Re: [9fans] Different representations of the same file/resource in a synthetic FS

[Roman V. Shaposhnik]

В Втр, 09/06/2009 в 11:27 -0600, andrey mirtchovski пишет:
 I think I've mentioned this before, but on a few of my synthetic file
 systems here I'm using what you describe to slice a database by
 specific orderings. For example, I have a (long) list of resources
 which I'm managing in a particular environment each has an owner,
 type, status and a few static data containers. It's all backed by a
 relational database, but the file server presents different slices
 of that to external users, where the directory structure is rigidly
 defined as:
 
 /
  available/
  by-type/
  by-owner/
  inuse/
  ...
 
 with all data to fill the directories being dynamically pulled from
 the database.

This looks like a slightly different use case than what I'm worried
about. Mainly it seems that you don't really have to deal with
the representations of the same resource, your problem is how to
group these resources in a reasonable fashion. Essentially you're
mapping a relational database to a tree hierarchy.

In your case, the sooner you have the fork of
  by-this/
  by-that/
  
in your hierarchy -- the better.

My case is a flip side of that. In fact, my worst case scenario is
that I can't really predict all the representations of existing
resources down the road, thus it appears that I have to push
that part of a filename as close to an actual file as possible:
   /long-path/file.representation
I'm almost tempted to consider virtual extensions:
   /long-path/file ## default representation
   /long-path/file.gif
   
   /long-path/file.pdf
but at that point it becomes no more appealing than the content
negotiation techniques of HTTP.

Thanks,
Roman.

[9fans] Different representations of the same file/resource in a synthetic FS

[Roman V Shaposhnik]

Working on a RESTful API lately (which is as close to working on a 9P
filesystem as I can get these days) I've been puzzling over this issue:
is content negotiation a good thing or a bad thing? Or to justify
posting to this list: what would be the proper 9P way of not only
representing different renditions of the same information in
a synthetic filesystem but also give consumer a chance to declare
*a set* of preferred ones.

Lets assume a classical example (modified slightly to fit 9P): 
a synthetic filesystem that serves images from a web cam. 
The very same frame can be asked for in different formats
(.gif, .png, .pdf, etc.). Is serving 
   /date/time/camera-id/gif/frame
   /date/time/camera-id/png/frame
   ...
   /date/time/camera-id/pdf/frame
and relying on reading 
   /date/time/camera-id
for the list of supported representations really better
than what HTTP content negotiation offers?

Thanks,
Roman.