C++ Networking Evolved

LibSourcey is a collection of cross platform C++14 modules and classes that provide developers with an arsenal for rapidly developing high performance network based p2p and media streaming applications. Think of it as the power and performance of libuv combined with the features of FFmpeg, OpenCV and WebRTC, all integrated with the ease and readability of the stl (C++ Standard Library).

• Documentation: https://sourcey.com/libsourcey
• Repository: https://github.com/sourcey/libsourcey
• Licence: LGPL-2.1+

• Event-based IO — Core modules are built on top of libuv (the underlying C library that powers nodejs) and use event-based asynchronous IO throughout to maximize performance and minimize concurrency reliance for building mission critical native and server side apps.

• Cross platform — The codebase is cross platform and should compile on any system with access to a modern C++14 compiler.

• Modular libraries — Libraries are modular for easy integration into your existing projects, so you can just "include what you need" without incurring extra incumbent bloat.

• Well tested — Core modules are well tested with unit tests and stress tested daily in production.

• Clean and readable code — Modern C++ design principles have been adhered to throughout for clean and readable code.

• Easy packaging and installation — LibSourcey can be compiled and installed on most platforms with CMake. For straight forward distribution and integration with existing projects the libraries be also packaged as a deb, rpm, tar.gz, zip, and more formats with a single command.

• Docker images — Semantically versioned images are available on Docker Hub. Just type docker pull sourcey/libsourcey to grab the latest.

• Solid networking layer — At the core of LibSourcey is a solid and blazing fast networking layer build on libuv and openssl primitives, with TCP, SSL and UDP socket implementations.

• Web servers and clients — A HTTP stack is provided that includes servers, clients, WebSockets, media streaming, file transfers, and authentication. The HTTP parser is based on the super-fast C code used by nginx.

• Media streaming and encoding — The av library consists of thin wrappers around FFmpeg and OpenCV for media capture, encoding, recording, streaming, analysis and more.

• Realtime messaging — LibSourcey aims to bridge the gap between desktop, mobile and web by providing performance oriented messaging solutions that work across all platforms.

  • Socket.IO — Socket.IO C++ client that supports the latest protocol revision 4 (>= 1.0). Read more about Socket.IO.
  • Symple — Sourcey's home grown realtime messaging protocol that works over the top of Socket.IO to provide rostering, presence and many other features necessary for building online games and chat applications. More about Symple.

• WebRTC support — WebRTC native support allows you to build p2p desktop and server side applications that inherit LibSourcey's realtime messaging and media capabilities. Take a look at the examples for how to stream live webcam and microphone streams to the browser, and also how to record live WebRTC streams on the server side.

See the installation guides in the docs to get started playing with LibSourcey.

What better way to get acquainted with a new library then with some tasty code examples.

Lets start with the classic HTTP echo server, which looks something like this:

http::Server srv{ "127.0.0.1", 1337 };
srv.Connection += [](http::ServerConnection::Ptr conn) {
    conn->Payload += [](http::ServerConnection& conn, const MutableBuffer& buffer) {
        conn.send(bufferCast<const char*>(buffer), buffer.size());
        conn.close();
    };
};
srv.start();

Pretty neat right? Its crazy fast too, especially on Linux kernel 3.9 or newer where its optimized to use of kernel level multicore socket load balancing. Don't take our word for it though, here are some benchmarks using wrk:

LibSourcey httpechoserver

$ wrk -d10s --timeout 2s http://localhost:1337
Running 10s test @ http://localhost:1337
  2 threads and 10 connections
  Thread Stats   Avg      Stdev     Max   +/- Stdev
    Latency   265.76us  472.62us  12.42ms   97.51%
    Req/Sec    18.84k     1.26k   21.57k    74.50%
  375060 requests in 10.01s, 20.39MB read
Requests/sec:  37461.50
Transfer/sec:      2.04MB

Nodejs echo server

$ wrk -d10s --timeout 2s http://localhost:1337
Running 10s test @ http://localhost:1337
  2 threads and 10 connections
  Thread Stats   Avg      Stdev     Max   +/- Stdev
    Latency   502.70us  715.11us  14.83ms   97.90%
    Req/Sec    11.69k     1.46k   14.52k    70.50%
  232667 requests in 10.01s, 21.97MB read
Requests/sec:  23236.33
Transfer/sec:      2.19MB

As you can see the httpechoserver is almost twice as fast as the dead simple nodejs echo server, which is not a bad performance gain over one of the web's leading technologies thats touted for it's performance. Check the httpechoserver sample for the full code, including the nodejs echo server we used for benchmarking.

Interacting with system processes and piping IO doesn't have to be painful. The following code will run the ping sourcey.com and with stdio and exit callbacks:

Process proc{ "ping", "sourcey.com" };
proc.onstdout = [](std::string line)
{
    // handle process output
};
proc.onexit = [](std::int64_t status)
{
    // handle process exit
};
proc.spawn();

// write some random data to the stdin pipe
proc.in() << "random data"

A good starting point for learning LibSourcey is the PacketStream, which lets you create a dynamic delegate chain for piping, processing and outputting arbitrary data packets. This method of layering packet processors and makes it possible to develop complex data processing applications on the fly.

For example, the code below captures a live webcam stream, encodes it into H.264, and then finally broadcasts it in realtime over the internet:

// Create a PacketStream to pass packets from the
// input device captures -> encoder -> socket
PacketStream stream;

// Setup the encoder options
av::EncoderOptions options;
options.oformat = av::Format{"MP4", "mp4",
    { "H.264", "libx264", 640, 480, 25, 48000, 128000, "yuv420p" },
    { "AAC", "aac", 2, 44100, 64000, "fltp" }};

// Create a device manager instance to enumerate system devices
av::DeviceManager devman;
av::Device device;

// Create and attach the default video capture
av::VideoCapture::Ptr video;
if (devman.getDefaultCamera(device)) {
    video.open(device.id, 640, 480);
    video.getEncoderFormat(options.iformat);
    stream.attachSource(video, true);
}

// Create and attach the default audio capture
av::AudioCapture::Ptr audio;
if (devman.getDefaultMicrophone(device)) {
    audio.open(device.id, 2, 44100);
    audio.getEncoderFormat(options.iformat);
    stream.attachSource(audio, true);
}

// Create and attach the multiplex encoder
av::MultiplexPacketEncoder::Ptr encoder(options);
stream.attach(encoder);

// Attach the output net::Socket instance (instantiated elsewhere)
// to broadcast encoded packets over the network
stream.attach(socket);

// Start the stream
// This method call will start the device captures and begin
// pumping encoded media into the output socket
stream.start();

There are plenty more demos and sample code to play with over on the examples page.

A massive thanks to everyone who has contributed to making LibSourcey awesome:

• Kam Low (@auscaster) — Primary developer
• Yury Shulbn (@yuryshubin) — iOS build toolchain and platform fixes
• Vinci Xu (@VinciShark) — Windows documentation, testing and updates
• Michael Fig (@michael-fig) — Fixed compiler flags to build without FFmpeg
• Hyunuk Kim (@surinkim) — Fixed std::codecvt unicode character conversion on Windows
• Damian Zelim (@ZelimDamian) — Fixed compiler flags for OS X build
• Norm Ovenseri (@normano) — Added verbose logging output to build system
• Alexey (@deilos) — Fixed cross-platform FFmpeg build script
• Kryton (@Malesio) — Fixed segfaults in samples and tidied up Valgrind warnings

Pull Requests are always welcome, so if you fix or make anything better then feel free to float a PR back upstream :)

1. Fork LibSourcey on Github
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am 'Add some feature')
4. Push to the branch (git push origin my-new-feature)
5. Create new Pull Request