[XML-DEV Mailing List Archive Home] [By Thread] [By Date] [Recent Entries] [Reply To This Message] Interesting pair of comments (was Re: Schema
Interesting to read two comments in tandem: > Rogue Wave: "Many customer issues come from schemas that are not valid. In > almost all cases this is the result of a schema generated by a tool." WS-I: "...few web services implementers use validating XML Schema processors. Many users "validate" SOAP messages using only inherent SOAP-processing mechanisms, possible with some uncoordinated help from type serializers. This situation often means that XML Schema constructs like tyoe facets and PSVI are ignored when web services messages are being processed, which in turn discourages the use of such constructs by Schema Authors." Putting these two together, I find a paradox: When you are using a platform-specific data binding tool, it will generate good quality code for serializing the data into XML/SOAP and then recreating the objects at the other end fine. And it will also generate an XML Schema, if it didn't use a custom annotated one for its template. But that XML schema may be suspect or unacceptable to other tools. But no worries, the other end probably does not validate with the XML Schema or use its typing, anyway. The paradox? The way to use XML Schemas successfully in multi-vendor web services is to just pretend to use them. The schema and/or WSDL become just documentation, and should not be considered translatable specifications. Is that what is happening? If most multi-vendor web service servers do not actually use the XML Schemas (e.g. for validation, or for PSVI), then we might do well to up-weight the significance of bad interop reports: if only a few people have interop problems, but it turns out that only a few people actually use schema validation/typing/PSVI, then interop could be worse than we hope. With knitted brow Rick Jelliffe P.S. Full disclosure: my company Topologi makes validating tools of various kinds, including online tools for web services. We have a great new one, Interceptor, coming out next week sometime. We support XML Schemas (as well as Schematron, RELAX NG, DTDs). I certainly have a commercial interest in promoting validation, whether by XML Schemas or by some higher-level language like Schematron. So I hope no-one dismissed my comments as some kind of FUD about XML Schemas: it is one source of my bread and butter too, not some idle spoiling.
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