I'm not sure it will ever be necessary to support multiple containers in a single application. I wouldn't use Spring if I was using Pico and vice versa, and there could also be issues with cross-container dependancies.
I also think that enabling the resolver to resolve all dependencies is a good thing. If you wanted to remove knowledge of the InvocationAction, you could always pass-in a 'bean' and a list/array of references to resolve.
And you could even extend the ExternalReferenceResolver with an addional method -
public Object resolveReference(ExternalReference ref)
to allow for single component lookups, thus splitting the resolveReferences method into two methods.
I think the configuration is now much cleaner, declaring the resolver in an element rather than attribute.
Cheers,
Ross
Mike Cannon-Brookes wrote:
I talked to him about this on ICQ actually.
It does make it more flexible and powerful, but also more complex. I'm not sure that complexity is needed (even Cameron himself says he doesn't need it), so can we add it when/if someone requests it? :)
As for the resolver resolving one reference at once, I'm not sure I like that either. You should leave the resolution logic up to the Resolver class not the Interceptor IMHO, so you can do things like <external-ref ref="all" /> and your customer resolver class then knows to resolve _all_ references.
Overall though, the init params etc work just like the rest of WW, so as long as they're all optional (and it works with just one resolver and simple references) I don't really mind as I can keep my side simple.
My $0.02 :)
M
On 13/12/03 3:42 AM, "Jason Carreira" ([EMAIL PROTECTED]) penned the words:
So Mike,
You guys developed the external-ref stuff, what do you think of Cameron's changes? It sounds like he made it more flexible and powerful to me...
-----Original Message----- From: Mike Cannon-Brookes [mailto:[EMAIL PROTECTED] Sent: Friday, December 12, 2003 4:51 AM To: [EMAIL PROTECTED] Subject: Re: [OS-webwork] [OS-xwork] Spring IoC integration
Francois,
:)
As for why it's required, it makes everything more flexible - and it's not required at all. Just ignore it and it will do you no harm.
Pico is good (for somethings) but personally I much prefer Spring (that's a large debate for another time - each to their own) :)
- XWorks IoC container requires interfaces on your actions. - Pico requires a custom constructor and your own factories. - Spring requires external references (in one way)
You can also use Spring exactly like Pico if you want (using constructors), but I actually like the explicitly defined contracts that the external references give you.
Basically treat an external reference as a chance for some code to resolve references on the action (IoC is just one use for them) at a user defined time (you can't do this with Pico - it's a constructor, it's done when the object is constructed). With the ExternalReferenceInterceptor it's a part of the interceptor chain, so I can govern when those references are resolved (before Params? After Params? After Validation?) I have control.
Anyway - some thoughts - don't get fooled by the Pico folk, it's not the be-all-and-end-all of IoC - it's just one solution. :)
M
On 12/12/03 6:15 PM, "Francois Beauregard" ([EMAIL PROTECTED]) penned the words:
Why all of this external reference resolver thing gets into XWork?
Couldn't you just extend DefaultActionProxyFactory, DefaultActionInvocation and do whatever logic to integrate with the IoC container and/or use an interceptor?
Even XWorks own IoC container does not need this kind of
modification
to XWork.xml, it looks like it only needs an interceptor and stores its configuration in an xml file.
You can also have a look at PicoContainer's integration (in NanoContainer), it is neatly done.
Cheers, ___________________________ François Beauregard, b.ing. Vice-président Recherche et développement Pyxis Technologies www.pyxis-tech.com
T : (450) 681-9094, poste 102 F : (450) 681-5758 [EMAIL PROTECTED]
-----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
Behalf Of
Cameron Braid Sent: December 12, 2003 1:32 AM To: [EMAIL PROTECTED] Subject: Re: [OS-webwork] [OS-xwork] Spring IoC integration
It looks like noone else is interested in discussing this.
I have refactored xwork so that the external refrence resolvers are defined as described below
<xwork> <package name='test' extends='webwork-default'>
<external-resolvers> <external-resolver name="test" class="com.opensymphony.xwork.config.TestExternalReferenceResolver"> <param name='stringParam'>stringParamValue</param> </external-resolver> <external-resolver name="test2"
class="com.opensymphony.xwork.config.Test2ExternalReferenceResolver"/>
</external-resolvers>
<default-external-resolver-ref name='test'/>
<action name="TestExternalRefResolver3" class="com.opensymphony.xwork.ExternalReferenceAction"> <external-ref required="true"
name="Boo">myBoo</external-ref>
<interceptor-ref name="debugStack"/> <interceptor-ref name="defaultStack"/> </action>
<!-- test where external-resolver-ref overrides the package's resolver --> <action name="TestExternalRefResolver5" class="com.opensymphony.xwork.ExternalReferenceAction"> <external-ref name="foo" external-resolver-ref='test2'>myFoo</external-ref> <interceptor-ref name="debugStack"/> <interceptor-ref name="defaultStack"/> </action>
</package> </xwork>
I have updated the test cases to use this new structure, and added tests for the new features.
This has required that the ExternalReferenceResolver interface be changed a little bit, simplifying the implementation.
Previousally ExternalReferenceResolver.resolveReferences(..) had to resolve all external refrences for an action, where as now it just resolves a single refrence at a time.
public interface ExternalReferenceResolver { public void resolveReferences(ActionInvocation invocation, ExternalReference reference) throws ReferenceResolverException; }
This simplifies the implemetation of the resolver because
it doesn't
need to know about the ActionConfig at all, since ExternalReference contains the action property name, the external ref string and the required boolean.
It is the responsiblity of the
ExternalReferencesInterceptor to call
the relevant resolver for each <external-ref> tag for the action.
I can add a Jira task, and attach the patch if anyone is
interested.
I would prefer that this code gets added before the final release.
Cameron.
Cameron Braid wrote:
Ross Mason wrote:
Cameron Braid wrote:
Ross Mason wrote:
Cameron Braid wrote:
I have downloaded and integrated this code though and
the tests
run perfectly (after creating my my own ServletContextAware interface and removing refrences to the confluence packages)
I really like the work that you have done. Though I think some more work is required to be able to integrate into
xwork/webwork
Cool!
I can't see how the servlet context is set onto the SpringServletContextReferenceResolver or the
ApplicationContext
is set onto the SpringApplicationContextReferenceResolver (depending on the one that is used)
you construct the ExternalReferenceResolver using this
code, and
immediately add it to the package config.
Class erResolverClazz = ClassLoaderUtil.loadClass(externalReferenceResolver, ExternalReferenceResolver.class); erResolver = (ExternalReferenceResolver) erResolverClazz.newInstance();
I guess that the ServletContextAware interface could
be added to
webwork, though the question remains - how is the ServletContextAware.setServletContext(..) method going to get called ?
We could use a ServletContextListener to set the
contexts on our
resolvers... Could we access the packageConfig from a listener?
Yeah I guess we could, though this starts to get ugly when each different resolver needs its own listener that is bound to the action config api.
You only need one listener to set the Servlet context on all Resolvers that are ServletContextAware. I'll attach the one I'm using to the issue.
Sounds like we need to get the DefaultComponentManager to
bootstrap
the external refrence resolvers ;)
Actually... my point here was that each type of resolver... ie the spring one, the XXXFramework one and any other framework
integration
one will require someone to code a specific
ConfigurerListener to set
any external resources that the resolver requires. I think that if this can be done with simple parameter based configuration then it will be a lot simpler.
I propost the following soloution :
1 : have different SpringXXXReferenceResolver classes in xwork and webwork like this :
xwork :
Spring/ClassPathXmlApplicationContext/ReferenceResolver
or a Spring/FileSystemXmlApplicationContext/ReferenceResolver
webwork :
Spring/WebApplicationContext/ReferenceResolver - using
WebApplicationContextUtils.getWebApplicationContext(ServletActionConte
xt.get ServletContext())
to obtain the application context
I agree, we should have different implementations,
separated like
this. In my test case I have provided a Spring/XmlFileApplicationContext, so we could just
refactor that
out.
Certainly can.
This works find for webwork based apps, though for xwork based apps that the SpringClassPathXmlApplicationContextReferenceResolver and SpringFileSystemXmlApplicationContextReferenceResolver require configuration to specify the filename.. therfore step two is required :
2 : allow for external refrence resolvers to be
declards by name,
class and to be parameterizable like interceptors.
the refer to
the by name instead of className
e.g. :
<xwork> <package ... externalReferenceResolver="spring"> .... <!-- NEW FEATURE : new node set --> <externalRefrenceResolvers> <externalRefrenceResolver name='spring' class="SpringWebApplicationContextReferenceResolver"/> <externalRefrenceResolver name='springXmlFile' class="SpringClassPathXmlApplicationContextReferenceResolver"> <param
name="filename">myApplicationContext.xml</param>
</externalRefrenceResolver > </externalRefrenceResolvers> .... <action name='...' class='...'>
<!-- NEW FEATURE : externalRefrenceResolver
attribute -->
<external-ref
externalRefrenceResolver='springXmlFile'
name='foo'>myFoo</external-ref> <external-ref name='bar'>myBar</external-ref> </action> </package> </xwork>
this allows for reusing the same configured resolver
in multiple
packages - which you can do now, though without configuration. this allows for each external-ref tag to optionally use a different resolver as in the example above
Ok that looks like it would work, I think we should declare resolvers the way you suggested. Though I don't think
we need then
externalReferenceResolver attrib on the external-ref
element. We
can just assume all actions in a package use the same
Resolver. I
think it's neater that way; You can still use different
Containers
on different packages to resolve your references and
there would
be a more logical grouping of package/container.
I agree that is is not necessary to allow the resolver to be overriden per external-ref though I think it could be a usefull feature to have. Say you are using a thirs party spring based component package - say for security - and you want
each action's
securityManager property to be resolved from this
context instead
of the package's one.
I guess that another way of specifying it would be to use
<external-ref name='foo'>springXmlFile:myFoo</external-ref>
and to modify the interceptor to look for the : char.
just my 2c worth ;)
See your point, I guess we need to throw the notation up for discussion.
I don't really mind the syntax for specifying which
resolver to use.
SO there are two questions
1. Do we need to be able to override the resolver on a per
refrence
basis 2. If we can override, what is the syntax ?
Does anyone else have any thoughs or suggestions ?
I am sure that other frameworks will require some sort
of runtime
configuration for the external reference resolvers as well.
Any comments ?
yep!
Cameron
Cheers,
ross
Thanks
Cameron
Ross Mason wrote:
Cheers mate.
I've just attached the SpringExternalReferenceResolver implmentation and tests to the Jira Issue.
http://jira.opensymphony.com/secure/ViewIssue.jspa?key=XW-122
Ross
Patrick Lightbody wrote:
This is good stuff -- not sure about a 1.0 release though. We'll try to get a point release out shortly after though to support this.
-----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Ross Mason Sent: Monday, November 17, 2003 8:02 PM To: [EMAIL PROTECTED] Subject: Re: [OS-webwork] [OS-xwork] Spring IoC integration
I'll fix the commons dependancies first :-)
Ross Mason wrote:
I've tried running the patch again (through
Eclipse) and I get
the
same
problem - It only creates patch entries for new
files? I know
this isn't a subject for this list, but does anyone
know why
this happens?
Anyway Cameron, I'll create a zip of the changes
for now and
attach
it
to the the issue and this list.
Cheers,
Ross
Cameron Braid wrote:
The patch seems to be missing code in the configuration classes... since I have applied it, I am geting
compilation
errors :
not defined :
invocation.getProxy().getConfig().getPackageName() invocation.getProxy().getConfig().getExternalRefs(); packageConfig.getExternalRefResolver()
Thanks,
Cameron
Ross Mason wrote:
Hi,
As per the discussion late last week, we have a patch for Xwork so that it can use an external container to resolve component
references.
I've created the following issue -
http://jira.opensymphony.com/secure/ViewIssue.jspa?key=XW-12
2
I've added a breakdown of the changes below, in summary, this is how
it works-
You can configure a action to have external references in the xwork.xml using a new <external-ref> tag on the action
When the action is configured the external refs
are stored
on the action config.
When the action is invoked, there is a new
interceptor that
will resolve these references. It does this by
using a new
externalReferenceResolver="com.atlassian.xwork.ext.SpringServletContexattribute on the package config called externalReferenceResolver i.e.
<package name="default"
tR
eferenceResolver">
In this case, the SpringServletContextReferenceResolver implementation will handle the work of looking up and setting the references on the action. Note, if a
resolver is
not found on the actions package, it will
tranverse up the
package heirarchy to find one.
We have an implementation for Spring, but I have not included it in this patch as it should probably
go into an
xwork-ext sub-project. Let me know what you want
me to do
with this...
Here are the changes and additions to the xwork codebase -
1. added 2 new config attributes - - a new element external-ref to the action element in the
config.
i.e <external-ref name="foo">Foo</external-ref>
where name
is the setter method name and Foo is the reference to lookup. - added an attribute to the package element called externalReferenceResolver which supplies a FQ
classname to
an ExternalReferenceResolver implementation.
2. Updated the xwork DTD accordingly.
3. Added 4 new classes - - External Reference - an encapsulation of the
external-ref
tag - ExternalReferenceResolver - an interface to provide implementations for resolving references from an external container - ExternalReferencesInterceptor - will resolve
references on a
given
ActionInvocation - ReferenceResolverException - thrown by ExternalReferenceResolver
4. Added support for external references to the ActionConfig. I also
added the attribute packageName to the
ActionConfig, so that
the Interceptor could determine which package the action belonged to in order to find the
externalReferenceResolver.
5. Added support for the
externalReferenceResolver attribute
to the PackageConfig.
6. Added support for the extra configuration to the XMLConfigurationProvider and DefaultConfigurationProvider
7. Added tests in the
org.opensymphony.xwork.config.ExternalReferenceResolverTest
I've attached a cvs patch with all the changes.
I built the
patch against the latest src.
Cheers,
Ross
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