Certified coffee addict coding with passion: October 2008

Where we are working now we needed to have a fast way to create WebServices and I didn't want to deal/manage J2EE containers (packaging/deployment ...) so I tried what OpenEJB has to offer.

OpenEJB is an embedable and ligthweight implementation of EJB3, can be used as a standalone server also. In popular words, OpenEJB is a way in which you can have everything that is available in the EJB3 container, but 'outside' the container (well, not really).

Consider the next step by step tutorial for creating a webservice.

Create a sampleproject
Download openejb-3.0.zip from http://openejb.apache.org/download.html and unpack it
Add to the classpath of your sampleproject every .jar file that's in unpacked/lib
Create a META-INF folder inside your src directory and create a file inside that folder called ejb-jar.xml and just put in it this stringr "<ejb-jar/>" (without quotes)
Create now the interface that defines the contract of your webservice and anotate it with

@WebService(targetNamespace="http://yourcompany.com/wsdl")

public interface TestWs { ... }

Create the class that implements your interface and anotate it like this:

@Stateless

@WebService(portName = "TestPort",

serviceName = "TestWsService",

targetNamespace = "http://yourcompany.com/wsdl",

endpointInterface = "full.qualified.name.of.your.interface.TestWs")

public class TestImpl { ... }

To start the Webservice you need to do this:

pubilc static void main(String[] args) {

Properties properties = new Properties();

properties.setProperty(Context.INITIAL_CONTEXT_FACTORY,

"org.apache.openejb.client.LocalInitialContextFactory");

properties.setProperty("openejb.embedded.remotable", "true");

new InitialContext(properties); // here the magic starts ....

}

Taran !, after this steps what you have is a stateless bean exposed as a webservice in this location: http://localhost:4204/TestImpl?wsdl

You can use apache axis2 if you want to generate a Java client for it or just use a dynamic proxy like this:

   // this code can be placed rigth after InitialContext call, or
   // can be in another program or in another thread in the same program
   // Of course, the program that made the call to InitContext need to be
   // alive for the EJB3 services to be exposed

URL serviceUrl = new URL("http://localhost:4204/TestImpl?wsdl");
Service testService = Service.create(serviceUrl, null);

TestWs testWs = testService.getPort(TestWs.class);
// test the methods you've implemented ...

You would be wondering how does it works ?

Well, as you request the initial context, openejb automatically searchs for clases in your classpath containing ejb3-related anotations, it automaticaly exposes them as it founds, more or less as it happens when you deploy an application as a .ear in any aplication server, but simpler and with great flexibility due to its embedable architecture.

UPDATE 10 / 29 / 2008

By default openejb serves only to localhost request, if you want to use the exposed webservice from other computers add the next properties to InitialContext(prop)

prop.setProperty("httpejbd.bind", "0.0.0.0");

prop.setProperty("ejbd.bind", "0.0.0.0");

and if you want to change the default port in use, change the next properties:
httpejbd.port, ejbd.bind
Suppose your machine has more than one IP and you want that openejb answers only to requests comming from only one of the IPs in the server, then put the desired IP instead of 0.0.0.0

Easy WebServices in Java (not the common way)