Getting Started : Server

Here you will see how to code your own LWM2M server with Leshan.

Get Leshan

To develop your server you need to use the leshan-server-cf module.

IMPORTANT: To use this getting started guide, use the latest 1.x version: https://central.sonatype.com/artifact/org.eclipse.leshan/leshan-server-cf/1.5.0.

Using maven

<dependencies>
    <dependency>
        <groupId>org.eclipse.leshan</groupId>
        <artifactId>leshan-server-cf</artifactId>
        <version>1.5.0</version>                  
    </dependency>
    <!-- add any slf4j backend, here we use one of the smallest one: slf4j-simple -->
    <dependency>
        <groupId>org.slf4j</groupId>
        <artifactId>slf4j-simple</artifactId>
        <version>1.7.30</version>
        <scope>runtime</scope>
    </dependency>
</dependencies>

Create a Simple Server.

You need to use Leshan builder to create server.

LeshanServerBuilder builder = new LeshanServerBuilder();
LeshanServer server = builder.build();
server.start();

If you execute this code, you should see something like this in your log :

[...] INFO ... - LWM2M server started at coap://0.0.0.0/0.0.0.0:5683 coaps://0.0.0.0/0.0.0.0:5684

You can try to connect a client, for example using leshan-client-demo:

wget https://hudson.eclipse.org/leshan/job/leshan/lastSuccessfulBuild/artifact/leshan-client-demo.jar
java -jar ./leshan-client-demo.jar

You should see client successfully registered to your server:

... INFO ... - Trying to register to coap://localhost:5683 ...
... INFO ... - Registered with location '/rd/SfDZcGn8p7'.

Now let's print when devices connect or leave this server.

server.getRegistrationService().addListener(new RegistrationListener() {

    public void registered(Registration registration, Registration previousReg,
            Collection<Observation> previousObsersations) {
        System.out.println("new device: " + registration.getEndpoint());
    }

    public void updated(RegistrationUpdate update, Registration updatedReg, Registration previousReg) {
        System.out.println("device is still here: " + updatedReg.getEndpoint());
    }

    public void unregistered(Registration registration, Collection<Observation> observations, boolean expired,
            Registration newReg) {
        System.out.println("device left: " + registration.getEndpoint());
    }
});

Now let's try to send request on registration :

public void registered(Registration registration, Registration previousReg,
            Collection<Observation> previousObsersations) {
    System.out.println("new device: " + registration.getEndpoint());
    try {
        ReadResponse response = server.send(registration, new ReadRequest(3,0,13));
        if (response.isSuccess()) {
            System.out.println("Device time:" + ((LwM2mResource)response.getContent()).getValue());
        }else {
            System.out.println("Failed to read:" + response.getCode() + " " + response.getErrorMessage());
        }
    } catch (InterruptedException e) {
        e.printStackTrace();
    }
}

To go further

You can have a look to the code of our server demo: LeshanServerDemo in leshan-server-demo.