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[jsr236-spec users] [jsr236-experts] Re: Feedback

  • From: Anthony Lai < >
  • To:
  • Subject: [jsr236-spec users] [jsr236-experts] Re: Feedback
  • Date: Thu, 29 Nov 2012 12:57:44 -0800
  • List-id: <jsr236-experts.concurrency-ee-spec.java.net>

Thanks for the feedback.

If nobody objects, I can start working on adding default instances support for MES, MSES, ContextService, and MTF.

Agree that Naming, classloader, and security are good candidates as standard context. We can use these as the set of default set of contexts to be propagated.

To clarify "Container Context", how about rewriting this paragraph in section 2.3

"The contexts to be propagated are governed by the container but typically include naming context, class loader and security information."

with

"The contexts to be propagated includes naming context, class loader, and security information. Container must support propagation of these context types. In addition, containers can choose to support propagation of other types of context."

Regarding the issue of requiring JSR 236 objects to be bound to the java:comp/env/concurrent subcontext. I checked with Linda, the spec lead for Java EE 7, and she says that is not consistent with the other resource types. So I suggest that we should keep it as a recommendation.

About defining resources via annotations. Looks like we don't have an agreement yet. Let's see if we get more feedback from other experts.

Regards
Anthony



On 11/28/12 7:36 AM, Nathan Rauh wrote:
" type="cite">I really like the idea of default instances that would be consistent with other resource types in EE 7 as Anthony pointed out.   For the majority of apps, this would provide a simple, zero-configuration way to use ManagedExecutorService/ScheduledExecutorService/ContextService/ThreadFactory that is easily and straightforwardly overridable by the deployer.  Writing this up would just involve copying from EE 7 section 5.20 or 5.21 and replacing with the JSR 236 resource types, but on top of that I would recommend that we standardize a minimum set of contexts that must be propagated by the default instances, provided the container supports those contexts.  Naming/classloader/security as mentioned previously would make sense.

I would prefer that we not take the approach of having annotations that define new instances, which in the case of @ManagedExecutorService/@ManagedScheduledExecutorService results in a proliferation of separate thread pools across applications.  I would prefer not to see applications managing their own thread pools, but in the cases where it truly is necessary, the ability to use ThreadFactory (and ContextService) with the Java SE executors already allows for that.

Nathan Rauh
____________________________________________
Software Engineer, WebSphere Application Server
IBM Rochester Bldg 002-2 C111
3605 Highway 52N
Rochester, MN 55901-7802




From:        Frederick W Rowe/Raleigh/IBM@IBMUS
To:         ">
Date:        11/28/2012 07:14 AM
Subject:        [jsr236-experts] Re: Feedback




All,

Wrt to Adam's comments and Anthony's responses/questions.


3.  The terminology of the original comment is somewhat confusing: "start with the injection of plain Executor services managed by the container."  Isn't a plain Executor service managed by the container simply a ManagedExecutorService?  Is the proposal that the scope of the JSR be reduced to simply supporting MES?  I think MES by itself is useful without ContextService ONLY if there is a standard set of contexts propagated by default.  This goes back to my proposal earlier this year to make MES required and the other three APIs optional.  The problem with the default propagation of contexts is that we never got enough feedback on the discussion started by Nathan on an earlier thread of what that set of contexts was.


4. The comment: "Often mentioned "Container Context" is not clearly defined."  The intent of section 2.3,  Container Thread Context, is to define that, please make specific change proposals for that section to address any shortcomings.  As mentioned above however, there is not yet a general consensus of a finite set of contexts, so it is possible that simply listing all of the contexts currently known to the EG is the best we can do.


5. The comment: "We should reduce optional things. E.g. jndi names etc.", is misleading, JNDI names are mandatory:

JNDI name
: The arbitrary, but required, name to identify the service instance. The deployer uses this
value to map the service to the component’s resource environment reference.

What is not mandatory is the namespace into which they are bound.  If the proposal is to require the use of a specific namespace subcontext (like
java:comp/env/concurrent), I'm ok with that.
I think that defining annotations for the managed objects is a good idea and fairly easy to do.  Does someone want to make a proposal of what those would look like?


Separate from that discussion, please correct the following inconsistency in the document:

2.3.1.1 Optional Contextual Invocation Points

...

Configuration option Callback-Context is available in
ManagedExecutorService and
...


should state:

...

Configuration option
Contextual-Callback is available in ManagedExecutorService and
...


Regards,

Fred Rowe

WebSphere Architect
Senior Software Engineer
IBM Software Group
">


Anthony Lai ">< >

11/27/2012 04:48 PM

Please respond to
jsr236-experts

To
"> , Adam Bien ">< >
cc

Subject
[jsr236-experts] Re: Feedback









Hi Adam,

1. DI of resources
Thanks for pointing this out. I have fixed the incorrect usages of DI in the Early Draft.

2. Injection without XML confiuguration
Which instance should be injected without any configuration? Should the container inject some default instance similar to the "default Data Source" and "default JMS Connection" mechanism as described in sections 5.20 and 5.21 in the Java EE 7 spec?

3. Reduce the scope and start with the injection of plain Executor services
What do other experts feel about reducing the scope?

4. "Container Context" not clearly defined
The spec provides examples of what are the possible container context that could be propagated, such as naming context, class loader, security. It is up to the container to decide what context to be propagated. I guess this falls into the same issue as your next point about reducing optional things. Perhaps we should identify the common context and standardize them. I think JNDI and security would be the candidates.

I would think transaction is typically not one of the context to be propagated.

5. Reduce optional things
You suggested that we should require, instead of just recommend, that resources to be bound in the java:comp/env/concurrent subcontext. I saw a few examples in the Java EE spec that tends to provide recommendation instead of requirement when it talks about binding of particular types of objects into specific subcontext. Should we follow that convention? Are there any problems with making it an requirement to bind JSR 236 objects into java:comp/env/concurrent?

Your other suggestion is to remove all examples of configuration attributes, and select a few to become standard configuration attributes. I think we should do this. Any suggestions on which attributes we should consider to be standardize?

Furthermore, suppose we have defined a set of required attributes and their possible values, would it be useful to provide annotations for defining JSR 236 objects?

There are annotations in the Java EE 7 spec for defining various types of resources. Taking an example from section 5.19.6 in the Java EE spec, a mail session resource can be defined on a container-managed class by using this annotation:

@MailSessionDefinition( name="java:app/mail/MySession", host="somewhere.myco.com", from=
">" ")

For example, a ManagedExecutorService could be defined by something like

@ManagedExecutorService (name="java:comp/env/concurrent/executor1", context="all", threads="3")


Comments are welcome.

Regards
Anthony

On 10/16/12 12:46 PM, Adam Bien wrote:

HI *,

I read the proposal and probably found some problems / inconsistencies (or completely misunderstood that :-)).

I incorporated the comments into the PDF--see attachment.

Summary of my comments:
1. DI of resources into manually created tasks won't work, or has to be performed by the pools. We should clarify that.
2. We should rely more on Convention over Configuration. It means: injection should work without any XML configuration.
3. I would reduce the scope and start with the injection of plain Executor services managed by the container. It would already solve about 80% of challenges from my projects.
4. Often mentioned "Container Context" is not clearly defined. I guess TX are not covered by the definition. Otherwise a in EJB initiated TX could be propagated into an asynchronous task...
5. We should reduce optional things. E.g. jndi names etc. should be mandatory--otherwise the suggestions are worthless. I would reduce the scope of the whole spec to mandatory services, and discuss the optional things later.

Please see my comments in the PDF,

thanks!

adam






[jsr236-spec users] [jsr236-experts] Re: Feedback

Anthony Lai 11/27/2012

[jsr236-spec users] [jsr236-experts] Re: Feedback

Frederick W Rowe 11/28/2012

[jsr236-spec users] [jsr236-experts] Re: Feedback

Nathan Rauh 11/28/2012

[jsr236-spec users] [jsr236-experts] Re: Feedback

Anthony Lai 11/29/2012
 
 
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