| /* |
| * 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; |
| import org.onlab.osgi.ServiceDirectory; |
| |
| import java.util.Set; |
| |
| import static com.google.common.base.Preconditions.checkArgument; |
| import static com.google.common.base.Preconditions.checkNotNull; |
| |
| /** |
| * Abstraction of an entity capable of processing a JSON message from the user |
| * interface client. |
| * <p> |
| * The message is a JSON object with the following structure: |
| * <pre> |
| * { |
| * "type": "<em>event-type</em>", |
| * "sid": "<em>sequence-number</em>", |
| * "payload": { |
| * <em>arbitrary JSON object structure</em> |
| * } |
| * } |
| * </pre> |
| */ |
| public abstract class UiMessageHandler { |
| |
| private final Set<String> messageTypes; |
| private UiConnection connection; |
| private ServiceDirectory directory; |
| |
| /** Mapper for creating ObjectNodes and ArrayNodes etc. */ |
| protected final ObjectMapper mapper = new ObjectMapper(); |
| |
| /** |
| * Creates a new message handler for the specified set of message types. |
| * |
| * @param messageTypes set of message types |
| */ |
| protected UiMessageHandler(Set<String> messageTypes) { |
| this.messageTypes = checkNotNull(messageTypes, "Message types cannot be null"); |
| checkArgument(!messageTypes.isEmpty(), "Message types cannot be empty"); |
| } |
| |
| /** |
| * Returns the set of message types which this handler is capable of |
| * processing. |
| * |
| * @return set of message types |
| */ |
| public Set<String> messageTypes() { |
| return messageTypes; |
| } |
| |
| /** |
| * Processes a JSON message from the user interface client. |
| * |
| * @param message JSON message |
| */ |
| public abstract void process(ObjectNode message); |
| |
| /** |
| * Initializes the handler with the user interface connection and |
| * service directory context. |
| * |
| * @param connection user interface connection |
| * @param directory service directory |
| */ |
| public void init(UiConnection connection, ServiceDirectory directory) { |
| this.connection = connection; |
| this.directory = directory; |
| } |
| |
| /** |
| * Destroys the message handler context. |
| */ |
| public void destroy() { |
| this.connection = null; |
| this.directory = null; |
| } |
| |
| /** |
| * Returns the user interface connection with which this handler was primed. |
| * |
| * @return user interface connection |
| */ |
| public UiConnection connection() { |
| return connection; |
| } |
| |
| /** |
| * Returns the user interface connection with which this handler was primed. |
| * |
| * @return user interface connection |
| */ |
| public ServiceDirectory directory() { |
| return directory; |
| } |
| |
| /** |
| * 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 directory.get(serviceClass); |
| } |
| |
| /** |
| * Wraps a message payload into an event structure for the given event |
| * type and sequence ID. Generally the |
| * |
| * @param type event type |
| * @param sid sequence ID |
| * @param payload event payload |
| * @return the object node representation |
| */ |
| protected ObjectNode envelope(String type, long sid, ObjectNode payload) { |
| ObjectNode event = mapper.createObjectNode(); |
| event.put("event", type); |
| if (sid > 0) { |
| event.put("sid", sid); |
| } |
| event.set("payload", payload); |
| return event; |
| } |
| |
| } |