Fw: [annodex-dev] X-Accept-TimeURI

[illiminable]

Retry....

----- Original Message ----- 
From: "illiminable" <zen at illiminable.com>
To: "Conrad Parker" <conrad at metadecks.org>; <annodex-dev at lists.annodex.net>
Sent: Sunday, January 30, 2005 4:19 PM
Subject: Re: [annodex-dev] X-Accept-TimeURI


>
> ----- Original Message ----- 
> From: "Conrad Parker" <conrad at metadecks.org>
> To: <annodex-dev at lists.annodex.net>
> Sent: Sunday, January 30, 2005 3:24 PM
> Subject: [annodex-dev] X-Accept-TimeURI
>
>
>> Hi,
>>
>> Last week we came up with an "X-Accept-TimeURI" HTTP response header.
>>
>> The behaviour of this (the only behaviour that makes sense with HTTP) is
>> that a server may include this header in its response to a URL request
>> to indicate that the timed URI mechanism is allowed for the requested
>> resource.
>>
>> For example, if the response for:
>>
>>  http://media.company.com/blah.anx
>>
>> includes the header:
>>
>>  X-Accept-TimeURI: application/x-annodex, text/x-cmml
>>
>> then the client can expect that requesting
>>
>>  http://media.company.com/foo.anx?t=00:00:47
>>
>> will work (ie. won't 404).
>>
>> However, unfortunately that mechanism doesn't tell you about any other
>> resources; eg. after that response, you still have no idea if:
>>
>>  http://media.company.com/bar.anx?t=00:00:23
>>
>> is going to work, as it may be handled by a completely different
>> mechanism server side.
>>
>> Now, I'm starting to think the X-Accept-TimeURI header isn't such a good
>> idea after all. The main problem is that it's not a reliable negative
>> indicator, ie. if you ask for:
>>
>>  http://media.company.com/baz.anx
>>
>> and the response _doesn't_ contain the magic X-Accept-TimeURI header, is
>> it really a good idea to assume that timed URIs _don't_ work?
>>
>> However, a foolproof indicator is to simply try the request, eg:
>>
>>  http://media.company.com/baz.anx?t=00:00:00
>>
>> which requires no new headers, and is no extra work if done using an
>> existing persistent HTTP/1.1 connection.
>>
>> Of course, the other option is to mandate that a server MUST include the
>> X-Accept-TimeURI header, and that a client MUST check for it before
>> trying time offsets -- if either the client or the server were allowed to
>> ignore this header, then different combinations of clients and servers
>> would work / not work. It just adds a magic incantation all around, which
>> is sure to complicate things.
>>
>> Hence, I suggest we drop use of this header and simply suggest that, if
>> a client wishes to test the ability to do time offsets, it actually
>> requests a time URI (and perhaps suggest an offset of 0 as a means of
>> checking that).
>>
>> Conrad.
>>
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>>
>>