Can't access session bean from front-end

[nbhatia.bhatian.comcast.net]

I have just started learning Seam. I am trying to access a stateless session bean from the front end, but somehow it's not working.

Here's an excerpt from my facelets page:


`<h:inputText value="#{helloWorld.firstName}" />`


I am getting this error:


`javax.servlet.ServletException: /pages/login.xhtml @22,67 value="#{helloWorld.firstName}": Target Unreachable, identifier 'helloWorld' resolved to null`


Here's my stateless session bean:

@Stateless
@Name("helloWorld")
public class HelloWorldBean implements HelloWorld {
   
    private String firstName;
   
    public String getFirstName() {
        return firstName;
    }
    public void setFirstName(String firstName) {
        this.firstName = firstName;
    }

    ...
}

I can see that it is published in my JNDI tree as:

  +- helloworldseam-app-1.0
  |   +- HelloWorldBean
  |   |   +- local (proxy: $Proxy76 implements interface samples.helloworldseam.HelloWorld,interface org.jboss.ejb3.JBossProxy)


I have defined jndi-pattrn as follows in my components.xml:

<core:init jndi-pattern="helloworldseam-app-1.0/#{ejbName}/local" debug="true"/>

Why is the front-end not finding the bean? Which concept am I missing?

Thanks.
Naresh

[blabno]

Show deployment log. I bet you do not have seam.properties in your EJB module.

[nimo22]

Your HelloWorld.java must be an interface having at least two methods:

public String getFirstName();
public void setFirstName(String firstName);

Ensure that this is done.

[blabno]

This is not an issue here. The component itself cannot be found by Seam.

[cosmo]

Do you see the same error if your SLSB is local?

[nbhatia.bhatian.comcast.net]

Thank you all for your help.

1) Yes, I did not have seam.properties. That was my first problem. I was able to move one step forward after adding this file - the front-end seemed to reach "some" bean or proxy.

2) Next problem indeed was that I did not have getters and setters on my fields in the SLSB interface (got some cryptic message from facelets on this). Anyway, after I added getters and setters I moved forward one more step.

Now I am getting this error:

SEVERE: Error Rendering View[/pages/login.xhtml]
javax.faces.FacesException: javax.el.ELException: /pages/login.xhtml @22,67 value="#{helloWorld.firstName}": Error reading 'firstName' on type org.javassist.tmp.java.lang.Object_$$_javassist_2
Caused by: javax.el.ELException: /pages/login.xhtml @22,67 value="#{helloWorld.firstName}": Error reading 'firstName' on type org.javassist.tmp.java.lang.Object_$$_javassist_2
Caused by: java.lang.IllegalArgumentException: Could not invoke method by reflection: HelloWorld.getFirstName() on: $Proxy156
Caused by: java.lang.IllegalArgumentException: object is not an instance of declaring class
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
        at java.lang.reflect.Method.invoke(Method.java:597)
        at org.jboss.seam.util.Reflections.invoke(Reflections.java:21)
        ... 64 more

Where do I go from here?

Thanks.
Naresh

P.S. BTW, my SLSB is already in local scope:

@Stateless
@Name("helloWorld")
public class HelloWorldBean implements HelloWorld {
    ...
}

[monkeyden]

Does the interface have the @Local annotation?  Please post all relevant code.

[nbhatia.bhatian.comcast.net]

The interface does NOT have a @Local annotation - I thought that the EJB3 specification allows pure Java interfaces without any annotations (@Local and @Remote can only be specified on the implementation - @Local being the default). This has certainly worked for me in pure EJB3 applications. The JBoss EJB 3.0 TrailBlazer examples also show this approach.

Having said that, I see that the Seam samples do put @Local on the interface (e.g. in the registration example, the Register interface is annotated with @Local) - I don't understand why. Anyway, I tried putting @Local on my interface and I am getting a different error now:

java.lang.IllegalArgumentException: value of context variable is not an instance of the component bound to the context variable: helloWorld

What should I do next? Here's the current state of my code:

HelloWorld.java
===============
package samples.helloworldseam;

import javax.ejb.Local;

@Local
public interface HelloWorld {
    public String getFirstName();
    public void setFirstName(String firstName);
    public String getGreeting();
    public void setGreeting();
}

HelloWorldBean.java
===================
package samples.helloworldseam;

import javax.ejb.Stateless;

import org.jboss.seam.annotations.Name;

@Stateless
@Name("helloWorld")
public class HelloWorldBean implements HelloWorld {
   
    private String firstName;
    private String greeting;
   
    public String getFirstName() {
        return firstName;
    }
    public void setFirstName(String firstName) {
        this.firstName = firstName;
    }

    public String getGreeting() {
        return greeting;
    }
    public void setGreeting() {
        greeting = null;
        if (firstName != null && !firstName.isEmpty()) {
            greeting = "Hello " + firstName;
        }
    }
}

login.html
==========
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<ui:composition
    xmlns="http://www.w3.org/1999/xhtml"
    xmlns:c="http://java.sun.com/jstl/core"
    xmlns:f="http://java.sun.com/jsf/core"
    xmlns:h="http://java.sun.com/jsf/html"
    xmlns:ui="http://java.sun.com/jsf/facelets"
    template="/templates/template.xhtml">

    <ui:define name="body">

        <h:form id="login">
            <div>
                <table border="0">
                    <tr>
                        <td valign="top" align="right">
                            First Name:
                        </td>
                        <td>
                            <h:inputText style="width: 12em; border: solid 1px #808080;"
                                value="#{helloWorld.firstName}" />
                        </td>
                        <td>
                            <h:commandButton action="#{helloWorld.setGreeting}" value="Submit"/>
                        </td>
                    </tr>
                </table>
            </div>
        </h:form>
       
        <div>
            #{helloWorld.greeting}
        </div>

    </ui:define>

</ui:composition>

I can attach my complete code to a JIRA issue if needed. FYI, I am trying to create the entire project from scratch using Maven 2. The examples provided with Seam use non-standard Maven layout and it is too difficult understand. I am sure there is justification for this layout, but it certainly slows down the learning curve for people who are used to the standard Maven layout.

Thanks.
Naresh

[blabno]

Not sure but maybe ... setGreeting method breaks JavaBean contract. Name your action method differently i.e. public void greet().

[nbhatia.bhatian.comcast.net]

Good thought. I tried it and I am back to the original error:

javax.faces.FacesException: javax.el.ELException: /pages/login.xhtml @22,67 value="#{helloWorld.firstName}": Error reading 'firstName' on type

If I remove the @Local from the HelloWorld interface then I still get:

java.lang.IllegalArgumentException: value of context variable is not an instance of the component bound to the context variable: helloWorld

[blabno]

Do not remove @Local annotation. Post your bean code, and please format it well.
If you want, send me your project and I will debug it. s4237 at pjwstk dot edu dot pl

[blabno]

Error was trivial. Always show full stack trace for the last lines tend to be most meaningful. You had helloworldseam-server-1.0.jar (the ejb module) inside WEB-INF/lib which caused ClassCast family exception. Actually it was

Caused by: java.lang.IllegalArgumentException: Could not invoke method by reflection: HelloWorld.getFirstName() on: $Proxy85

and

Caused by: java.lang.IllegalArgumentException: HelloWorldBean

but the problem was in class loading.

[nbhatia.bhatian.comcast.net]

Thanks so much Bernard. That was indeed the problem.

Now that the app is running, I removed the @Local from the interface and it still works. So the only remaining question in my mind is why do Seam examples use @Local on the interface? I have not seen this in the EJB3 specs or even in JBoss EJB3 examples.

Thanks.
Naresh