Californium (Cf) - CoAP for Java

Eclipse Californium is a Java implementation of RFC7252 - Constrained Application Protocol for IoT Cloud services. Thus, the focus is on scalability and usability instead of resource-efficiency like for embedded devices. Yet Californium is also suitable for embedded JVMs.

More information can be found at http://www.eclipse.org/californium/ and http://coap.technology/.

Build using Maven

You need to have a working maven installation to build Californium. Then simply run the following from the project's root directory:

$ mvn clean install

Executable JARs of the examples with all dependencies can be found in the

demo-apps/run

The build-process is tested for jdk 7, jdk 8 and jdk 11. For jdk 7 the revapi maven-plugin is disabled, it requires at least java 8.

To generate the javadocs, add "-DcreateJavadoc=true" to the command line and set the

JAVA_HOME

$ mvn clean install -DcreateJavadoc=true

Build jdk7 compliant

Californium 2.x can be used with java 7 or newer. If you want to build it with a jdk 7, but use also plugins which are only supported for newer jdks, the toolchain plugin could be used. That requires a toolchains configuration in "toolchains.xml" in your maven ".m2" folder

    
    
        jdk
        
            1.7
        
        
            path..to..jdk7...home
        
    

To use the jdk7 toolchain, add "-DuseToolchain=true" to the command line.

$ mvn clean install -DuseToolchain=true

To use the jdk7 toolchain and create javadocs, add "-DuseToolchainJavadoc=true" to the command line (

JAVA_HOME

$ mvn clean install -DuseToolchainJavadoc=true

Build with jdk11 and EdDSA support

To support EdDSA, either java 15, or java 11 with ed25519-java is required at runtime. Using java 15 to build Californium, leaves out

ed25519-java

ed25519-java

ed25519-java

-Dno.net.i2p.crypto.eddsa=true

$ mvn clean install -Dno.net.i2p.crypto.eddsa=true

In that case, it's still possible to use

ed25519-java

Using Californium in Maven Projects

We are publishing Californium's artifacts for milestones and releases to Maven Central. To use the latest released version as a library in your projects, add the following dependency to your

pom.xml

  
    ...
    
            org.eclipse.californium
            californium-core
            2.6.1
    
    ...
  
  ...

Current Builds

You can also be bold and try out the most recent build from

master

pom.xml

  
    ...
    
      repo.eclipse.org
      Californium Repository
      https://repo.eclipse.org/content/repositories/californium/
    
    ...
  

You can then simply depend on

3.0.0-SNAPSHOT

Eclipse

The project can be easily imported into a recent version of the Eclipse IDE. Make sure to have the following before importing the Californium (Cf) projects:

• Eclipse EGit (should be the case with every recent Eclipse version)
• m2e - Maven Integration for Eclipse (should be the case with every recent Eclipse version)
• UTF-8 workspace text file encoding (Preferences » General » Workspace)

Then choose [Import... » Maven » Existing Maven Projects] to import

californium

IntelliJ

The project can also be imported to IntelliJ as follows:

In IntelliJ, choose [File.. » Open] then select the location of the cloned repository in your filesystem. IntelliJ will then automatically import all projects and resolve required Maven dependencies.

Interop Server

A test server is running at coap://californium.eclipseprojects.io:5683/

(Note: that changed from "californium.eclipse.org" on the 9th. December 2020. All 2.x demo- and plugtest-clients must therefore use the new destination "californium.eclipseprojects.io" explicitly!)

It is an instance of the cf-plugtest-server from the demo-apps. The root resource responds with its current version.

More information can be found at http://www.eclipse.org/californium and technical details at https://projects.eclipse.org/projects/iot.californium.

Another interop server with a different implementation can be found at coap://coap.me:5683/. More information can be found at http://coap.me/.

Adapter Selection

For some systems (particularly when multicasting), it may be necessary to specify/restrict californium to a particular network interface, or interfaces. This can be achieved by setting the

COAP_NETWORK_INTERFACES

java -DCOAP_NETWORK_INTERFACES='.*wpan0' -jar target/cf-helloworld-server-2.6.1.jar MulticastTestServer

Contact

A bug, an idea, an issue? Join the Mailing list or create an issue here on GitHub.

Contributing

Please check out our contribution guidelines