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

[David M. Lloyd]

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.

> 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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>>>>>>> jboss-as7-dev at lists.jboss.org
>>>>>>> https://lists.jboss.org/mailman/listinfo/jboss-as7-dev
>>>>>>>
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