SOAP Faces a New Challenger

A new development approach to Web services transport is giving users of the popular Simple Object Access Protocol pause and could place some at a development crossroads.

SOAP came under scrutiny last week at the Software Development Conference and Expo East here as developers mulled the future of an alternative technology, Representation State Transfer, or REST.

REST is a model for distributed computing and for building Web services and is focused on transactions as opposed to publishing, said Scott Means, president and CEO of Enterprise Web Machines Inc., in Columbia, S.C., who spoke on REST at the conference. Means co-authored the book "XML in a Nutshell" with Elliotte Rusty Harold, a lecturer at the Polytechnic University of Brooklyn.

Harold said SOAP was made to tunnel through firewalls and thus is inherently insecure. "SOAP piggybacked on HTTP to tunnel through firewalls," Harold said. "That doesnt fit the architecture of the Web. ... The Web as it works today is REST. HTTP is REST. Everything you do with HTTP is all REST at work."

But others say the debate is moot, as REST is an architectural style and SOAP is a protocol. What most agree on, however, is that at the center of the debate is not technology but oversight; SOAP is promoted mainly by Microsoft Corp. and IBM, while REST is a grass-roots solution.

"I believe the emotions surrounding this issue run so high because it is a key battleground in the Web services are for people versus Web services are for companies debate," said Jason Bloomberg, an analyst with ZapThink LLC, in Cambridge, Mass.

"It boils down to a matter of the best tool for the job," Bloomberg said. "REST is simpler but less powerful than SOAP, so if REST will do, then go for it. But for some tasks, SOAP is more appropriate."

While no real standard exists in this area, SOAP will continue to go through the World Wide Web Consortium process, fueled by IBM and Microsoft. The existing specification, Version 1.2, has never been ratified as a standard by the W3C. But sources say SOAP 1.2 will likely move to recommendation status late in the first quarter or early in the second quarter of next year.

The grass-roots REST effort, meanwhile, is likely to gain steam as more developers adopt it as an architectural style that can sometimes be used in conjunction with SOAP. Nevertheless, the odds are stacked in favor of SOAP. "REST has a good technical basis, and there is every indication that SOAP will absorb some of the best features of REST," said Graham Glass, CEO of The Mind Electric Inc., in Addison, Texas.

"SOAP [was created] to make it easy to build applications that viewed the Internet as if it were a LAN," said Dave Winer, chairman and CEO of UserLand Software Inc., in Acton, Mass., and a submitter of the original SOAP specification. "It builds on the philosophy of personal computers. REST was a retrofit by people who dont like personal computers to try to stop progress in building GUI software that ran over the Internet. Too little, too late. SOAP is a good idea. Has been a good idea for a long time."