DanielPocock.com

Software engineer, Free/Open Source Software Innovator, Debian Developer

5 April 2013

Quickstart: Integrating SIP support into any application with reSIProcate

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Today's applications are more dynamic and interactive than ever before, typically offering the user many ways to collaborate or get live data about their community or environment as they need it.

Two open standards exist with a broad focus on real-time messaging and session control, SIP and XMPP (Jabber). Both of them have been supercharged by the development of technologies like WebRTC that makes every browser into a communications endpoint. Here, we look at integrating SIP into any C++ application (either client or server). We use the industry standard SIP stack reSIProcate.

The quickest way to get started is with a Debian, Ubuntu or Fedora development environment. reSIProcate is conveniently packaged on all those platforms (for Fedora, it is not yet in yum and must be built from the tarball using rpmbuild).

Getting the environment set up

Once you have Debian or Ubuntu installed, just do:

# apt-get build-dep resiprocate
# apt-get install libresiprocate-1.8-dev

This will install all the necessary tools, libraries and header files. Headers are under /usr/include/resip

Writing some code

The object orientated nature of C++ is heavily leveraged by reSIProcate, and this makes it easy to code. The stack is based on a callback paradigm: you create some objects based on well-defined interfaces, give your objects to the stack, and put the stack into a loop. The stack will call your object when some event occurs (e.g. new incoming call, new text message)

The easiest way to see this in practice is to browse the test cases. The test cases under the resip/dum(mirrored on github) section of the source tree provide good high-level examples of the type of code an application writes when using reSIProcate in an existing application.

Sending a SIP text message

Based on the basicMessage test case, I've created a trivial piece of code below to send a text message over SIP. The whole demo project is uploaded into github, see the README for instructions on how to build and run.

Here, we have a quick look at the one object in the demo, it is notified on the progress of the SIP text message:

class ClientMessageHandler : public ClientPagerMessageHandler {
public:
   ClientMessageHandler()
      : finished(false),
        successful(false)
   {
   };

   virtual void onSuccess(ClientPagerMessageHandle, const SipMessage& status)
   {
      InfoLog(<<"ClientMessageHandler::onSuccess\n");
      successful = true;
      finished = true;
   }

   virtual void onFailure(ClientPagerMessageHandle, const SipMessage& status, std::auto_ptr contents)
   {
      ErrLog(<<"ClientMessageHandler::onFailure\n");
      successful = false;
      finished = true;
   }

   bool isFinished() { return finished; };
   bool isSuccessful() { return successful; };

private:
   bool finished;
   bool successful;
};


int main(int argc, char *argv[])
{
   // boilerplate initialisation code...
...
   NameAddr naTo(to.c_str());
   ClientPagerMessageHandle cpmh = clientDum.makePagerMessage(naTo);

   Data messageBody("Hello world!");
   auto_ptr content(new PlainContents(messageBody));
   cpmh.get()->page(content);
...
}

Going further with reSIProcate

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