Straw Man, SOAPy Water
  Posted July 16, 2003    PermaLink    Comments (0)  

Here we have a piece of RDF advocacy masquerading as a SOAP RPC vs. Document Encoding article. The problem is that once you get past the first section the arguments the author uses supports in no way the contention made in the opening setction, they are in fact blasting some unrelated topic that he has vaugle associated witht he original contention.

This is a common argumentation fallicy referred to as a "Straw Man Arguement." The layman's definition is that the arguer brings in some unrelated issue (the straw man) and proceeds to destroy it, and then claim that he was actually destroying the original argument, while actually not addressing the issue in any tangible fashion.

Here's the essential summary of the technical porton of the article: "Using RDF is more descriptive than a real bad tree encoding stored in a hash table." A slightly longer version is "Using RDF (let's demonstrate this with a document encoding) is more descriptive than a real bad tree encoding stored in a hash table (let's use RPC encoding for this example)." The issue of SOAP binding encoding has absolutely nothing to do with the real philosphical issue at hand, and instead he is beating the RDF drum. His "perfect" RDF example could just as easily been done with the <soap:binding style="RPC" ... > . But that would have ruined his groove, so he ignores that fact.

Despite the misplaced direction there are some good practices that we can draw from this example. Fist, use the WSDL file as the master definition. In the first example he uses a .jws to deploy the first web service, which is quick and dirty, with an emphasis on the dirty. Despite how hard you try you cannot separate the quick from the dirty using .jws files. By using a WSDL as the master in the second he has also increased the interoperability of the entire system since leaky abstractioins from Java to WSDL won't get translated into any third language, with second level abstracton leaks. With the WSDL as the master each client has to only map the WSDL issues and not inherit old Java issues.

Second: some data structures jus plain old suck. Anything is better than the encoded mess that is the hashtable/tuple mapping with encoded data. Not to mention that using a tree path as a string is so LDAP. Even RDF was better than the first example (it wasn't that hard).

Third: If you have data format already in XML Schema, just go ahead and use it in the WSDL. You don't need to re-invent the wheel if you already have your data format. If you want to use RDF as your message parts in a WSDL call go for it! This issue is totally unrelated to whether the client should consider this an RPC or document/literal call (which they can freely ignore if they choose).

Lots of good issues in that article, but it fell prey to the trendy RPC vs. document debate in the SOAP community while having nothing to do with it. And why the blind allegence to document, is he applying for a job at Microsoft?

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