--On Monday, 14 August, 2006 03:41 -0400 "Paul E. Jones" <paulej@xxxxxxxxxxxxxx> wrote: > Brian, > > The problem with using "image" is that it would mean that a > gateway would have to do one of: > 1) Close the audio session and open an image session > 2) Open a second "image" session during mid-call > 3) Open both an audio session and image session at the outset > > For a lot of reasons, none of those options are preferred. In > the latter case, gateways just waste memory and CPU resources > servicing sockets that are never used. In the first two > cases, there is a lot of extra signaling on the wire. (For > SIP networks, and especially IMS-based SIP networks, this is > horrible due to the widespread use of UDP, slow timer >... Paul, I think there may be a fundamental misunderstanding, or at least difference in understanding, about top-level media types implied in the above. From a process standpoint, if you are just finding out about it now, something has, IMO, failed (see my other note). But, putting that aside... The "text/" top-level type, and only the "text/" top-level type has the property that one can reasonably expect to be able to display the contents to the user without understanding the subtype. Whether that is realistic or not, and how narrowly that requirement should (or must) be interpreted to make something "text/" has been widely debated in the past. But, for all other media types, one cannot interpret them without both the top-level type and the subtype. As far as transmission issues are concerned, the type-subtype distinction is largely irrelevant: there is not, meaningfully, an "audio session" or an "image session" as far as the media type is concerned. Where they do become somewhat relevant is at the receiving end: if I don't have any way to render any image, then an image type is, at best, going to need to be stored for later retrieval even if it were to be fully understood. Similarly for audio: if the recipient does not have the capability to reproduce or otherwise render sounds, then one can only store the transmission contents for future processing or forward it elsewhere (or reject the transmission on that basis). A gateway that isn't structured around that model -- a model that, at its most general, implies that the transmission forms of media types are more or less just bits except to the network end-points -- isn't necessarily wrong, but it will have far more problems interworking smoothly and with minimal information loss than the names of media types or the status attached to them. regards, john _______________________________________________ Ietf@xxxxxxxx https://www1.ietf.org/mailman/listinfo/ietf