also add a method isTransient() to CmisObject.
>>>>>>>> There should be a way to discover the state of the CmisObject.
>>>>>>>
>>>>>>> Yes that would be useful.
>>>>>>>
>>>>>>>> I suggest that if the object is not transient, the transient methods
>>>>>>>> should throw an IllegalStateException.
>>>>>>>
>>>>>>> Ok.
>>>>>>>
>>>>>>>> I agree that keeping the number of interfaces and classes low helps
>>>>>>>> to learn and understand an API. But blending two semantics in one class
>>>>>>>> could be even more confusing.
>>>>>>>> For example, what should happen if updateProperties(Map) is called on
>>>>>>>> a transient object? There are multiple options:
>>>>>>>> a) updateProperties(Map) throws an exception because it only works
>>>>>>>> for non-transient objects.
>>>>>>>> b) updateProperties(Map) writes instantly to the repository and
>>>>>>>> the transient object is refreshed.
>>>>>>>
>>>>>>> (which btw means that transient changes are lost)
>>>>>>>>
>>>>>>>> c) updateProperties(Map) writes instantly to the repository and
>>>>>>>> but object keep its (now outdated) state.
>>>>>>>> d) The property map is merged with the transient properties and
>>>>>>>> written when save() is called.
>>>>>>>
>>>>>>> And also:
>>>>>>> e) The property map is merged with the transient properties and then
>>>>>>> save() is automatically called.
>>>>>>>
>>>>>>>> It is not obvious. All semantics would be right and wrong at the same
>>>>>>>> time.
>>>>>>>
>>>>>>> Agreed, we have to make a choice. But we would make a similar choice
>>>>>>> when deciding what methods would be available on the TransientDocument
>>>>>>> interface and what they would do.
>>>>>>>
>>>>>>> But anyway my choices in order of preference would be e) then a).
>>>>>>> I don't like b) because it loses changes.
>>>>>>> I don't like c) because there's an issue with not keeping the changes
>>>>>>> in order.
>>>>>>> I don't like d) because if you didn't do any transient operation it
>>>>>>> doesn't behave like its non-transient counterpart.
>>>>>>>
>>>>>>> Florent
>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>> On 22/10/2010 13:43, Florent Guillaume wrote:
>>>>>>>>>
>>>>>>>>> Hi,
>>>>>>>>>
>>>>>>>>> Looking back at your example:
>>>>>>>>>
>>>>>>>>> Document doc = (Document) session.getObject(id);
>>>>>>>>> TransientDocument transDoc = doc.createTransientDocument():
>>>>>>>>> transDoc.setProperty("prop1", "value1");
>>>>>>>>> transDoc.setProperty("prop2", "value2");
>>>>>>>>> transDoc.save();
>>>>>>>>>
>>>>>>>>> I agree with the need to explicitly getting a transient object if
>>>>>>>>> you
>>>>>>>>> need different semantics.
>>>>>>>>> One thing that will be painful though is having different classes:
>>>>>>>>> TransientCmisObject, TransientDocument, TransientFolder, etc.
>>>>>>>>> Couldn't we simply have all the methods available on the CmisObject,
>>>>>>>>> Document, Folder, etc. and make them throw
>>>>>>>>> UnsupportedOperationException when called on a non-transient object?
>>>>>>>>> This would tremendously help learning about the API and avoid
>>>>>>>>> juggling
>>>>>>>>> with many different interfaces for the users.
>>>>>>>>>
>>>>>>>>> Florent
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> On Mon, Oct 18, 2010 at 10:43 PM, Florian Müller
>>>>>>>>> <fl...@alfresco.com> wrote:
>>>>>>>>>>
>>>>>>>>>> Hi Florent,
>>>>>>>>>>
>>>>>>>>>> Well, no, there would be no CmisObject.save() method. The save()
>>>>>>>>>> method
>>>>>>>>>> would only be on the transient object.
>>>>>>>>>>
>>>>>>>>>> CmisObject would have updateProperties(Map), applyAcl(List<Ace>,
>>>>>>>>>> List<Ace>,
>>>>>>>>>> AclPropagation), applyPolicy(ObjectId), etc. And all of them would
>>>>>>>>>> write
>>>>>>>>>> instantly to the repository and refresh the object.
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> Florian
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> On 18/10/2010 17:49, Florent Guillaume wrote:
>>>>>>>>>>>
>>>>>>>>>>> Ok understood and agreed. There would be a new CmisObject.save()
>>>>>>>>>>> to
>>>>>>>>>>> replace updateProperties() then? That works for me as it's a less
>>>>>>>>>>> restrictive name that allows for different implementations of the
>>>>>>>>>>> transient space that don't deal with just properties.
>>>>>>>>>>>
>>>>>>>>>>> Regarding your examples I don't need to do all that, because in
>>>>>>>>>>> the
>>>>>>>>>>> Nuxeo use cases I described the client Session I'm providing to
>>>>>>>>>>> the
>>>>>>>>>>> user of the API is not a PersistentSessionImpl but a completely
>>>>>>>>>>> new
>>>>>>>>>>> Nuxeo class that does all the wrapping it needs around native
>>>>>>>>>>> Nuxeo
>>>>>>>>>>> objects. So I'm not constrained by the semantics of the current
>>>>>>>>>>> PersistentSessionImpl. It's just that I need a save()-like API to
>>>>>>>>>>> exist on the CmisObject. And of course I want to have semantics
>>>>>>>>>>> that
>>>>>>>>>>> are not too far to what's available when you use an actual remote
>>>>>>>>>>> connection using pure OpenCMIS PersistentSessionImpl.
>>>>>>>>>>>
>>>>>>>>>>> Florent
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>> On Mon, Oct 18, 2010 at 6:06 PM, Florian Müller
>>>>>>>>>>> <fl...@alfresco.com> wrote:
>>>>>>>>>>>>
>>>>>>>>>>>> Hi Florent,
>>>>>>>>>>>>
>>>>>>>>>>>> We don't want to remove the transient space entirely. The
>>>>>>>>>>>> proposal is to
>>>>>>>>>>>> detach the transient from the non-transient part. We would have
>>>>>>>>>>>> two
>>>>>>>>>>>> separate
>>>>>>>>>>>> objects.
>>>>>>>>>>>>
>>>>>>>>>>>> The non-transient object is always consistent, can be shared
>>>>>>>>>>>> across
>>>>>>>>>>>> threads
>>>>>>>>>>>> and is cached. Changes are directly written to the repository.
>>>>>>>>>>>> This
>>>>>>>>>>>> object
>>>>>>>>>>>> would have an updateProperties(Map) method that immediately
>>>>>>>>>>>> refreshes the
>>>>>>>>>>>> object after the update.
>>>>>>>>>>>>
>>>>>>>>>>>> The transient object is owned by one thread and not thread safe.
>>>>>>>>>>>> That
>>>>>>>>>>>> should
>>>>>>>>>>>> prevent inconsistent views on the object. This object would have
>>>>>>>>>>>> setProperty() and save() methods. Internally it would use the
>>>>>>>>>>>> non-transient
>>>>>>>>>>>> object to access all unchanged data. It's a wrapper around the
>>>>>>>>>>>> non-transient
>>>>>>>>>>>> object that holds the transient data.
>>>>>>>>>>>>
>>>>>>>>>>>> So you still could use the pattern that you are using today. The
>>>>>>>>>>>> only
>>>>>>>>>>>> difference would be that you have to create a transient wrapper
>>>>>>>>>>>> object.
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>> That could look like this:
>>>>>>>>>>>>
>>>>>>>>>>>> Document doc = (Document) session.getObject(id);
>>>>>>>>>>>> TransientDocument transDoc = new TransientDocument(doc);
>>>>>>>>>>>>
>>>>>>>>>>>> transDoc.setProperty("prop1", "value1");
>>>>>>>>>>>> transDoc.setProperty("prop2", "value2");
>>>>>>>>>>>> transDoc.save(); // that also refreshes the underlying
>>>>>>>>>>>> non-transient
>>>>>>>>>>>> object
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>> Or maybe we do something like this:
>>>>>>>>>>>>
>>>>>>>>>>>> Document doc = (Document) session.getObject(id);
>>>>>>>>>>>> TransientDocument transDoc = doc.createTransientDocument():
>>>>>>>>>>>>
>>>>>>>>>>>> transDoc.setProperty("prop1", "value1");
>>>>>>>>>>>> transDoc.setProperty("prop2", "value2");
>>>>>>>>>>>> transDoc.save();
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>> Florian
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>> On 18/10/2010 16:07, Florent Guillaume wrote:
>>>>>>>>>>>>>
>>>>>>>>>>>>> Hi,
>>>>>>>>>>>>>
>>>>>>>>>>>>> In Nuxeo the OpenCMIS client API is made available locally as
>>>>>>>>>>>>> another
>>>>>>>>>>>>> API to manipulate documents, in addition to the Nuxeo native
>>>>>>>>>>>>> APIs.
>>>>>>>>>>>>>
>>>>>>>>>>>>> I have a problem with removing CmisObject.updateProperties() and
>>>>>>>>>>>>> the
>>>>>>>>>>>>> mini transient space because for me it's quite useful. The Nuxeo
>>>>>>>>>>>>> internal non-CMIS session has a notion of a property-only
>>>>>>>>>>>>> transient
>>>>>>>>>>>>> space, so in Nuxeo you update several properties and do some
>>>>>>>>>>>>> kind of
>>>>>>>>>>>>> object save() to flush them. Without a similar flushing concept
>>>>>>>>>>>>> on the
>>>>>>>>>>>>> OpenCMIS client API, I'm obliged to make a flush on every
>>>>>>>>>>>>> property
>>>>>>>>>>>>> write, which leads to severely degraded performance.
>>>>>>>>>>>>>
>>>>>>>>>>>>> If all method calls on a CmisObject immediately write everything
>>>>>>>>>>>>> through the network and potentially refetch a full object there
>>>>>>>>>>>>> will
>>>>>>>>>>>>> be many people that aren't happy with CMIS performance once they
>>>>>>>>>>>>> get
>>>>>>>>>>>>> to use OpenCMIS. The client API is supposed to provide some
>>>>>>>>>>>>> convenience to the user, and having a mini transient space for
>>>>>>>>>>>>> properties is IMHO the very first step of convenience. There may
>>>>>>>>>>>>> be
>>>>>>>>>>>>> problems with the semantics of interactions between this
>>>>>>>>>>>>> transient
>>>>>>>>>>>>> space and caching / refetches, but let's solve them rather than
>>>>>>>>>>>>> remove
>>>>>>>>>>>>> them.
>>>>>>>>>>>>>
>>>>>>>>>>>>> Dave wrote:
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> For example, with a transient space, what is the behaviour when
>>>>>>>>>>>>>> setProperty has been called and an "update" method is then
>>>>>>>>>>>>>> called prior
>>>>>>>>>>>>>> to
>>>>>>>>>>>>>> updateProperties. Are the transient changes discarded, flushed,
>>>>>>>>>>>>>> or just
>>>>>>>>>>>>>> left
>>>>>>>>>>>>>> as is?
>>>>>>>>>>>>>
>>>>>>>>>>>>> So if I understand correctly you're talking about the case:
>>>>>>>>>>>>> 1. doc.setPropertyValue("foo", ...);
>>>>>>>>>>>>> 2. doc.updateProperties(map);
>>>>>>>>>>>>> 3. doc.setPropertyValue("bar", ...);
>>>>>>>>>>>>> 4. doc.updateProperties();
>>>>>>>>>>>>>
>>>>>>>>>>>>> And you're asking if the "foo" change is sent with 2. or with 4.
>>>>>>>>>>>>> or
>>>>>>>>>>>>> discarded? I'd say let's keep this undefined, as I feel that
>>>>>>>>>>>>> it's a
>>>>>>>>>>>>> use pattern that's not natural. If we really want to specify
>>>>>>>>>>>>> this then
>>>>>>>>>>>>> I have no problem mandating that the "foo" change should be sent
>>>>>>>>>>>>> with
>>>>>>>>>>>>> 2. by saying that updateProperties(map) is the same as
>>>>>>>>>>>>> setPropertyValue() on all the properties of the map then calling
>>>>>>>>>>>>> updateProperties() with the transient map.
>>>>>>>>>>>>>
>>>>>>>>>>>>> Florent
>>>>>>>>>>>>>
>>>>>>>>>>>>>
>>>>>>>>>>>>>
>>>>>>>>>>>>> On Mon, Oct 18, 2010 at 4:05 PM, Klevenz, Stephan
>>>>>>>>>>>>> <st...@sap.com> wrote:
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> Hi,
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> Coming back to the cache discussion. I would like to support
>>>>>>>>>>>>>> this
>>>>>>>>>>>>>> proposal by Dave/Florian and think we can also delete Methods
>>>>>>>>>>>>>> on
>>>>>>>>>>>>>> Session
>>>>>>>>>>>>>> class like cancel() and save() which are currently not
>>>>>>>>>>>>>> implemented.
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> +1 for this:
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> - All write operations provided by CmisObject should
>>>>>>>>>>>>>>> automatically do
>>>>>>>>>>>>>>> an
>>>>>>>>>>>>>>> object
>>>>>>>>>>>>>>> refresh after the update. That guarantees that the object is
>>>>>>>>>>>>>>> always
>>>>>>>>>>>>>>> consistent.
>>>>>>>>>>>>>>> The cost for this consistency is an additional call to the
>>>>>>>>>>>>>>> repository.
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> - Is some cases you don't need or want this addition cost.
>>>>>>>>>>>>>>> Lets say
>>>>>>>>>>>>>>> you
>>>>>>>>>>>>>>> just
>>>>>>>>>>>>>>> want to update a bunch of objects but you don't work with them
>>>>>>>>>>>>>>> afterwards.
>>>>>>>>>>>>>>> That's what the operations provided by Session are good for.
>>>>>>>>>>>>>>> They just
>>>>>>>>>>>>>>> do
>>>>>>>>>>>>>>> that and nothing else.
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> About the transient support we can design this as an optional
>>>>>>>>>>>>>> add on
>>>>>>>>>>>>>> with
>>>>>>>>>>>>>> additional interfaces and additional implementations. With a
>>>>>>>>>>>>>> clear
>>>>>>>>>>>>>> separation the API become easier to use.
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> Regards,
>>>>>>>>>>>>>> Stephan
>>>>
>>>
>>>
>>>
>>
>>
>
>
>
Re: Proposal to clarify CmisObject caching behaviour
Posted by Florent Guillaume <fg...@nuxeo.com>.
It would be an interface.
I agree that it's not obvious in this case that transient behavior can
be obtained using an adapter (and autocompletion doc.get... does not
immediately provide it). But this can be solved by simple
documentation I think. Yes if we think transient documents are
fundamental we can make createTransientDocument a synonym to get this
adapter. It's not mandatory though.
Florent
On Wed, Nov 10, 2010 at 3:16 PM, Florian Müller
<fl...@alfresco.com> wrote:
> Hi Florent,
>
> Could you elaborate a bit more on that proposal?
> Would TransientDocument.class be an Interface or a Class?
>
> I like the idea of adapters. But it is not intuitive that there is an
> adapter the provides a transient paradigm. Would it make sense to add
> another method that provides a shortcut to the "transient adapter"?
>
>
> Thanks,
>
> Florian
>
>
> On 10/11/2010 13:27, Florent Guillaume wrote:
>>
>> I've come around to agreeing that 2. is probably better.
>>
>> I can see either:
>> TransientDocument transDoc = doc.createTransientDocument():
>> or
>> TransientDocument transDoc = doc.getAdapter(TransientDocument.class);
>>
>> The latter is more extensible for other uses besides transience
>> (protocol extensions, application-specific adapters).
>>
>> WDYT?
>>
>> Florent
>>
>>
>> On Wed, Nov 10, 2010 at 10:41 AM, Florian Müller
>> <fl...@alfresco.com> wrote:
>>>
>>> I would like to see that sorted out soon. There are more and more users
>>> of OpenCMIS and API changes are usually painful for them. We should also
>>> consider a new release (0.2.0) when this is done.
>>>
>>> So, where are we?
>>>
>>> The main question is where we want to handle transient data. We have two
>>> opinions:
>>> 1. Transient and non-transient data access should be covered by the
>>> CmisObject interface. (Florent)
>>> 2. Transient data access should be covered by a new interface and
>>> non-transient data access should be covered by the CmisObject interface.
>>> (Florian)
>>>
>>> Personally, I still want to go for option 2 since it provides cleaner
>>> semantics -- especially in multi-threaded environments.
>>>
>>> Other opinions?
>>>
>>>
>>> - Florian
>>>
>>>
>>> On 08/11/2010 11:51, David Caruana wrote:
>>>>
>>>> Have we reached a conclusion on this issue? It's been a while since we
>>>> last discussed.
>>>>
>>>> Regards,
>>>> Dave
>>>>
>>>> On 22 Oct 2010, at 15:06, Florian Müller wrote:
>>>>
>>>>> Oh, right, there is yet another option. :)
>>>>>
>>>>> I support all your arguments against b), c) and d). But there are also
>>>>> two issues with e).
>>>>> 1. Which value wins if a property is changed in the transient object
>>>>> _and_ present in the map?
>>>>> 2. save() stores the whole object. If we make ACLs and Policies
>>>>> transient too (do we want that?) than updateProperties() has the side effect
>>>>> of storing those as well.
>>>>>
>>>>> Which leaves us with a) which is pretty strong. And in this case I
>>>>> prefer two interfaces because it much is easier to understand and provides
>>>>> more compile checks and less runtime surprises.
>>>>>
>>>>>
>>>>> - Florian
>>>>>
>>>>>
>>>>> On 22/10/2010 14:44, Florent Guillaume wrote:
>>>>>>
>>>>>> On Fri, Oct 22, 2010 at 3:33 PM, Florian Müller
>>>>>> <fl...@alfresco.com> wrote:
>>>>>>>
>>>>>>> So your proposal is to add a method getTransientObject() (or
>>>>>>> something like that) to CmisObject. And that method would return a
>>>>>>> transient, not thread-safe version of the object but with setProperty(),
>>>>>>> save(), etc. enabled?
>>>>>>> Is that correct?
>>>>>>
>>>>>> Yes.
>>>>>>
>>>>>>> In this case we should also add a method isTransient() to CmisObject.
>>>>>>> There should be a way to discover the state of the CmisObject.
>>>>>>
>>>>>> Yes that would be useful.
>>>>>>
>>>>>>> I suggest that if the object is not transient, the transient methods
>>>>>>> should throw an IllegalStateException.
>>>>>>
>>>>>> Ok.
>>>>>>
>>>>>>> I agree that keeping the number of interfaces and classes low helps
>>>>>>> to learn and understand an API. But blending two semantics in one class
>>>>>>> could be even more confusing.
>>>>>>> For example, what should happen if updateProperties(Map) is called on
>>>>>>> a transient object? There are multiple options:
>>>>>>> a) updateProperties(Map) throws an exception because it only works
>>>>>>> for non-transient objects.
>>>>>>> b) updateProperties(Map) writes instantly to the repository and
>>>>>>> the transient object is refreshed.
>>>>>>
>>>>>> (which btw means that transient changes are lost)
>>>>>>>
>>>>>>> c) updateProperties(Map) writes instantly to the repository and
>>>>>>> but object keep its (now outdated) state.
>>>>>>> d) The property map is merged with the transient properties and
>>>>>>> written when save() is called.
>>>>>>
>>>>>> And also:
>>>>>> e) The property map is merged with the transient properties and then
>>>>>> save() is automatically called.
>>>>>>
>>>>>>> It is not obvious. All semantics would be right and wrong at the same
>>>>>>> time.
>>>>>>
>>>>>> Agreed, we have to make a choice. But we would make a similar choice
>>>>>> when deciding what methods would be available on the TransientDocument
>>>>>> interface and what they would do.
>>>>>>
>>>>>> But anyway my choices in order of preference would be e) then a).
>>>>>> I don't like b) because it loses changes.
>>>>>> I don't like c) because there's an issue with not keeping the changes
>>>>>> in order.
>>>>>> I don't like d) because if you didn't do any transient operation it
>>>>>> doesn't behave like its non-transient counterpart.
>>>>>>
>>>>>> Florent
>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> On 22/10/2010 13:43, Florent Guillaume wrote:
>>>>>>>>
>>>>>>>> Hi,
>>>>>>>>
>>>>>>>> Looking back at your example:
>>>>>>>>
>>>>>>>> Document doc = (Document) session.getObject(id);
>>>>>>>> TransientDocument transDoc = doc.createTransientDocument():
>>>>>>>> transDoc.setProperty("prop1", "value1");
>>>>>>>> transDoc.setProperty("prop2", "value2");
>>>>>>>> transDoc.save();
>>>>>>>>
>>>>>>>> I agree with the need to explicitly getting a transient object if
>>>>>>>> you
>>>>>>>> need different semantics.
>>>>>>>> One thing that will be painful though is having different classes:
>>>>>>>> TransientCmisObject, TransientDocument, TransientFolder, etc.
>>>>>>>> Couldn't we simply have all the methods available on the CmisObject,
>>>>>>>> Document, Folder, etc. and make them throw
>>>>>>>> UnsupportedOperationException when called on a non-transient object?
>>>>>>>> This would tremendously help learning about the API and avoid
>>>>>>>> juggling
>>>>>>>> with many different interfaces for the users.
>>>>>>>>
>>>>>>>> Florent
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>> On Mon, Oct 18, 2010 at 10:43 PM, Florian Müller
>>>>>>>> <fl...@alfresco.com> wrote:
>>>>>>>>>
>>>>>>>>> Hi Florent,
>>>>>>>>>
>>>>>>>>> Well, no, there would be no CmisObject.save() method. The save()
>>>>>>>>> method
>>>>>>>>> would only be on the transient object.
>>>>>>>>>
>>>>>>>>> CmisObject would have updateProperties(Map), applyAcl(List<Ace>,
>>>>>>>>> List<Ace>,
>>>>>>>>> AclPropagation), applyPolicy(ObjectId), etc. And all of them would
>>>>>>>>> write
>>>>>>>>> instantly to the repository and refresh the object.
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> Florian
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> On 18/10/2010 17:49, Florent Guillaume wrote:
>>>>>>>>>>
>>>>>>>>>> Ok understood and agreed. There would be a new CmisObject.save()
>>>>>>>>>> to
>>>>>>>>>> replace updateProperties() then? That works for me as it's a less
>>>>>>>>>> restrictive name that allows for different implementations of the
>>>>>>>>>> transient space that don't deal with just properties.
>>>>>>>>>>
>>>>>>>>>> Regarding your examples I don't need to do all that, because in
>>>>>>>>>> the
>>>>>>>>>> Nuxeo use cases I described the client Session I'm providing to
>>>>>>>>>> the
>>>>>>>>>> user of the API is not a PersistentSessionImpl but a completely
>>>>>>>>>> new
>>>>>>>>>> Nuxeo class that does all the wrapping it needs around native
>>>>>>>>>> Nuxeo
>>>>>>>>>> objects. So I'm not constrained by the semantics of the current
>>>>>>>>>> PersistentSessionImpl. It's just that I need a save()-like API to
>>>>>>>>>> exist on the CmisObject. And of course I want to have semantics
>>>>>>>>>> that
>>>>>>>>>> are not too far to what's available when you use an actual remote
>>>>>>>>>> connection using pure OpenCMIS PersistentSessionImpl.
>>>>>>>>>>
>>>>>>>>>> Florent
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> On Mon, Oct 18, 2010 at 6:06 PM, Florian Müller
>>>>>>>>>> <fl...@alfresco.com> wrote:
>>>>>>>>>>>
>>>>>>>>>>> Hi Florent,
>>>>>>>>>>>
>>>>>>>>>>> We don't want to remove the transient space entirely. The
>>>>>>>>>>> proposal is to
>>>>>>>>>>> detach the transient from the non-transient part. We would have
>>>>>>>>>>> two
>>>>>>>>>>> separate
>>>>>>>>>>> objects.
>>>>>>>>>>>
>>>>>>>>>>> The non-transient object is always consistent, can be shared
>>>>>>>>>>> across
>>>>>>>>>>> threads
>>>>>>>>>>> and is cached. Changes are directly written to the repository.
>>>>>>>>>>> This
>>>>>>>>>>> object
>>>>>>>>>>> would have an updateProperties(Map) method that immediately
>>>>>>>>>>> refreshes the
>>>>>>>>>>> object after the update.
>>>>>>>>>>>
>>>>>>>>>>> The transient object is owned by one thread and not thread safe.
>>>>>>>>>>> That
>>>>>>>>>>> should
>>>>>>>>>>> prevent inconsistent views on the object. This object would have
>>>>>>>>>>> setProperty() and save() methods. Internally it would use the
>>>>>>>>>>> non-transient
>>>>>>>>>>> object to access all unchanged data. It's a wrapper around the
>>>>>>>>>>> non-transient
>>>>>>>>>>> object that holds the transient data.
>>>>>>>>>>>
>>>>>>>>>>> So you still could use the pattern that you are using today. The
>>>>>>>>>>> only
>>>>>>>>>>> difference would be that you have to create a transient wrapper
>>>>>>>>>>> object.
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>> That could look like this:
>>>>>>>>>>>
>>>>>>>>>>> Document doc = (Document) session.getObject(id);
>>>>>>>>>>> TransientDocument transDoc = new TransientDocument(doc);
>>>>>>>>>>>
>>>>>>>>>>> transDoc.setProperty("prop1", "value1");
>>>>>>>>>>> transDoc.setProperty("prop2", "value2");
>>>>>>>>>>> transDoc.save(); // that also refreshes the underlying
>>>>>>>>>>> non-transient
>>>>>>>>>>> object
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>> Or maybe we do something like this:
>>>>>>>>>>>
>>>>>>>>>>> Document doc = (Document) session.getObject(id);
>>>>>>>>>>> TransientDocument transDoc = doc.createTransientDocument():
>>>>>>>>>>>
>>>>>>>>>>> transDoc.setProperty("prop1", "value1");
>>>>>>>>>>> transDoc.setProperty("prop2", "value2");
>>>>>>>>>>> transDoc.save();
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>> Florian
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>> On 18/10/2010 16:07, Florent Guillaume wrote:
>>>>>>>>>>>>
>>>>>>>>>>>> Hi,
>>>>>>>>>>>>
>>>>>>>>>>>> In Nuxeo the OpenCMIS client API is made available locally as
>>>>>>>>>>>> another
>>>>>>>>>>>> API to manipulate documents, in addition to the Nuxeo native
>>>>>>>>>>>> APIs.
>>>>>>>>>>>>
>>>>>>>>>>>> I have a problem with removing CmisObject.updateProperties() and
>>>>>>>>>>>> the
>>>>>>>>>>>> mini transient space because for me it's quite useful. The Nuxeo
>>>>>>>>>>>> internal non-CMIS session has a notion of a property-only
>>>>>>>>>>>> transient
>>>>>>>>>>>> space, so in Nuxeo you update several properties and do some
>>>>>>>>>>>> kind of
>>>>>>>>>>>> object save() to flush them. Without a similar flushing concept
>>>>>>>>>>>> on the
>>>>>>>>>>>> OpenCMIS client API, I'm obliged to make a flush on every
>>>>>>>>>>>> property
>>>>>>>>>>>> write, which leads to severely degraded performance.
>>>>>>>>>>>>
>>>>>>>>>>>> If all method calls on a CmisObject immediately write everything
>>>>>>>>>>>> through the network and potentially refetch a full object there
>>>>>>>>>>>> will
>>>>>>>>>>>> be many people that aren't happy with CMIS performance once they
>>>>>>>>>>>> get
>>>>>>>>>>>> to use OpenCMIS. The client API is supposed to provide some
>>>>>>>>>>>> convenience to the user, and having a mini transient space for
>>>>>>>>>>>> properties is IMHO the very first step of convenience. There may
>>>>>>>>>>>> be
>>>>>>>>>>>> problems with the semantics of interactions between this
>>>>>>>>>>>> transient
>>>>>>>>>>>> space and caching / refetches, but let's solve them rather than
>>>>>>>>>>>> remove
>>>>>>>>>>>> them.
>>>>>>>>>>>>
>>>>>>>>>>>> Dave wrote:
>>>>>>>>>>>>>
>>>>>>>>>>>>> For example, with a transient space, what is the behaviour when
>>>>>>>>>>>>> setProperty has been called and an "update" method is then
>>>>>>>>>>>>> called prior
>>>>>>>>>>>>> to
>>>>>>>>>>>>> updateProperties. Are the transient changes discarded, flushed,
>>>>>>>>>>>>> or just
>>>>>>>>>>>>> left
>>>>>>>>>>>>> as is?
>>>>>>>>>>>>
>>>>>>>>>>>> So if I understand correctly you're talking about the case:
>>>>>>>>>>>> 1. doc.setPropertyValue("foo", ...);
>>>>>>>>>>>> 2. doc.updateProperties(map);
>>>>>>>>>>>> 3. doc.setPropertyValue("bar", ...);
>>>>>>>>>>>> 4. doc.updateProperties();
>>>>>>>>>>>>
>>>>>>>>>>>> And you're asking if the "foo" change is sent with 2. or with 4.
>>>>>>>>>>>> or
>>>>>>>>>>>> discarded? I'd say let's keep this undefined, as I feel that
>>>>>>>>>>>> it's a
>>>>>>>>>>>> use pattern that's not natural. If we really want to specify
>>>>>>>>>>>> this then
>>>>>>>>>>>> I have no problem mandating that the "foo" change should be sent
>>>>>>>>>>>> with
>>>>>>>>>>>> 2. by saying that updateProperties(map) is the same as
>>>>>>>>>>>> setPropertyValue() on all the properties of the map then calling
>>>>>>>>>>>> updateProperties() with the transient map.
>>>>>>>>>>>>
>>>>>>>>>>>> Florent
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>> On Mon, Oct 18, 2010 at 4:05 PM, Klevenz, Stephan
>>>>>>>>>>>> <st...@sap.com> wrote:
>>>>>>>>>>>>>
>>>>>>>>>>>>> Hi,
>>>>>>>>>>>>>
>>>>>>>>>>>>> Coming back to the cache discussion. I would like to support
>>>>>>>>>>>>> this
>>>>>>>>>>>>> proposal by Dave/Florian and think we can also delete Methods
>>>>>>>>>>>>> on
>>>>>>>>>>>>> Session
>>>>>>>>>>>>> class like cancel() and save() which are currently not
>>>>>>>>>>>>> implemented.
>>>>>>>>>>>>>
>>>>>>>>>>>>> +1 for this:
>>>>>>>>>>>>>
>>>>>>>>>>>>>> - All write operations provided by CmisObject should
>>>>>>>>>>>>>> automatically do
>>>>>>>>>>>>>> an
>>>>>>>>>>>>>> object
>>>>>>>>>>>>>> refresh after the update. That guarantees that the object is
>>>>>>>>>>>>>> always
>>>>>>>>>>>>>> consistent.
>>>>>>>>>>>>>> The cost for this consistency is an additional call to the
>>>>>>>>>>>>>> repository.
>>>>>>>>>>>>>
>>>>>>>>>>>>>> - Is some cases you don't need or want this addition cost.
>>>>>>>>>>>>>> Lets say
>>>>>>>>>>>>>> you
>>>>>>>>>>>>>> just
>>>>>>>>>>>>>> want to update a bunch of objects but you don't work with them
>>>>>>>>>>>>>> afterwards.
>>>>>>>>>>>>>> That's what the operations provided by Session are good for.
>>>>>>>>>>>>>> They just
>>>>>>>>>>>>>> do
>>>>>>>>>>>>>> that and nothing else.
>>>>>>>>>>>>>
>>>>>>>>>>>>> About the transient support we can design this as an optional
>>>>>>>>>>>>> add on
>>>>>>>>>>>>> with
>>>>>>>>>>>>> additional interfaces and additional implementations. With a
>>>>>>>>>>>>> clear
>>>>>>>>>>>>> separation the API become easier to use.
>>>>>>>>>>>>>
>>>>>>>>>>>>> Regards,
>>>>>>>>>>>>> Stephan
>>>
>>
>>
>>
>
>
--
Florent Guillaume, Director of R&D, Nuxeo
Open Source, Java EE based, Enterprise Content Management (ECM)
http://www.nuxeo.com http://www.nuxeo.org +33 1 40 33 79 87
Re: Proposal to clarify CmisObject caching behaviour
Posted by Florian Müller <fl...@alfresco.com>.
Hi Florent,
Could you elaborate a bit more on that proposal?
Would TransientDocument.class be an Interface or a Class?
I like the idea of adapters. But it is not intuitive that there is an
adapter the provides a transient paradigm. Would it make sense to add
another method that provides a shortcut to the "transient adapter"?
Thanks,
Florian
On 10/11/2010 13:27, Florent Guillaume wrote:
> I've come around to agreeing that 2. is probably better.
>
> I can see either:
> TransientDocument transDoc = doc.createTransientDocument():
> or
> TransientDocument transDoc = doc.getAdapter(TransientDocument.class);
>
> The latter is more extensible for other uses besides transience
> (protocol extensions, application-specific adapters).
>
> WDYT?
>
> Florent
>
>
> On Wed, Nov 10, 2010 at 10:41 AM, Florian Müller
> <fl...@alfresco.com> wrote:
>> I would like to see that sorted out soon. There are more and more users of OpenCMIS and API changes are usually painful for them. We should also consider a new release (0.2.0) when this is done.
>>
>> So, where are we?
>>
>> The main question is where we want to handle transient data. We have two opinions:
>> 1. Transient and non-transient data access should be covered by the CmisObject interface. (Florent)
>> 2. Transient data access should be covered by a new interface and non-transient data access should be covered by the CmisObject interface. (Florian)
>>
>> Personally, I still want to go for option 2 since it provides cleaner semantics -- especially in multi-threaded environments.
>>
>> Other opinions?
>>
>>
>> - Florian
>>
>>
>> On 08/11/2010 11:51, David Caruana wrote:
>>> Have we reached a conclusion on this issue? It's been a while since we last discussed.
>>>
>>> Regards,
>>> Dave
>>>
>>> On 22 Oct 2010, at 15:06, Florian Müller wrote:
>>>
>>>> Oh, right, there is yet another option. :)
>>>>
>>>> I support all your arguments against b), c) and d). But there are also two issues with e).
>>>> 1. Which value wins if a property is changed in the transient object _and_ present in the map?
>>>> 2. save() stores the whole object. If we make ACLs and Policies transient too (do we want that?) than updateProperties() has the side effect of storing those as well.
>>>>
>>>> Which leaves us with a) which is pretty strong. And in this case I prefer two interfaces because it much is easier to understand and provides more compile checks and less runtime surprises.
>>>>
>>>>
>>>> - Florian
>>>>
>>>>
>>>> On 22/10/2010 14:44, Florent Guillaume wrote:
>>>>> On Fri, Oct 22, 2010 at 3:33 PM, Florian Müller
>>>>> <fl...@alfresco.com> wrote:
>>>>>> So your proposal is to add a method getTransientObject() (or something like that) to CmisObject. And that method would return a transient, not thread-safe version of the object but with setProperty(), save(), etc. enabled?
>>>>>> Is that correct?
>>>>>
>>>>> Yes.
>>>>>
>>>>>> In this case we should also add a method isTransient() to CmisObject. There should be a way to discover the state of the CmisObject.
>>>>>
>>>>> Yes that would be useful.
>>>>>
>>>>>> I suggest that if the object is not transient, the transient methods should throw an IllegalStateException.
>>>>>
>>>>> Ok.
>>>>>
>>>>>> I agree that keeping the number of interfaces and classes low helps to learn and understand an API. But blending two semantics in one class could be even more confusing.
>>>>>> For example, what should happen if updateProperties(Map) is called on a transient object? There are multiple options:
>>>>>> a) updateProperties(Map) throws an exception because it only works for non-transient objects.
>>>>>> b) updateProperties(Map) writes instantly to the repository and the transient object is refreshed.
>>>>> (which btw means that transient changes are lost)
>>>>>> c) updateProperties(Map) writes instantly to the repository and but object keep its (now outdated) state.
>>>>>> d) The property map is merged with the transient properties and written when save() is called.
>>>>>
>>>>> And also:
>>>>> e) The property map is merged with the transient properties and then
>>>>> save() is automatically called.
>>>>>
>>>>>> It is not obvious. All semantics would be right and wrong at the same time.
>>>>>
>>>>> Agreed, we have to make a choice. But we would make a similar choice
>>>>> when deciding what methods would be available on the TransientDocument
>>>>> interface and what they would do.
>>>>>
>>>>> But anyway my choices in order of preference would be e) then a).
>>>>> I don't like b) because it loses changes.
>>>>> I don't like c) because there's an issue with not keeping the changes in order.
>>>>> I don't like d) because if you didn't do any transient operation it
>>>>> doesn't behave like its non-transient counterpart.
>>>>>
>>>>> Florent
>>>>>
>>>>>>
>>>>>>
>>>>>> On 22/10/2010 13:43, Florent Guillaume wrote:
>>>>>>> Hi,
>>>>>>>
>>>>>>> Looking back at your example:
>>>>>>>
>>>>>>> Document doc = (Document) session.getObject(id);
>>>>>>> TransientDocument transDoc = doc.createTransientDocument():
>>>>>>> transDoc.setProperty("prop1", "value1");
>>>>>>> transDoc.setProperty("prop2", "value2");
>>>>>>> transDoc.save();
>>>>>>>
>>>>>>> I agree with the need to explicitly getting a transient object if you
>>>>>>> need different semantics.
>>>>>>> One thing that will be painful though is having different classes:
>>>>>>> TransientCmisObject, TransientDocument, TransientFolder, etc.
>>>>>>> Couldn't we simply have all the methods available on the CmisObject,
>>>>>>> Document, Folder, etc. and make them throw
>>>>>>> UnsupportedOperationException when called on a non-transient object?
>>>>>>> This would tremendously help learning about the API and avoid juggling
>>>>>>> with many different interfaces for the users.
>>>>>>>
>>>>>>> Florent
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> On Mon, Oct 18, 2010 at 10:43 PM, Florian Müller
>>>>>>> <fl...@alfresco.com> wrote:
>>>>>>>> Hi Florent,
>>>>>>>>
>>>>>>>> Well, no, there would be no CmisObject.save() method. The save() method
>>>>>>>> would only be on the transient object.
>>>>>>>>
>>>>>>>> CmisObject would have updateProperties(Map), applyAcl(List<Ace>, List<Ace>,
>>>>>>>> AclPropagation), applyPolicy(ObjectId), etc. And all of them would write
>>>>>>>> instantly to the repository and refresh the object.
>>>>>>>>
>>>>>>>>
>>>>>>>> Florian
>>>>>>>>
>>>>>>>>
>>>>>>>> On 18/10/2010 17:49, Florent Guillaume wrote:
>>>>>>>>>
>>>>>>>>> Ok understood and agreed. There would be a new CmisObject.save() to
>>>>>>>>> replace updateProperties() then? That works for me as it's a less
>>>>>>>>> restrictive name that allows for different implementations of the
>>>>>>>>> transient space that don't deal with just properties.
>>>>>>>>>
>>>>>>>>> Regarding your examples I don't need to do all that, because in the
>>>>>>>>> Nuxeo use cases I described the client Session I'm providing to the
>>>>>>>>> user of the API is not a PersistentSessionImpl but a completely new
>>>>>>>>> Nuxeo class that does all the wrapping it needs around native Nuxeo
>>>>>>>>> objects. So I'm not constrained by the semantics of the current
>>>>>>>>> PersistentSessionImpl. It's just that I need a save()-like API to
>>>>>>>>> exist on the CmisObject. And of course I want to have semantics that
>>>>>>>>> are not too far to what's available when you use an actual remote
>>>>>>>>> connection using pure OpenCMIS PersistentSessionImpl.
>>>>>>>>>
>>>>>>>>> Florent
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> On Mon, Oct 18, 2010 at 6:06 PM, Florian Müller
>>>>>>>>> <fl...@alfresco.com> wrote:
>>>>>>>>>>
>>>>>>>>>> Hi Florent,
>>>>>>>>>>
>>>>>>>>>> We don't want to remove the transient space entirely. The proposal is to
>>>>>>>>>> detach the transient from the non-transient part. We would have two
>>>>>>>>>> separate
>>>>>>>>>> objects.
>>>>>>>>>>
>>>>>>>>>> The non-transient object is always consistent, can be shared across
>>>>>>>>>> threads
>>>>>>>>>> and is cached. Changes are directly written to the repository. This
>>>>>>>>>> object
>>>>>>>>>> would have an updateProperties(Map) method that immediately refreshes the
>>>>>>>>>> object after the update.
>>>>>>>>>>
>>>>>>>>>> The transient object is owned by one thread and not thread safe. That
>>>>>>>>>> should
>>>>>>>>>> prevent inconsistent views on the object. This object would have
>>>>>>>>>> setProperty() and save() methods. Internally it would use the
>>>>>>>>>> non-transient
>>>>>>>>>> object to access all unchanged data. It's a wrapper around the
>>>>>>>>>> non-transient
>>>>>>>>>> object that holds the transient data.
>>>>>>>>>>
>>>>>>>>>> So you still could use the pattern that you are using today. The only
>>>>>>>>>> difference would be that you have to create a transient wrapper object.
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> That could look like this:
>>>>>>>>>>
>>>>>>>>>> Document doc = (Document) session.getObject(id);
>>>>>>>>>> TransientDocument transDoc = new TransientDocument(doc);
>>>>>>>>>>
>>>>>>>>>> transDoc.setProperty("prop1", "value1");
>>>>>>>>>> transDoc.setProperty("prop2", "value2");
>>>>>>>>>> transDoc.save(); // that also refreshes the underlying non-transient
>>>>>>>>>> object
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> Or maybe we do something like this:
>>>>>>>>>>
>>>>>>>>>> Document doc = (Document) session.getObject(id);
>>>>>>>>>> TransientDocument transDoc = doc.createTransientDocument():
>>>>>>>>>>
>>>>>>>>>> transDoc.setProperty("prop1", "value1");
>>>>>>>>>> transDoc.setProperty("prop2", "value2");
>>>>>>>>>> transDoc.save();
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> Florian
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> On 18/10/2010 16:07, Florent Guillaume wrote:
>>>>>>>>>>>
>>>>>>>>>>> Hi,
>>>>>>>>>>>
>>>>>>>>>>> In Nuxeo the OpenCMIS client API is made available locally as another
>>>>>>>>>>> API to manipulate documents, in addition to the Nuxeo native APIs.
>>>>>>>>>>>
>>>>>>>>>>> I have a problem with removing CmisObject.updateProperties() and the
>>>>>>>>>>> mini transient space because for me it's quite useful. The Nuxeo
>>>>>>>>>>> internal non-CMIS session has a notion of a property-only transient
>>>>>>>>>>> space, so in Nuxeo you update several properties and do some kind of
>>>>>>>>>>> object save() to flush them. Without a similar flushing concept on the
>>>>>>>>>>> OpenCMIS client API, I'm obliged to make a flush on every property
>>>>>>>>>>> write, which leads to severely degraded performance.
>>>>>>>>>>>
>>>>>>>>>>> If all method calls on a CmisObject immediately write everything
>>>>>>>>>>> through the network and potentially refetch a full object there will
>>>>>>>>>>> be many people that aren't happy with CMIS performance once they get
>>>>>>>>>>> to use OpenCMIS. The client API is supposed to provide some
>>>>>>>>>>> convenience to the user, and having a mini transient space for
>>>>>>>>>>> properties is IMHO the very first step of convenience. There may be
>>>>>>>>>>> problems with the semantics of interactions between this transient
>>>>>>>>>>> space and caching / refetches, but let's solve them rather than remove
>>>>>>>>>>> them.
>>>>>>>>>>>
>>>>>>>>>>> Dave wrote:
>>>>>>>>>>>>
>>>>>>>>>>>> For example, with a transient space, what is the behaviour when
>>>>>>>>>>>> setProperty has been called and an "update" method is then called prior
>>>>>>>>>>>> to
>>>>>>>>>>>> updateProperties. Are the transient changes discarded, flushed, or just
>>>>>>>>>>>> left
>>>>>>>>>>>> as is?
>>>>>>>>>>>
>>>>>>>>>>> So if I understand correctly you're talking about the case:
>>>>>>>>>>> 1. doc.setPropertyValue("foo", ...);
>>>>>>>>>>> 2. doc.updateProperties(map);
>>>>>>>>>>> 3. doc.setPropertyValue("bar", ...);
>>>>>>>>>>> 4. doc.updateProperties();
>>>>>>>>>>>
>>>>>>>>>>> And you're asking if the "foo" change is sent with 2. or with 4. or
>>>>>>>>>>> discarded? I'd say let's keep this undefined, as I feel that it's a
>>>>>>>>>>> use pattern that's not natural. If we really want to specify this then
>>>>>>>>>>> I have no problem mandating that the "foo" change should be sent with
>>>>>>>>>>> 2. by saying that updateProperties(map) is the same as
>>>>>>>>>>> setPropertyValue() on all the properties of the map then calling
>>>>>>>>>>> updateProperties() with the transient map.
>>>>>>>>>>>
>>>>>>>>>>> Florent
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>> On Mon, Oct 18, 2010 at 4:05 PM, Klevenz, Stephan
>>>>>>>>>>> <st...@sap.com> wrote:
>>>>>>>>>>>>
>>>>>>>>>>>> Hi,
>>>>>>>>>>>>
>>>>>>>>>>>> Coming back to the cache discussion. I would like to support this
>>>>>>>>>>>> proposal by Dave/Florian and think we can also delete Methods on
>>>>>>>>>>>> Session
>>>>>>>>>>>> class like cancel() and save() which are currently not implemented.
>>>>>>>>>>>>
>>>>>>>>>>>> +1 for this:
>>>>>>>>>>>>
>>>>>>>>>>>>> - All write operations provided by CmisObject should automatically do
>>>>>>>>>>>>> an
>>>>>>>>>>>>> object
>>>>>>>>>>>>> refresh after the update. That guarantees that the object is always
>>>>>>>>>>>>> consistent.
>>>>>>>>>>>>> The cost for this consistency is an additional call to the repository.
>>>>>>>>>>>>
>>>>>>>>>>>>> - Is some cases you don't need or want this addition cost. Lets say
>>>>>>>>>>>>> you
>>>>>>>>>>>>> just
>>>>>>>>>>>>> want to update a bunch of objects but you don't work with them
>>>>>>>>>>>>> afterwards.
>>>>>>>>>>>>> That's what the operations provided by Session are good for. They just
>>>>>>>>>>>>> do
>>>>>>>>>>>>> that and nothing else.
>>>>>>>>>>>>
>>>>>>>>>>>> About the transient support we can design this as an optional add on
>>>>>>>>>>>> with
>>>>>>>>>>>> additional interfaces and additional implementations. With a clear
>>>>>>>>>>>> separation the API become easier to use.
>>>>>>>>>>>>
>>>>>>>>>>>> Regards,
>>>>>>>>>>>> Stephan
>>
>
>
>
Re: Proposal to clarify CmisObject caching behaviour
Posted by Florent Guillaume <fg...@nuxeo.com>.
I've come around to agreeing that 2. is probably better.
I can see either:
TransientDocument transDoc = doc.createTransientDocument():
or
TransientDocument transDoc = doc.getAdapter(TransientDocument.class);
The latter is more extensible for other uses besides transience
(protocol extensions, application-specific adapters).
WDYT?
Florent
On Wed, Nov 10, 2010 at 10:41 AM, Florian Müller
<fl...@alfresco.com> wrote:
> I would like to see that sorted out soon. There are more and more users of OpenCMIS and API changes are usually painful for them. We should also consider a new release (0.2.0) when this is done.
>
> So, where are we?
>
> The main question is where we want to handle transient data. We have two opinions:
> 1. Transient and non-transient data access should be covered by the CmisObject interface. (Florent)
> 2. Transient data access should be covered by a new interface and non-transient data access should be covered by the CmisObject interface. (Florian)
>
> Personally, I still want to go for option 2 since it provides cleaner semantics -- especially in multi-threaded environments.
>
> Other opinions?
>
>
> - Florian
>
>
> On 08/11/2010 11:51, David Caruana wrote:
>> Have we reached a conclusion on this issue? It's been a while since we last discussed.
>>
>> Regards,
>> Dave
>>
>> On 22 Oct 2010, at 15:06, Florian Müller wrote:
>>
>>> Oh, right, there is yet another option. :)
>>>
>>> I support all your arguments against b), c) and d). But there are also two issues with e).
>>> 1. Which value wins if a property is changed in the transient object _and_ present in the map?
>>> 2. save() stores the whole object. If we make ACLs and Policies transient too (do we want that?) than updateProperties() has the side effect of storing those as well.
>>>
>>> Which leaves us with a) which is pretty strong. And in this case I prefer two interfaces because it much is easier to understand and provides more compile checks and less runtime surprises.
>>>
>>>
>>> - Florian
>>>
>>>
>>> On 22/10/2010 14:44, Florent Guillaume wrote:
>>>> On Fri, Oct 22, 2010 at 3:33 PM, Florian Müller
>>>> <fl...@alfresco.com> wrote:
>>>>> So your proposal is to add a method getTransientObject() (or something like that) to CmisObject. And that method would return a transient, not thread-safe version of the object but with setProperty(), save(), etc. enabled?
>>>>> Is that correct?
>>>>
>>>> Yes.
>>>>
>>>>> In this case we should also add a method isTransient() to CmisObject. There should be a way to discover the state of the CmisObject.
>>>>
>>>> Yes that would be useful.
>>>>
>>>>> I suggest that if the object is not transient, the transient methods should throw an IllegalStateException.
>>>>
>>>> Ok.
>>>>
>>>>> I agree that keeping the number of interfaces and classes low helps to learn and understand an API. But blending two semantics in one class could be even more confusing.
>>>>> For example, what should happen if updateProperties(Map) is called on a transient object? There are multiple options:
>>>>> a) updateProperties(Map) throws an exception because it only works for non-transient objects.
>>>>> b) updateProperties(Map) writes instantly to the repository and the transient object is refreshed.
>>>> (which btw means that transient changes are lost)
>>>>> c) updateProperties(Map) writes instantly to the repository and but object keep its (now outdated) state.
>>>>> d) The property map is merged with the transient properties and written when save() is called.
>>>>
>>>> And also:
>>>> e) The property map is merged with the transient properties and then
>>>> save() is automatically called.
>>>>
>>>>> It is not obvious. All semantics would be right and wrong at the same time.
>>>>
>>>> Agreed, we have to make a choice. But we would make a similar choice
>>>> when deciding what methods would be available on the TransientDocument
>>>> interface and what they would do.
>>>>
>>>> But anyway my choices in order of preference would be e) then a).
>>>> I don't like b) because it loses changes.
>>>> I don't like c) because there's an issue with not keeping the changes in order.
>>>> I don't like d) because if you didn't do any transient operation it
>>>> doesn't behave like its non-transient counterpart.
>>>>
>>>> Florent
>>>>
>>>>>
>>>>>
>>>>> On 22/10/2010 13:43, Florent Guillaume wrote:
>>>>>> Hi,
>>>>>>
>>>>>> Looking back at your example:
>>>>>>
>>>>>> Document doc = (Document) session.getObject(id);
>>>>>> TransientDocument transDoc = doc.createTransientDocument():
>>>>>> transDoc.setProperty("prop1", "value1");
>>>>>> transDoc.setProperty("prop2", "value2");
>>>>>> transDoc.save();
>>>>>>
>>>>>> I agree with the need to explicitly getting a transient object if you
>>>>>> need different semantics.
>>>>>> One thing that will be painful though is having different classes:
>>>>>> TransientCmisObject, TransientDocument, TransientFolder, etc.
>>>>>> Couldn't we simply have all the methods available on the CmisObject,
>>>>>> Document, Folder, etc. and make them throw
>>>>>> UnsupportedOperationException when called on a non-transient object?
>>>>>> This would tremendously help learning about the API and avoid juggling
>>>>>> with many different interfaces for the users.
>>>>>>
>>>>>> Florent
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>> On Mon, Oct 18, 2010 at 10:43 PM, Florian Müller
>>>>>> <fl...@alfresco.com> wrote:
>>>>>>> Hi Florent,
>>>>>>>
>>>>>>> Well, no, there would be no CmisObject.save() method. The save() method
>>>>>>> would only be on the transient object.
>>>>>>>
>>>>>>> CmisObject would have updateProperties(Map), applyAcl(List<Ace>, List<Ace>,
>>>>>>> AclPropagation), applyPolicy(ObjectId), etc. And all of them would write
>>>>>>> instantly to the repository and refresh the object.
>>>>>>>
>>>>>>>
>>>>>>> Florian
>>>>>>>
>>>>>>>
>>>>>>> On 18/10/2010 17:49, Florent Guillaume wrote:
>>>>>>>>
>>>>>>>> Ok understood and agreed. There would be a new CmisObject.save() to
>>>>>>>> replace updateProperties() then? That works for me as it's a less
>>>>>>>> restrictive name that allows for different implementations of the
>>>>>>>> transient space that don't deal with just properties.
>>>>>>>>
>>>>>>>> Regarding your examples I don't need to do all that, because in the
>>>>>>>> Nuxeo use cases I described the client Session I'm providing to the
>>>>>>>> user of the API is not a PersistentSessionImpl but a completely new
>>>>>>>> Nuxeo class that does all the wrapping it needs around native Nuxeo
>>>>>>>> objects. So I'm not constrained by the semantics of the current
>>>>>>>> PersistentSessionImpl. It's just that I need a save()-like API to
>>>>>>>> exist on the CmisObject. And of course I want to have semantics that
>>>>>>>> are not too far to what's available when you use an actual remote
>>>>>>>> connection using pure OpenCMIS PersistentSessionImpl.
>>>>>>>>
>>>>>>>> Florent
>>>>>>>>
>>>>>>>>
>>>>>>>> On Mon, Oct 18, 2010 at 6:06 PM, Florian Müller
>>>>>>>> <fl...@alfresco.com> wrote:
>>>>>>>>>
>>>>>>>>> Hi Florent,
>>>>>>>>>
>>>>>>>>> We don't want to remove the transient space entirely. The proposal is to
>>>>>>>>> detach the transient from the non-transient part. We would have two
>>>>>>>>> separate
>>>>>>>>> objects.
>>>>>>>>>
>>>>>>>>> The non-transient object is always consistent, can be shared across
>>>>>>>>> threads
>>>>>>>>> and is cached. Changes are directly written to the repository. This
>>>>>>>>> object
>>>>>>>>> would have an updateProperties(Map) method that immediately refreshes the
>>>>>>>>> object after the update.
>>>>>>>>>
>>>>>>>>> The transient object is owned by one thread and not thread safe. That
>>>>>>>>> should
>>>>>>>>> prevent inconsistent views on the object. This object would have
>>>>>>>>> setProperty() and save() methods. Internally it would use the
>>>>>>>>> non-transient
>>>>>>>>> object to access all unchanged data. It's a wrapper around the
>>>>>>>>> non-transient
>>>>>>>>> object that holds the transient data.
>>>>>>>>>
>>>>>>>>> So you still could use the pattern that you are using today. The only
>>>>>>>>> difference would be that you have to create a transient wrapper object.
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> That could look like this:
>>>>>>>>>
>>>>>>>>> Document doc = (Document) session.getObject(id);
>>>>>>>>> TransientDocument transDoc = new TransientDocument(doc);
>>>>>>>>>
>>>>>>>>> transDoc.setProperty("prop1", "value1");
>>>>>>>>> transDoc.setProperty("prop2", "value2");
>>>>>>>>> transDoc.save(); // that also refreshes the underlying non-transient
>>>>>>>>> object
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> Or maybe we do something like this:
>>>>>>>>>
>>>>>>>>> Document doc = (Document) session.getObject(id);
>>>>>>>>> TransientDocument transDoc = doc.createTransientDocument():
>>>>>>>>>
>>>>>>>>> transDoc.setProperty("prop1", "value1");
>>>>>>>>> transDoc.setProperty("prop2", "value2");
>>>>>>>>> transDoc.save();
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> Florian
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> On 18/10/2010 16:07, Florent Guillaume wrote:
>>>>>>>>>>
>>>>>>>>>> Hi,
>>>>>>>>>>
>>>>>>>>>> In Nuxeo the OpenCMIS client API is made available locally as another
>>>>>>>>>> API to manipulate documents, in addition to the Nuxeo native APIs.
>>>>>>>>>>
>>>>>>>>>> I have a problem with removing CmisObject.updateProperties() and the
>>>>>>>>>> mini transient space because for me it's quite useful. The Nuxeo
>>>>>>>>>> internal non-CMIS session has a notion of a property-only transient
>>>>>>>>>> space, so in Nuxeo you update several properties and do some kind of
>>>>>>>>>> object save() to flush them. Without a similar flushing concept on the
>>>>>>>>>> OpenCMIS client API, I'm obliged to make a flush on every property
>>>>>>>>>> write, which leads to severely degraded performance.
>>>>>>>>>>
>>>>>>>>>> If all method calls on a CmisObject immediately write everything
>>>>>>>>>> through the network and potentially refetch a full object there will
>>>>>>>>>> be many people that aren't happy with CMIS performance once they get
>>>>>>>>>> to use OpenCMIS. The client API is supposed to provide some
>>>>>>>>>> convenience to the user, and having a mini transient space for
>>>>>>>>>> properties is IMHO the very first step of convenience. There may be
>>>>>>>>>> problems with the semantics of interactions between this transient
>>>>>>>>>> space and caching / refetches, but let's solve them rather than remove
>>>>>>>>>> them.
>>>>>>>>>>
>>>>>>>>>> Dave wrote:
>>>>>>>>>>>
>>>>>>>>>>> For example, with a transient space, what is the behaviour when
>>>>>>>>>>> setProperty has been called and an "update" method is then called prior
>>>>>>>>>>> to
>>>>>>>>>>> updateProperties. Are the transient changes discarded, flushed, or just
>>>>>>>>>>> left
>>>>>>>>>>> as is?
>>>>>>>>>>
>>>>>>>>>> So if I understand correctly you're talking about the case:
>>>>>>>>>> 1. doc.setPropertyValue("foo", ...);
>>>>>>>>>> 2. doc.updateProperties(map);
>>>>>>>>>> 3. doc.setPropertyValue("bar", ...);
>>>>>>>>>> 4. doc.updateProperties();
>>>>>>>>>>
>>>>>>>>>> And you're asking if the "foo" change is sent with 2. or with 4. or
>>>>>>>>>> discarded? I'd say let's keep this undefined, as I feel that it's a
>>>>>>>>>> use pattern that's not natural. If we really want to specify this then
>>>>>>>>>> I have no problem mandating that the "foo" change should be sent with
>>>>>>>>>> 2. by saying that updateProperties(map) is the same as
>>>>>>>>>> setPropertyValue() on all the properties of the map then calling
>>>>>>>>>> updateProperties() with the transient map.
>>>>>>>>>>
>>>>>>>>>> Florent
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> On Mon, Oct 18, 2010 at 4:05 PM, Klevenz, Stephan
>>>>>>>>>> <st...@sap.com> wrote:
>>>>>>>>>>>
>>>>>>>>>>> Hi,
>>>>>>>>>>>
>>>>>>>>>>> Coming back to the cache discussion. I would like to support this
>>>>>>>>>>> proposal by Dave/Florian and think we can also delete Methods on
>>>>>>>>>>> Session
>>>>>>>>>>> class like cancel() and save() which are currently not implemented.
>>>>>>>>>>>
>>>>>>>>>>> +1 for this:
>>>>>>>>>>>
>>>>>>>>>>>> - All write operations provided by CmisObject should automatically do
>>>>>>>>>>>> an
>>>>>>>>>>>> object
>>>>>>>>>>>> refresh after the update. That guarantees that the object is always
>>>>>>>>>>>> consistent.
>>>>>>>>>>>> The cost for this consistency is an additional call to the repository.
>>>>>>>>>>>
>>>>>>>>>>>> - Is some cases you don't need or want this addition cost. Lets say
>>>>>>>>>>>> you
>>>>>>>>>>>> just
>>>>>>>>>>>> want to update a bunch of objects but you don't work with them
>>>>>>>>>>>> afterwards.
>>>>>>>>>>>> That's what the operations provided by Session are good for. They just
>>>>>>>>>>>> do
>>>>>>>>>>>> that and nothing else.
>>>>>>>>>>>
>>>>>>>>>>> About the transient support we can design this as an optional add on
>>>>>>>>>>> with
>>>>>>>>>>> additional interfaces and additional implementations. With a clear
>>>>>>>>>>> separation the API become easier to use.
>>>>>>>>>>>
>>>>>>>>>>> Regards,
>>>>>>>>>>> Stephan
>
--
Florent Guillaume, Director of R&D, Nuxeo
Open Source, Java EE based, Enterprise Content Management (ECM)
http://www.nuxeo.com http://www.nuxeo.org +33 1 40 33 79 87
RE: Proposal to clarify CmisObject caching behaviour
Posted by "Klevenz, Stephan" <st...@sap.com>.
Hi,
I do agree to go for a 0.2.0 release and vote for option (2).
Regards,
Stephan
PS.: I did send a mail to mailing list using my private mail account yesterday. This did not show up. Could this an issue with Apache spam filter policy?
-----Original Message-----
From: Florian Müller [mailto:florian.mueller@alfresco.com]
Sent: Mittwoch, 10. November 2010 10:41
To: chemistry-dev@incubator.apache.org
Subject: Re: Proposal to clarify CmisObject caching behaviour
I would like to see that sorted out soon. There are more and more users of OpenCMIS and API changes are usually painful for them. We should also consider a new release (0.2.0) when this is done.
So, where are we?
The main question is where we want to handle transient data. We have two opinions:
1. Transient and non-transient data access should be covered by the CmisObject interface. (Florent)
2. Transient data access should be covered by a new interface and non-transient data access should be covered by the CmisObject interface. (Florian)
Personally, I still want to go for option 2 since it provides cleaner semantics -- especially in multi-threaded environments.
Other opinions?
- Florian
On 08/11/2010 11:51, David Caruana wrote:
> Have we reached a conclusion on this issue? It's been a while since we last discussed.
>
> Regards,
> Dave
>
> On 22 Oct 2010, at 15:06, Florian Müller wrote:
>
>> Oh, right, there is yet another option. :)
>>
>> I support all your arguments against b), c) and d). But there are also two issues with e).
>> 1. Which value wins if a property is changed in the transient object _and_ present in the map?
>> 2. save() stores the whole object. If we make ACLs and Policies transient too (do we want that?) than updateProperties() has the side effect of storing those as well.
>>
>> Which leaves us with a) which is pretty strong. And in this case I prefer two interfaces because it much is easier to understand and provides more compile checks and less runtime surprises.
>>
>>
>> - Florian
>>
>>
>> On 22/10/2010 14:44, Florent Guillaume wrote:
>>> On Fri, Oct 22, 2010 at 3:33 PM, Florian Müller
>>> <fl...@alfresco.com> wrote:
>>>> So your proposal is to add a method getTransientObject() (or something like that) to CmisObject. And that method would return a transient, not thread-safe version of the object but with setProperty(), save(), etc. enabled?
>>>> Is that correct?
>>>
>>> Yes.
>>>
>>>> In this case we should also add a method isTransient() to CmisObject. There should be a way to discover the state of the CmisObject.
>>>
>>> Yes that would be useful.
>>>
>>>> I suggest that if the object is not transient, the transient methods should throw an IllegalStateException.
>>>
>>> Ok.
>>>
>>>> I agree that keeping the number of interfaces and classes low helps to learn and understand an API. But blending two semantics in one class could be even more confusing.
>>>> For example, what should happen if updateProperties(Map) is called on a transient object? There are multiple options:
>>>> a) updateProperties(Map) throws an exception because it only works for non-transient objects.
>>>> b) updateProperties(Map) writes instantly to the repository and the transient object is refreshed.
>>> (which btw means that transient changes are lost)
>>>> c) updateProperties(Map) writes instantly to the repository and but object keep its (now outdated) state.
>>>> d) The property map is merged with the transient properties and written when save() is called.
>>>
>>> And also:
>>> e) The property map is merged with the transient properties and then
>>> save() is automatically called.
>>>
>>>> It is not obvious. All semantics would be right and wrong at the same time.
>>>
>>> Agreed, we have to make a choice. But we would make a similar choice
>>> when deciding what methods would be available on the TransientDocument
>>> interface and what they would do.
>>>
>>> But anyway my choices in order of preference would be e) then a).
>>> I don't like b) because it loses changes.
>>> I don't like c) because there's an issue with not keeping the changes in order.
>>> I don't like d) because if you didn't do any transient operation it
>>> doesn't behave like its non-transient counterpart.
>>>
>>> Florent
>>>
>>>>
>>>>
>>>> On 22/10/2010 13:43, Florent Guillaume wrote:
>>>>> Hi,
>>>>>
>>>>> Looking back at your example:
>>>>>
>>>>> Document doc = (Document) session.getObject(id);
>>>>> TransientDocument transDoc = doc.createTransientDocument():
>>>>> transDoc.setProperty("prop1", "value1");
>>>>> transDoc.setProperty("prop2", "value2");
>>>>> transDoc.save();
>>>>>
>>>>> I agree with the need to explicitly getting a transient object if you
>>>>> need different semantics.
>>>>> One thing that will be painful though is having different classes:
>>>>> TransientCmisObject, TransientDocument, TransientFolder, etc.
>>>>> Couldn't we simply have all the methods available on the CmisObject,
>>>>> Document, Folder, etc. and make them throw
>>>>> UnsupportedOperationException when called on a non-transient object?
>>>>> This would tremendously help learning about the API and avoid juggling
>>>>> with many different interfaces for the users.
>>>>>
>>>>> Florent
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> On Mon, Oct 18, 2010 at 10:43 PM, Florian Müller
>>>>> <fl...@alfresco.com> wrote:
>>>>>> Hi Florent,
>>>>>>
>>>>>> Well, no, there would be no CmisObject.save() method. The save() method
>>>>>> would only be on the transient object.
>>>>>>
>>>>>> CmisObject would have updateProperties(Map), applyAcl(List<Ace>, List<Ace>,
>>>>>> AclPropagation), applyPolicy(ObjectId), etc. And all of them would write
>>>>>> instantly to the repository and refresh the object.
>>>>>>
>>>>>>
>>>>>> Florian
>>>>>>
>>>>>>
>>>>>> On 18/10/2010 17:49, Florent Guillaume wrote:
>>>>>>>
>>>>>>> Ok understood and agreed. There would be a new CmisObject.save() to
>>>>>>> replace updateProperties() then? That works for me as it's a less
>>>>>>> restrictive name that allows for different implementations of the
>>>>>>> transient space that don't deal with just properties.
>>>>>>>
>>>>>>> Regarding your examples I don't need to do all that, because in the
>>>>>>> Nuxeo use cases I described the client Session I'm providing to the
>>>>>>> user of the API is not a PersistentSessionImpl but a completely new
>>>>>>> Nuxeo class that does all the wrapping it needs around native Nuxeo
>>>>>>> objects. So I'm not constrained by the semantics of the current
>>>>>>> PersistentSessionImpl. It's just that I need a save()-like API to
>>>>>>> exist on the CmisObject. And of course I want to have semantics that
>>>>>>> are not too far to what's available when you use an actual remote
>>>>>>> connection using pure OpenCMIS PersistentSessionImpl.
>>>>>>>
>>>>>>> Florent
>>>>>>>
>>>>>>>
>>>>>>> On Mon, Oct 18, 2010 at 6:06 PM, Florian Müller
>>>>>>> <fl...@alfresco.com> wrote:
>>>>>>>>
>>>>>>>> Hi Florent,
>>>>>>>>
>>>>>>>> We don't want to remove the transient space entirely. The proposal is to
>>>>>>>> detach the transient from the non-transient part. We would have two
>>>>>>>> separate
>>>>>>>> objects.
>>>>>>>>
>>>>>>>> The non-transient object is always consistent, can be shared across
>>>>>>>> threads
>>>>>>>> and is cached. Changes are directly written to the repository. This
>>>>>>>> object
>>>>>>>> would have an updateProperties(Map) method that immediately refreshes the
>>>>>>>> object after the update.
>>>>>>>>
>>>>>>>> The transient object is owned by one thread and not thread safe. That
>>>>>>>> should
>>>>>>>> prevent inconsistent views on the object. This object would have
>>>>>>>> setProperty() and save() methods. Internally it would use the
>>>>>>>> non-transient
>>>>>>>> object to access all unchanged data. It's a wrapper around the
>>>>>>>> non-transient
>>>>>>>> object that holds the transient data.
>>>>>>>>
>>>>>>>> So you still could use the pattern that you are using today. The only
>>>>>>>> difference would be that you have to create a transient wrapper object.
>>>>>>>>
>>>>>>>>
>>>>>>>> That could look like this:
>>>>>>>>
>>>>>>>> Document doc = (Document) session.getObject(id);
>>>>>>>> TransientDocument transDoc = new TransientDocument(doc);
>>>>>>>>
>>>>>>>> transDoc.setProperty("prop1", "value1");
>>>>>>>> transDoc.setProperty("prop2", "value2");
>>>>>>>> transDoc.save(); // that also refreshes the underlying non-transient
>>>>>>>> object
>>>>>>>>
>>>>>>>>
>>>>>>>> Or maybe we do something like this:
>>>>>>>>
>>>>>>>> Document doc = (Document) session.getObject(id);
>>>>>>>> TransientDocument transDoc = doc.createTransientDocument():
>>>>>>>>
>>>>>>>> transDoc.setProperty("prop1", "value1");
>>>>>>>> transDoc.setProperty("prop2", "value2");
>>>>>>>> transDoc.save();
>>>>>>>>
>>>>>>>>
>>>>>>>> Florian
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>> On 18/10/2010 16:07, Florent Guillaume wrote:
>>>>>>>>>
>>>>>>>>> Hi,
>>>>>>>>>
>>>>>>>>> In Nuxeo the OpenCMIS client API is made available locally as another
>>>>>>>>> API to manipulate documents, in addition to the Nuxeo native APIs.
>>>>>>>>>
>>>>>>>>> I have a problem with removing CmisObject.updateProperties() and the
>>>>>>>>> mini transient space because for me it's quite useful. The Nuxeo
>>>>>>>>> internal non-CMIS session has a notion of a property-only transient
>>>>>>>>> space, so in Nuxeo you update several properties and do some kind of
>>>>>>>>> object save() to flush them. Without a similar flushing concept on the
>>>>>>>>> OpenCMIS client API, I'm obliged to make a flush on every property
>>>>>>>>> write, which leads to severely degraded performance.
>>>>>>>>>
>>>>>>>>> If all method calls on a CmisObject immediately write everything
>>>>>>>>> through the network and potentially refetch a full object there will
>>>>>>>>> be many people that aren't happy with CMIS performance once they get
>>>>>>>>> to use OpenCMIS. The client API is supposed to provide some
>>>>>>>>> convenience to the user, and having a mini transient space for
>>>>>>>>> properties is IMHO the very first step of convenience. There may be
>>>>>>>>> problems with the semantics of interactions between this transient
>>>>>>>>> space and caching / refetches, but let's solve them rather than remove
>>>>>>>>> them.
>>>>>>>>>
>>>>>>>>> Dave wrote:
>>>>>>>>>>
>>>>>>>>>> For example, with a transient space, what is the behaviour when
>>>>>>>>>> setProperty has been called and an "update" method is then called prior
>>>>>>>>>> to
>>>>>>>>>> updateProperties. Are the transient changes discarded, flushed, or just
>>>>>>>>>> left
>>>>>>>>>> as is?
>>>>>>>>>
>>>>>>>>> So if I understand correctly you're talking about the case:
>>>>>>>>> 1. doc.setPropertyValue("foo", ...);
>>>>>>>>> 2. doc.updateProperties(map);
>>>>>>>>> 3. doc.setPropertyValue("bar", ...);
>>>>>>>>> 4. doc.updateProperties();
>>>>>>>>>
>>>>>>>>> And you're asking if the "foo" change is sent with 2. or with 4. or
>>>>>>>>> discarded? I'd say let's keep this undefined, as I feel that it's a
>>>>>>>>> use pattern that's not natural. If we really want to specify this then
>>>>>>>>> I have no problem mandating that the "foo" change should be sent with
>>>>>>>>> 2. by saying that updateProperties(map) is the same as
>>>>>>>>> setPropertyValue() on all the properties of the map then calling
>>>>>>>>> updateProperties() with the transient map.
>>>>>>>>>
>>>>>>>>> Florent
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> On Mon, Oct 18, 2010 at 4:05 PM, Klevenz, Stephan
>>>>>>>>> <st...@sap.com> wrote:
>>>>>>>>>>
>>>>>>>>>> Hi,
>>>>>>>>>>
>>>>>>>>>> Coming back to the cache discussion. I would like to support this
>>>>>>>>>> proposal by Dave/Florian and think we can also delete Methods on
>>>>>>>>>> Session
>>>>>>>>>> class like cancel() and save() which are currently not implemented.
>>>>>>>>>>
>>>>>>>>>> +1 for this:
>>>>>>>>>>
>>>>>>>>>>> - All write operations provided by CmisObject should automatically do
>>>>>>>>>>> an
>>>>>>>>>>> object
>>>>>>>>>>> refresh after the update. That guarantees that the object is always
>>>>>>>>>>> consistent.
>>>>>>>>>>> The cost for this consistency is an additional call to the repository.
>>>>>>>>>>
>>>>>>>>>>> - Is some cases you don't need or want this addition cost. Lets say
>>>>>>>>>>> you
>>>>>>>>>>> just
>>>>>>>>>>> want to update a bunch of objects but you don't work with them
>>>>>>>>>>> afterwards.
>>>>>>>>>>> That's what the operations provided by Session are good for. They just
>>>>>>>>>>> do
>>>>>>>>>>> that and nothing else.
>>>>>>>>>>
>>>>>>>>>> About the transient support we can design this as an optional add on
>>>>>>>>>> with
>>>>>>>>>> additional interfaces and additional implementations. With a clear
>>>>>>>>>> separation the API become easier to use.
>>>>>>>>>>
>>>>>>>>>> Regards,
>>>>>>>>>> Stephan
Re: Proposal to clarify CmisObject caching behaviour
Posted by Florian Müller <fl...@alfresco.com>.
I would like to see that sorted out soon. There are more and more users of OpenCMIS and API changes are usually painful for them. We should also consider a new release (0.2.0) when this is done.
So, where are we?
The main question is where we want to handle transient data. We have two opinions:
1. Transient and non-transient data access should be covered by the CmisObject interface. (Florent)
2. Transient data access should be covered by a new interface and non-transient data access should be covered by the CmisObject interface. (Florian)
Personally, I still want to go for option 2 since it provides cleaner semantics -- especially in multi-threaded environments.
Other opinions?
- Florian
On 08/11/2010 11:51, David Caruana wrote:
> Have we reached a conclusion on this issue? It's been a while since we last discussed.
>
> Regards,
> Dave
>
> On 22 Oct 2010, at 15:06, Florian Müller wrote:
>
>> Oh, right, there is yet another option. :)
>>
>> I support all your arguments against b), c) and d). But there are also two issues with e).
>> 1. Which value wins if a property is changed in the transient object _and_ present in the map?
>> 2. save() stores the whole object. If we make ACLs and Policies transient too (do we want that?) than updateProperties() has the side effect of storing those as well.
>>
>> Which leaves us with a) which is pretty strong. And in this case I prefer two interfaces because it much is easier to understand and provides more compile checks and less runtime surprises.
>>
>>
>> - Florian
>>
>>
>> On 22/10/2010 14:44, Florent Guillaume wrote:
>>> On Fri, Oct 22, 2010 at 3:33 PM, Florian Müller
>>> <fl...@alfresco.com> wrote:
>>>> So your proposal is to add a method getTransientObject() (or something like that) to CmisObject. And that method would return a transient, not thread-safe version of the object but with setProperty(), save(), etc. enabled?
>>>> Is that correct?
>>>
>>> Yes.
>>>
>>>> In this case we should also add a method isTransient() to CmisObject. There should be a way to discover the state of the CmisObject.
>>>
>>> Yes that would be useful.
>>>
>>>> I suggest that if the object is not transient, the transient methods should throw an IllegalStateException.
>>>
>>> Ok.
>>>
>>>> I agree that keeping the number of interfaces and classes low helps to learn and understand an API. But blending two semantics in one class could be even more confusing.
>>>> For example, what should happen if updateProperties(Map) is called on a transient object? There are multiple options:
>>>> a) updateProperties(Map) throws an exception because it only works for non-transient objects.
>>>> b) updateProperties(Map) writes instantly to the repository and the transient object is refreshed.
>>> (which btw means that transient changes are lost)
>>>> c) updateProperties(Map) writes instantly to the repository and but object keep its (now outdated) state.
>>>> d) The property map is merged with the transient properties and written when save() is called.
>>>
>>> And also:
>>> e) The property map is merged with the transient properties and then
>>> save() is automatically called.
>>>
>>>> It is not obvious. All semantics would be right and wrong at the same time.
>>>
>>> Agreed, we have to make a choice. But we would make a similar choice
>>> when deciding what methods would be available on the TransientDocument
>>> interface and what they would do.
>>>
>>> But anyway my choices in order of preference would be e) then a).
>>> I don't like b) because it loses changes.
>>> I don't like c) because there's an issue with not keeping the changes in order.
>>> I don't like d) because if you didn't do any transient operation it
>>> doesn't behave like its non-transient counterpart.
>>>
>>> Florent
>>>
>>>>
>>>>
>>>> On 22/10/2010 13:43, Florent Guillaume wrote:
>>>>> Hi,
>>>>>
>>>>> Looking back at your example:
>>>>>
>>>>> Document doc = (Document) session.getObject(id);
>>>>> TransientDocument transDoc = doc.createTransientDocument():
>>>>> transDoc.setProperty("prop1", "value1");
>>>>> transDoc.setProperty("prop2", "value2");
>>>>> transDoc.save();
>>>>>
>>>>> I agree with the need to explicitly getting a transient object if you
>>>>> need different semantics.
>>>>> One thing that will be painful though is having different classes:
>>>>> TransientCmisObject, TransientDocument, TransientFolder, etc.
>>>>> Couldn't we simply have all the methods available on the CmisObject,
>>>>> Document, Folder, etc. and make them throw
>>>>> UnsupportedOperationException when called on a non-transient object?
>>>>> This would tremendously help learning about the API and avoid juggling
>>>>> with many different interfaces for the users.
>>>>>
>>>>> Florent
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> On Mon, Oct 18, 2010 at 10:43 PM, Florian Müller
>>>>> <fl...@alfresco.com> wrote:
>>>>>> Hi Florent,
>>>>>>
>>>>>> Well, no, there would be no CmisObject.save() method. The save() method
>>>>>> would only be on the transient object.
>>>>>>
>>>>>> CmisObject would have updateProperties(Map), applyAcl(List<Ace>, List<Ace>,
>>>>>> AclPropagation), applyPolicy(ObjectId), etc. And all of them would write
>>>>>> instantly to the repository and refresh the object.
>>>>>>
>>>>>>
>>>>>> Florian
>>>>>>
>>>>>>
>>>>>> On 18/10/2010 17:49, Florent Guillaume wrote:
>>>>>>>
>>>>>>> Ok understood and agreed. There would be a new CmisObject.save() to
>>>>>>> replace updateProperties() then? That works for me as it's a less
>>>>>>> restrictive name that allows for different implementations of the
>>>>>>> transient space that don't deal with just properties.
>>>>>>>
>>>>>>> Regarding your examples I don't need to do all that, because in the
>>>>>>> Nuxeo use cases I described the client Session I'm providing to the
>>>>>>> user of the API is not a PersistentSessionImpl but a completely new
>>>>>>> Nuxeo class that does all the wrapping it needs around native Nuxeo
>>>>>>> objects. So I'm not constrained by the semantics of the current
>>>>>>> PersistentSessionImpl. It's just that I need a save()-like API to
>>>>>>> exist on the CmisObject. And of course I want to have semantics that
>>>>>>> are not too far to what's available when you use an actual remote
>>>>>>> connection using pure OpenCMIS PersistentSessionImpl.
>>>>>>>
>>>>>>> Florent
>>>>>>>
>>>>>>>
>>>>>>> On Mon, Oct 18, 2010 at 6:06 PM, Florian Müller
>>>>>>> <fl...@alfresco.com> wrote:
>>>>>>>>
>>>>>>>> Hi Florent,
>>>>>>>>
>>>>>>>> We don't want to remove the transient space entirely. The proposal is to
>>>>>>>> detach the transient from the non-transient part. We would have two
>>>>>>>> separate
>>>>>>>> objects.
>>>>>>>>
>>>>>>>> The non-transient object is always consistent, can be shared across
>>>>>>>> threads
>>>>>>>> and is cached. Changes are directly written to the repository. This
>>>>>>>> object
>>>>>>>> would have an updateProperties(Map) method that immediately refreshes the
>>>>>>>> object after the update.
>>>>>>>>
>>>>>>>> The transient object is owned by one thread and not thread safe. That
>>>>>>>> should
>>>>>>>> prevent inconsistent views on the object. This object would have
>>>>>>>> setProperty() and save() methods. Internally it would use the
>>>>>>>> non-transient
>>>>>>>> object to access all unchanged data. It's a wrapper around the
>>>>>>>> non-transient
>>>>>>>> object that holds the transient data.
>>>>>>>>
>>>>>>>> So you still could use the pattern that you are using today. The only
>>>>>>>> difference would be that you have to create a transient wrapper object.
>>>>>>>>
>>>>>>>>
>>>>>>>> That could look like this:
>>>>>>>>
>>>>>>>> Document doc = (Document) session.getObject(id);
>>>>>>>> TransientDocument transDoc = new TransientDocument(doc);
>>>>>>>>
>>>>>>>> transDoc.setProperty("prop1", "value1");
>>>>>>>> transDoc.setProperty("prop2", "value2");
>>>>>>>> transDoc.save(); // that also refreshes the underlying non-transient
>>>>>>>> object
>>>>>>>>
>>>>>>>>
>>>>>>>> Or maybe we do something like this:
>>>>>>>>
>>>>>>>> Document doc = (Document) session.getObject(id);
>>>>>>>> TransientDocument transDoc = doc.createTransientDocument():
>>>>>>>>
>>>>>>>> transDoc.setProperty("prop1", "value1");
>>>>>>>> transDoc.setProperty("prop2", "value2");
>>>>>>>> transDoc.save();
>>>>>>>>
>>>>>>>>
>>>>>>>> Florian
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>> On 18/10/2010 16:07, Florent Guillaume wrote:
>>>>>>>>>
>>>>>>>>> Hi,
>>>>>>>>>
>>>>>>>>> In Nuxeo the OpenCMIS client API is made available locally as another
>>>>>>>>> API to manipulate documents, in addition to the Nuxeo native APIs.
>>>>>>>>>
>>>>>>>>> I have a problem with removing CmisObject.updateProperties() and the
>>>>>>>>> mini transient space because for me it's quite useful. The Nuxeo
>>>>>>>>> internal non-CMIS session has a notion of a property-only transient
>>>>>>>>> space, so in Nuxeo you update several properties and do some kind of
>>>>>>>>> object save() to flush them. Without a similar flushing concept on the
>>>>>>>>> OpenCMIS client API, I'm obliged to make a flush on every property
>>>>>>>>> write, which leads to severely degraded performance.
>>>>>>>>>
>>>>>>>>> If all method calls on a CmisObject immediately write everything
>>>>>>>>> through the network and potentially refetch a full object there will
>>>>>>>>> be many people that aren't happy with CMIS performance once they get
>>>>>>>>> to use OpenCMIS. The client API is supposed to provide some
>>>>>>>>> convenience to the user, and having a mini transient space for
>>>>>>>>> properties is IMHO the very first step of convenience. There may be
>>>>>>>>> problems with the semantics of interactions between this transient
>>>>>>>>> space and caching / refetches, but let's solve them rather than remove
>>>>>>>>> them.
>>>>>>>>>
>>>>>>>>> Dave wrote:
>>>>>>>>>>
>>>>>>>>>> For example, with a transient space, what is the behaviour when
>>>>>>>>>> setProperty has been called and an "update" method is then called prior
>>>>>>>>>> to
>>>>>>>>>> updateProperties. Are the transient changes discarded, flushed, or just
>>>>>>>>>> left
>>>>>>>>>> as is?
>>>>>>>>>
>>>>>>>>> So if I understand correctly you're talking about the case:
>>>>>>>>> 1. doc.setPropertyValue("foo", ...);
>>>>>>>>> 2. doc.updateProperties(map);
>>>>>>>>> 3. doc.setPropertyValue("bar", ...);
>>>>>>>>> 4. doc.updateProperties();
>>>>>>>>>
>>>>>>>>> And you're asking if the "foo" change is sent with 2. or with 4. or
>>>>>>>>> discarded? I'd say let's keep this undefined, as I feel that it's a
>>>>>>>>> use pattern that's not natural. If we really want to specify this then
>>>>>>>>> I have no problem mandating that the "foo" change should be sent with
>>>>>>>>> 2. by saying that updateProperties(map) is the same as
>>>>>>>>> setPropertyValue() on all the properties of the map then calling
>>>>>>>>> updateProperties() with the transient map.
>>>>>>>>>
>>>>>>>>> Florent
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> On Mon, Oct 18, 2010 at 4:05 PM, Klevenz, Stephan
>>>>>>>>> <st...@sap.com> wrote:
>>>>>>>>>>
>>>>>>>>>> Hi,
>>>>>>>>>>
>>>>>>>>>> Coming back to the cache discussion. I would like to support this
>>>>>>>>>> proposal by Dave/Florian and think we can also delete Methods on
>>>>>>>>>> Session
>>>>>>>>>> class like cancel() and save() which are currently not implemented.
>>>>>>>>>>
>>>>>>>>>> +1 for this:
>>>>>>>>>>
>>>>>>>>>>> - All write operations provided by CmisObject should automatically do
>>>>>>>>>>> an
>>>>>>>>>>> object
>>>>>>>>>>> refresh after the update. That guarantees that the object is always
>>>>>>>>>>> consistent.
>>>>>>>>>>> The cost for this consistency is an additional call to the repository.
>>>>>>>>>>
>>>>>>>>>>> - Is some cases you don't need or want this addition cost. Lets say
>>>>>>>>>>> you
>>>>>>>>>>> just
>>>>>>>>>>> want to update a bunch of objects but you don't work with them
>>>>>>>>>>> afterwards.
>>>>>>>>>>> That's what the operations provided by Session are good for. They just
>>>>>>>>>>> do
>>>>>>>>>>> that and nothing else.
>>>>>>>>>>
>>>>>>>>>> About the transient support we can design this as an optional add on
>>>>>>>>>> with
>>>>>>>>>> additional interfaces and additional implementations. With a clear
>>>>>>>>>> separation the API become easier to use.
>>>>>>>>>>
>>>>>>>>>> Regards,
>>>>>>>>>> Stephan