You are viewing a plain text version of this content. The canonical link for it is here.
Posted to user@cayenne.apache.org by "Florin T.PATRASCU" <fl...@gmail.com> on 2007/09/23 04:09:37 UTC
Best practices for using Cayenne's ObjectContext in a web framework?
Hi there,
I am trying to add Cayenne support to the JPublish web framework
(http://code.google.com/p/jpublish/) and being very new to Cayenne I
would like, if possible, to find which is the best practice for
obtaining and using the OC?
I browsed the threads here and most of the information I have show
that one of the most common solution is to use the HttpSession.
That's clear and I can do that very easy, but I wonder if there is a
better way because I would like to use Cayenne for session-less
requests as well. So, would it be prohibitive to create an OC for
every HttpRequest? aka:
ObjectContext oc = DataContext.createDataContext();
If not, would this pattern affect the server stability (memory,
handlers, threads, db pools, etc.)? What about having a global OC
instance per application?
Also, is it safe to start developing on top of the Cayenne 3.x version?
Being my first post on this forum, I would like to thank Cayenne's
creators for making it available and to you, the users, for the
useful information accumulated in this forum during the time.
Thank you,
-florin
Re: Best practices for using Cayenne's ObjectContext in a web framework?
Posted by Andrus Adamchik <an...@objectstyle.org>.
> What about having a global OC instance per application?
For read-only apps this is the way go (although switching to 3.0 is a
good idea if you go this way, as 3.0 fixes a number of
synchronization issues that affect shared context use). For read/
write apps you can't do that.
> Also, is it safe to start developing on top of the Cayenne 3.x
> version?
It depends. 3.0 is used in production by a number of people already,
so the runtime is reasonably stable. What is unstable is the API for
the new features - it can change between the milestones. If you are
comfortable with using bleeding edge API, 3.0 is definitely a good
option.
Andrus
On Sep 23, 2007, at 5:09 AM, Florin T.PATRASCU wrote:
> Hi there,
>
> I am trying to add Cayenne support to the JPublish web framework
> (http://code.google.com/p/jpublish/) and being very new to Cayenne
> I would like, if possible, to find which is the best practice for
> obtaining and using the OC?
>
> I browsed the threads here and most of the information I have show
> that one of the most common solution is to use the HttpSession.
> That's clear and I can do that very easy, but I wonder if there is
> a better way because I would like to use Cayenne for session-less
> requests as well. So, would it be prohibitive to create an OC for
> every HttpRequest? aka:
>
> ObjectContext oc = DataContext.createDataContext();
>
> If not, would this pattern affect the server stability (memory,
> handlers, threads, db pools, etc.)? What about having a global OC
> instance per application?
>
> Also, is it safe to start developing on top of the Cayenne 3.x
> version?
>
> Being my first post on this forum, I would like to thank Cayenne's
> creators for making it available and to you, the users, for the
> useful information accumulated in this forum during the time.
>
> Thank you,
> -florin
>
>
Re: Best practices for using Cayenne's ObjectContext in a web framework?
Posted by "Florin T.PATRASCU" <fl...@rogers.com>.
Hi Andrus,
I believe I found a correct balance in using the OC between Session,
Request and Application. As soon as I am done with writing the Demo
app for the new JPublish-Cayenne integration I'll also start stress
testing it and let you guys know how it goes. If I could only learn
faster the Cayenne query language :)
For example, my implementation will detect if the HttpRequest is for
an url where the Session is enabled; with JPublish one can specify
the url paths where the Session will be disabled. If there is a
Session then it will be used and the OC will follow the Session life
cycle.
If the Session is not enabled at all or the request is for an url
where the application or the programmer explicitly denies the session
creation, the OC will be created in the local thread for the Request
and passed through towards the following chained Actions and
ViewRenderer. At the end of the request, I have an "after" advice-
like Action which is just setting the OC to null:
DataContext.bindThreadDataContext(null); // using Cayenne 2.x's DC
for now, OC next
but before that is checking if there is a need for auto rolling back.
For R/O calls (as illustrated in the xml below) a global OC (per
Application) is used. This global instance is initiated when JPublish
starts and is cleaned at shutdown or on Servlet destroy event,
nothing new here.
What's nice about this is that in the same Action/Velocity/Freemarker
code, one can mix R/W with R/O Cayenne calls and I have very good
results so far :)
Most probably I will commit the code this week and I will let you
guys know in case you are curious to see how it's working, if you
don't mind.
Thanks for support guys,
-florin
On 26-Sep-07, at 04:24 , Andrus Adamchik wrote:
> Hi Florin,
>
>> Thank you for reply. Following your advice and Malcolm's -the
>> author of the CLICK web framework-, I (almost :) got a prototype
>> working.
>
> Nice.
>
>> Though I am not sure I have to do anything for the OC, after a
>> request was executed?!
>
> Probably nothing. Some people who use a session context and never
> care to preserve the state between requests, may want to rollback
> (or commit?) the session context at the end of the cycle. Not sure
> how widespread such pattern is.
>
> Andrus
>
>
> On Sep 23, 2007, at 9:38 PM, Florin T.PATRASCU wrote:
>
>> Hi Andrus,
>>
>> Thank you for reply. Following your advice and Malcolm's -the
>> author of the CLICK web framework-, I (almost :) got a prototype
>> working.
>>
>> I am configuring my module like this:
>>
>> <!--JPublish Cayenne support -->
>> <module classname="org.jpublish.module.cayenne.JPCayenneModule">
>> <cayenne-config-path>/WEB-INF/cayenne</cayenne-config-path>
>> <auto-rollback>true</auto-rollback>
>> <session-scope>false</session-scope>
>> <shared-cache>true</shared-cache>
>> <!--
>> ~ Http request paths using a per-request or a per-session
>> Cayenne ObjectContext (OC),
>> ~ the read-only paths will be interpreted first and will
>> use a global OC one defined
>> ~ per web app instance.
>> ~ -->
>> <cayenne-enabled-urls>
>> <url path="/info/*" readonly="true"/>
>> <url path="/status/*" readonly="true"/>
>> <url path="/rss/*" readonly="true"/>
>> <url path="/users/*" readonly="false"/>
>> <url path="/companies/*"/> <!--readonly="false" by
>> default, if not defined-->
>> </cayenne-enabled-urls>
>>
>> <debug>true</debug>
>> </module>
>>
>> , where the module executes Before and After Actions for a request
>> following the request path rules above. Though I am not sure I
>> have to do anything for the OC, after a request was executed?!
>>
>> And since I am not using a Filter nor an additional Servlet (so
>> the user can control the Cayenne behavior from the JPublish
>> configuration file only), I can disable/enable the use/creation of
>> the HttpSession, and when the session is disabled an "OC per
>> request" will be created, otherwise I'll use the HttpSession as
>> some of the web frameworks I was looking at are already doing it.
>>
>> For the read-only requests I will use an "OC per app" as you
>> recommended.
>>
>> Even though I am very new to Cayenne I can say already that I like
>> Cayenne :)
>>
>> Many thanks for support,
>> -florin
>>
>>
>> On 23-Sep-07, at 13:41 , Andrus Adamchik wrote:
>>
>>>> I generally use a new DataContext per thread, with a Filter
>>>> binding the DataContext to request thread.
>>>
>>> I think at some point we should update the docs for 3.0 with
>>> information discussing 3 main patterns with all drawbacks and
>>> benefits. Here is a short summary:
>>>
>>> * OC per request
>>>
>>> - no synchronization issues, smallest memory footprint
>>> - some overhead in creating a new DataContext on every request
>>> - no "local" caching (can be good or bad depending on the app)
>>> - no uncommitted state is allowed between requests
>>>
>>> * OC per session:
>>>
>>> - Potential synchronization issues on update (if the same user
>>> clicks too fast). Possible solution - nested DataContexts per
>>> request working off of a single session context. Another
>>> solution is synchronization of action methods.
>>> - efficient local cache
>>> - uncommitted state can be preserved between requests
>>>
>>> OC per app
>>>
>>> - applicable for read-only applications (no special
>>> synchronization required in this case)
>>> - very efficient local cache
>>>
>>> Andrus
>>>
>>>
>>> On Sep 23, 2007, at 2:09 PM, Malcolm Edgar wrote:
>>>> Hi Florin,
>>>>
>>>> I generally use a new DataContext per thread, with a Filter
>>>> binding the DataContext to request thread. Please see the
>>>> attached example.
>>>>
>>>> regards Malcolm Edgar
>>>> http://click.sourceforge.net
>>>>
>>>> On 9/23/07, Florin T.PATRASCU <fl...@gmail.com> wrote:
>>>> Hi there,
>>>>
>>>> I am trying to add Cayenne support to the JPublish web framework
>>>> ( http://code.google.com/p/jpublish/) and being very new to
>>>> Cayenne I
>>>> would like, if possible, to find which is the best practice for
>>>> obtaining and using the OC?
>>>>
>>>> I browsed the threads here and most of the information I have show
>>>> that one of the most common solution is to use the HttpSession.
>>>> That's clear and I can do that very easy, but I wonder if there
>>>> is a
>>>> better way because I would like to use Cayenne for session-less
>>>> requests as well. So, would it be prohibitive to create an OC for
>>>> every HttpRequest? aka:
>>>>
>>>> ObjectContext oc = DataContext.createDataContext();
>>>>
>>>> If not, would this pattern affect the server stability (memory,
>>>> handlers, threads, db pools, etc.)? What about having a global OC
>>>> instance per application?
>>>>
>>>> Also, is it safe to start developing on top of the Cayenne 3.x
>>>> version?
>>>>
>>>> Being my first post on this forum, I would like to thank Cayenne's
>>>> creators for making it available and to you, the users, for the
>>>> useful information accumulated in this forum during the time.
>>>>
>>>> Thank you,
>>>> -florin
>>>
>>
>>
>
Re: Best practices for using Cayenne's ObjectContext in a web framework?
Posted by Andrus Adamchik <an...@objectstyle.org>.
Hi Florin,
> Thank you for reply. Following your advice and Malcolm's -the
> author of the CLICK web framework-, I (almost :) got a prototype
> working.
Nice.
> Though I am not sure I have to do anything for the OC, after a
> request was executed?!
Probably nothing. Some people who use a session context and never
care to preserve the state between requests, may want to rollback (or
commit?) the session context at the end of the cycle. Not sure how
widespread such pattern is.
Andrus
On Sep 23, 2007, at 9:38 PM, Florin T.PATRASCU wrote:
> Hi Andrus,
>
> Thank you for reply. Following your advice and Malcolm's -the
> author of the CLICK web framework-, I (almost :) got a prototype
> working.
>
> I am configuring my module like this:
>
> <!--JPublish Cayenne support -->
> <module classname="org.jpublish.module.cayenne.JPCayenneModule">
> <cayenne-config-path>/WEB-INF/cayenne</cayenne-config-path>
> <auto-rollback>true</auto-rollback>
> <session-scope>false</session-scope>
> <shared-cache>true</shared-cache>
> <!--
> ~ Http request paths using a per-request or a per-session
> Cayenne ObjectContext (OC),
> ~ the read-only paths will be interpreted first and will
> use a global OC one defined
> ~ per web app instance.
> ~ -->
> <cayenne-enabled-urls>
> <url path="/info/*" readonly="true"/>
> <url path="/status/*" readonly="true"/>
> <url path="/rss/*" readonly="true"/>
> <url path="/users/*" readonly="false"/>
> <url path="/companies/*"/> <!--readonly="false" by
> default, if not defined-->
> </cayenne-enabled-urls>
>
> <debug>true</debug>
> </module>
>
> , where the module executes Before and After Actions for a request
> following the request path rules above. Though I am not sure I have
> to do anything for the OC, after a request was executed?!
>
> And since I am not using a Filter nor an additional Servlet (so the
> user can control the Cayenne behavior from the JPublish
> configuration file only), I can disable/enable the use/creation of
> the HttpSession, and when the session is disabled an "OC per
> request" will be created, otherwise I'll use the HttpSession as
> some of the web frameworks I was looking at are already doing it.
>
> For the read-only requests I will use an "OC per app" as you
> recommended.
>
> Even though I am very new to Cayenne I can say already that I like
> Cayenne :)
>
> Many thanks for support,
> -florin
>
>
> On 23-Sep-07, at 13:41 , Andrus Adamchik wrote:
>
>>> I generally use a new DataContext per thread, with a Filter
>>> binding the DataContext to request thread.
>>
>> I think at some point we should update the docs for 3.0 with
>> information discussing 3 main patterns with all drawbacks and
>> benefits. Here is a short summary:
>>
>> * OC per request
>>
>> - no synchronization issues, smallest memory footprint
>> - some overhead in creating a new DataContext on every request
>> - no "local" caching (can be good or bad depending on the app)
>> - no uncommitted state is allowed between requests
>>
>> * OC per session:
>>
>> - Potential synchronization issues on update (if the same user
>> clicks too fast). Possible solution - nested DataContexts per
>> request working off of a single session context. Another solution
>> is synchronization of action methods.
>> - efficient local cache
>> - uncommitted state can be preserved between requests
>>
>> OC per app
>>
>> - applicable for read-only applications (no special
>> synchronization required in this case)
>> - very efficient local cache
>>
>> Andrus
>>
>>
>> On Sep 23, 2007, at 2:09 PM, Malcolm Edgar wrote:
>>> Hi Florin,
>>>
>>> I generally use a new DataContext per thread, with a Filter
>>> binding the DataContext to request thread. Please see the
>>> attached example.
>>>
>>> regards Malcolm Edgar
>>> http://click.sourceforge.net
>>>
>>> On 9/23/07, Florin T.PATRASCU <fl...@gmail.com> wrote:
>>> Hi there,
>>>
>>> I am trying to add Cayenne support to the JPublish web framework
>>> ( http://code.google.com/p/jpublish/) and being very new to
>>> Cayenne I
>>> would like, if possible, to find which is the best practice for
>>> obtaining and using the OC?
>>>
>>> I browsed the threads here and most of the information I have show
>>> that one of the most common solution is to use the HttpSession.
>>> That's clear and I can do that very easy, but I wonder if there is a
>>> better way because I would like to use Cayenne for session-less
>>> requests as well. So, would it be prohibitive to create an OC for
>>> every HttpRequest? aka:
>>>
>>> ObjectContext oc = DataContext.createDataContext();
>>>
>>> If not, would this pattern affect the server stability (memory,
>>> handlers, threads, db pools, etc.)? What about having a global OC
>>> instance per application?
>>>
>>> Also, is it safe to start developing on top of the Cayenne 3.x
>>> version?
>>>
>>> Being my first post on this forum, I would like to thank Cayenne's
>>> creators for making it available and to you, the users, for the
>>> useful information accumulated in this forum during the time.
>>>
>>> Thank you,
>>> -florin
>>
>
>
Re: Best practices for using Cayenne's ObjectContext in a web framework?
Posted by "Florin T.PATRASCU" <fl...@rogers.com>.
Hi Andrus,
Thank you for reply. Following your advice and Malcolm's -the author
of the CLICK web framework-, I (almost :) got a prototype working.
I am configuring my module like this:
<!--JPublish Cayenne support -->
<module classname="org.jpublish.module.cayenne.JPCayenneModule">
<cayenne-config-path>/WEB-INF/cayenne</cayenne-config-path>
<auto-rollback>true</auto-rollback>
<session-scope>false</session-scope>
<shared-cache>true</shared-cache>
<!--
~ Http request paths using a per-request or a per-session
Cayenne ObjectContext (OC),
~ the read-only paths will be interpreted first and will
use a global OC one defined
~ per web app instance.
~ -->
<cayenne-enabled-urls>
<url path="/info/*" readonly="true"/>
<url path="/status/*" readonly="true"/>
<url path="/rss/*" readonly="true"/>
<url path="/users/*" readonly="false"/>
<url path="/companies/*"/> <!--readonly="false" by
default, if not defined-->
</cayenne-enabled-urls>
<debug>true</debug>
</module>
, where the module executes Before and After Actions for a request
following the request path rules above. Though I am not sure I have
to do anything for the OC, after a request was executed?!
And since I am not using a Filter nor an additional Servlet (so the
user can control the Cayenne behavior from the JPublish configuration
file only), I can disable/enable the use/creation of the HttpSession,
and when the session is disabled an "OC per request" will be created,
otherwise I'll use the HttpSession as some of the web frameworks I
was looking at are already doing it.
For the read-only requests I will use an "OC per app" as you
recommended.
Even though I am very new to Cayenne I can say already that I like
Cayenne :)
Many thanks for support,
-florin
On 23-Sep-07, at 13:41 , Andrus Adamchik wrote:
>> I generally use a new DataContext per thread, with a Filter
>> binding the DataContext to request thread.
>
> I think at some point we should update the docs for 3.0 with
> information discussing 3 main patterns with all drawbacks and
> benefits. Here is a short summary:
>
> * OC per request
>
> - no synchronization issues, smallest memory footprint
> - some overhead in creating a new DataContext on every request
> - no "local" caching (can be good or bad depending on the app)
> - no uncommitted state is allowed between requests
>
> * OC per session:
>
> - Potential synchronization issues on update (if the same user
> clicks too fast). Possible solution - nested DataContexts per
> request working off of a single session context. Another solution
> is synchronization of action methods.
> - efficient local cache
> - uncommitted state can be preserved between requests
>
> OC per app
>
> - applicable for read-only applications (no special
> synchronization required in this case)
> - very efficient local cache
>
> Andrus
>
>
> On Sep 23, 2007, at 2:09 PM, Malcolm Edgar wrote:
>> Hi Florin,
>>
>> I generally use a new DataContext per thread, with a Filter
>> binding the DataContext to request thread. Please see the
>> attached example.
>>
>> regards Malcolm Edgar
>> http://click.sourceforge.net
>>
>> On 9/23/07, Florin T.PATRASCU <fl...@gmail.com> wrote:
>> Hi there,
>>
>> I am trying to add Cayenne support to the JPublish web framework
>> ( http://code.google.com/p/jpublish/) and being very new to Cayenne I
>> would like, if possible, to find which is the best practice for
>> obtaining and using the OC?
>>
>> I browsed the threads here and most of the information I have show
>> that one of the most common solution is to use the HttpSession.
>> That's clear and I can do that very easy, but I wonder if there is a
>> better way because I would like to use Cayenne for session-less
>> requests as well. So, would it be prohibitive to create an OC for
>> every HttpRequest? aka:
>>
>> ObjectContext oc = DataContext.createDataContext();
>>
>> If not, would this pattern affect the server stability (memory,
>> handlers, threads, db pools, etc.)? What about having a global OC
>> instance per application?
>>
>> Also, is it safe to start developing on top of the Cayenne 3.x
>> version?
>>
>> Being my first post on this forum, I would like to thank Cayenne's
>> creators for making it available and to you, the users, for the
>> useful information accumulated in this forum during the time.
>>
>> Thank you,
>> -florin
>
Re: Best practices for using Cayenne's ObjectContext in a web framework?
Posted by Andrus Adamchik <an...@objectstyle.org>.
> I generally use a new DataContext per thread, with a Filter
> binding the DataContext to request thread.
I think at some point we should update the docs for 3.0 with
information discussing 3 main patterns with all drawbacks and
benefits. Here is a short summary:
* OC per request
- no synchronization issues, smallest memory footprint
- some overhead in creating a new DataContext on every request
- no "local" caching (can be good or bad depending on the app)
- no uncommitted state is allowed between requests
* OC per session:
- Potential synchronization issues on update (if the same user
clicks too fast). Possible solution - nested DataContexts per
request working off of a single session context. Another solution is
synchronization of action methods.
- efficient local cache
- uncommitted state can be preserved between requests
OC per app
- applicable for read-only applications (no special
synchronization required in this case)
- very efficient local cache
Andrus
On Sep 23, 2007, at 2:09 PM, Malcolm Edgar wrote:
> Hi Florin,
>
> I generally use a new DataContext per thread, with a Filter binding
> the DataContext to request thread. Please see the attached example.
>
> regards Malcolm Edgar
> http://click.sourceforge.net
>
> On 9/23/07, Florin T.PATRASCU <fl...@gmail.com> wrote: Hi
> there,
>
> I am trying to add Cayenne support to the JPublish web framework
> ( http://code.google.com/p/jpublish/) and being very new to Cayenne I
> would like, if possible, to find which is the best practice for
> obtaining and using the OC?
>
> I browsed the threads here and most of the information I have show
> that one of the most common solution is to use the HttpSession.
> That's clear and I can do that very easy, but I wonder if there is a
> better way because I would like to use Cayenne for session-less
> requests as well. So, would it be prohibitive to create an OC for
> every HttpRequest? aka:
>
> ObjectContext oc = DataContext.createDataContext();
>
> If not, would this pattern affect the server stability (memory,
> handlers, threads, db pools, etc.)? What about having a global OC
> instance per application?
>
> Also, is it safe to start developing on top of the Cayenne 3.x
> version?
>
> Being my first post on this forum, I would like to thank Cayenne's
> creators for making it available and to you, the users, for the
> useful information accumulated in this forum during the time.
>
> Thank you,
> -florin
Re: Best practices for using Cayenne's ObjectContext in a web framework?
Posted by Malcolm Edgar <ma...@gmail.com>.
Hi Florin,
I generally use a new DataContext per thread, with a Filter binding the
DataContext to request thread. Please see the attached example.
regards Malcolm Edgar
http://click.sourceforge.net
On 9/23/07, Florin T.PATRASCU <fl...@gmail.com> wrote:
>
> Hi there,
>
> I am trying to add Cayenne support to the JPublish web framework
> (http://code.google.com/p/jpublish/) and being very new to Cayenne I
> would like, if possible, to find which is the best practice for
> obtaining and using the OC?
>
> I browsed the threads here and most of the information I have show
> that one of the most common solution is to use the HttpSession.
> That's clear and I can do that very easy, but I wonder if there is a
> better way because I would like to use Cayenne for session-less
> requests as well. So, would it be prohibitive to create an OC for
> every HttpRequest? aka:
>
> ObjectContext oc = DataContext.createDataContext();
>
> If not, would this pattern affect the server stability (memory,
> handlers, threads, db pools, etc.)? What about having a global OC
> instance per application?
>
> Also, is it safe to start developing on top of the Cayenne 3.x version?
>
> Being my first post on this forum, I would like to thank Cayenne's
> creators for making it available and to you, the users, for the
> useful information accumulated in this forum during the time.
>
> Thank you,
> -florin
>
>