Make the persistence method of hanging protocols configurable

- Implement ProtocolStore interface to allow persisting hanging protocols using different strategies
- Implement and set default strategy to persist hanging protocols in the MongoDB collection “HangingProtocols” in the application server

Packages/ohif-hanging-protocols/client/protocolStore/protocolStore.js

@@ -0,0 +1,85 @@
+// The ProtocolStore module allows persisting hanging protocols using different strategies.
+// For example, one strategy stores hanging protocols in the application server while
+// another strategy stores them in a remote machine, but only one strategy can be used at a time.
+
+HP.ProtocolStore = (function () {
+
+    var strategy;
+
+    /**
+     * Sets the strategy used to persist hanging protocols
+     *
+     * @param preferredStrategy A preferred strategy will be using to persist hanging protocols
+     */
+    function setStrategy(preferredStrategy) {
+        strategy = preferredStrategy;
+    }
+
+    /**
+     * Registers a function to be called when the protocol store is ready to persist hanging protocols
+     *
+     * NOTE: Strategies should implement this function
+     *
+     * @param callback The function to be called as a callback
+     */
+    function onReady(callback) {
+        strategy.onReady(callback);
+    }
+
+    /**
+     * Gets the hanging protocol by protocolId if defined, otherwise all stored hanging protocols
+     *
+     * NOTE: Strategies should implement this function
+     *
+     * @param protocolId The protocol ID used to find the hanging protocol
+     * @returns {object|array} The hanging protocol by protocolId or array of the stored hanging protocols
+     */
+    function getProtocol(protocolId) {
+        return strategy.getProtocol(protocolId);
+    }
+
+    /**
+     * Stores the hanging protocol
+     *
+     * NOTE: Strategies should implement this function
+     *
+     * @param protocol The hanging protocol to be stored
+     */
+    function addProtocol(protocol) {
+        strategy.addProtocol(protocol);
+    }
+
+    /**
+     * Updates the hanging protocol by protocolId
+     *
+     * NOTE: Strategies should implement this function
+     *
+     * @param protocolId The protocol ID used to find the hanging protocol to update
+     * @param protocol The updated hanging protocol
+     */
+    function updateProtocol(protocolId, protocol) {
+        strategy.updateProtocol(protocolId, protocol);
+    }
+
+    /**
+     * Removes the hanging protocol
+     *
+     * NOTE: Strategies should implement this function
+     *
+     * @param protocolId The protocol ID used to remove the hanging protocol
+     */
+    function removeProtocol(protocolId) {
+        strategy.removeProtocol(protocolId);
+    }
+
+    // Module Exports
+    return {
+        setStrategy: setStrategy,
+        onReady: onReady,
+        getProtocol: getProtocol,
+        addProtocol: addProtocol,
+        updateProtocol: updateProtocol,
+        removeProtocol: removeProtocol
+    };
+
+})();