[Live-devel] To use openRTSP in a multi-thread program

[Ehsan Adeli]

Dear Ross,

Thanks for your reply. Well, I do understand your point. That was why I
tried to explain every solution that came to my mind and all were not right
for my case.

About the first solution to run each one in a separate process, all the
controlling is not killing a process or the like. I am recording files from
incoming RTSP connections, and whenever I am done with a file I want the
parent program know about that, so I call a callback function. Or whenever
there is a connection error or any type of error, I want to handle the
error by letting the main program know about that and resolve the issue. I
also need to stop the RTSP connection neatly, and not to just KILL the
process. I ask the connection to stop (anytime the user asks me to) and it
will wrap everything up and close any open connections and files. And many
more. If I use multiple processes, I would need to use inter process
communication or something like that, and that is not right.

The right solution is to do like something done in the testRTSPClient test
project. I am doing that and it seems to be working fine.

BTW, I am not afraid of using multiple processes. I use such a solution,
when I need to. But sometimes you need to have control over your own
program and interact with your program, rather than giving everything to
the OS. I know the idea for openRTSP was to be used as an stand alone
program and to be used in a shell-script. I also think that it is the best
solution for such applications. I just simply asked a question here, to see
if anybody has taught about it before or not (although I have seen old
emails about the same issue, with the answer to use shell-scripting).

Again, thank you all very much, for this great library and all your great
efforts.

Regards,
Ehsan



On Mon, Jan 6, 2014 at 1:51 PM, Ross Finlayson <finlayson at live555.com>wrote:

> I am trying to use the openRTSP code in my program and use it to record
> from multiple sources at the same time. Therefore, I need to run each
> instance in a separate thread.
>
>
> No, the second sentence does not follow logically from the first.  (See
> below.)
>
>
> But openRTSP code is not thread safe (many global variables). I will be
> left with three options:
> 1- To run openRTSP as a stand-alone process for each client stream.
>
>
> Yes, that is what you should do.  E.g., use a shell script to exec
> multiple "openRTSP" commands concurrently.
>
> This would not be efficient, and I would lose control over each openRTSP
> running process.
>
>
> No, this would still be efficient, and you could easily control each
> "openRTSP" process, from your shell script.  E.g., your shell script could
> note the pid of each "openRTSP" process, so it can kill them, if necessary.
>
> I continue to be surprised how - in this century - so many programmers
> have become afraid of (or unaware of) structuring applications as multiple
> processes, resorting instead to using multiple threads within a single
> process - which is *much* more difficult, and *much* more error-prone (and
> is something that's required only when you need shared memory).
>
>
> 2- To re-implement openRTSP with a same scheme as in testRTSPClient test
> program. Creating my own StreamClientState, ourRTSPClient and DummySink
> classes. But I would lose all the functionality implemented in openRTSP.
> Implementing every one of them would be hard.
>
>
> You wouldn't need 'all' the functionality of "openRTSP" - just the parts
> that you want.  But in any case, I don't recommend that you do this, unless
> you need only very basic functionality of "openRTSP".  (Especially as this
> is a hobby for you.)
>
>
> 3- Try to make the current openRTSP implementation thread-safe, by
> defining StreamClientState and putting all global variables in playcomm.cpp
> in that class and trying to over ride RTSPClient used there. But the
> RTSPClient is initiated in the HandlerServerForREGISTERCommand and finding
> the correspondences is a bit hard.
>
>
> No, I don't recommend that you do this.  The "openRTSP" code is very
> complex (in part because it's also used for "playSIP" - a SIP client).
>  It's not something to mess with.
>
>
> Ross Finlayson
> Live Networks, Inc.
> http://www.live555.com/
>
>
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> live-devel at lists.live555.com
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>
>
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