How can session beans share objects?

[peterlen]

Hello,

I am having problems figuring out how to get two session beans to share an object.  The goal is to have Bean A declare an object, let Bean B fill the object's value, and then get Bean A to access to value set by Bean B.  I was looking at the @In and @Out SEAM annotations but have not fugured out if this will work.

I have Bean A with:

@Out private ExceptionMessageHandler messageHandler;
public ClientUtilityBean() { messageHandler = new ExceptionMessageHandler(); }

I have Bean B with:

@In ExceptionMessageHandler messageHandler;

Again, Bean A is the central point managing the messageHandler object and Bean B, Bean C, Bean D, etc would simply populate the object with a value.

When I go to my page, however, I get the exception:

15:48:25,499 ERROR [TxPolicy] javax.ejb.EJBTransactionRolledbackException: @In a
ttribute requires non-null value: DataFolders.messageHandler

where "DataFolders" is the interface for Bean B.   I have obviously not declared these correctly and may not be using the annotations properly in the first place.  I can't find any code examples that show what I am trying to do so I have been doing trial and error with no success.

Does anyone know how I can properly use the @In and @Out annotations to work as I am intending or whether that is not the way to use the annotations and I need to do something else.

Any thoughts would be greatly appreciated.

Thanks - Peter

[amarkhel]

1. ExceptionMessageHandler has @Name annotation?

2. You can use @In(require=false, create=true) ExceptionMessageHandler messageHandler;

[peterlen]

Andrey - Thanks for the reply.  I am unsure about what your reference to a @Name annotation is.  I don't list a @Name annotation.  Are you saying that I should?  For #2, I had declared it earlier like:

@In(create=true) ExceptionMessageHandler messageHandler;

But I get the same error.  I am wondering if both beans need the @In and @Out annotations but, again, an unsure about how these annotations really work in my scenario.

[amarkhel]

Every component, that you wan't put in any Context(request, session etc..) by @Out annotation, should have @Name annotation. Are your ExceptionMessageHandler bean has this annotation?

And can you try @Autocreate annotation on your ExceptionMessageHandler? This annotation tell Seam, that component should be created by demand.

And what scopes you use for all that beans(beanA, beanB, ExceptionMessageHandler)?

[peterlen]

Andrey,

This is where it is confusing to me.  Let me explain it a little better then I previous did.

Two of my beans (Bean A and Bean B) are session beans and each uses the @Name annotation.  Each of these beans are "connected" to my facelets page (my .xhtml file).  Depending on what the user does on the page, Bean A might be called or Bean B might be called.  These are typically a4j type calls.  I have a third bean which is also a session bean with a @Name annotation.  This third Bean (UtilityBean) is where I declared my

@Out

ExceptionMessageHandler messageHandler;

ExceptionMessageHandler is just a POJO with a couple of getters/setters.

My goal was trying to find a way that allowed these session beans to share a common object (ie the messageHandler).  I thought that the @In and @Out annotations were used for this purpose, but I am thinking that those annotations are for injection/outjection between a given bean and the client web page rather than for one bean to set a value on an object that is accessible in another bean.

Maybe I should never have listed the @In and @Out annotations in my original posting to keep any confusion out.  So, do you know if the @In and @Out annotations can be used to "pass" object values between session beans?  Essentially this would give access to one instance of a variable to different beans to set/get values.

- Peter

[amarkhel]

Hi, Peter.

To solve your problem your shouldn't use MessageNandler as one of fields of other session bean. Why you won't use messageHandler as undependent component(with @Name and @scope annotation)? Then you could inject it in all other beans through @In, and if you change state of messageHandler @Out annotation?

Simple Use case..

@Name("messageHandler")

@Scope(SESSION)

@AutoCreate

public class MessageHandler

....

@Name("beanA")

@Scope(SESSION)

BeanA{

@In MessageHandler messageHandler(only @In annotation if you won't change the state messageHandler)

....

public String getInfo(){

     return messageHandler.getInfo();

}

@Name("beanB")

@Scope(SESSION)

BeanB{

@In @Out MessageHandler messageHandler(in case where you want change the state messageHandler)

public String getInfo(){

     return messageHandler.getInfo();

}

public void setInfo(String info){

     messageHandler.setInfo(info);

}

NOTE: @In and @Out annotation on class work after call on each method of this class.

So, after call beanB.setInfo(info), when you change state of messageHandler, @Out annotation push your messageHandler in session context.

[peterlen]

Andrey,

Part of my problem was not fully understanding the usage of the @In and @Out.  I just tried what you listed in your last reply and it works just fine.  I appreciate your time and effort in helping with this.

Thanks - Peter