- From: Thomson, Martin <Martin.Thomson@andrew.com>
- Date: Thu, 10 Jun 2010 07:18:09 +0800
- To: Adrien de Croy <adrien@qbik.com>
- CC: Mark Nottingham <mnot@mnot.net>, HTTP Working Group <ietf-http-wg@w3.org>, Greg Wilkins <gregw@webtide.com>, Salvatore Loreto <salvatore.loreto@ericsson.com>
Adrien writes: > I can understand the issue between negotiating this on a hop-by-hop > basis so a client can know how long an idle connection (no request sent > yet) may be usable. However the discussion of long-polling confuses > this, since long-polling is different, it's not later use of an idle > connection for a request, it's a delayed response. That's right. The discussion of long-polling relates to a request (Timeout) rather than a connection (Connection-Timeout). > However I don't understand the issue where you discuss non-idempotent > requests, and using a new connection. I don't know what this actually > gives you. > > In the case where there is a proxy, and say the proxy starts sending > the > request on an idle connection to a server at the same time as the > server > closes the connection, then the proxy will report an error to the > client, and the server never got the request, and the client can retry. That's precisely the problem - they can't. If you send a non-idempotent request, it's not safe to retry the request. Without a response you have no idea what happened. You can't retry automatically. Many HTTP implementations create a new connection for non-idempotent requests, which reduces the chances of losing the connection. That's inefficient. Hence: Connection-Timeout. > What are you referring to when you mention a "null response"? Is this > like a 204 response? I've seen 200, 204, 304 - it matters little, though we should probably clarify that point :) > I guess if intermediaries are between the client > and server, the next request could come in on another connection. > However if you used a 1xx response, the same connection could be used > to > send the final response when an event actually occurs. So I believe > 1xx > response has benefits for long polling. To the extent that it ensures that the connection remains open, sure. You still need to know when the 1xx is required. --Martin
Received on Wednesday, 9 June 2010 23:16:54 UTC