- From: Al Gilman <asg@severn.wash.inmet.com>
- Date: Tue, 21 Nov 1995 12:19:33 -0500 (EST)
- To: elevinso@Accurate.COM (Ed Levinson)
- Cc: ietf-types@cs.utk.edu, uri@bunyip.com
I need another MIME lesson. As I look at the draft proposed schemes for mid and cid URLs, a couple of thoughts come up: 1. By construction, these two nominal schemes are one scheme and we should only use one name for them. MID or MIDCID are possibles. 2. A more URL-traditional syntax would be something like "mid:" //host-net-path/message-unique where the RFC Message-ID object was <message-unique@host-net-path>. 3. The structure of a MIME multipart defines a well-ordered hierarchical space where at each level there is a linear sequence of parts. We could index into this part tree with part numbers. MIME message/partial usage establishes the precedent that parts number from 1 and the generic Internet URL syntax sets the precedent that paths punctuate with '/'. If we simply extrapolate from these two boundary conditions, we get a part URL more or less like this: midcidurl ::= "mid:" //host-net-path/message-unique part-number part-number ::= *( / decimal-integer ) where the interpretation of the decimal integers is as follows: For each level of hierarchy (defined separator) 0 refers to the unPart before the first opening-separator 1 refers to the Part after the first opening-separator ... ; there are N parts and N opening-separators n > N refers to the unPart after the closing-separator opening-separator ::= "--" separator-key closing-separator ::= "--" separator-key "--" 4. To retrieve an object by its Content-ID, the usage cidurl ::= "mid:" //host-net-path/message-unique?part-designation part-designation ::= part-unique [@host-path-if-different] where Content-ID == <part-unique@(host-net-path | host-path-if-different)> ; and I have not addressed encoding problems is more consistent with general Internet URL usage than introducing the Content-ID with '#'. In particular, for the general pattern of URLs, the #fragment clause makes no difference in the object that is served, only its state as presented. Since the retrieval of a part by Content-ID only needs to get the content of the part, the ? syntax which supports searching and can affect the scope of the object retrieved is more consistent. This usage would establish, as a rule under the mid: scheme, that searching defaults to matching part-designation as constructed above. Al Gilman
Received on Tuesday, 21 November 1995 12:23:59 UTC