added initial support for service definition

Util/Collection.php

@@ -0,0 +1,52 @@
+<?php
+
+namespace Bundle\WebServiceBundle\Util;
+
+class Collection implements \IteratorAggregate, \Countable
+{
+    private $elements = array();
+    private $keyPropertyGetter;
+
+    public function __construct($keyPropertyGetter)
+    {
+        $this->keyPropertyGetter = $keyPropertyGetter;
+    }
+
+    public function add($element)
+    {
+        $this->elements[call_user_func(array($element, $this->keyPropertyGetter))] = $element;
+    }
+
+    public function addAll($elements)
+    {
+        foreach ($elements as $element)
+        {
+            $this->add($element);
+        }
+    }
+
+    public function has($key)
+    {
+        return isset($this->elements[$key]);
+    }
+
+    public function get($key)
+    {
+        return $this->has($key) ? $this->elements[$key] : null;
+    }
+
+    public function clear()
+    {
+        $this->elements = array();
+    }
+
+    public function count()
+    {
+        return count($this->elements);
+    }
+
+    public function getIterator ()
+    {
+        return new \ArrayIterator($this->elements);
+    }
+}