How to get up to speed on SOA?

Question

I've been given the task of laying the groundwork of a SOA for my client. The goal is to open up various processes in an end-client independent way and also to make data available offline e.g. for reps visiting customers.

I do have extensive experience with J2EE (Websphere) and web services but I would appreciate advice on how to build up such an SOA.

Where are the pitfalls? What about security? How finely granulated should services be? etc.

Links to tutorials and book recommendations would also be useful.

Thanks!

Answer 1

Pitfalls

• Versioning/backwards compatibility: it gets really hard to change a contract once you have loads of clients. I have seen many sites version the APIs by introducing the version in the URL

Granularity

• Each service should be reasonly self-contained (don't expect people to do 3 calls before they get what they need)

Platform Independence

• Try to give more than one way of accessing your APIs (WS, JSON, REST...)

Answer 2

Get an ESB (enterprise service bus): Mulesource is a good choice (Opensource, Mature, yet bleeding edge) . Once you understand it, you will understand SOA.

Answer 3

People can't agree on what SOA actually means.

http://martinfowler.com/bliki/ServiceOrientedAmbiguity.html

(although consensus may have grown since that was written)

I suggest quizzing your client to find out exactly what they mean - if anything. Then give them something that actually provides business value, while ticking any SOA boxes that might coincide with that effort.

Answer 4

Found this IBM Redbook (#sg246303) which is quite a good introduction to the basics of SOA.

Answer 5

The goal is to open up various processes in an end-client independent way and also to make data available offline e.g. for reps visiting customers.

The second half of that isn't really an SOA topic, it's more of a replication to mobile devices problem. I would stay far, far away from trying implement a buzzword and focus on the problems that you are stating. Web services are good way to open up process to client independent ways.

Answer 6

As Alan said, I'd start reading the Enterprise Integration Patterns book. There are a number of ways to implement them either using a messaging system directly such as JMS or using open source projects like Apache Camel, for example see the pattern catalogue.

I'd also look at understanding how to build good RESTful services using JAX-RS with Jersey as a simple way to expose resources for your systems to anyone on the web from any language/platform easily without falling into the SOAP/WS-* deathstar :)