Since the REST/RPC/SOAP discussion flared up again, I've been looking for a single clear statement about what kind of problem may exist, and what to do about it. I found it in Paul Prescod's Google's Gaffe:
The point that has not yet filtered through to the mainstream of web services implementors is that linking is just as important for machine-to-machine applications as it is for human-facing applications. If it is impossible to link to SOAP-exposed resources, then they are less powerful and useful than HTTP-exposed ones. Until SOAP has an addressing mechanism as rich as HTTP URIs, SOAP is less, rather than more powerful than HTTP.A hugely important class of web services is addressable by URI, and accessible to GET. We call these things web pages. The fact that such pages can be consumed by human-operated browsers and machine-operated scripts in the same way was, and remains, a great thing. As some pages evolve into services intended mainly for programmatic use, XML becomes a natural representation format. This need not undermine the value of the URL-line which, as I've pointed out, remains an incredibly vital style of access.
In practice, though, I don't find that SOAP undermines the URL-line. Toolkits seem perfectly happy to let me turn service names, method names, and parameters into URLs. I have here, for example, both Visual Studio.NET and GLUE. If I write a SOAP service called StockQuote in either of these, with a method called getQuote, then in addition to the SOAP/RPC interface I can automatically use:
http://host/StockQuote/getQuote?sym=VRSN
or:
http://host/StockQuote.asmx/getQuote?sym=VRSN
Should Google have done something like this? Absolutely. I miss being able to type http://google.com/xml?q=roy+fielding. As I pointed out in a essay on monetizing web services, this was possible a few months ago. Arguably it still should be. But that's just a business decision Google has made. In practice, given the restrictions placed on the Google API, the regular web-friendly HTTP GET remains the preferred way to link to the infinite space of Google queries, as people do every day.
So, SOAP toolkits already support a RESTful mode for GET-style (though not for POST-style) operations. Since GET-style reads are what both people and machines mainly use the Web to do, I'd say we're in pretty good shape.
PS: The top Google result for "restful soap" -- ahead of a bunch of W3C mailing list postings -- is an ad for a restful soap full of aromatic fragrance.The name of this restful soap? Desert Storm. Go figure.
Former URL: http://weblog.infoworld.com/udell/2002/05/02.html#a213