Application tutorial

<?xml version="1.0" encoding="UTF-8"?>
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  ~ Copyright 2014 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
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<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <parent>
        <groupId>org.onosproject</groupId>
        <artifactId>onos-apps</artifactId>
        <version>1.0.0-SNAPSHOT</version>
        <relativePath>../pom.xml</relativePath>
    </parent>

    <artifactId>onos-app-ifwd</artifactId>
    <packaging>bundle</packaging>

    <description>ONOS simple reactive forwarding app that uses intent service</description>

</project>

    <feature name="onos-app-ifwd" version="1.0.0"
             description="ONOS sample forwarding application using intents">
        <feature>onos-api</feature>
        <bundle>mvn:org.onosproject/onos-app-ifwd/1.0.0-SNAPSHOT</bundle>
    </feature>

/*
 * Copyright 2014 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.ifwd;
 
import org.apache.felix.scr.annotations.Activate;
import org.apache.felix.scr.annotations.Component;
import org.apache.felix.scr.annotations.Deactivate;
import org.apache.felix.scr.annotations.Reference;
import org.apache.felix.scr.annotations.ReferenceCardinality;
 
import org.onosproject.core.ApplicationId;
import org.onosproject.core.CoreService;
import org.onosproject.net.Host;
import org.onosproject.net.HostId;
import org.onosproject.net.PortNumber;
import org.onosproject.net.flow.DefaultTrafficSelector;
import org.onosproject.net.flow.DefaultTrafficTreatment;
import org.onosproject.net.flow.TrafficSelector;
import org.onosproject.net.flow.TrafficTreatment;
import org.onosproject.net.host.HostService;
import org.onosproject.net.intent.HostToHostIntent;
import org.onosproject.net.intent.IntentService;
import org.onosproject.net.packet.DefaultOutboundPacket;
import org.onosproject.net.packet.InboundPacket;
import org.onosproject.net.packet.OutboundPacket;
import org.onosproject.net.packet.PacketContext;
import org.onosproject.net.packet.PacketProcessor;
import org.onosproject.net.packet.PacketService;
import org.onosproject.net.topology.TopologyService;
import org.onlab.packet.Ethernet;
import org.slf4j.Logger;
 
import static org.slf4j.LoggerFactory.getLogger
 
/**
 * Sample reactive forwarding application.
 */
@Component(immediate = true)
public class IntentReactiveForwarding {
 
    // a list of our dependencies :
    // to register with ONOS as an application - described next
    @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
    protected CoreService coreService;

    // topology information
    @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
    protected TopologyService topologyService;

	// to receive Packet-in events that we'll respond to
    @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
    protected PacketService packetService;
 
    // to submit/withdraw intents for traffic manipulation
    @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
    protected IntentService intentService;

    // end host information
    @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
    protected HostService hostService;

    // method called at startup
    @Activate
    public void activate() {
    }

    // method called at shutdown
    @Deactivate
    public void deactivate() {
    }
}

public class IntentReactiveForwarding {
    // for verbose output
    private final Logger log = getLogger(getClass());
 	
// ... <services go here> ...
 
	// our application-specific event handler 
    private ReactivePacketProcessor processor = new ReactivePacketProcessor();
 
    // our unique identifier
    private ApplicationId appId;
 
    @Activate
    public void activate() {
        // "org.onlab.onos.ifwd" is the FQDN of our app
        appId = coreService.registerApplication("org.onlab.onos.ifwd");
        // register our event handler
        packetService.addProcessor(processor, PacketProcessor.ADVISOR_MAX + 2);
        log.info("Started");
    }

    @Deactivate
    public void deactivate() {
        // deregister and null our handler
        packetService.removeProcessor(processor);
        processor = null;
        log.info("Stopped");
    }
 
    // our handler defined as a private inner class
    /**
     * Packet processor responsible for forwarding packets along their paths.
     */
    private class ReactivePacketProcessor implements PacketProcessor {
        @Override
        public void process(PacketContext context) {
        }
    }
}

    // our handler defined as a private inner class
    /**
     * Packet processor responsible for forwarding packets along their paths.
     */
    private class ReactivePacketProcessor implements PacketProcessor {
        @Override
        public void process(PacketContext context) {
            // Stop processing if the packet has been handled, since we
            // can't do any more to it.
            if (context.isHandled()) {
                return;
            }

            // Extract the original Ethernet frame from the packet information
            InboundPacket pkt = context.inPacket();
            Ethernet ethPkt = pkt.parsed();

            // Find and source and destination hosts
            HostId srcId = HostId.hostId(ethPkt.getSourceMAC());
            HostId dstId = HostId.hostId(ethPkt.getDestinationMAC());

            // Do we know who this is for? If not, flood and bail.
            Host dst = hostService.getHost(dstId);
            if (dst == null) {
                flood(context);
                return;
            }

            // Otherwise forward and be done with it.
            setUpConnectivity(context, srcId, dstId);
            forwardPacketToDst(context, dst);
        }
    }

    // Floods the specified packet if permissible.
    private void flood(PacketContext context) {
        if (topologyService.isBroadcastPoint(topologyService.currentTopology(),
                                             context.inPacket().receivedFrom())) {
            packetOut(context, PortNumber.FLOOD);
        } else {
            context.block();
        }
    }

    // Sends a packet out the specified port.
    private void packetOut(PacketContext context, PortNumber portNumber) {
        context.treatmentBuilder().setOutput(portNumber);
        context.send();
    }

    private void forwardPacketToDst(PacketContext context, Host dst) {
        TrafficTreatment treatment = DefaultTrafficTreatment.builder().setOutput(dst.location().port()).build();
        OutboundPacket packet = new DefaultOutboundPacket(dst.location().deviceId(),
                                                          treatment, context.inPacket().unparsed());
        packetService.emit(packet);
        log.info("sending packet: {}", packet);
    }

    // Install a rule forwarding the packet to the specified port.
    private void setUpConnectivity(PacketContext context, HostId srcId, HostId dstId) {
        TrafficSelector selector = DefaultTrafficSelector.builder().build();
        TrafficTreatment treatment = DefaultTrafficTreatment.builder().build();

        HostToHostIntent intent = new HostToHostIntent(appId, srcId, dstId,
                                                       selector, treatment);
        intentService.submit(intent);
    }