Dropwizard ZeroMQ

This modules provides basic integration for ZeroMQ with Dropwizard. Both the native JZMQ and the pure-Java JeroMQ implementations are supported.

Dependency

Add a dependency to your project:

<dependency>
    <groupId>com.datasift.dropwizard</groupId>
    <artifactId>dropwizard-zeromq</artifactId>
    <version>${dropwizard.version}-1-SNAPSHOT</version>
</dependency>

Where ${dropwizard.version} is the version of Dropwizard you're using (e.g. 0.7.0).

You will also need to explicitly select a ZeroMQ binding, add ONE of the following:

JZMQ

JZMQ is a JNI wrapper around the native libzmq API. As such, you will need to ensure that the libjzmq.so has been properly compiled and is available to your application.

<dependency>
    <groupId>org.zeromq</groupId>
    <artifactId>jzmq</artifactId>
    <version>3.0.1</version>
</dependency>

JeroMQ

JeroMQ is a pure-Java implementation of the ZeroMQ protocol. It's developed in parallel to the mainline ZeroMQ project.

<dependency>
    <groupId>org.zeromq</groupId>
    <artifactId>jeromq</artifactId>
    <version>0.3.4</version>
</dependency>

You must include exactly one of the above.

Usage

To work with a ZeroMQ context in your Dropwizard application, first add the necessary configuration to your applications' Configuration class:

public class MyConfiguration extends Configuration {

    @NotNull
    @Valid
    private ZeroMQFactory zeromq = new ZeroMQFactory();

    @JsonProperty("zeromq")
    public ZeroMQFactory getZeroMQFactory() {
        return zeromq;
    }

    @JsonProperty("zeromq")
    public void setZeroMQFactory(ZeroMQFactory zeromq) {
        this.zeromq = zeromq;
    }
}

Then, in your application, build a ZContext:

public class MyApplication extends Application<MyConfiguration> {
    
    @Override
    public void run(MyConfiguration configuration, Environment environment) {
        ZContext context = configuration.getZeroMQFactory().build(environment);
    }
}

To configure ZeroMQ Sockets, you'll want to include a ZeroMQSocketFactory:

public MyConfiguration extends Configuration {
    
    // elided: context configuration
    
    @NotNull
    @Valid
    private ZeroMQSocketFactory socket = new ZeroMQPushSocketFactory();

    @JsonProperty("socket")
    public ZeroMQSocketFactory getSocket() {
        return socket;
    }

    @JsonProperty("socket")
    public void setSocket(ZeroMQSocketFactory socket) {
        this.socket = socket;
    }
}

In your YAML, you can define the full socket configuration, including the type of the Socket. ZeroMQSocketFactory uses the same SPI mechanism as AppenderFactory (logging), ServerFactory and ConnectorFactory (web server); so the configuration will look familiar:

zeromq:
  ioThreads: 3

socket:
  type: push
  endpoints:
    - tcp://localhost:1234
  highWaterMark: 50000
  sendTimeout: 100ms

If you want to mandate a particular type of socket in your application, make this explicit in the type signature of its configuration:

public MyConfiguration extends Configuration {
    
    // elided: context configuration
    
    @NotNull
    @Valid
    private ZeroMQPushSocketFactory socket = new ZeroMQPushSocketFactory();
    //            ^^^^

    @JsonProperty("socket")
    public ZeroMQPushSocketFactory getSocket() {
    //           ^^^^
        return socket;
    }

    @JsonProperty("socket")
    public void setSocket(ZeroMQPushSocketFactory socket) {
    //                          ^^^^
        this.socket = socket;
    }
}

This will make the type property invalid, and only sockets of that type will be buildable.