Re: Soup Connection Management for SPDY in libsoup

[Dan Winship <danw gnome org>]

On 02/25/2013 10:12 AM, ANUJ MISHRA wrote:
> I want some of your suggestion regarding multiple stream handling in
> libsoup. I can see that libsoup is tradition client server based library
> and maintaining state for everything. But for SPDY we need to keep only
> one connection and deal with streams. Where multiple streams would
> arrive through single connection and we will do de-muxing of it and
> provide it to application layer. Libsoup's connection, session, message
> objects are tightly coupled with request/response mechanism.

I was assuming that SoupMessage itself would be unchanged.

SoupSession would want to keep track in SoupSessionHost whether a host
supported SPDY or not (the same way it tracks ssl_fallback now).
SoupConnection would become a superclass, with SoupHTTPConnection and
SoupSPDYConnection subclasses. I can see two possibilities for how
SoupSPDYConnection would work:

    1. a SPDY SoupSessionHost would have only a single
       SoupSPDYConnection, which internally would multiplex into
       multiple GIOStreams

    2. a SPDY SoupSessionHost would have a single
       "SoupSPDYMasterConnection" from which you could create multiple
       SoupSPDYConnections each representing a stream within the single
       connection

Not sure which would be cleaner/easier. Other than this change to
host/connection management, I don't think you should need to make any
changes to SoupSession.

Some of the code in soup-message-io would make sense to share between
HTTP and SPDY, but some would not. I'm not sure what the best way to
reorganize this would be. At a high level though, the idea is that
eventually, whether you're using HTTP or SPDY, you'd end up with an
io->body_istream that could be read to get the response body, so the
parts of soup-message-io that deal with that would not need to be
changed (and, eg, soup_message_io_run_until_read() and
soup_message_io_get_response_istream() would both work exactly the same
way they do now, from SoupSession's perspective.)

-- Dan