RE: dynamically generated XML Schema?! Re: R: [xml-d
[Please see comment at end] > -----Original Message----- > From: Burak Emir [mailto:Burak.Emir@e...] > Sent: Thursday, November 04, 2004 3:15 AM > To: Chiusano Joseph > Cc: XML Developers List > Subject: Re: dynamically generated XML Schema?! Re: > R: Number of active public XML schemas > > Joseph, > > I agree WSDL documents should be generated rather than > written by hand, but doesn't schema provide means to pass > trees around whose structure you don't know (or at least, do > not need to know for the sake of web service invocation?). > > Generating WSDL dynamically (like creating a new type of service at > runtime) seems rather odd to me, because sure the invoker > program has to make sense out of the web service description. > If some form of negotiation takes place that leads to a new > service, the form of this negotiation is surely > predetermined, and you don't really need to create a new > schema for that. > > It might make sense for contexts, ports (e.g. suppose google > rents out a searching web service with 20.000 instead of > 1.000 queries a day, they generate the WSDL after payment has > been confirmed.) But dynamically changing the type of the > data that goes over the wire does not happen there. > > Maybe the point is that some specialization occurs (I am > inspired by what Mike Kay suggested, that later in a process > you might want to apply stricter validation). Suppose two > components talking to each other, finding out that they can > both deal with more specific messages, and then switch to the > new protocol. But again, this requires that both know the > protocol (the schema tht is more specific) in advance. > > Maybe some unanticipated reconfiguration mechanism might > benefit from dynamically generated schemas, but I am still > missing a good example for such a reconfigurable component. > > What would be an ad-hoc interaction that involves the change > in the type of messages? One example that comes to mind is what I will call "message path context" - that is, if a message from system A to system B was passed to system A by system C, then an additional piece of information is required to be sent to system B. That is, the path would look as follows: Without the context discussed here: A -> B With the context discussed here: C -> A -> B In more abstract terms, if we think of these as people making verbal requests to each other, perhaps person C has an additional request such as "and I would like that done within 3 days" (sort of like a high-priority flag). Of course, the issue here is that system B may or may not be able to interpret/accommodate such a request. I believe this gets into Natural Language Processing and perhaps Matchmaking, some of the things the Semantic Web Services folks are working with now. Whether this will *ever* be possible is, I believe, still up for much debate. Kind Regards, Joseph Chiusano Booz Allen Hamilton Strategy and Technology Consultants to the World > Chiusano Joseph wrote: > > >I have often thought about the concept of dynamically generated WSDL > >documents, for cases in which more ad-hoc interaction among systems > >needs to occur, perhaps driven by the context of a request. > But I think > >we're a ways off from that in terms of standards and > products - if it > >is indeed a useful concept. > > > >Kind Regards, > >Joseph Chiusano > >Booz Allen Hamilton > >Strategy and Technology Consultants to the World > > > > > > > > > cheers, > Burak Emir > > http://lamp.epfl.ch/~buraq >
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