Wednesday, August 29, 2007

Guerilla SOA, MEST

InfoQ has posted an interview with Jim Webber of ThoughtWorks about "Guerilla SOA", where he talks about how to design scalable SOA solutions that are evolvable and allow innovation in the different services that make up the solution.

The advice he offers covers topics that I have written about in my posts these last months:
  • Share business messages owned by the business people (business process information model)
  • SOA has no operations, only business messages delivered to letter boxes - services exchange messages to fulfill business processes
  • Services cannot be invoked, they just receive event+payload messages and decide if and how to process it: "Could you possibly have a look at this message and maybe if it suits you do some processing on it" (semantic covenant: the service is always right)
  • Business processes are workflows; you need to model long-lived conversations beyond request/response (SSDL, check out the Soya WCF SSDL toolkit at SourceForge)
This architectual style is coined MEST, as it resembles REST: it is based on message exchange through a uniform interface - the letterbox. As you will see, MEST is a decoupled scalable design pattern along the lines of EDA.

Listen to the interview and read the transcript: Jim Webber on "Guerilla SOA"

No comments: