Hoa is a modular, extensible and structured set of PHP libraries. Moreover, Hoa aims at being a bridge between industrial and research worlds.

Hoa\Socket

This library provides an abstract layer to build safe, fast and modular clients and servers.

It represents a connection as a stream (please, see the Hoa\Stream library) that is used to build clients and servers. A connection supports timeout, options, context, encryption, remote informations etc. Such a connection, along with an abstract connection handler, allows to embed and “merge” many connections inside the same processus side-by-side.

Installation

With Composer, to include this library into your dependencies, you need to require hoa/socket:

{
    "require": {
        "hoa/socket": "~0.0"
    }
}

Please, read the website to get more informations about how to install.

Quick usage

As a quick overview, we will look at creating a server and a client, and introduce the respective API.

A connection behind

Both server and client extend a connection, namely the Hoa\Socket\Connection\Connection class, which is a stream represented by the Hoa\Stream library. This latter provides the common stream API whose the read and write methods (from Hoa\Stream\IStream\In, Hoa\Stream\IStream\Out and also Hoa\Stream\IStream\Pathable). Since it is also responsible of the connection, we are able to manipulate the underlying socket resource, the timeout, the different flags, the stream context, the encryption, the remote informations etc.

To start a connection, we will use the connect method (the constructor does not start the connection by itself). For a server, we will often prefer to use the connectAndWait method (see bellow). To stop a connection, most of the time, we will use the disconnect method.

A remote connection (a client for the server, a server for the client) is represented by a node: an object that holds several informations about the remote connection. The default node is Hoa\Socket\Node and can be easily extended. To use a new node, we have to call the Hoa\Socket\Connection\Connection::setNodeName method.

A connection needs a socket URI, represented by the Hoa\Socket\Socket class, to know where to connect. This latter represents an IPv4 or IPv6 address, a domain or a path (for Unix socket), along with the transport scheme (tcp://, udp:// etc.) and the port.

Manipulating a server or a client

We will instanciate the Hoa\Socket\Server class and start a connection to tcp://127.0.0.1:4242. Then, to select active nodes, we will use the Hoa\Socket\Connection\Connection::select method that returns an iterator. Finally, we will read a line and write an uppercassed echo. Thus:

$server = new Hoa\Socket\Server('tcp://127.0.0.1:4242');
$server->connectAndWait();

while (true) {
    foreach ($server->select() as $node) {
        $line = $server->readLine();

        if (empty($line)) {
            $server->disconnect();
            continue;
        }

        echo '< ', $line, "\n";
        $server->writeLine(strtoupper($line));
    }
}

And then, with telnet:

$ telnet 127.0.0.1 4242
Trying 127.0.0.1...
Connected to localhost.
Escape character is '^]'.
foobar
FOOBAR
hello world
HELLO WORLD

From the server, we will see:

< foobar
< hello world

To reproduce the same behavior with our own client, we will write (thanks to Hoa\Console\Readline\Readline, please see the Hoa\Console library):

$client = new Hoa\Socket\Client('tcp://127.0.0.1:4242');
$client->connect();

$readline = new Hoa\Console\Readline\Readline();

while (true) {
    $line = $readline->readLine('> ');

    if ('quit' === $line) {
        break;
    }

    $client->writeLine($line);

    echo '< ', $client->readLine(), "\n";
}

Finally:

$ php Client.php
> foobar
< FOOBAR
> hello world
< HELLO WORLD
> quit

Handle servers and clients

A connection has advanced operations but they are low-levels and not obvious. Moreover, there is repetitive and not so trivial tasks that we need often, such as broadcasting messages. The Hoa\Socket\Connection\Handler provides an easy way to create and embed a very flexible server or client. (A good and complete example is the Hoa\Websocket library).

We will focus on a server. A server has the magic run method that starts an infinite loop and make some computation on active nodes. This is basically the while (true) in our previous examples. In addition, we would like to easily send a message to a specific node, or send a message to all nodes except one. The Hoa\Socket\Connection\Handler class asks the user to implement only two methods: _run and _send, and provides the run method, along with send and broadcast. Then, we no longer need to start the connection or to take care about the implementation of different network topologies. All is managed by the handler. Thus:

class MyServer extends Hoa\Socket\Connection\Handler
{
    protected function _run (Hoa\Socket\Node $node)
    {
        $connection = $node->getConnection();
        $line       = $connection->readLine();

        if (empty($line)) {
            $connection->disconnect();
            return;
        }

        echo '< ', $line, "\n";
        $this->send(strtoupper($line));

        return;
    }

    protected function _send ($message, Hoa\Socket\Node $node)
    {
        return $node->getConnection()->writeLine($message);
    }
}

And then, all we need to do is:

$server = new MyServer(new Hoa\Socket\Server('tcp://127.0.0.1:4242'));
$server->run();

We see that the connection is embeded inside our server, and that all the logic has been moved inside the _run method. If we change the call to send by broadcast, we will see all connected clients receiving the message, something like:

        echo '< ', $line, "\n";
        $this->broadcast(strtoupper($line));

The _send method gives an implementation of “sending one message”, which is the basis. Because the _run method does not start an infinite loop, we have more flexibility (see the next section).

We can add listeners (with Hoa\Core\Event, please see the Hoa\Core library) to interact with the server, something like $server->on('message', function ( … ) { … }); etc.

Merging connections

Another huge advantage of using handlers is that they can be used inside a Hoa\Socket\Connection\Group object. The run method is an infinite loop, so we are not able to run two servers side-by-side in the same process. Fortunately, the Hoa\Socket\Connection\Group allows to “merge” connections (this is an underlying feature of Hoa\Socket\Connection\Connection but a group abstracts and manages all the complexity). Consequently, we are able to run several servers and clients together, inside the same processus, at the same time.

For example, we will run an instance of Hoa\Irc\Client (please, see the Hoa\Irc library) with a Hoa\Websocket\Server (please, see the Hoa\Websocket library: all messages received by the WebSocket server will be redirected on the IRC client. Thus:

$websocket = new Hoa\Websocket\Server(new Hoa\Socket\Server('tcp://…'));
$irc       = new Hoa\Irc\Client(new Hoa\Socket\Client('tcp://…'));
$group     = new Hoa\Socket\Connection\Group();
$group[]   = $websocket;
$group[]   = $irc;

$websocket->on(
    'message',
    function (Hoa\Core\Event\Bucket $bucket) use ($irc) {
        $data = $bucket->getData();
        $irc->say($data['message']);

        return;
    }
);

// $irc->…

$group->run();

This is an illustration of the power provided by the Hoa\Socket\Connection classes.

Documentation

Different documentations can be found on the website: http://hoa-project.net/.

License

Hoa is under the New BSD License (BSD-3-Clause). Please, see LICENSE.