SOA Reuse

Back in August, David Chappell posted his opinion on SOA and reuse (and comments on the response he received). David said that reusing services is next to impossible.

David Ing commented on that, saying that in order to do any reuse of services you should focus on data and on exposing it. Harry Pierson said that Object/Component reuse has been partially successful for non-business aspects (sting classes, UI widgets etc.) but when you introduce context (as in business context) reuse becomes more complicated. Harry commented on reuse again (after attending a workshop by Thomas Erl) that he doesn't really see how reuse is going to happen.

I agree with all of them. However, I do see some potential for reuse in SOA--not the kind of "write once, integrate everywhere" but rather in don't throw everything when you need to make changes to the business. This is something that is done even on the initial stages of SOA when, instead of writing everything from scratch, SOA developers use what I call "Legacy Bridge" and expose existing business application in their SOAs.

Also as David Ing said that since the data doesn't change as much as business rules and processes so as the service evolve you can reuse these parts of the service.

Another aspect of reuse can be in the "non-contextual" aspect; that is, reusing the software infrastructure you build for one service to build the other ones (i.e. the stuff that deals with security, auditing, monitoring etc.).

Nevertheless at the end of the day I agree with Udi Dahan who said "Bottom line, do SOA for the value, or don't do it at all."

Posted by Arnon Rotem-Gal-Oz at 07:10 AM  Permalink