easywsclient/README.md

easywsclient

Easywsclient is an easy and powerful WebSocket client to C++ get your code connected to a web stack right away. It depends only on the standard libraries. It makes use of C++11 std::function and lambda, if they're available (it's not required though). RFC 6455 Version 13 WebSocket is supported this version is compatible with all major, modern WebSocket implementations, including Node.js.

Rationale: This library is intended to help a C++ project start using WebSocket rapidly. This small library can easily be thrown into an existing project. For complicated builds that you can't figure out right away, you can even cheat by piggy-backing the .cpp file into one of the project's existing files. Yes, WebSocket is awesome enough to warrant getting it integrated into your project! This project imposes no special interface requirements, and can work happily with new C++11 features or with older C++ projects.

As an additional benefit, easywsclient is very simple, with just a single implementation file and can serve as a cruft-free concise reference. You are most welcome to use this code as a reference for creating alternative implementations that may better suit your needs.

Usage

The WebSocket class interface looks like this:

// Factory method to create a WebSocket:
static pointer from_url(std::string url);
// Factory method to create a dummy WebSocket (all operations are noop):
static pointer create_dummy();

// Function to perform actual network send()/recv() I/O:
void poll();

// Receive a message, and pass it to callable(). Really, this just looks at
// a buffer (filled up by poll()) and decodes any messages in the buffer.
// Callable must have signature: void(const std::string & message).
// Should work with C functions, C++ functors, and C++11 std::function and
// lambda:
template<class Callable>
void dispatch(Callable callable);

// Sends a TEXT type message (gets put into a buffer for poll() to send
// later):
void send(std::string message);

Put together, the usage looks like this:

#include "easywsclient.hpp"
#include "easywsclient.cpp" // <-- include only if you don't want compile separately

int
main()
{
    ...
    using easywsclient::WebSocket;
    WebSocket::pointer ws = WebSocket::from_url("ws://localhost:8126/foo");
    assert(ws);
    while (true) {
        ws->poll();
        ws->send("hello");
        ws->dispatch(handle_message);
        // ...do more stuff...
    }
    ...
}

Example

# Launch a test server:
node example-server.js

# Build and launch the client:
g++ example-client.cpp -o example-client
./example-client

# ...or build and launch a C++11 client:
g++ -std=gnu++0x example-client-cpp11.cpp -o example-client-cpp11
./example-client-cpp11

# Expect the output from example-client:
Connected to: ws://localhost:8126/foo
>>> galaxy
>>> world

Threading

This library is not thread safe. The user must take care to use locks if accessing an instance of WebSocket from multiple threads. If you need a quick threading library and don't have Boost or something else already, I recommend TinyThread++.

Future Work

(contributions appreciated!)

• Parameterize the pointer type (especially for shared_ptr).
• Support optional integration on top of an async (event-driven) library, especially Asio.