Ideas about OFBiz servlet filters

[Jacopo Cappellato <ja...@hotwaxsystems.com>]

A web application, in order to leverage the OFBiz framework, requires that
a series of objects are in its contexts (servlet context, session and
request) such as "delegator", "delegatorName", "dispatcher", "security"
etc. etc...
This setup is performed by the logic contained in the servlet filter
implemented by the following class:

org.apache.ofbiz.webapp.control.ContextFilter

The execution of this logic is required for the application to run properly.
However, this filter is deployed in most but not all the web application in
the OFBiz codebase: there are few exceptions due to the fact that a few web
applications require the execution of other filters (e.g. CatalogUrlFilter,
etc...).

Unfortunately the way these filters have been implemented have issues
including:
* some of them extend the ContextFilter and override its behavior by
copying some logic and adding new one; in these cases the ContextFilter is
also deployed but after the execution of the extended filter
* some of them have been copied from ContextFilter and then adapted,
introducing a lot of redundant code difficult to maintain; in these cases
the ContextFilter is not deployed

There is now a chance for the community to help cleaning up these classes
and I am proposing the following guidelines:

1) servlet filters should be chained (rather than extended or replaced)
2) ContextFilter should always be used and should always be the first
(OFBiz) filter in the chain
3) if some of the behavior/logic of ContextFilter conflicts with the ones
of other filters, then ContextFilter should be enhanced to prevent that
(e.g. we can improve the code, move some of its logic in a separate filter
that can be executed after etc...)
4) the other filters should work well after the ContextFilter and add
behavior rather than overriding behavior or duplicating behavior

As a beneficial side effect of this effort, we will get a cleaner picture
(documented by the logic of ContextFilter) of all the context objects
required by OFBiz web applications.

I hope it helps

Jacopo

Re: Ideas about OFBiz servlet filters

[Jacques Le Roux <ja...@les7arts.com>]

Thanks Jacopo,

This sounds like a plan to me. I see Jinghai is already working on the most culprits, I hope he will get this message ASAP, to avoid doing useless 
work. Then we can work together to clean the stuff

Jacques

Le 09/09/2016 � 10:07, Jacopo Cappellato a �crit :
> A web application, in order to leverage the OFBiz framework, requires that
> a series of objects are in its contexts (servlet context, session and
> request) such as "delegator", "delegatorName", "dispatcher", "security"
> etc. etc...
> This setup is performed by the logic contained in the servlet filter
> implemented by the following class:
>
> org.apache.ofbiz.webapp.control.ContextFilter
>
> The execution of this logic is required for the application to run properly.
> However, this filter is deployed in most but not all the web application in
> the OFBiz codebase: there are few exceptions due to the fact that a few web
> applications require the execution of other filters (e.g. CatalogUrlFilter,
> etc...).
>
> Unfortunately the way these filters have been implemented have issues
> including:
> * some of them extend the ContextFilter and override its behavior by
> copying some logic and adding new one; in these cases the ContextFilter is
> also deployed but after the execution of the extended filter
> * some of them have been copied from ContextFilter and then adapted,
> introducing a lot of redundant code difficult to maintain; in these cases
> the ContextFilter is not deployed
>
> There is now a chance for the community to help cleaning up these classes
> and I am proposing the following guidelines:
>
> 1) servlet filters should be chained (rather than extended or replaced)
> 2) ContextFilter should always be used and should always be the first
> (OFBiz) filter in the chain
> 3) if some of the behavior/logic of ContextFilter conflicts with the ones
> of other filters, then ContextFilter should be enhanced to prevent that
> (e.g. we can improve the code, move some of its logic in a separate filter
> that can be executed after etc...)
> 4) the other filters should work well after the ContextFilter and add
> behavior rather than overriding behavior or duplicating behavior
>
> As a beneficial side effect of this effort, we will get a cleaner picture
> (documented by the logic of ContextFilter) of all the context objects
> required by OFBiz web applications.
>
> I hope it helps
>
> Jacopo
>

Re: Ideas about OFBiz servlet filters

[Jacopo Cappellato <ja...@hotwaxsystems.com>]

I prefer to start the discussion in this list and consider to move to Jira
only in a second phase if a more structured coordination of tasks will be
useful.

Jacopo

On Fri, Sep 9, 2016 at 10:25 AM, Pierre Smits <pi...@gmail.com>
wrote:

> I hope the proposal for actionable items will materialise rather sooner
> than later in our JIRA.
>
> Best regards,
>
> Pierre Smits
>
> ORRTIZ.COM <http://www.orrtiz.com>
> OFBiz based solutions & services
>
> OFBiz Extensions Marketplace
> http://oem.ofbizci.net/oci-2/
>
> On Fri, Sep 9, 2016 at 10:23 AM, Jacopo Cappellato <
> jacopo.cappellato@hotwaxsystems.com> wrote:
>
> > And here is a proposal for some actionable items to contribute to this
> > effort:
> >
> > 1) review and document the current usage (by application) of filters
> > (classes and their order)
> > 2) review the logic in the filters and compare it to the one of
> > ContextFilter (what is different, what is added, what is duplicated
> etc...)
> > 3) identify the filters that "extends" the ContextFilter class and figure
> > out how to refactor their code to work in a filter chain where the first
> > filter is ContextFilter
> >
> > Jacopo
> >
> > On Fri, Sep 9, 2016 at 10:07 AM, Jacopo Cappellato <
> > jacopo.cappellato@hotwaxsystems.com> wrote:
> >
> > > A web application, in order to leverage the OFBiz framework, requires
> > that
> > > a series of objects are in its contexts (servlet context, session and
> > > request) such as "delegator", "delegatorName", "dispatcher", "security"
> > > etc. etc...
> > > This setup is performed by the logic contained in the servlet filter
> > > implemented by the following class:
> > >
> > > org.apache.ofbiz.webapp.control.ContextFilter
> > >
> > > The execution of this logic is required for the application to run
> > > properly.
> > > However, this filter is deployed in most but not all the web
> application
> > > in the OFBiz codebase: there are few exceptions due to the fact that a
> > few
> > > web applications require the execution of other filters (e.g.
> > > CatalogUrlFilter, etc...).
> > >
> > > Unfortunately the way these filters have been implemented have issues
> > > including:
> > > * some of them extend the ContextFilter and override its behavior by
> > > copying some logic and adding new one; in these cases the ContextFilter
> > is
> > > also deployed but after the execution of the extended filter
> > > * some of them have been copied from ContextFilter and then adapted,
> > > introducing a lot of redundant code difficult to maintain; in these
> cases
> > > the ContextFilter is not deployed
> > >
> > > There is now a chance for the community to help cleaning up these
> classes
> > > and I am proposing the following guidelines:
> > >
> > > 1) servlet filters should be chained (rather than extended or replaced)
> > > 2) ContextFilter should always be used and should always be the first
> > > (OFBiz) filter in the chain
> > > 3) if some of the behavior/logic of ContextFilter conflicts with the
> ones
> > > of other filters, then ContextFilter should be enhanced to prevent that
> > > (e.g. we can improve the code, move some of its logic in a separate
> > filter
> > > that can be executed after etc...)
> > > 4) the other filters should work well after the ContextFilter and add
> > > behavior rather than overriding behavior or duplicating behavior
> > >
> > > As a beneficial side effect of this effort, we will get a cleaner
> picture
> > > (documented by the logic of ContextFilter) of all the context objects
> > > required by OFBiz web applications.
> > >
> > > I hope it helps
> > >
> > > Jacopo
> > >
> >
>

Re: Ideas about OFBiz servlet filters

[Pierre Smits <pi...@gmail.com>]

I hope the proposal for actionable items will materialise rather sooner
than later in our JIRA.

Best regards,

Pierre Smits

ORRTIZ.COM <http://www.orrtiz.com>
OFBiz based solutions & services

OFBiz Extensions Marketplace
http://oem.ofbizci.net/oci-2/

On Fri, Sep 9, 2016 at 10:23 AM, Jacopo Cappellato <
jacopo.cappellato@hotwaxsystems.com> wrote:

> And here is a proposal for some actionable items to contribute to this
> effort:
>
> 1) review and document the current usage (by application) of filters
> (classes and their order)
> 2) review the logic in the filters and compare it to the one of
> ContextFilter (what is different, what is added, what is duplicated etc...)
> 3) identify the filters that "extends" the ContextFilter class and figure
> out how to refactor their code to work in a filter chain where the first
> filter is ContextFilter
>
> Jacopo
>
> On Fri, Sep 9, 2016 at 10:07 AM, Jacopo Cappellato <
> jacopo.cappellato@hotwaxsystems.com> wrote:
>
> > A web application, in order to leverage the OFBiz framework, requires
> that
> > a series of objects are in its contexts (servlet context, session and
> > request) such as "delegator", "delegatorName", "dispatcher", "security"
> > etc. etc...
> > This setup is performed by the logic contained in the servlet filter
> > implemented by the following class:
> >
> > org.apache.ofbiz.webapp.control.ContextFilter
> >
> > The execution of this logic is required for the application to run
> > properly.
> > However, this filter is deployed in most but not all the web application
> > in the OFBiz codebase: there are few exceptions due to the fact that a
> few
> > web applications require the execution of other filters (e.g.
> > CatalogUrlFilter, etc...).
> >
> > Unfortunately the way these filters have been implemented have issues
> > including:
> > * some of them extend the ContextFilter and override its behavior by
> > copying some logic and adding new one; in these cases the ContextFilter
> is
> > also deployed but after the execution of the extended filter
> > * some of them have been copied from ContextFilter and then adapted,
> > introducing a lot of redundant code difficult to maintain; in these cases
> > the ContextFilter is not deployed
> >
> > There is now a chance for the community to help cleaning up these classes
> > and I am proposing the following guidelines:
> >
> > 1) servlet filters should be chained (rather than extended or replaced)
> > 2) ContextFilter should always be used and should always be the first
> > (OFBiz) filter in the chain
> > 3) if some of the behavior/logic of ContextFilter conflicts with the ones
> > of other filters, then ContextFilter should be enhanced to prevent that
> > (e.g. we can improve the code, move some of its logic in a separate
> filter
> > that can be executed after etc...)
> > 4) the other filters should work well after the ContextFilter and add
> > behavior rather than overriding behavior or duplicating behavior
> >
> > As a beneficial side effect of this effort, we will get a cleaner picture
> > (documented by the logic of ContextFilter) of all the context objects
> > required by OFBiz web applications.
> >
> > I hope it helps
> >
> > Jacopo
> >
>

Re: Ideas about OFBiz servlet filters

[Jacopo Cappellato <ja...@hotwaxsystems.com>]

And here is a proposal for some actionable items to contribute to this
effort:

1) review and document the current usage (by application) of filters
(classes and their order)
2) review the logic in the filters and compare it to the one of
ContextFilter (what is different, what is added, what is duplicated etc...)
3) identify the filters that "extends" the ContextFilter class and figure
out how to refactor their code to work in a filter chain where the first
filter is ContextFilter

Jacopo

On Fri, Sep 9, 2016 at 10:07 AM, Jacopo Cappellato <
jacopo.cappellato@hotwaxsystems.com> wrote:

> A web application, in order to leverage the OFBiz framework, requires that
> a series of objects are in its contexts (servlet context, session and
> request) such as "delegator", "delegatorName", "dispatcher", "security"
> etc. etc...
> This setup is performed by the logic contained in the servlet filter
> implemented by the following class:
>
> org.apache.ofbiz.webapp.control.ContextFilter
>
> The execution of this logic is required for the application to run
> properly.
> However, this filter is deployed in most but not all the web application
> in the OFBiz codebase: there are few exceptions due to the fact that a few
> web applications require the execution of other filters (e.g.
> CatalogUrlFilter, etc...).
>
> Unfortunately the way these filters have been implemented have issues
> including:
> * some of them extend the ContextFilter and override its behavior by
> copying some logic and adding new one; in these cases the ContextFilter is
> also deployed but after the execution of the extended filter
> * some of them have been copied from ContextFilter and then adapted,
> introducing a lot of redundant code difficult to maintain; in these cases
> the ContextFilter is not deployed
>
> There is now a chance for the community to help cleaning up these classes
> and I am proposing the following guidelines:
>
> 1) servlet filters should be chained (rather than extended or replaced)
> 2) ContextFilter should always be used and should always be the first
> (OFBiz) filter in the chain
> 3) if some of the behavior/logic of ContextFilter conflicts with the ones
> of other filters, then ContextFilter should be enhanced to prevent that
> (e.g. we can improve the code, move some of its logic in a separate filter
> that can be executed after etc...)
> 4) the other filters should work well after the ContextFilter and add
> behavior rather than overriding behavior or duplicating behavior
>
> As a beneficial side effect of this effort, we will get a cleaner picture
> (documented by the logic of ContextFilter) of all the context objects
> required by OFBiz web applications.
>
> I hope it helps
>
> Jacopo
>

Re: Ideas about OFBiz servlet filters

[Pierre Smits <pi...@gmail.com>]

I like the concept.

Best regards,

Pierre Smits

ORRTIZ.COM <http://www.orrtiz.com>
OFBiz based solutions & services

OFBiz Extensions Marketplace
http://oem.ofbizci.net/oci-2/

On Fri, Sep 9, 2016 at 10:07 AM, Jacopo Cappellato <
jacopo.cappellato@hotwaxsystems.com> wrote:

> A web application, in order to leverage the OFBiz framework, requires that
> a series of objects are in its contexts (servlet context, session and
> request) such as "delegator", "delegatorName", "dispatcher", "security"
> etc. etc...
> This setup is performed by the logic contained in the servlet filter
> implemented by the following class:
>
> org.apache.ofbiz.webapp.control.ContextFilter
>
> The execution of this logic is required for the application to run
> properly.
> However, this filter is deployed in most but not all the web application in
> the OFBiz codebase: there are few exceptions due to the fact that a few web
> applications require the execution of other filters (e.g. CatalogUrlFilter,
> etc...).
>
> Unfortunately the way these filters have been implemented have issues
> including:
> * some of them extend the ContextFilter and override its behavior by
> copying some logic and adding new one; in these cases the ContextFilter is
> also deployed but after the execution of the extended filter
> * some of them have been copied from ContextFilter and then adapted,
> introducing a lot of redundant code difficult to maintain; in these cases
> the ContextFilter is not deployed
>
> There is now a chance for the community to help cleaning up these classes
> and I am proposing the following guidelines:
>
> 1) servlet filters should be chained (rather than extended or replaced)
> 2) ContextFilter should always be used and should always be the first
> (OFBiz) filter in the chain
> 3) if some of the behavior/logic of ContextFilter conflicts with the ones
> of other filters, then ContextFilter should be enhanced to prevent that
> (e.g. we can improve the code, move some of its logic in a separate filter
> that can be executed after etc...)
> 4) the other filters should work well after the ContextFilter and add
> behavior rather than overriding behavior or duplicating behavior
>
> As a beneficial side effect of this effort, we will get a cleaner picture
> (documented by the logic of ContextFilter) of all the context objects
> required by OFBiz web applications.
>
> I hope it helps
>
> Jacopo
>

Re: Ideas about OFBiz servlet filters

[Jacopo Cappellato <ja...@hotwaxsystems.com>]

In rev. 1761424 I did some additional cleanup.
Please test and report any issues you may find.

Thanks,

Jacopo

On Mon, Sep 19, 2016 at 8:44 AM, Jacopo Cappellato <
jacopo.cappellato@hotwaxsystems.com> wrote:

> Thank you Carsten,
>
> this is exactly the feedback I was looking for, very interesting.
> During the weekend I have committed additional cleanups/fixes and it would
> be great if you could test your applications with them and report any
> issues you may find.
> Over the years, several layers of changes piled up in the *Filters,
> ControlServlet, *ViewHandler, *Widget, *Login code dealing with context
> values and it has become a scary exercise to try to define the ones (and
> their rules) that should be expected and used by the applications.
> I took some risks and my recent work is a small step in that direction,
> that I am sure will be beneficial to several adopters.
> My next step is to further refactor the ContextFilter (and impacted
> artifacts) and document its behavior; I am also planning to contribute some
> unit tests for this refactored classes.
>
> Yours and anyone feedback and help is very much appreciated!
>
> Regards,
>
> Jacopo
>
> On Sat, Sep 17, 2016 at 6:22 PM, Carsten Schinzer <c....@gmail.com>
> wrote:
>
>> Great proposal, I had quite some headaches with this 2-3 years ago when I
>> was diving deep into the multitenancy with several (mini) shops and
>> content
>> sites for different tenants.. ContextFilter handles it well, but the
>> others
>> don't for the reasons you mention. I was hesitating to propose anything
>> because I did not feel safe enough with my .. .well ... workarounds. They
>> were likely not generic and robust enough under different circumstances
>> (more traffic, concurrent traffic to different sites).
>>
>> Good to have a documented guideline now.
>>
>> Thanks & regards
>>
>> Carsten
>>
>>

Re: Ideas about OFBiz servlet filters

[Jacopo Cappellato <ja...@hotwaxsystems.com>]

Thank you Carsten,

this is exactly the feedback I was looking for, very interesting.
During the weekend I have committed additional cleanups/fixes and it would
be great if you could test your applications with them and report any
issues you may find.
Over the years, several layers of changes piled up in the *Filters,
ControlServlet, *ViewHandler, *Widget, *Login code dealing with context
values and it has become a scary exercise to try to define the ones (and
their rules) that should be expected and used by the applications.
I took some risks and my recent work is a small step in that direction,
that I am sure will be beneficial to several adopters.
My next step is to further refactor the ContextFilter (and impacted
artifacts) and document its behavior; I am also planning to contribute some
unit tests for this refactored classes.

Yours and anyone feedback and help is very much appreciated!

Regards,

Jacopo

On Sat, Sep 17, 2016 at 6:22 PM, Carsten Schinzer <c....@gmail.com>
wrote:

> Great proposal, I had quite some headaches with this 2-3 years ago when I
> was diving deep into the multitenancy with several (mini) shops and content
> sites for different tenants.. ContextFilter handles it well, but the others
> don't for the reasons you mention. I was hesitating to propose anything
> because I did not feel safe enough with my .. .well ... workarounds. They
> were likely not generic and robust enough under different circumstances
> (more traffic, concurrent traffic to different sites).
>
> Good to have a documented guideline now.
>
> Thanks & regards
>
> Carsten
>
>

Re: Ideas about OFBiz servlet filters

[Carsten Schinzer <c....@gmail.com>]

Great proposal, I had quite some headaches with this 2-3 years ago when I
was diving deep into the multitenancy with several (mini) shops and content
sites for different tenants.. ContextFilter handles it well, but the others
don't for the reasons you mention. I was hesitating to propose anything
because I did not feel safe enough with my .. .well ... workarounds. They
were likely not generic and robust enough under different circumstances
(more traffic, concurrent traffic to different sites).

Good to have a documented guideline now.

Thanks & regards

Carsten

2016-09-09 10:07 GMT+02:00 Jacopo Cappellato <
jacopo.cappellato@hotwaxsystems.com>:

> A web application, in order to leverage the OFBiz framework, requires that
> a series of objects are in its contexts (servlet context, session and
> request) such as "delegator", "delegatorName", "dispatcher", "security"
> etc. etc...
> This setup is performed by the logic contained in the servlet filter
> implemented by the following class:
>
> org.apache.ofbiz.webapp.control.ContextFilter
>
> The execution of this logic is required for the application to run
> properly.
> However, this filter is deployed in most but not all the web application in
> the OFBiz codebase: there are few exceptions due to the fact that a few web
> applications require the execution of other filters (e.g. CatalogUrlFilter,
> etc...).
>
> Unfortunately the way these filters have been implemented have issues
> including:
> * some of them extend the ContextFilter and override its behavior by
> copying some logic and adding new one; in these cases the ContextFilter is
> also deployed but after the execution of the extended filter
> * some of them have been copied from ContextFilter and then adapted,
> introducing a lot of redundant code difficult to maintain; in these cases
> the ContextFilter is not deployed
>
> There is now a chance for the community to help cleaning up these classes
> and I am proposing the following guidelines:
>
> 1) servlet filters should be chained (rather than extended or replaced)
> 2) ContextFilter should always be used and should always be the first
> (OFBiz) filter in the chain
> 3) if some of the behavior/logic of ContextFilter conflicts with the ones
> of other filters, then ContextFilter should be enhanced to prevent that
> (e.g. we can improve the code, move some of its logic in a separate filter
> that can be executed after etc...)
> 4) the other filters should work well after the ContextFilter and add
> behavior rather than overriding behavior or duplicating behavior
>
> As a beneficial side effect of this effort, we will get a cleaner picture
> (documented by the logic of ContextFilter) of all the context objects
> required by OFBiz web applications.
>
> I hope it helps
>
> Jacopo
>