[jboss-as7-dev] JBoss Modules: can I dynamically add dependency?

[ssilvert at redhat.com]

On 9/24/2012 12:45 PM, David M. Lloyd wrote:
> On 09/24/2012 11:39 AM, ssilvert at redhat.com wrote:
>> On 9/24/2012 12:18 PM, Jason Greene wrote:
>>> There are two solutions to this problem.
>>>
>>> 1) Switch the interaction to use plugable constructs (common SPI (interfaces & superclasses), dynamically loaded implementation which depends on the common SPI)
>> Unfortunately, we don't control that part.  It's defined by the JSF impl.
>>> 2) Dynamically generate a module with an extra resource root to the same jar
>> That's what I wanted to do, but David says dynamic generation of modules
>> is not possible given our performance constraints.
> That's not what I said - I said the *initial* module loader is 
> static-only.  Of course modules can be dynamically generated, else our 
> deployment mechanism would not work.
Great.  In that case I'm back in business.  Is there some doco on this? 
If not I guess I'll start looking at deployment code to see how this is
done.
>
>> The only other thing I can think of is to have a tool that installs and
>> configures the modules for you.  Then the user or admin wouldn't have to
>> do it by hand.  But such a tool would get rather complex in a domain
>> configuration.
>>
>>>
>>> On Sep 24, 2012, at 10:29 AM, ssilvert at redhat.com wrote:
>>>
>>>> OK.  Thanks.
>>>>
>>>> This is alright for now because we only have two JSF impls.  But we want
>>>> to allow users to install additional impls.  So it's a little ugly to
>>>> tell them that they have to make another copy of the jsf-injection
>>>> module for each one.
>>>>
>>>>
>>>> On 9/24/2012 9:47 AM, David M. Lloyd wrote:
>>>>> On 09/24/2012 07:49 AM, ssilvert at redhat.com wrote:
>>>>>> On 9/24/2012 8:15 AM, David M. Lloyd wrote:
>>>>>>> Unfortunately this premise is flawed from the start: if you had two
>>>>>>> apps, each requiring a different JSF implementation, this idea could
>>>>>>> never work.
>>>>>> I'm not sure what you mean here.  This is already working.
>>>>>>> In any case you cannot change the dependencies of a static module at
>>>>>>> runtime.  Normally when multiple implementations are available you would
>>>>>>> use reflection to instantiate the implementation you need.  If this is
>>>>>>> not possible then you'll need a separate module for each implementation
>>>>>>> type.
>>>>>> That's the problem.  It's not that I need to instantiate something.
>>>>>> Rather, I need to put jsf-injection in a position where the JSF impl
>>>>>> will find my service and instantiate it.   So the way things are now I
>>>>>> have to statically define a new jsf-injection module for each JSF impl.
>>>>>> Those modules are exactly the same except for one dependency declaration.
>>>>> If JSF is instantiating your module via SPI or similar then yes, you
>>>>> will need to clone your classes for each implementation because you're
>>>>> statically linking to the Mojarra API (meaning at run time your modules
>>>>> are no longer exactly the same as classes have different supertypes and
>>>>> so on).
>>>>>
>>>>>> If I could programatically define the module then I wouldn't have to
>>>>>> repeat myself.
>>>>>>
>>>>>> Maybe JBoss Modules was never meant to be used that way?
>>>>> If every Mojarra implementation is statically defined as a module, then
>>>>> you will have to create separate static modules for each one.  If you're
>>>>> loading them in from a deployment then you should use the deployers' API
>>>>> for defining module dependencies to automatically tack on a copy of your
>>>>> integration classes.
>>>>>
>>>>> The reason this is so is that in order to have the very fast startup we
>>>>> have today, the initial module loader runs in a purely static environment.
>>>>>
>>>>>>> On 09/24/2012 07:06 AM, ssilvert at redhat.com wrote:
>>>>>>>> I have a module defined like this (currently in master with main and
>>>>>>>> slot="1.2):
>>>>>>>> <module xmlns="urn:jboss:module:1.1" name="org.jboss.as.jsf-injection">
>>>>>>>>       <resources>
>>>>>>>>           <resource-root
>>>>>>>> path="jboss-as-jsf-injection-7.2.0.Alpha1-SNAPSHOT.jar"/>
>>>>>>>>       </resources>
>>>>>>>>
>>>>>>>>       <dependencies>
>>>>>>>>           <module name="com.sun.jsf-impl"/>   <----- this needs to be dynamic
>>>>>>>>           <module name="javax.api"/>
>>>>>>>>           <module name="org.jboss.as.web"/>
>>>>>>>>           <module name="javax.servlet.api"/>
>>>>>>>>       </dependencies>
>>>>>>>> </module>
>>>>>>>>
>>>>>>>> Inside a DeploymentUnitProcessor, the module above is added to the
>>>>>>>> ModuleSpecification along with the module for the selected JSF
>>>>>>>> implementation.  The problem I have is that the JSF Injection code is
>>>>>>>> the same for any Mojarra implementation.  But to support multiple
>>>>>>>> implementations I need to declare a separate jsf-injection module with a
>>>>>>>> hard-coded dependency on each implementation installed.
>>>>>>>>
>>>>>>>> If I could create a module dynamically and dynamically add its
>>>>>>>> dependencies then there would be no need to create more and more modules
>>>>>>>> containing the same jsf-injection jar.
>>>>>>>>
>>>>>>>> I've been looking at the JBoss Modules API and I don't see how to do
>>>>>>>> this.  Is it possible?
>>>>>>>>
>>>>>>>> Stan
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