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/SingleConnectionInterface.php

@@ -0,0 +1,58 @@
+<?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\Command\CommandInterface;
+
+/**
+ * Defines a connection object used to communicate with a single Redis server.
+ *
+ * @author Daniele Alessandri <suppakilla@gmail.com>
+ */
+interface SingleConnectionInterface extends ConnectionInterface
+{
+    /**
+     * Returns a string representation of the connection.
+     *
+     * @return string
+     */
+    public function __toString();
+
+    /**
+     * Returns the underlying resource used to communicate with a Redis server.
+     *
+     * @return mixed
+     */
+    public function getResource();
+
+    /**
+     * Gets the parameters used to initialize the connection object.
+     *
+     * @return ConnectionParametersInterface
+     */
+    public function getParameters();
+
+    /**
+     * Pushes the instance of a Redis command to the queue of commands executed
+     * when the actual connection to a server is estabilished.
+     *
+     * @param CommandInterface $command Instance of a Redis command.
+     */
+    public function pushInitCommand(CommandInterface $command);
+
+    /**
+     * Reads a reply from the server.
+     *
+     * @return mixed
+     */
+    public function read();
+}