It's about SOAP, it's about REST. It's about whatever your enterprise chooses to support in its service orientation efforts. As two of the guiding principles of the SOA Manifesto state: "SOA can be realized through a variety of technologies and standards... Establish a uniform set of enterprise standards and policies based on industry, de facto, and community standards."
A quiet move away from WS-*
But do current product offerings support this diversity -- the ability to go with an enterprise's chosen standards or methodologies? In my recent discussion with the Coast Guard, for example, Steve Munson said the lack of non-WS-* capabilities has been holding back the governance of the organization's primarily REST-based implementation. Most solutions, he said, “are still tailored to the Web services approach. Many of them don't have good answers for non-WS-* type of registration.”
There seems to be some momentum emerging to support of REST-based services within some SOA governance products. James Governor, for one, says IBM -- without much fanfare -- is now enabling service oriented architecture through the REST style of architecture on its WebSphere registry/repository platform. In all fairness, IBM claims it did send out the memo on that. Nevertheless, this represents a sea change of sorts for Big SOA platforms.
As James puts it, an IBM executive just kind of matter-of-factly announced the shift to REST, apparently without blaring press releases. Application Integration and Middleware (AIM) General Manager Craig Hayman discussed features in the latest release of WebSphere Service Registry and Repository (WSRR), a tool for managing SOA services, at Connect09, IBM’s annual Software Group (SWG) analyst conference. As James relates:
"I wasn’t really sure what the session would be about, but I expected some cloud and Big SOA stuff. I sat listening to a pitch that seemed to basically run: 'We told you guys to do SOA but instead you did point to point ESB integration, and are now complaining you didn’t get the benefits of SOA, so now we have to offer you some products that make your poor architectural choices less of a problem. File under 'federation...' So there I was, probably tweeting or something, when suddenly I realised Craig was saying something pretty revolutionary. REST-style development and integration is part of the SOA world, and AIM is increasingly supporting REST in its products."
James says that the new offering is not based on Big SOA WS-* style integration, but intended to "make point-to-point integration more programmatic... While that may have initially meant implement UDDI, today we have a nice ATOM-based store, with a more metadata, and less WS-* specific approach. IBM took a flexible, modern approach to architecting WSRR, and it shows."
However, this doesn't mean SOAP and WS-* are likely to fade away anytime soon as a primary choice within SOA-based efforts. As Lorain Lawson puts it, "it's unlikely IBM's shift to REST will settle the whole REST versus SOAP debate, since SOAP has a heavyweight of its own: Microsoft and its popular SharePoint." However, IBM's growing support of REST is "too promising to ignore." That's because the REST architectural approach opens up the door to potentially stronger SOA deployments – "with easier integration and more reuse of services (read: more agile) than you'll get from an SOA built on an ESBs or the SOAP-based WS-*."
And the IBM move is also a sign that vendors are acknowledging that cloud-based services need the same governance as on-premise services. As James puts it, the result is both "hybrid cloud and on-premise models for the enterprise. Hybrid is now just the reality of how we get things done."