- From: Tim Berners-Lee <timbl@w3.org>
- Date: Mon, 15 Jul 2002 14:47:09 -0400
- To: "Williams, Stuart" <skw@hplb.hpl.hp.com>, <www-tag@w3.org>
I have used "dereference" to mean to "get that identified by" as in dereferencing a pointer. The meaning here is I think the same as your "retrieval, except that I prefer "dereference" as it seems to me to be an abstract function -- the referent as a function of the identifier, while 'retrieve" indicates motion of something (as in a Labrador trotting back with a duck). In a computer system, you can dereference something which identifies a file or a document. Tim ----- Original Message ----- From: "Williams, Stuart" <skw@hplb.hpl.hp.com> To: <www-tag@w3.org> Sent: Friday, July 12, 2002 10:58 AM Subject: Architecture Document: Terminology: Dereferencable, Retrivable, R esolvable. > > The retentive in me is coming out... > > In writing about the things folks might do with URI (and URI references) we > speak variously of resolvable, dereferencable and retrievable URI. However > it's not clear to me whether or not we have consistent notions the different > shades of gray that might be associated with these terms. If there are good > pre-existing definitions for these notions a pointer would be welcome. > > For instance, a TAG finding might say that "All important resources should > be identified using deferencable URI" (for example). One might take that to > mean that a representation of the resource should be 'retrievable' using the > relevant URI (that's what it says at [1]). But I think one could also argue > that any of HTTP PUT, POST, HEAD or DELETE involve "deferencing" the URI. In > programming languages we apply the notion of dereference wrt to an object > reference or a pointer regardless of whether it is used on the left or right > hand side of an assignment. So... whilst to be 'retrievable' a URI must also > be 'deferencable' the act of 'derefencing' a URI does not necessarily imply > a safe 'retrival' operation. Likewise, to be 'dereferencable' a URI must > also be 'resolvable', the act of 'resolving' a URI being a pre-cursor to and > possibly entailed within the process of dereferencing a URI. > > Does this make any sense or do such fine grain differences not matter in our > architectural writings? > > Anyway, some proto defintions to chew on: > > URI Resolution: > The process of determining the access mechanism and > appropriate parameters necessary to dereference a > URI. e.g. in the case of an HTTP URI, this process > resolves the URI into an IP address, a port number, > a host name (possibly optional) and a request URI. > > Resolution may require several iterations. > > URI Dereference: > The process of using the access mechanism and > parameters generated by URI resolution to create, > inspect or modify resource state. > > URI Retrieval: > The use of URI dereference to retrieve > representations of resource state. > [On the Web Retrival is always safe]. > > Comments? > > Regards > > Stuart Williams > > [1] http://www.w3.org/2001/tag/2002/0701-intro.html#dereference >
Received on Monday, 15 July 2002 14:47:06 UTC