SOA/OO/WS

Great post about the basic premises of SOA:

·        Business systems are autonomous. They evolve independently of each other. They protect their internal state. For example, most enterprises use Siebel for CRM, Peoplesoft for HRMS and SAP for others.

·        Corollary 1- Heterogeneity is the reality.

·        Corollary 2 – Loose coupling is necessary for interaction between these systems. Otherwise, a change in one system (like upgrade) will have serious consequence on other systems.

·        This one is little bit controversial. Business systems don’t trust each other and hence doesn’t support Atomic transactions.

He goes on to talk about using distributed objects technologies like COM or CORBA rather than SOAP/XML/WS-* stuff - possible, but you lose the “loosely coupled” nature using distributed objects instead of the SOAP/XML stuff.

Pretty much sums up what Joel has had in his head for at least two or three years, its a shame I didn't tune into the IJH^* factor earlier (and he keeps reminding me).

And Rod, in case you're reading this, “Long Live WIS!“ (poke, poke)

Mike

^*IJH = “In Joel's Head” - a phenomena where the requirements and design of a project is complete in Joel's brain before the rest of the team can even begin user interviews and formal requirements gathering. Successful projects with Joel usually involve a requirements gathering process somewhat akin to a frontal lobotomy to extract from Joel what is self-evident to Joel. On a somewhat disturbing note, recently Joel has been referring to another part of his anatomy where he pulls stuff out of, and I'm not sure I'm looking forward to tuning in to the IJA factor on the next project.