Felipe Gaucho's Blog

Should I use EJB3 as web-services?

More than a community and business event, Jazoon'08 offers you a chance to discuss technology free of pressure. You can meet the top evangelists and share with international developers your technical issues and questions - a pervasive brain storm about the Java platform. Excellent opportunity to validate your ideas on how to do better software - and if they don't survive the community's scrutiny, you can always blame the beers and back home with good learned lessons :). I have my own set of (Not So) Stupid Questions, and the first one I want to discuss with you is about web-services and EJB3.

Is it a good design to expose EJB3 Session Facade as web-services?

Reading patterns and examples on the Internet, EJB3 + @WebService seem to be a fast and furious way to go straight to SOA with few lines of code and a good container. Despite the simplicity of annotations, I started designing an Open Source Classifieds system based on J2EE technologies and I have some observations about that.

Instead of replicating here all discussions about web-services design and its technology support, I prefer to bring you a few design options and get your feedback live during Jazoon.

1. Web Client -> JAXWS SOAP web-services -> Session Facade -> Domain Model Facade -> @Entities
2. Web Client -> @WebService Session Facade -> Domain Model Facade -> @Entities
3. Web Client -> @WebService Session Facade -> @Entities

Some considerations about the above design options:

• If I use annotations, I am assuming SOAP web-services, right? And what about REST?
• If I do expose my Session Facade directly, how can I change later my interface from SOAP web-service to something else ?
• What about validation and security? My business component should care about data input validation and authorization and authentication?
• Load balance and orchestration. Can I use a web server (Tomcat?) to expose the service interface and a j2ee container to do the business? What about service collaboration? The session beans will have references one to each other?

Using a same class to expose services interface and realizing business use cases seems a bit overlapped to me, but eventually I am missing some point here. It is up to you, see you in Zürich :)

Comments

• I'm interested in the answer to the questions, but unable to go to Zurich to find out. Will you post your results sometime afterward? My company is just heading toward SOA, and we have not adopted EJBs (any flavor/version) yet, but with the latest JEE it's looking more like an option, especially with web services on top of EJBs to enable multiple interfaces in the SOA. Thanks!

  Posted by: gerryg on June 02, 2008 at 10:15 AM

• EJB ease two interesting features to your web-service application:
  transactional operationsinterceptors - that help you to monitor your operations without using AOP
  Of course you can have this features without EJBs, but it is much easier to do that through annotated beans than programatically.

  Posted by: felipegaucho on June 03, 2008 at 03:50 AM

• I will be in Zurich to discuss this in person (if we manage to find each other) but I would also like to post one insight now while it is on my mind.

  To answer your question regarding security, I highly recommend that you check out Seam's approach to this problem. Seam combines a security interceptor with its conversation model to create a stateful web service. The initial call establishes your credentials and any number of followup calls can use that session to execute business services with an active UserPrincipal. The nice part is all this is done with standard Java EE with Seam's solution layered on top of it.

  Dan Allen
  Author of Seam in Action
  http://www.mojavelinux.com/seaminaction

  Posted by: mojavelinux on June 03, 2008 at 10:18 PM

• well, roles are automatically cascaded between web-applications and J2EE applications in the same container, so I guess Seam does the same as the standard j2ee application does. Seam is fantastic, but regarding this detail about security, I can't see great advantage of Seam...

  Posted by: felipegaucho on June 03, 2008 at 11:47 PM

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