How to call EJB from another app on the same server? - websphere-8

Question

I have java SE sample client which run on desktop (code below). But I have access to WebSphere were called EJB is deployed. How to rewrite below code to work on WebSphere? (When I leave this code just like it is program works but I think this can be done more simple and clear)
Main method:
WSConn connection = new WSConn();
final Plan plan = connection.getPlanBean();
com.ibm.websphere.security.auth.WSSubject.doAs(connection.getSubject(), new java.security.PrivilegedAction<Object>() {
public Object run() {
try {
// App logic
} catch (Throwable t) {
System.err.println("PrivilegedAction - Error calling EJB: " + t);
t.printStackTrace();
}
return null;
}
}); // end doAs
WSConn class:
public class WSConn {
private static final String INITIAL_CONTEXT_FACTORY = "com.ibm.websphere.naming.WsnInitialContextFactory";
private static final String JAAS_MODULE = "WSLogin";
private static final String MODEL_EJB_NAME_LONG = "ejb/com/ibm/ModelHome";
private static final String PLAN_EJB_NAME_LONG = "ejb/com/ibm/PlanHome";
private Subject subject;
private InitialContext initialContext;
private String serverName;
private String serverPort;
private String uid;
private String pwd;
private String remoteServerName;
private Model modelBean;
private Plan planBean;
public WSConn() {
Properties props = new Properties();
try {
props.load(WSConn.class.getClassLoader().getResourceAsStream("WSConn.properties"));
} catch (IOException e) {
e.printStackTrace();
}
serverName = props.getProperty("WSConn.serverName");
serverPort = props.getProperty("WSConn.serverPort");
uid = props.getProperty("WSConn.userID");
pwd = props.getProperty("WSConn.password");
remoteServerName = props.getProperty("WSConn.remoteServerName");
}
private void init() {
if (subject == null || initialContext == null) {
subject = login();
}
}
private Subject login() {
Subject subject = null;
try {
LoginContext lc = null;
// CRATE LOGIN CONTEXT
Hashtable<String, String> env = new Hashtable<String, String>();
env.put(Context.INITIAL_CONTEXT_FACTORY, INITIAL_CONTEXT_FACTORY);
env.put(Context.PROVIDER_URL, "corbaloc:iiop:" + serverName + ":" + serverPort);
initialContext = new InitialContext(env);
// Just to test the connection
initialContext.lookup("");
lc = new LoginContext(JAAS_MODULE, new WSCallbackHandlerImpl(uid, pwd));
lc.login();
subject = lc.getSubject();
} catch (javax.naming.NoPermissionException exc) {
System.err.println("[WSConn] - Login Error: " + exc);
} catch (Exception exc) {
System.err.println("[WSConn] - Error: " + exc);
}
return subject;
}
public wModel getModelBean() {
if (modelBean == null) {
init();
modelBean = (wModel) com.ibm.websphere.security.auth.WSSubject.doAs(subject,
new java.security.PrivilegedAction<wModel>() {
public wModel run() {
wModel session = null;
try {
Object o = initialContext.lookup(MODEL_EJB_NAME_LONG);
wModelHome home = (wModelHome) PortableRemoteObject.narrow(o, wModelHome.class);
if (home != null) {
session = home.create(remoteServerName);
}
} catch (Exception exc) {
System.err.println("Error getting model bean: " + exc);
}
return session;
}
}); // end doAs
}
return modelBean;
}
public wPlan getPlanBean() {
if (planBean == null) {
init();
planBean = (wPlan) com.ibm.websphere.security.auth.WSSubject.doAs(subject,
new java.security.PrivilegedAction<wPlan>() {
public wPlan run() {
wPlan session = null;
try {
Object o = initialContext.lookup(PLAN_EJB_NAME_LONG);
wPlanHome home = (wPlanHome) PortableRemoteObject.narrow(o, wPlanHome.class);
if (home != null) {
session = home.create(remoteServerName);
}
} catch (Exception exc) {
System.err.println("Error getting plan bean: " + exc);
}
return session;
}
}); // end doAs
}
return planBean;
}
public Subject getSubject() {
if (subject == null) {
init();
}
return subject;
}
}

Answer 1

As indicated in another answer, the classic mechanism is to lookup and narrow the home interface.
Get the initial context
final InitialContext initialContext = new InitialContext();
Lookup for the home by jndi name, specifying either the full jndi name
Object obj = initialContext.lookup("ejb/com/ibm/tws/conn/plan/ConnPlanHome");
or you can create e reference in your WAR and use java:comp/env/yourname
Then narrow the home to the home interface class
ConnPlanHome planHome = (ConnPlanHome)PortableRemoteObject.narrow(obj, ConnPlanHome.class);
and then create the EJB remote interface
ConnPlan plan = planHome.create();
The about calls should work for IBM Workload Scheduler distributed.
For IBM Workload Scheduler z/OS the JNDI name and the class names are different:
final InitialContext initialContext = new InitialContext();
String engineName = "XXXX";
Object obj = initialContext.lookup("ejb/com/ibm/tws/zconn/plan/ZConnPlanHome");
ZConnPlanHome planHome = (ZConnPlanHome)PortableRemoteObject.narrow(obj, ZConnPlanHome.class);
ZConnPlan plan = planHome.create(engineName);
User credentials are propagated from the client to the engine, the client need to be authenticated otherwise the engine will reject the request.

Answer 2

If you're trying to access an EJB from a POJO class, then there is nothing more simple than lookup+narrow. However, if the POJO is included in an application (EAR or WAR), then you could declare and lookup an EJB reference (java:comp/ejb/myEJB), and then the container would perform the narrow rather than your code. If you change your code to be a managed class like a servlet, another EJB, or a CDI bean, then you could use #EJB injection, and then you would not even need a lookup.