GUI -- Huge Refactoring of server-side message handlers (Part Two).
--- Well, it compiles, and seems to work, with the cursory testing I've done...
Change-Id: I0e59657c134e109850e4770766083370dfd9fdc2
diff --git a/core/api/src/main/java/org/onosproject/ui/RequestHandler.java b/core/api/src/main/java/org/onosproject/ui/RequestHandler.java
new file mode 100644
index 0000000..7231dcf
--- /dev/null
+++ b/core/api/src/main/java/org/onosproject/ui/RequestHandler.java
@@ -0,0 +1,125 @@
+/*
+ * Copyright 2015 Open Networking Laboratory
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.onosproject.ui;
+
+import com.fasterxml.jackson.databind.ObjectMapper;
+import com.fasterxml.jackson.databind.node.ObjectNode;
+
+/**
+ * Abstraction of an entity that handles a specific request from the
+ * user interface client.
+ *
+ * @see UiMessageHandlerTwo
+ */
+public abstract class RequestHandler {
+
+ protected static final ObjectMapper MAPPER = new ObjectMapper();
+
+ private final String eventType;
+ private UiMessageHandlerTwo parent;
+
+
+ public RequestHandler(String eventType) {
+ this.eventType = eventType;
+ }
+
+ // package private
+ void setParent(UiMessageHandlerTwo parent) {
+ this.parent = parent;
+ }
+
+ /**
+ * Returns the event type that this handler handles.
+ *
+ * @return event type
+ */
+ public String eventType() {
+ return eventType;
+ }
+
+ /**
+ * Processes the incoming message payload from the client.
+ *
+ * @param sid message sequence identifier
+ * @param payload request message payload
+ */
+ public abstract void process(long sid, ObjectNode payload);
+
+
+
+ // ===================================================================
+ // === Convenience methods...
+
+ /**
+ * Returns implementation of the specified service class.
+ *
+ * @param serviceClass service class
+ * @param <T> type of service
+ * @return implementation class
+ * @throws org.onlab.osgi.ServiceNotFoundException if no implementation found
+ */
+ protected <T> T get(Class<T> serviceClass) {
+ return parent.directory().get(serviceClass);
+ }
+
+ /**
+ * Sends a message back to the client.
+ *
+ * @param eventType message event type
+ * @param sid message sequence identifier
+ * @param payload message payload
+ */
+ protected void sendMessage(String eventType, long sid, ObjectNode payload) {
+ parent.connection().sendMessage(eventType, sid, payload);
+ }
+
+ /**
+ * Sends a message back to the client.
+ * Here, the message is preformatted; the assumption is it has its
+ * eventType, sid and payload attributes already filled in.
+ *
+ * @param message the message to send
+ */
+ protected void sendMessage(ObjectNode message) {
+ parent.connection().sendMessage(message);
+ }
+
+ /**
+ * Allows one request handler to pass the event on to another for
+ * further processing.
+ * Note that the message handlers must be defined in the same parent.
+ *
+ * @param eventType event type
+ * @param sid sequence identifier
+ * @param payload message payload
+ */
+ protected void chain(String eventType, long sid, ObjectNode payload) {
+ parent.exec(eventType, sid, payload);
+ }
+
+ // ===================================================================
+
+
+ // FIXME : Javadocs
+ protected String string(ObjectNode node, String key) {
+ return JsonUtils.string(node, key);
+ }
+
+ protected String string(ObjectNode node, String key, String defValue) {
+ return JsonUtils.string(node, key, defValue);
+ }
+
+}