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/ClientInterface.php

@@ -0,0 +1,66 @@
+<?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;
+
+use Predis\Connection\ConnectionInterface;
+use Predis\Option\ClientOptionsInterface;
+use Predis\Profile\ServerProfileInterface;
+
+/**
+ * Interface defining the most important parts needed to create an
+ * high-level Redis client object that can interact with other
+ * building blocks of Predis.
+ *
+ * @author Daniele Alessandri <suppakilla@gmail.com>
+ */
+interface ClientInterface extends BasicClientInterface
+{
+    /**
+     * Returns the server profile used by the client.
+     *
+     * @return ServerProfileInterface
+     */
+    public function getProfile();
+
+    /**
+     * Returns the client options specified upon initialization.
+     *
+     * @return ClientOptionsInterface
+     */
+    public function getOptions();
+
+    /**
+     * Opens the connection to the server.
+     */
+    public function connect();
+
+    /**
+     * Disconnects from the server.
+     */
+    public function disconnect();
+
+    /**
+     * Returns the underlying connection instance.
+     *
+     * @return ConnectionInterface
+     */
+    public function getConnection();
+
+    /**
+     * Creates a new instance of the specified Redis command.
+     *
+     * @param  string                   $method    The name of a Redis command.
+     * @param  array                    $arguments The arguments for the command.
+     * @return Command\CommandInterface
+     */
+    public function createCommand($method, $arguments = array());
+}