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/*
* 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 UiMessageHandler
*/
public abstract class RequestHandler {
protected static final ObjectMapper MAPPER = new ObjectMapper();
private final String eventType;
private UiMessageHandler parent;
public RequestHandler(String eventType) {
this.eventType = eventType;
}
// package private
void setParent(UiMessageHandler 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
*/
// TODO: remove sid from signature
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
*/
// TODO: remove sid from signature
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
*/
// TODO: remove sid from signature
protected void chain(String eventType, long sid, ObjectNode payload) {
parent.exec(eventType, sid, payload);
}
// ===================================================================
/**
* Returns the specified node property as a string.
*
* @param node message event
* @param key property name
* @return property as a string
*/
protected String string(ObjectNode node, String key) {
return JsonUtils.string(node, key);
}
/**
* Returns the specified node property as a string, with a default fallback.
*
* @param node object node
* @param key property name
* @param defValue fallback value if property is absent
* @return property as a string
*/
protected String string(ObjectNode node, String key, String defValue) {
return JsonUtils.string(node, key, defValue);
}
}
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