[XML-DEV Mailing List Archive Home] [By Thread] [By Date] [Recent Entries] [Reply To This Message] Re: idempotent POSTs
Hi Paul, > Ramin Firoozye wrote: > > > > Actually, even if you do a GET to the database, if it goes through an > > intermediary function (like a servlet) it will end up changing the resource. Paul replied: > How does going through a servlet change the resource state? Didier replies: If what is identified by the resource's URI is the application then no, this latter is not modified (at least on most of the application I saw :-). But this application may change the state of something stored on the server. If the URI represents an abstract name space then let's say that the resource identified by http://www.mydomain.com/myapps?action=delete_all_information_stored_on_this_ server (I am just using an outrageous example here ;-) is the object associated to this abstract namespace identifier (i.e. domain.com or "crème brule"). Since the namespace may represent about anything and since this hierarchy is an abstraction representing the resource the game is open governed by the URI owner. The URI semantic is left to the resource owner. So, yes going through a servlet may change the resource state if the resource is an object based on a hierarchy of objects. If URI can represent abstract resources then the namespace interpretation is left to the resource owner therefore based on this premise, the servlet may change the state of the resource because you don't know what exactly the resource is, you may have received just a fragment of it as a response. Gee... this mental game reminds me of the fun we got about the bugs created by URIs during the Apple Project X and its language that preceded RDF[1]. If a name space is lacking any semantics then the URI inrepretation monster may awake you in the middle of the night. Please don't talk about the URI interpretation monster to my daughter, since Project X she don't like it :-) Conclusion: yes going through a servlet may change the state since you don't know what is associated to the resource. You just get fragments of it. Moreover, the returned fragments may be as numerous as !param. Who ever saw an atom? who can say for sure what is a resource? a program? a document? an elephant? a bug? a bank? an abstraction? god? all these answers? But if the URL just mean its a location then its OK, its just a location. The guy living at this location may be a good guy or a monster who knows? cheers Didier PH Martin [1] At that time MCF wasn't based on an XML syntax. it was based on a syntax like attribute:value. Guha did a first version, we then produced Guha and me and second one, then Guha went to Netscape after Apple Research closed its doors, MCF evolved into an XML syntax version, then Guha and al. created RDF under the W3c umbrella. <End of historical recap>
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