Re: LYNX-DEV proxy and 'z'apped transfer - suggestion

[David Woolley]

> I was talking about client singalling other than "failure" (see below).

There is no mechanism available for clients to signal to the server within
the protocol, although the de facto position is that they can close the
connection.

> This possibility beyond of my exact knowlege, but
> HTTP1.1 (rfc2068, section 8.1) says:

The basic reason for this is that clients which don't check the Contents
Length header or receive replies that don't contain one can end up with
an incomplete copy if the server drops the connection in mid transfer,
as they will take the close of the connection as the end of the data,
not an abort.

I don't think the specification writers wanted to specify how you detected
a client or network failure.

Note that maintaining a connection after a client close will normally result
in resources being tied up until some higher level timeout decides to abandon
the connection.  As clients aborting a connection is very common, trying to
continue to send after a connection close would normally be highly undesirable.

> 
> 
>                   ...    Servers SHOULD NOT close a connection in the
>    middle of transmitting a response, unless a network or client failure
>    is suspected.
> 
>    Clients that use persistent connections SHOULD limit the number of
>    simultaneous connections that they maintain to a given server. A
>    single-user client SHOULD maintain AT MOST 2 connections with any

I'm not sure why you are quoting this, but I think the basic idea here is
that you can read the main page on one connection and all the graphics on
the other connection, which would allow you to start filling in the graphics
before the complete document arrived, and therefore progressively render
the page - this assumes that there are no tables or all the dimensioning
information is given up front.

The point about persistent connections is that connection setup is relatively
expensive and most web pages these days are really compound documents, rather
than linked independent documents.

>    server or proxy. A proxy SHOULD use up to 2*N connections to another
>    server or proxy, where N is the number of simultaneously active
>    users. These guidelines are intended to improve HTTP response times
>    and avoid congestion of the Internet or other networks.
>