This is an archive of the ONOS 1.4 wiki. For the current ONOS wiki, look here.

Overview

This tutorial will show you how to create a CLI command to print the endpoints found by the reactive forwarding application from the Application tutorial. After completing this tutorial, you will understand:

  • How to extend applications with new services
  • How to extend the Karaf-based ONOS CLI with new commands


As a reference, our collection of additions/modifications can be summarized in the following directory layout:

${ONOS_ROOT}/apps/pom.xml (apps parent POM)
         |    |  
         |    /ifwd/pom.xml (application POM)
         |         |
         |         /src/main/java/org/onosproject/ifwd/IntentReactiveForwarding.java (the application)
         |             |                              |
         |             |                              /package-info.java (optional documentation/annotations)
         |             |
         |             /test/java/org/onosproject/ifwd/ (Unit tests go here)
         |
         /core/api/src/main/java/org/onosproject/net/apps/ForwardingMapService.java (the service interface)
         |
         /cli/src/main/java/org/onosproject/cli/net/ForwardingMapCommand.java (the command)
                      |
                      /resources/OSGI-INF/blueprint/shell-config.xml (Karaf shell configuration)

Conventions

${ONOS_ROOT} refers to the project root directory for ONOS. For example, if the project directory is ~/onos_next,  cd ${ONOS_ROOT} is equivalent to cd ~/onos_next .

We also assume that the you have a Mininet installation, as we will be testing our work against it. 

Offering services to other modules

If you want your module to be able to provide services to other modules, you should define a service interface and have your module class implement it.

1. Define a service interface.

We start by defining a new interface for the service in the onos-api package (${ONOS_ROOT}/core/api/src/main/java/org/onosproject/net/). We also create a new directory, apps/, for our service interface to reside in. The interface is added to this location so that the cli package that implements the commands has access to it.

ForwardingMapService.java 
/*
 * 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.net.apps;

import java.util.Map;

import org.onosproject.net.HostId;

/**
 * A demonstrative service for the intent reactive forwarding application to
 * export.
 */
public interface ForwardingMapService {

    /**
     * Get the endpoints of the host-to-host intents that were installed.
     *
     * @return maps of source to destination
     */
    public Map<HostId, HostId> getEndPoints();

}

2. Import the service interface.

Next, we implement our service in IntentReactiveForwarding. We also indicate to Karaf that the application exports a service, using the the Felix SCR annotation @Service:

IntentReactiveForwarding.java 
/*
 * 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 java.util.Collections;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;

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.apache.felix.scr.annotations.Service;
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.apps.ForwardingMapService;
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;

@Component(immediate = true)
@Service
public class IntentReactiveForwarding implements ForwardingMapService {

	private final Logger log = getLogger(getClass());

    @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
    protected CoreService coreService;

    // ...<snip>...
 
    // 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);
    }
 
    // the new service method, to be filled out
    @Override
    public Map<HostId, HostId> getEndPoints() {
        return null;
    }
}


Although we won't be using it here in this manner in this tutorial, the @Service annotation enables another class to reference the service through the @Reference annotation:

Felix annotation reference
@Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
protected ForwardingMapService fwdMapService;

3. Implement the service.

We can now define the new method. We add a new Map, endPoints, to IntentReactiveForwarding. The map is populated when the ReactivePacketProcessor's process() method finds endpoints known by the HostService.

IntentReactiveForwarding.java - service 
@Component(immediate = true)
@Service
public class IntentReactiveForwarding implements ForwardingMapService {

    // ...<snip>...
    private ApplicationId appId;

    // Map for storing found endpoints, for our service. It is protected
    // so that process() can access it.
    protected final ConcurrentMap<HostId, HostId> endPoints = new ConcurrentHashMap<>();

    // ...<snip>...
    /**
     * 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()) {
            
            // ...<snip>...
            
            if (dst == null) {
                flood(context);
                return;
            }
            // Add found endpoints to map.
            endPoints.put(srcId, dstId);

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

    // ...<snip>...

    @Override
    public Map<HostId, HostId> getEndPoints() {
        // Return our map as a read-only structure.
        return Collections.unmodifiableMap(endPoints);
    }
}

Now, a module referencing the ForwardingMapService may call getEndPoints() to get a list of directional endpoints for which intents were installed, and traffic can flow between.

Next, we will create a CLI command to use this new service. This command will list the contents of this map, and also provide the option to take a parameter (a host ID), to filter on that host as a source.

Creating a command 

The CLI commands are defined in the project directory ${ONOS_ROOT}/cli/. There are two types of commands, with their source files located in the following locations:

  • ${ONOS_ROOT}/cli/src/main/java/org/onosproject/cli - Commands related to system configuration and monitoring
  • ${ONOS_ROOT}/cli/src/main/java/org/onosproject/cli/net - Commands related to network configuration and monitoring

Since our command will display network-related  information, we will add our command to the second net directory. 

1. Create a command class.

We create the following class skeleton for our new command, tentatively named ForwardingMapCommand. Our class is a child of AbstractShellCommand, and uses some command-related annotations: 

  • @Command -  used to set a command's name, scope, and description.
  • @Argument - used to indicate that a variable is set by a command-line argument.

 

ForwardingMapCommand.java 
/*
 * 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.cli.net;

import org.apache.karaf.shell.commands.Argument;
import org.apache.karaf.shell.commands.Command;
import org.onosproject.cli.AbstractShellCommand;
import org.onosproject.net.HostId;
import org.onosproject.net.apps.ForwardingMapService;

/**
 * A demo service that lists the endpoints for which intents are installed.
 */
@Command(scope = "onos", name = "fwdmap",
        description = "Lists the endpoints for which intents are installed")
public class ForwardingMapCommand extends AbstractShellCommand {
 
    @Argument(index = 0, name = "hostId", description = "Host ID of source",
            required = false, multiValued = false)
    private HostId hostId = null;

    @Override
    protected void execute() {
    }
}

The annotations enable this particular command to be invoked as fwdmap or onos:fwdmap at the CLI. In addition, it can also take a host ID as an option, e.g. fwdmap 06:38:27:D5:68:88/-1.

2. Incorporate the new service.

Next, we implement the command. In our case, it is pretty simple - we ask the service for its endpoint map, and if we were given a host ID, we search for it in the map. The full class definition looks like this:

ForwardingMapCommand.java 
/*
 * 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.cli.net;

import java.util.Map;

import org.apache.karaf.shell.commands.Argument;
import org.apache.karaf.shell.commands.Command;
import org.onosproject.cli.AbstractShellCommand;
import org.onosproject.net.HostId;
import org.onosproject.net.apps.ForwardingMapService;

/**
 * A demo service that lists the endpoints for which intents are installed.
 */
@Command(scope = "onos", name = "fwdmap",
        description = "Lists the endpoints for which intents are installed")
public class ForwardingMapCommand extends AbstractShellCommand {
 
    // formatted string for output to CLI
    private static final String FMT = "src=%s, dst=%s";

    // the String to hold the optional argument
    @Argument(index = 0, name = "hostId", description = "Host ID of source",
            required = false, multiValued = false)
    private String hostId = null;

    // reference to our service
    private ForwardingMapService service;
    // to hold the service's response
    private Map<HostId, HostId> hmap;

    @Override
    protected void execute() {
        // get a reference to our service
        service = get(ForwardingMapService.class);

        /*
         * getEndPoints() returns an empty map even if it contains nothing, so
         * we don't need to check for null hmap here.
         */
        hmap = service.getEndPoints();

        // check for an argument, then display information accordingly
        if (hostId != null) {
            // we were given a hostId to filter on, print only those that match
            HostId host = HostId.hostId(hostId);
            for (Map.Entry<HostId, HostId> el : hmap.entrySet()) {
                if (el.getKey().equals(hostId)) {
                    print(FMT, el.getKey(), el.getValue());
                }
            }
        } else {
            // print everything we have
            for (Map.Entry<HostId, HostId> el : hmap.entrySet()) {
                print(FMT, el.getKey(), el.getValue());
            }
        }
    }
}

 3. Register the command with Karaf CLI.

Next, we need to tell Karaf about our new command by editing shell-config.xml, located in ${ONOS_ROOT}/cli/src/main/resources/OSGI-INF/blueprint/. We add the following to the contents between the <command-bundle></command-bundle> clause in the file:

shell-config.xml
        <command>
            <!--Our command implementation's FQDN-->
            <action class="org.onosproject.cli.net.ForwardingMapCommand"/>
            <!--A command completer for Host IDs-->
            <completers>
                <ref component-id="hostIdCompleter"/>
                <null/>
            </completers>
        </command>

Verification

Once we rebuild ONOS, we can test our command out. 

1. Rebuild and restart ONOS.

Rebuild and relaunch ONOS. 

$ cd ${ONOS_ROOT}
$ mvn clean install
$ karaf clean

The last command re-launches the CLI. The new command should be available as part of the listing for help onos:

onos> help onos | grep fwdmap
onos:fwdmap
onos> fwdmap --help
DESCRIPTION
    onos:fwdmap

	Lists the endpoints for which intents are installed

SYNTAX
        onos:fwdmap [options] [hostId] 

ARGUMENTS
        hostId
                Host ID of source

OPTIONS
        -j, --json
                Output JSON
        --help
                Display this help message

2. Launch a Mininet test network.

Launch a small Mininet network with four hosts, pointing at our ONOS instance (192.168.56.20 in this example):

$ sudo mn --topo=tree,2,2 --controller=remote,ip=192.168.56.20 --mac
*** Creating network
...
mininet>

Your ONOS instance should see four hosts:

onos> hosts
id=00:00:00:00:00:01/-1, mac=00:00:00:00:00:01, location=of:0000000000000002/1, vlan=-1, ip(s)=[]
id=00:00:00:00:00:02/-1, mac=00:00:00:00:00:02, location=of:0000000000000002/2, vlan=-1, ip(s)=[]
id=00:00:00:00:00:03/-1, mac=00:00:00:00:00:03, location=of:0000000000000003/1, vlan=-1, ip(s)=[]
id=00:00:00:00:00:04/-1, mac=00:00:00:00:00:04, location=of:0000000000000003/2, vlan=-1, ip(s)=[]

3. Test out the command.

Without traffic, the command won't return anything:

onos> fwdmap
onos>

So, generate traffic on Mininet:

mininet> pingall
*** Ping: testing ping reachability
h1 -> h2 h3 h4 
h2 -> h1 h3 h4 
h3 -> h1 h2 h4 
h4 -> h1 h2 h3 
*** Results: 0% dropped (12/12 received)

And retry the command. You should see four entries:

onos> fwdmap
src=00:00:00:00:00:04/-1, dst=00:00:00:00:00:03/-1
src=00:00:00:00:00:03/-1, dst=00:00:00:00:00:04/-1
src=00:00:00:00:00:02/-1, dst=00:00:00:00:00:04/-1
src=00:00:00:00:00:01/-1, dst=00:00:00:00:00:02/-1

Since we have specified for an optional argument, we can also filter on source host ID:

onos> fwdmap 00:00:00:00:00:04/-1
src=00:00:00:00:00:04/-1, dst=00:00:00:00:00:03/-1

We had also configured autocomplete, so we are presented with the available options when we hit Tab:

onos> fwdmap <tab>
onos> fwdmap 00:00:00:00:00:0
00:00:00:00:00:01/-1   00:00:00:00:00:02/-1   00:00:00:00:00:03/-1   00:00:00:00:00:04/-1

 

What next?

  • Check out the Documentation Set for deep dives into the architecture or the development process.

 

Return To : Tutorials and Walkthroughs

 

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1 Comment

  1. Richard Liu

    It looks like the "ifwd" package can only be seen in onos 1.1. I cannot found it for version later than 1.2.