Article:Managing Complexity with BPEL Environment

SOA World published an article on BPEL Management written by me with Arvind Maheshwari.

You can read the article: Managing Complexity with BPEL Management!

Enterprise Java – State of the World!

One of my friends commented: “Java is no longer cool! Not hot either! What is the current state of enterprise Java?”

First it was .Net and then came a bonanza of scripting languages such as Ruby. All these technologies were there to eclipse the popularity of Java and J2EE. The hypes for these technologies were short-lived. The forecast for demise of Java EE was highly exaggerated. Java and J2EE still lives on!

I divide the players in the enterprise Java markets primarily into two buckets. The commercial vendors selling J2EE application server and the vendors building open source and so called free products. However a third force is emerging that is looking to disrupt the J2EE market space.

The commercial market space is now officially two horses’ race after Oracle acquired BEA. The battle is still on for the two traditional rivals! One application server (WebLogic) is stylish and always ahead with emerging technology and the other one proprietary loaded (Websphere) with the old baggage. Java EE 5 finalized in June 2006 and IBM Websphere just got certified with Java EE 5. That’s more than two years since the spec was finalized. That’s not strange though. JBoss that still do not have a production release that is Java EE 5 certified. Although they announced it's arrival more than a month back, I do not see a production version available as yet. They have a release candidate!

Now that we discussed JBoss’s certification issue let us look at the open source products. About two years back JBoss was the crown prince in the open source market. None of the other products Jonas, Glassfish or Geronimo had capabilities to challenge its supremacy. However JBoss lost the momentum in past year and half after being acquired by RedHat. Glassfish has gained a significant mindshare in last year and half thanks to their quality Java EE 5 implementation. I think the delay in shipping a quality Java EE 5 implementation by JBoss was a primary reason. Geronimo has not gotten much traction! However we should not forget that many customers still use Tomcat with just web applications. Although Tomcat does not have all bells and whistles of Java EE – it is still the most dominant open source container.

I put Spring in the third bucket. Spring is a great framework that makes application development simple. Java EE 5 borrowed a lot of great ideas from the Spring framework. Spring Framework certainly helped enterprise Java to go further. SpringSource, the company behind Spring Framework launched their OSGi-based application server named Spring dm Server. Spring dm Server not only competes with other application server vendors in the market. It also competes with Java EE! It allows you to deploy WAR modules and OSGi bundles. It is at its first version and lacks good high availability, manageability features. SpringSource hopes to implement part of Java EE 6 specs. If they are successful – Spring dm Server may be a disruptive force for the Java EE application server market. I will blog about my first impressions on Spring dm Server (write capabilities and limitations) in my upcoming blog.

Many people have raised concerns about slow adoption rate of Java EE 5. Is the slow adoption by two major players (IBM and JBoss) inhibiting the adoption rate for Java EE 5? Possibly! However we have to remember that for most companies, generating revenue is more important than the underlying technology. Many customers have deployed their applications using J2EE 1.4 and they achieved their performance and scalability goals so they cannot just throw those away and jump on to the Java EE 5 bandwagon. Having said that many customers are using Java EE 5 only with new development projects. The sales of my book has picked up lately.

With economy going down south- budgets for new projects are limited! Having said that Java is still the leading platform for building enterprise applications.

The JCP team is gearing up to finalize Java EE 6 by JavaOne 2009. This gives a fuzzy feeling that enterprise Java is still thriving. What do you think?

Using EJBContext from an EJB 3 Interceptor

I got a question from a customer that he wants to use EJBContext from an EJB 3 Interceptor.

Yes, it’s very simple. Just inject the EJBContext into the interceptor using @Resource injection.

See the example code that uses methods of SessionContext as follows:


package actionbazaar.buslogic;

import javax.annotation.Resource;
import javax.interceptor.AroundInvoke;
import javax.interceptor.InvocationContext;

public class CheckPermissionInterceptor {
@Resource
private javax.ejb.SessionContext ctx;


@AroundInvoke
public Object checkUserRole(InvocationContext ic) throws Exception {
System.out.println("*** CheckPermission Interceptor invoked for "
+ ic.getTarget() + " ***");
if (!ctx.isCallerInRole("admin")) {
throw new SecurityException("User: '"
+ ctx.getCallerPrincipal().getName()
+ "' does not have permissions for method "
+ ic.getMethod());
}
return ic.proceed();
}
}

If you want the run-able version of the example code, you can download from http://manning.com/panda and look at Chapter 5 example.

My Sessions at Oracle Open World 2008

I’ve two sessions at Oracle Open World 2008, San Francisco. Here are my session details:

S298520 : Best Practices for Managing Your Oracle WebLogic Environment with Oracle Enterprise Manager
Track: Application Server and Transaction Processing
Room: Rm 2006
Date: 2008-09-22
Start Time: 11:30

S298522 : Top Five Things DBAs Must Know About Managing Middleware
Track: Application Server and Transaction Processing
Room: Rm 2003
Date: 2008-09-25
Start Time: 15:00

See you at San Francisco!

EJB 3 In Action available at Safari Online

If you enjoy reading online then it's a good news for readers of EJB 3 in Action. It is now available online at Safari

Introduction to EclipseLink

Doug Clarke has written a nice article that introduces EclipseLink.

EJB 3 Stateless bean Web service in WebLogic Server

I recently got some questions from customers about the procedure for deploying EJB 3 Session Bean Web service in WebLogic 10. In this blog, I will outline the steps.

First develop your EJB3 session bean web service as follows:

@WebService(name="PlaceBid",
serviceName="PlaceBidService", portName = "PlaceBidPort",
targetNamespace = "http://actionbazaar.com/xml")
@SOAPBinding(style = SOAPBinding.Style.DOCUMENT)
@PersistenceContext(unitName="actionBazaar",name="actionBazaar")
@Stateless
public class PlaceBidBean {

@WebMethod

public Long addBid(String userId, Long itemId, Double bidPrice) throws BidException {

….

}

}

Deployment

Unlike OC4J, WebLogic do not support parsing of JAX-WS annotations at deployment time and if you try to deploy the compiled EJB 3 Web service, you will get deployment time exception. You have to run the EJB 3 WS thru annotation parsing tool (jwsc –java web services compile) supplied with WebLogic to generate the artifacts and package in your ejb-jar module.

Here is an example ant task to create the web service:

<target
name="build-ws-server" description="Target that builds the
target Web Service">
<jwsc
srcdir="${src.ejb.dir}"
destdir="${bld.service.dir}"
classpath="${common.j2ee.class.path}"
fork="true"
keepGenerated="true"
deprecation="${deprecation}"
keepTempFiles="true"
listfiles="true"
debug="${debug}">
<jws
file="actionbazaar/buslogic/PlaceBidBean.java" type="JAXWS"
explode="true"/>
</jwsc>
</target>

<target name="package-ejb"
depends="compile-ejb-classes,build-ws-server">;

<mkdir dir="${bld.ejb.dir}/actionbazaar/buslogic/jaxws" />

<copy todir="${bld.ejb.dir}/actionbazaar/buslogic/jaxws">

<fileset dir="${bld.service.dir}/actionbazaar/buslogic/PlaceBidBean/actionbazaar/buslogic/jaxws" includes="*"/> </copy>
<echo message="-----> Create EJB jar file"/>
<jar jarfile="${bld.ear.dir}/${ejb.name}.jar">
<fileset dir="${bld.ejb.dir}" includes="**" />
</jar>
</target >

Make sure to package the generated artifacts in the EJB JAR and then deploy the EJB-JAR or EAR to the WebLogic Server. Note that if your web service depends upon custom Java objects - the generated artifacts contain duplicate Java classes that you already may have. These duplicated classes are on a separate package structure and cause ClassCastException for me. So I avoid packaging these classes.

Accessing EJB 3 Web service

After successful deployment you can access the web service as follows:

http://hostname:port/ejb-name/web-service-name?wsdl

http://localhost:7001/PlaceBidBean/PlaceBidBeanService?wsdl



Hope this helps.

You can download the working examples from here. Chapter 15 contains web services example.

EJB 3, JPA, Web Services and Spring Examples for WebLogic Server

Finally I was able to complete porting of all book examples of EJB 3 In Action to run on WebLogic Server.

You can download these from here

These contain a host of examples on EJB 3, JPA, Web Services and Spring Framework. Now we have complete examples for four servers: Glassfish, OC4J, WebLogic and JBoss.

Note that I tested the examples with an Oracle XE database. For simplicity, the examples are configured to use the exampleServer and default PointBase DB that is shipped with it. However some of these examples will properly not on PointBase because it does not support DB Sequence.

All chapters have the common domain model based on our famous ActionBazaar Application

Chapter 5: EJB 3 Interceptors, Timers
Chapter 8: O-R Mapping Annotations
Chapter 9: Entity Manager API
Chapter 10: JPQL and Native SQL Queries
Chapter 11: O-R Mapping with XML
Chapter 12: EM API from Web Tier, Java SE
Chapter 13: Extended Persistence Context
Chapter 15: EJB 3 Web services
Chapter 16: Spring with EJB 3 and JPA

Please try these out and let me know if you find any bugs!

EJB 3 Dependency Injection Refcard

I wrote a Reference Card on EJB 3 Dependency Injection for Developer Zone. This is a quick reference card that describes metadata annotations and XML descriptor elements that you use for injecting resources and services.

You can access this reference card for free from Developer Zone at http://refcardz.dzone.com/refcardz/dependency-injection-in-ejb3

EJB 3 In Action Code Examples on WebLogic 10

In my previous blog, I made the code examples available for first four chapters of EJB 3 In Action for WebLogic 10. However I did not provide you instructions to run these examples (Chapter 2-4) for WebLogic 10.

Chapter 2 example has a stateless session bean, stateful session bean, an MDB and a JPA Entity. The JPA persistence unit requires a JDBC DataSource and the Stateful/MDB uses a JMS queue.

Chapter 3 depends upon a JDBC DataSource and Chapter 4 uses JDBC DataSource and a JMS Queue.

I’ve provided a build script to configure these resources on the default examplesServer that gets created when you install WebLogic 10.

1. Download examples from here and unzip to a directory say c:\ejb3inaction\weblogic

2. Set the environment variables for your server as follows:

%BEA_HOME%/wlserver_10.0/samples/domains/wl_server/setExamplesEnv

3. Change to your directory to the directory

cd c:\ejb3inaction\weblogic

ant CreateResources

This will configure resources such as JDBC DataSource, JMS Connection Factory, Queues, etc.

4. To deploy the application, you can use WLS Admin Console. If you prefer you can use ant to deploy the application for a specific chapter.

cd chapter2
ant

4. To run the application client:

ant run

Hope this helps! I'm working on porting rest of the examples and will make these available sooner.

Diagnosing Production Java applications with AD4J

One of my applications that uses EJB 3 and JPA was running much slower today and I had no clue what was going on. It is a very simple application to manage service requests. When I was trying to update some data for a service request – it was taking ever. Also searching of service requests by some search criteria was taking much longer than it does.

So I thought I would give Oracle AD4J a spin and will try to find out what is going! It is good that Oracle AD4J does not require any code changes in application, because it does not use byte code instrumentation. Nor does it require to restart/redeploy the application – so it was a perfect fit.

And it really helped diagnose the problem by me get into bottom of the issues. It was indeed a DB issue as I had initially suspected.

I will not bore you with installation and configuration steps of AD4J – rather I will outline how AD4J helped me diagnose the issue.

Finding the Offending Thread

As soon as I logon to AD4J console and clicked to view active threads – it showed all threads with the correct state and I saw one thread is with status “DBWait”.

That gave me an indication that something going fishy in the database request from from JPA provider.

Finding DB issue

When I clicked on DB Wait link to view details, it became clear that the transaction is running into some row lock contention with another user session.

Finding the SQL statement

Interestingly it allowed to me to view the SQL Statement that is taking forever by clicking the SQL hash. My application uses JPA 1.0 and I could view the SQL statements causing problem without increasing the log level from my JPA provider as in the following figure:

It also helped me find the other session that held the lock. Apparently we found that it was a batch process that was hanging for some reasons. After the hanging session was killed the application ran like a champ again!

Also I found that the JPQL query for retrieving SRs was running slower because of some missing indexes on the column and it was making a full table scan. Nice, it also AD4J allows to run explain for sql statements.

Downloading AD4J

You can download AD4J from OTN (http://www.oracle.com/technology/software/products/oem/htdocs/jade.html)

Installing AD4J Console and agents

Installing AD4J Console is easy. You can follow this guide to do this installation of AD4J Console and agent.

After you deploy the agent you are good to go. Your JVM for application server will be automatically discovered in the console.

The AD4J agent is a WAR file that needs to be deployed to the server. You can follow the instructions in the install guide to install the agent in favorite application server. I was using my favorite container OC4J, however it supports BEA WebLogic, IBM Websphere, JBoss, and Tomcat. You can run AD4J also with standalone Java.

If you want to trace the problem to the DB tier you can install the DB Agent. You can follow the instructions in this guide.

I will play around with AD4J and blog little more about its feature in future. In the meantime you can review it's usage scenario documented in here.

My interview @Java Lobby

Java Lobby just published my interview with them. You can read this here.

Using JMX to Start/Stop Message Driven Bean

OC4J 10.1.3.x allows users to start/stop MDBs dynamically without having recycle container or application.

For example, you can disable an MDB upon start/deployment by adding enabled="false" in your orion-ejb-jar.xml as follows

<message-driven-deployment name="MessageLogger" enabled="false">

MDB will not start when the application is deployed/started.

You can use Application Server Control to start the MDB later as shown in the following screen shot:


You may want to perform this operation from command line. You can download this zip file that contains code to stop/start MDB using JMX.

• Unpackage the zip and change ant-oracle.properties file to change your URL, userid and password

• Set ORACLE_HOME to the directory where OC4J installed

• To start your MDB:

ant start -DappName=ejb30mdb -DejbModule=ejb30mdb-ejb -DmdbName MessageLogger

• To stop it

ant stop -DappName=ejb30mdb -DejbModule=ejb30mdb-ejb -DmdbName MessageLogger

Following is the code snippet from the Java Class that perform the stop/start operation:

StartStopMDB mdb = new StartStopMDB();

try {

mdb.connect("service:jmx:"+args[0], args[1] ,args[2] );

System.out.println(mdb);

System.out.printf("Client connected? %s\n",mdb.isConnected());

MBeanServerConnection mbs = jmxCon.getMBeanServerConnection();

String objName = "oc4j:j2eeType=MessageDrivenBean,EJBModule=\""+args[4]

+"\",J2EEApplication="+args[3]+",J2EEServer=standalone,name=\""+args[5]+"\"";

ObjectName myMDBObjectName = new ObjectName(objName);

MessageDrivenBeanMBeanProxy MDBMBean =

(MessageDrivenBeanMBeanProxy)MBeanServerInvocationHandler.newProxyInstance(mbs,

myMDBObjectName, MessageDrivenBeanMBeanProxy.class, false);

if (args[6].equals("start"))

{

System.out.println("Starting up MDB: "+args[5] +" in ejb module:"+args[4]+

" in application name:"+args[3]);

MDBMBean.start();

System.out.println("Successfully started MDB!");

}

else if (args[6].equals("stop")) {

System.out.println("Stopping MDB: "+args[5] +

" in ejb module:"+args[4]+ " in application name:"+args[3]);

MDBMBean.stop();

System.out.println("Successfully started MDB!");

}

mdb.close();

} catch (Exception e) {

e.printStackTrace();

}

}

Hope this helps!

Using TopLink Essentials as the JPA Provider for WebLogic 10

A couple of weeks ago, one customer asked me for instructions for using TopLink Essentials as the JPA provider with WebLogic 10. I thought I would give it a try as I’m working on migrating my book examples to WebLogic 10.

First, you have to download TopLink Essentials either from OTN or Glassfish web site.
I packaged the toplink-essentals.jar, toplink-essentials-agent.jar in the lib directory for the EAR so the structure of EAR looked like as follows:

chapter2-ejb.jar
lib/toplink-essentials.jar
lib/toplink-essentials-agent.jar

I specified provider class oracle.toplink.essentials.PersistenceProvider
in my persistence.xml packaged in my EJB module as follows:

<persistence-unit name="actionBazaar">
<provider>
class oracle.toplink.essentials.PersistenceProvider
</provider>
<properties>
<property name="toplink.ddl-generation" value="create-tables"> <property name="toplink.ddl-generation.output-mode" value="database">

If you want to use container managed entity manager with WebLogic’s JTA transaction manager you have to create your server platform class by extending oracle.toplink.essentials.transaction.JTATransactionController as follows:

package debu.weblogic;
import javax.transaction.TransactionManager;
import oracle.toplink.essentials.transaction.JTATransactionController;

public class WebLogicTransactionController extends JTATransactionController
{

private static final String WLS_TRANSACTION_MANAGER_NAME = "javax.transaction.TransactionManager";
public WebLogicTransactionController(){

}

protected TransactionManager acquireTransactionManager() throws Exception {
TransactionManager tm = (TransactionManager)jndiLookup(WLS_TRANSACTION_MANAGER_NAME);
return tm;
}
}

As you might have seen already that I’ve specified this class as the target-server property in persistence class.

You can package this class as a part of your application in the same EAR file where you packaged the TopLink Essentials jar files and the entity classes.

Using TopLink 11 with WebLogic 10

If you are using TopLink 11 preview (or EclipseLink) you do not have to create your own server platform class but you can use the server platform shipped in toplink.jar for WebLogic 10.

Here is how your persistence.xml look like when you use TopLink 11.

<persistence-unit name="actionBazaar">
<provider>
oracle.toplink.PersistenceProvider
</provider>
<jta-data-source>
jdbc/ActionBazaarDS</jta-data-source>

<properties>
<property name="toplink.ddl-generation" value="create-tables">
<property name="toplink.ddl-generation.output-mode" value="database">

<property name="toplink.target-server" value="WebLogic_10">

</property>


Note that you have to package toplink-ojdbc.jar in addition to toplink.jar and antlr.jar if you are using Oracle DB as the underlying database.

Hope this helps.
Need to go to bed, feeling sleepy now!

EJB 3 In Action Examples on WebLogic 10

Several readers requested me to provide the code examples of EJB 3 in Action for BEA WebLogic 10. We have earlier provided examples for Glassfish, Oracle Application Server and JBoss. I spent sometime last weekend to port these examples to Weblogic 10. You can download examples for first four chapters.

These examples have been modified to run on the default examplesServer on the Weblogic in the default server domain. To run the examples, first the set the environment variables by the running the SetExamplesEnv script in $BEA_HOME/wlserver_10.0/samples/domains/wl_server directory.

For example, if you are running on Windows and you have installed WebLogic 10 in C:\bea\wlserver_10.0\ directory you can run the script as follows:

C:\bea\wlserver_10.0\samples\domains\wl_server\SetExamplesEnv.bat

If you unzipped the samples in c:\WLS examples change directory to chapter 1 and you can build and deploy as follows:

cd c:\WLS examples\chapter1

ant - -> attempts to build and deploy in the examplesServer

To run the example:

ant run

You must be wondering what are the changes that I made in the to run on WebLogic 10.

Java EE promises write once run anywhere ! Then why I had to make changes in the code?

Every application server has its minor quirks here and there and code changes were very minimal.

I could not make dependency injection work in the application client code in WebLogic 10, not sure they support it. So I had to change thick client to make use JNDI lookup instead. I modified the Session bean code to define a global JNDI name for the HelloUser session bean as follows: @Stateless(mappedName="HelloUser")

public class HelloUserBean implements HelloUser

I modified the client code to lookup the remote EJB as follows:

Context ctx = new InitialContext(); helloUser = (HelloUser) ctx.lookup("HelloUser#ejb3inaction.example.HelloUser");

As you would expect, I updated the jndi.properties in the client jar file to have right environment properties for WebLogic as follows:

java.naming.factory.initial=weblogic.jndi.WLInitialContextFactory

java.naming.provider.url=t3://localhost:7001
That's it ..

In the next blog entry, I will discuss the code changes the instructions to run Chapter 2-4 and outline changes made to run JPA and MDB examples.

EJB 3.1 New features

Reza Rehman, my co-author of EJB 3 in Action has authored an article on EJB 3.1 new features.

To summarize the major changes that are planned in EJB 3.1 are:

• Singleton Beans. Using a new @Singleton annotation will support
  this.
• Optional interfaces similar to web services. Container will generate
  the interface for you. Anyway IMHO it’s always good practice to build an
  interface your bean
• Stateful Web services using stateful session beans
  EJB
• Timers to include cron timers. Just to note that OC4J already supports cron
  timer as an extension.
  

Note that Java Persistence API is now worked under a completely new specification.

You can read the article at http://www.theserverside.com/tt/articles/article.tss?l=NewFeaturesinEJB3-1.

Managing JBoss Application Server from Oracle Enterprise Manager Grid Control

Although I would like that you use Oracle Application Server always I realize that heterogeneous platforms are reality today :) You may have JBoss application server in your environment and you may want to monitor that from Grid Control. Oracle provides a management plug-in for Grid Control to monitor health and performance of JBoss Application Server.
In this blog entry, I will outline the steps to discover JBoss Application Server from Grid Control.
Let us assume that you have installed JBoss Application Server in a server named dpanda-pc in c:\jboss\jboss4.0.2 directory (call it JBoss_Home), your agent is running on a remote host named dpanda-lap.
1. Login to Grid Control 10g R4
2. Click on Application Servers Menu item
3. Select Add -> JBoss Application Server and click on GO
4. Enter name of the server where JBoss is running as Application Server Host
5. Enter the JBoss Home -> the top level directory where JBoss is installed. Note this is not required if you are using Agent installed on a separate host.
6. You have to supply userid/password only if you have enabled security for JMX Console. See http://wiki.jboss.org/wiki/Wiki.jsp?page=SecureTheJmxConsole how you can make JBoss Console secured. This credential will be used by Agent to make JMX connection to gather health/statistics.
7. You can use a remote Intelligent Agent to discover JBoss. If so you have to appropriately select the check box as depicted in the following figure figure:








The Agent requires the JBoss JMX client jar files to make JMX connection to JMS.

Hence you have to copy the following files to a directory e.g. c:\jboss\lib and make it available to the Agent as Library Path:

• jboss-management.jar from JBoss_Home/server//lib


• jnp-client.jar from JBoss_Home/client


• jbossall-client.jar from JBoss_Home/client


• dom4j.jar from JBoss_Home/lib

Note: Make sure that you restart IA otherwise the current status of JBoss Servers will not be reported correctly post discovery.



8. You have to supply the JNDI port for JBoss server and click next

9. Then you have to supply the credentials for the server/host where JBoss is running

10. It will provide a list of the JBoss partitions and/or Servers that it found in the host and you can select the servers that you want to manage and then click Next



After you confirm at the end of wizard , the JBoss servers will be discovered and you can monitor JBoss Application Server from Grid Control.