Just-in-scope (or just-if-i-care) validation
by William VambenepeI started my Christmas wish list early this year. In January I described how I would like a development tool that tests XPath statements not just against instance documents but also against the schema. Since I am planning to be good this year for a change, I might get away with a second item on my wish list, so here it is. It’s the runtime companion of my January design-time request.
Once I have written an application that consumes messages by providing XPath expressions to retrieve the parts I care about, I would like to have the runtime validate that the incoming messages are compatible with the app. But not reject messages that I could process. One approach would be to schema-validate all incoming messages and reject the messages that fail. Assuming that I validated my XPath statements against the schema using the tool from my January wish, this should protect me. But this might also reject messages that I would be able to process. For example, even if the schema does not allow element extensibility at the end of the document, it shouldn’t break my application if the incoming message does contain an extra element at the end, if all I do with the message is retrieve the value of a well-defined foo/bar element. So what I would like is a runtime that is able to compare the incoming message with the schema I used and reject it only if the deviations from the schema are in locations that can possibly be reached by my application through the XPath statements it uses to access the message. Otherwise allow the message to be processed.
Steve, could Alpine do that?
