Originally posted by preeti khane:
I would like to know the role Web Services play in the big picture of J2EE... How do they tie into or complement EJB design... EJB's themselves have a huge overhead for implementation and are not recommended for simple applications which do not have immense business logic.. Do Web services just act as a messaging communication medium to EJB's... If so how do Web Services complement JMS architecture,, which is what is currently used for messaging.. Do Web Services remove the need for JMS completely...
I am also trying to understand the need for web services / SOAP , as building blocks for J2EE, adding new paradigms / to existing J2EE architecture...How do they really help real -life J2EE architecture systems... I do know that XML exchange via web services makes it an easy communication service..
Also what I have seen so far about SOAP , it not an easy to implement / master type of protocol... Will building of web services be made easier with some sort of Web Services Application Server , so the application developer need not be concerned with the actual binding/ registering of the Web Services...
thank you for all your replies
The upcoming J2EE 1.4 release (June, 03) focusses primarily on Web services, especially making J2EE application components to participate in Web services. J2EE 1.4 also support WS-I Basic Profile 1.0 (Recommended by Web Services Interoperability Oragnization (ws-i.org). This enables Web services exposed by J2EE 1.4 compliant Application server interoperate with all WS-I Basic Profile compliant Web services.
In particular, All Stateless EJBs can participate Web services using a SOAP Endpoint. The SOAP Endpoint and it service name will be set in the EJB deployment descriptor. All other components can be encapsulated as Web services using JAX-RPC or SAAJ. Both JAX-RPC and SAAJ implementation required are required as part of J2EE 1.4.
For asynchronous communication, MessageDrivenBeans in J2EE 1.4 can receive SOAP messages similiar to JMS messages. It means MessageDrivenBeans can implement "RequestResponseListener" or "OneWayListener" which allows to receive SOAP Messages asynchronously.
If you are really serious about choosing J2EE based Web services, then you must consider using Application servers which implement JAX APIs like JAX-RPC, SAAJ, JAXR and JAXM. Currently very few J2EE 1.3 Application servers support these APIs. One of my favorite application server (which support JAX APIs) is SunONE Application Server 7.0. The PLatform Edition is free to download, development and production. Take a look at
http://wwws.sun.com/software/products/appsrvr/appsrvr_download.html.