Java tutorial
/* * Copyright (c) 2013 Cisco Systems, Inc. and others. All rights reserved. * * This program and the accompanying materials are made available under the * terms of the Eclipse Public License v1.0 which accompanies this distribution, * and is available at http://www.eclipse.org/legal/epl-v10.html */ package org.opendaylight.controller.netconf.util; import com.google.common.base.Optional; import com.google.common.base.Preconditions; import io.netty.channel.Channel; import io.netty.handler.ssl.SslHandler; import io.netty.util.Timeout; import io.netty.util.Timer; import io.netty.util.TimerTask; import io.netty.util.concurrent.Future; import io.netty.util.concurrent.GenericFutureListener; import io.netty.util.concurrent.Promise; import org.opendaylight.controller.netconf.api.NetconfMessage; import org.opendaylight.controller.netconf.api.NetconfSession; import org.opendaylight.controller.netconf.api.NetconfSessionPreferences; import org.opendaylight.controller.netconf.util.handler.FramingMechanismHandlerFactory; import org.opendaylight.controller.netconf.util.handler.NetconfMessageAggregator; import org.opendaylight.controller.netconf.util.handler.NetconfMessageChunkDecoder; import org.opendaylight.controller.netconf.util.messages.FramingMechanism; import org.opendaylight.controller.netconf.util.xml.XmlElement; import org.opendaylight.controller.netconf.util.xml.XmlNetconfConstants; import org.opendaylight.controller.netconf.util.xml.XmlUtil; import org.opendaylight.protocol.framework.AbstractSessionNegotiator; import org.opendaylight.protocol.framework.SessionListener; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import org.w3c.dom.Document; import org.w3c.dom.NodeList; import java.util.concurrent.TimeUnit; public abstract class AbstractNetconfSessionNegotiator<P extends NetconfSessionPreferences, S extends NetconfSession> extends AbstractSessionNegotiator<NetconfMessage, S> { // TODO what time ? private static final long INITIAL_HOLDTIMER = 1; private static final Logger logger = LoggerFactory.getLogger(AbstractNetconfSessionNegotiator.class); protected final P sessionPreferences; private final SessionListener sessionListener; /** * Possible states for Finite State Machine */ private enum State { IDLE, OPEN_WAIT, FAILED, ESTABLISHED } private State state = State.IDLE; private final Timer timer; protected AbstractNetconfSessionNegotiator(P sessionPreferences, Promise<S> promise, Channel channel, Timer timer, SessionListener sessionListener) { super(promise, channel); this.sessionPreferences = sessionPreferences; this.timer = timer; this.sessionListener = sessionListener; } @Override protected void startNegotiation() throws Exception { final Optional<SslHandler> sslHandler = getSslHandler(channel); if (sslHandler.isPresent()) { Future<Channel> future = sslHandler.get().handshakeFuture(); future.addListener(new GenericFutureListener<Future<? super Channel>>() { @Override public void operationComplete(Future<? super Channel> future) throws Exception { Preconditions.checkState(future.isSuccess(), "Ssl handshake was not successful"); logger.debug("Ssl handshake complete"); start(); } }); } else start(); } private static Optional<SslHandler> getSslHandler(Channel channel) { final SslHandler sslHandler = channel.pipeline().get(SslHandler.class); return sslHandler == null ? Optional.<SslHandler>absent() : Optional.of(sslHandler); } private void start() { final NetconfMessage helloMessage = this.sessionPreferences.getHelloMessage(); logger.debug("Session negotiation started with hello message {}", XmlUtil.toString(helloMessage.getDocument())); sendMessage(helloMessage); changeState(State.OPEN_WAIT); this.timer.newTimeout(new TimerTask() { @Override public void run(final Timeout timeout) throws Exception { synchronized (this) { if (state != State.ESTABLISHED) { final IllegalStateException cause = new IllegalStateException( "Session was not established after " + timeout); negotiationFailed(cause); changeState(State.FAILED); } } } }, INITIAL_HOLDTIMER, TimeUnit.MINUTES); } private void sendMessage(NetconfMessage message) { this.channel.writeAndFlush(message); } @Override protected void handleMessage(NetconfMessage netconfMessage) { final Document doc = netconfMessage.getDocument(); if (isHelloMessage(doc)) { if (containsBase11Capability(doc) && containsBase11Capability(sessionPreferences.getHelloMessage().getDocument())) { channel.pipeline().replace("frameEncoder", "frameEncoder", FramingMechanismHandlerFactory.createHandler(FramingMechanism.CHUNK)); channel.pipeline().replace("aggregator", "aggregator", new NetconfMessageAggregator(FramingMechanism.CHUNK)); channel.pipeline().addAfter("aggregator", "chunkDecoder", new NetconfMessageChunkDecoder()); } changeState(State.ESTABLISHED); S session = getSession(sessionListener, channel, doc); negotiationSuccessful(session); } else { final IllegalStateException cause = new IllegalStateException( "Received message was not hello as expected, but was " + XmlUtil.toString(doc)); negotiationFailed(cause); } } protected abstract S getSession(SessionListener sessionListener, Channel channel, Document doc); private boolean isHelloMessage(Document doc) { try { XmlElement.fromDomElementWithExpected(doc.getDocumentElement(), "hello", XmlNetconfConstants.URN_IETF_PARAMS_XML_NS_NETCONF_BASE_1_0); } catch (IllegalArgumentException | IllegalStateException e) { return false; } return true; } private void changeState(final State newState) { logger.debug("Changing state from : {} to : {}", state, newState); Preconditions.checkState(isStateChangePermitted(state, newState), "Cannot change state from %s to %s", state, newState); this.state = newState; } private boolean containsBase11Capability(final Document doc) { final NodeList nList = doc.getElementsByTagName("capability"); for (int i = 0; i < nList.getLength(); i++) { if (nList.item(i).getTextContent().contains("base:1.1")) { return true; } } return false; } private static boolean isStateChangePermitted(State state, State newState) { if (state == State.IDLE && newState == State.OPEN_WAIT) return true; if (state == State.OPEN_WAIT && newState == State.ESTABLISHED) return true; if (state == State.OPEN_WAIT && newState == State.FAILED) return true; return false; } }