| /* |
| * Copyright 2015-present 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.ArrayNode; |
| import com.fasterxml.jackson.databind.node.ObjectNode; |
| import org.onlab.osgi.ServiceDirectory; |
| import org.slf4j.Logger; |
| import org.slf4j.LoggerFactory; |
| |
| import java.util.Collection; |
| import java.util.Collections; |
| import java.util.HashMap; |
| import java.util.Map; |
| 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 JSON messages from the user |
| * interface client. |
| * <p> |
| * The message structure is: |
| * </p> |
| * <pre> |
| * { |
| * "type": "<em>event-type</em>", |
| * "payload": { |
| * <em>arbitrary JSON object structure</em> |
| * } |
| * } |
| * </pre> |
| * On {@link #init initialization} the handler will create and cache |
| * {@link RequestHandler} instances, each of which are bound to a particular |
| * <em>event-type</em>. On {@link #process arrival} of a new message, |
| * the <em>event-type</em> is determined, and the message dispatched to the |
| * corresponding <em>RequestHandler</em>'s |
| * {@link RequestHandler#process process} method. |
| */ |
| public abstract class UiMessageHandler { |
| |
| private final Logger log = LoggerFactory.getLogger(getClass()); |
| private final Map<String, RequestHandler> handlerMap = new HashMap<>(); |
| |
| private final ObjectMapper mapper = new ObjectMapper(); |
| |
| private UiConnection connection; |
| private ServiceDirectory directory; |
| |
| |
| /** |
| * Subclasses must create and return the collection of request handlers |
| * for the message types they handle. |
| * <p> |
| * Note that request handlers should be stateless. When we are |
| * {@link #destroy destroyed}, we will simply drop our references to them |
| * and allow them to be garbage collected. |
| * |
| * @return the message handler instances |
| */ |
| protected abstract Collection<RequestHandler> createRequestHandlers(); |
| |
| /** |
| * Returns the set of message types which this handler is capable of |
| * processing. |
| * |
| * @return set of message types |
| */ |
| public Set<String> messageTypes() { |
| return Collections.unmodifiableSet(handlerMap.keySet()); |
| } |
| |
| /** |
| * Processes a JSON message from the user interface client. |
| * |
| * @param message JSON message |
| */ |
| public void process(ObjectNode message) { |
| String type = JsonUtils.eventType(message); |
| ObjectNode payload = JsonUtils.payload(message); |
| // TODO: remove sid |
| exec(type, 0, payload); |
| } |
| |
| /** |
| * Finds the appropriate handler and executes the process method. |
| * |
| * @param eventType event type |
| * @param sid sequence identifier |
| * @param payload message payload |
| */ |
| // TODO: remove sid from signature |
| void exec(String eventType, long sid, ObjectNode payload) { |
| RequestHandler requestHandler = handlerMap.get(eventType); |
| if (requestHandler != null) { |
| requestHandler.process(sid, payload); |
| } else { |
| log.warn("no request handler for event type {}", eventType); |
| } |
| } |
| |
| /** |
| * 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; |
| |
| Collection<RequestHandler> handlers = createRequestHandlers(); |
| checkNotNull(handlers, "Handlers cannot be null"); |
| checkArgument(!handlers.isEmpty(), "Handlers cannot be empty"); |
| |
| for (RequestHandler h : handlers) { |
| h.setParent(this); |
| handlerMap.put(h.eventType(), h); |
| } |
| } |
| |
| /** |
| * Destroys the message handler context. |
| */ |
| public void destroy() { |
| this.connection = null; |
| this.directory = null; |
| handlerMap.clear(); |
| } |
| |
| /** |
| * Returns the user interface connection with which this handler was primed. |
| * |
| * @return user interface connection |
| */ |
| public UiConnection connection() { |
| return connection; |
| } |
| |
| /** |
| * Returns the service directory with which this handler was primed. |
| * |
| * @return service directory |
| */ |
| public ServiceDirectory directory() { |
| return directory; |
| } |
| |
| /** |
| * Returns an 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); |
| } |
| |
| /** |
| * Returns a freshly minted object node. |
| * |
| * @return new object node |
| */ |
| protected ObjectNode objectNode() { |
| return mapper.createObjectNode(); |
| } |
| |
| /** |
| * Returns a freshly minted array node. |
| * |
| * @return new array node |
| */ |
| protected ArrayNode arrayNode() { |
| return mapper.createArrayNode(); |
| } |
| |
| /** |
| * Sends the specified data to the client. |
| * It is expected that the data is in the prescribed JSON format for |
| * events to the client. |
| * |
| * @param data data to be sent |
| */ |
| protected synchronized void sendMessage(ObjectNode data) { |
| UiConnection connection = connection(); |
| if (connection != null) { |
| connection.sendMessage(data); |
| } |
| } |
| } |