Retwis ported to modern Redis data types.

The example (and related documentation at redis.io) was not updated for
5 years. Redis had no sorted sets and hashes when the original code was
written (!). An update was really needed.

We also use a modern PHP client now: Predis. A copy is shipped within
this repository to make life easier to newcomers trying Redis for the
first time via this example.

Predis/Connection/ComposableConnectionInterface.php

@@ -0,0 +1,57 @@
+<?php
+
+/*
+ * This file is part of the Predis package.
+ *
+ * (c) Daniele Alessandri <suppakilla@gmail.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Predis\Connection;
+
+use Predis\Protocol\ProtocolInterface;
+
+/**
+ * Defines a connection object used to communicate with a single Redis server
+ * that leverages an external protocol processor to handle pluggable protocol
+ * handlers.
+ *
+ * @author Daniele Alessandri <suppakilla@gmail.com>
+ */
+interface ComposableConnectionInterface extends SingleConnectionInterface
+{
+    /**
+     * Sets the protocol processor used by the connection.
+     *
+     * @param ProtocolInterface $protocol Protocol processor.
+     */
+    public function setProtocol(ProtocolInterface $protocol);
+
+    /**
+     * Gets the protocol processor used by the connection.
+     */
+    public function getProtocol();
+
+    /**
+     * Writes a buffer that contains a serialized Redis command.
+     *
+     * @param string $buffer Serialized Redis command.
+     */
+    public function writeBytes($buffer);
+
+    /**
+     * Reads a specified number of bytes from the connection.
+     *
+     * @param string
+     */
+    public function readBytes($length);
+
+    /**
+     * Reads a line from the connection.
+     *
+     * @param string
+     */
+    public function readLine();
+}