Add subscription consumer interface

src/PsrSubscriptionConsumer.php

@@ -0,0 +1,40 @@
+<?php
+namespace Interop\Queue;
+
+interface PsrSubscriptionConsumer
+{
+    /**
+     * @param float|int $timeout Milliseconds 1000 is 1 second, a zero is consume endlessly.
+     */
+    public function consume($timeout = 0);
+
+    /**
+     * Notify broker that the client is interested in consuming messages from this queue.
+     *
+     * A callback function to which the consumed message will be passed.
+     * The function must accept at a minimum one parameter, an \Interop\Queue\PsrMessage object,
+     * and an optional second parameter the \Interop\Queue\PsrConsumer from which the message was
+     * consumed. The consumer will not return the processing thread back to
+     * the PHP script until the callback function returns FALSE.
+     *
+     * @param PsrConsumer $consumer
+     * @param callable     $callback
+     *
+     * @return void
+     */
+    public function subscribe(PsrConsumer $consumer, callable $callback);
+
+    /**
+     * @param PsrConsumer $consumer
+     *
+     * @return void
+     */
+    public function unsubscribe(PsrConsumer $consumer);
+
+    /**
+     * Unsubscribe all subscribed consumers.
+     *
+     * @return void
+     */
+    public function unsubscribeAll();
+}

src/PsrSubscriptionConsumerAwareContext.php

@@ -0,0 +1,10 @@
+<?php
+namespace Interop\Queue;
+
+interface PsrSubscriptionConsumerAwareContext
+{
+    /**
+     * @return PsrSubscriptionConsumer
+     */
+    public function createSubscriptionConsumer();
+}