"EJB series" (ii) remote invocation and local invocation of EJBS in--JBOSS7

Guide

This is because the jboss6,7 version differs from the previous version in the syntax for local and remote invocation of the EJB. Therefore, the code example is given in this article for informational purposes only. Environment

MyEclipse10
JBOSS7 Theoretical knowledge remote Access process

Remote Client

Run on a different machine or a different JVM process than the EJB
It can be a Web component (such as a JSP, a Servlet), an application client, or other EJB
For the client, the EJB's location is transparent.
In order to create an EJB that can be accessed by a remote client, you must define these EJBS with @remote annotations. parameter Passing method

Pass Value

Reason:

Because the client and the server belong to different processes, the memory space cannot be shared.
After the client's user object has been serialized and deserialized, it becomes another user object on the service side, and the property of the client's user object is unchanged when the server modifies a property of the user object. We will show this in the following code. Precautions

The passed parameter, if it is an object, needs to implement the serialized interface implements Serializable the local calling procedure

Local Client

Running on the same JVM process as the EJB
It can be a Web component (such as a JSP, Servlet), or other EJB
For the client, the EJB's location is transparent.
In order to create an EJB that can be accessed by a remote client, you must define these EJBS with @local annotations. parameter Passing method

Transfer address

Reason: The object is passed a reference, whether the client or the server to modify the object, are modified by the same copy. Code interface and implementation of EJB

Unlike previous versions of JBoss, EJBS here cannot be declared as @remote and @local at the same time.

Project directory

User.java (be sure to implement the Serializable interface)

Package COM.TGB.EJB;

Import java.io.Serializable;

@SuppressWarnings ("Serial") Public
class User implements Serializable {
    private String username;
    private int id;
    Public String GetUserName () {
        return username;
    }
    public void Setusername (String username) {
        this.username = username;
    }
    public int getId () {
        return ID;
    }
    public void setId (int id) {
        this.id = ID;
    }

}

Usermanagerremote.java (Remote Call interface)

Package COM.TGB.EJB;

Public interface Usermanagerremote {public
    void AddUser (user user);

Usermanagerlocal.java (Local call interface)

Package COM.TGB.EJB;

Public interface Usermanagerlocal {public
    void AddUser (user user);

Usermanagerbean.java (Implementation)

Package COM.TGB.EJB;


Import javax.ejb.Local;
Import Javax.ejb.Remote;
Import javax.ejb.Stateless;

@Stateless
@Local (usermanagerlocal.class)
@Remote (usermanagerremote.class) Public
class Usermanagerbean implements Usermanagerremote,usermanagerlocal {

    @Override public
    void AddUser (user user) { C17/>system.out.println ("User.username=" +user.getusername ());
        User.setid (9);

    }

}

When you're done, remember to deploy to JBoss and run JBoss. Remote Call

A common Javaproject

Detailed steps refer to the previous post "EJB series" (i) developing a simple EJB application in--JBOSS7

Results

Although the server performed SetID (9), the client GetID () was still 0. Local Call Create Web Project writing and configuring a servlet

Userservlet.java

Package com.tgb.web;
Import java.io.IOException;
Import Java.io.PrintWriter;

Import java.util.Hashtable;
Import Javax.naming.Context;
Import Javax.naming.InitialContext;
Import javax.naming.NamingException;
Import javax.servlet.ServletException;
Import Javax.servlet.http.HttpServlet;
Import Javax.servlet.http.HttpServletRequest;

Import Javax.servlet.http.HttpServletResponse;
Import Com.tgb.ejb.User;


Import com.tgb.ejb.UserManagerLocal; @SuppressWarnings ("Serial") public class Userservlet extends HttpServlet {public void doget (HttpServletRequest requ EST, httpservletresponse response) throws Servletexception, IOException {response.setcontenttype ("
        Text/html ");
        PrintWriter out = Response.getwriter (); Out.println ("<!
        DOCTYPE HTML public \ "-//W3C//DTD HTML 4.01 transitional//en\" > ");
        Out.println ("<HTML>");
        Out.println (" 
Xml

<servlet>   
    <servlet-name>UserServlet</servlet-name>
    <servlet-class> com.tgb.web.userservlet</servlet-class>
  </servlet>

  <servlet-mapping>
    < Servlet-name>userservlet</servlet-name>
    <url-pattern>/servlet/userservlet</url-pattern >
  </servlet-mapping>
 
Deploy Project Access servlet 
My project's access is connected when Http://localhost:8091/ejb_03_webclient/servlet/UserServlet

The port number of the project should be based on JBoss configuration file standalone.xml.

Package The jar file into the Lib directory

Export the EJB project "ejb_03" four Java files into a jar package and add them to the Web-inf Lib path of this project

Writing Clients

Final Hashtable jndiproperties = new Hashtable (); Jndiproperties.put (context.url_pkg_prefixes, "org.jboss.ejb.client.naming");//Let the Jndi API know who manages what we use to find Jndi
        The name of the namespace.
        Context context;
            try {context = new InitialContext (jndiproperties);  AppName and ModuleName are packaged separately//if yes. Ear is AppName, others are modulename (. Jar,.war) Final String AppName
            = "";
            Final String modulename = "Ejb_03_webclient";
            Final String distinctname = "";
            Implement class name final String beanname = "Usermanagerbean";
            System.out.println (Beanname);
            Interface class name final String Viewclassname = UserManagerLocal.class.getName ();
            System.out.println (Viewclassname);
            String Jndi = "java:module/" + Beanname + "!" + viewclassname;

            System.out.println (Jndi);  
            Usermanagerlocal usermanagerlocal; Usermanagerlocal = (usermanagerlocal) context.loOkup (Jndi);
            User User=new user ();            
            User.setusername ("Xu Chen Yang");
            Usermanagerlocal.adduser (user);
        SYSTEM.OUT.PRINTLN ("User id:" +user.getid ());
        } catch (Namingexception e) {//TODO auto-generated catch block E.printstacktrace (); }
 
Run JBoss 
From the console we can see the path of our deployed EJB in Jndi, the above code we use one of the paths, the remaining two can also:

Java:global/ejb_03_webclient/usermanagerbean!com.tgb.ejb.usermanagerlocal
java:app/ejb_03_webclient/ Usermanagerbean!com.tgb.ejb.usermanagerlocal
 


We see that the last user ID entered is 9, indicating the service side changes, the client can see that the operation is the same user object. Summary

The problems encountered in this process include:

1. Local calls do not need to introduce Jboss-client.jar, and do not need to configure jboss-ejb-client.properties, but to introduce Ejb_03.jar, and to be placed in the Lib directory, Otherwise it will report classdefnotfound,classcastexception and other errors.
2. The other is the name passed when Context.lookup.

The remote invocation is:

String Jndi = "EJB:" + appName + "/" + ModuleName + "/"
                + distinctname + "/" + Beanname + "!" + viewclassname;
 
When calling locally:

Remove the previous "EJB:". Change to "Java:global" or "Java:app" or "java:module", but be aware that ModuleName is ejb_03_webclient instead of "ejb_03". The specific path of the stitching, referring to our console output of the three paths, slightly different. Reference

JNDI Reference
[AS7.1.1] EJB JNDI lookup confusion:remote vs Local