[Qt5-feedback] Fast IPC for Qt5?

[andrew.stanley-jones at nokia.com]

This is continuing the same discussion Ville, Thiago and I had in January 2011 about this topic.  So I'll skip all the arguments that were made then, and jump to the crux of the mater.  For an idea of data rates, the request then was to transfer 1080p (or 720p?) raw video frame between applications.

1. Qt Service Framework (SFW) is designed to be very simple, and very easy.  This covers the majority of use casese in general systems.

2. Service Framework currently provides 3 backends, and defaults to the backend that integrates best with the platform.  

3. SFW can be used for "rendezvous" so apps who wish to establish high performance IPC. They can find each other easily, verify the interface version, etc, then connect and start their own IPC method.

4. "Fast" means many things to many people.  I'm not sure a generic backend that does: "please turn on the accelerometer", "please share this picture file to your image service" and "here's a 380 mByte/sec (1080p60) datastream" can be simple and meet points 1 & 2. I'm a huge KISS fan btw.

Service Framework as it stands has been released is in use, and the API can't change much.  If someone contributed a backend that met point 1 & 2 I think it would be most welcome.  

On the other hand, SFW, P&S and the project formerly called QtService will end up in a module, and maybe there's space for a high speed IPC module.  As Thiago points out though there are external projects that work will with Qt, so why bring in that support load?

-Andrew

--
Andrew Stanley-Jones, Software Engineer
Nokia, Qt Development Frameworks
Level 1, 53 Brandl St,
Brisbane Technology Park, Eight Mile Plains, QLD, Australia, 4113 http://qt.nokia.com/


-----Original Message-----
From: qt5-feedback-bounces+andrew.stanley-jones=nokia.com at qt.nokia.com [mailto:qt5-feedback-bounces+andrew.stanley-jones=nokia.com at qt.nokia.com] On Behalf Of ext Ville M. Vainio
Sent: Monday, 13 June 2011 10:43 PM
To: Picciani Arvid (Nokia-MP/Berlin)
Cc: qt5-feedback at qt.nokia.com
Subject: Re: [Qt5-feedback] Fast IPC for Qt5?

On Mon, Jun 13, 2011 at 3:13 PM,  <arvid.picciani at nokia.com> wrote:

>> Doing high performance IPC has so far required a roll-your-own
>> approach [...]
>> Perhaps Qt could provide such a thing as a module?
>
> Why would it? What's wrong with using the non qt solutions out there?

Well, Qt (in the extended sense of the word) already provides Service
Framework. It also provides "blessed" DBUS binding. So such things are
not entirely out of scope.

My preferred approach would be to rewrite Service Framework to use a
low latency solution. This was suggested before and shot down, but
that transpired before feb 11 and open governance so some things may
be different now.

> Also i know at least 5 solutions _with_ Qt, existing built from the community.
> Maybe it makes more sense to raise awareness for such community projects.

Agreed. I'm not particularly interested in bloating Qt - but pointing
at a fast way to do IPC as a "Qt endorsed" solution might be a good
idea.
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