Jim, Nelson, all, So, now that we all agree that SOAP is just a framing protocol and processing model, and XML Schema is that de-facto type system for defining interoperable data types...
The $50,000 Question: What problems can we solve with SOAP based Web Services? A colleague of mine has suggested three criteria for "when to use SOAP," in light of WS-I and past experience. These are by no means definitive, and open to discussion. 1) Functionality or Data to be exposed must useful across many types of systems. (The need for interop) 2) The data being returned can be expressed as a document conforming to an XML Schema. (WS-I) 3) The size of the documents being returned are relatively small. (The cost of XML serialization, much less XML Signature or Encryption) The $5000 Question: Should we not have native support in a programming language for XML Schema? Why all this mapping nonsense? To quote another colleague of mine: "the W3C really created a monster with XML Schema. It's far more powerful and expressive than most OO type systems like C# or Java." One of the Axis developers, Richard Kellogg I believe, posted this paper awhile ago concerning the mismatch of XML Schema and OO languages. It's a good read. Realize that Axis is not schema aware out of the box, hence the Axis-Castor integration effort. Check it out if you have not already - it's in Axis CVS. http://www.cl.cam.ac.uk/~gmb/Papers/vanilla-xml2003.html Food for thought. Is it not an interesting time to be a developer? -Jon Nelson Minar wrote: >> This seems to be the central quesiton of web services design. I know a >> lot of people are thinking about it and it's driving a lot of >> technology development. It's latent in the WS-I spec. But I haven't >> seen so much clear writing about WS interface design directly. Jim Murphy wrote: >Halleluah! I'm just starting to blog about that! IMHO, Web Service >Message design has been an afterthought of the spec working groups that >comprise your typical WS stack. You need to know a lot of grunge to >design an easy to consume service: >1. XSD - what to use and what to avoid is the hard part especially when >modeling non trivial data. What will axis do with a .NET DataSet, or >collections or... >2. WSDL - WSDL 1.1 is chaos. Hopefully WSDL 2.0 will improve that but >it looks m ore complex not less to me though several problem have been >addressed. There is the question of migration from WSDL 1.1 to WSDL 2.0 >as well. Not exactly straight forward. >3. Various language bindings. What will you interface be like to code >against in the foo language?
