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> From: Roger L. Costello [mailto:costello@m...] > > > This XML message is identical to the earlier XML message > except for the root element. The root element implies > action. The root element is directly correlated to a method > name. Its child elements are the parameters. The difference I can see is not that the root element has a different name, that a human might reasonably interpret by default as a verb. It is that in the second case the _emitting_ software understands the root element as a verb, not a noun. Changing tags doesn't make data action-oriented, invoking code with that data does. > I contend that this action-oriented root element gives the > message a very different feel. I contend that it tightly > couples the message to a particular kind of service - one > that returns flight information. The data-oriented approach, > on the other hand, is not coupled to any service, so it could > be used by a variety of services. The tightness in your examples are in any assumptions the *emitting* software is making about what will be done to its data. i.e. how that data will be acted on. Either way it's emitting data, passing a message, uttering, or whatever. Tight coupling comes from faking a single thread of execution on a network, not enough indirection, and hard coding assumptions in software about what other software should be doing. The distinction I do see between action and data is this: -data: the emitter doesn't assume how the message is to be processed. -action: the emitter assumes the message will be processed according to its understanding of a verb. (the latter sounds like hard-coding to me) I'd rather see a classification of web services data based on speech act theory. regards, Bill de hOra
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