IPP> Why HTTP and thoughts on forms etc

IPP> Why HTTP and thoughts on forms etc

IPP> Why HTTP and thoughts on forms etc

Andy Newman andy at research.canon.com.au
Thu Dec 5 23:11:16 EST 1996

Robert Herriot writes:

> Your description of the difference between the way information is
> passed into a CGI script for GET and POST makes me wonder if
> we shouldn't use POST for GetAttributes and GetJobs too.

Good point however HTTP has specific meanings for its requests that,
although abusable maybe should be respected. A GET is supposed to
(according to the HTTP spec.) "retrieve whatever information (in
the form of an entity) as identified" by the request's URI. The POST
method is used "to request that the destination server accept the
entity enclosed in the request as a new subordinate of the resource
identified buy the Request-URI." The practical side comes into play
too where passing parameters to a CGI program invoked with the GET
request can run into limits on the size of command lines or environment
space where POST doesn't have this limitation.

> You show Content-length and Document-length fields. These fields are
> nice in some circumstances, but they create a problem of receiving
> documents via stdin where the length is unknown.

Content-length is mandatory when using the POST method, HTTP requires it.
This is one of the issues for tunnelling data inside HTTP. As is mentioned
in the draft IPP spec. HTTP/1.1 offers the ability to send "chunks" which
helps here.

Andy Newman <andy at research.canon.com.au>

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