Sunday, April 11, 2010

Web Services and the Law of Standards

I was recently asked why SOAP, WSDL, UDDI, and the various WS-* specifcations are fairly uncommon in practice compared to simple REST interfaces. Personally I think this is another example of John F. Sowa's Law of Standards. The basic statement is:
Whenever a major organization develops a new system as an official standard for X, the primary result is the widespread adoption of some simpler system as a de facto standard for X.
A quick look at some big online companies seems to confirm this:

Amazon:
I was recently talking with Jeff Barr, creator of syndic8 and now Amazon's chief web services evangelist. He let drop an interesting tidbit. Amazon has both SOAP and REST interfaces to their web services, and 85% of their usage is of the REST interface. Despite all of the corporate hype over the SOAP stack, this is pretty compelling evidence that developers like the simpler REST approach. (I know there are many more complex applications where SOAP is better, but I've always liked technologies that have low barriers to entry and grassroots adoption, and simple XML over HTTP approach seems to have that winning combination.)

Google:
Finally, we'd like to bid a fond adieu to one of our first developer products, the venerable SOAP Search API. It has been deprecated since 2006, when we stopped accepting new developers for the API, and it's finally hanging up the gloves and retiring on August 31st. It has been steadily declining in usage over the last couple years and we believe that the majority of use cases are sufficiently handled by the more comprehensive AJAX Search API (which supports not only web search, but local, news, images, video, and more). For those interested in migrating, there are more details in the AJAX APIs blog.

Yahoo!:
Q: Does Yahoo! plan to support SOAP?
Not at this time. We may provide SOAP interfaces in the future, if there is significant demand. We believe REST has a lower barrier to entry, is easier to use than SOAP, and is entirely sufficient for these services.

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