Netty

Netty Component

Available as of Camel 2.3

The netty component in Camel is a socket communication component, based on the Netty project.
Netty is a NIO client server framework which enables quick and easy development of network applications such as protocol servers and clients.
Netty greatly simplifies and streamlines network programming such as TCP and UDP socket server.

This camel component supports both producer and consumer endpoints.

The Netty component has several options and allows fine-grained control of a number of TCP/UDP communication parameters (buffer sizes, keepAlives, tcpNoDelay etc) and facilitates both In-Only and In-Out communication on a Camel route.

Maven users will need to add the following dependency to their pom.xml for this component:

<dependency>
    <groupId>org.apache.camel</groupId>
    <artifactId>camel-netty</artifactId>
    <version>x.x.x</version>
    <!-- use the same version as your Camel core version -->
</dependency>

URI format

The URI scheme for a netty component is as follows

netty:tcp://localhost:99999[?options]
netty:udp://remotehost:99999/[?options]

This component supports producer and consumer endpoints for both TCP and UDP.

You can append query options to the URI in the following format, ?option=value&option=value&...

Options

Registry based Options

Codec Handlers and SSL Keystores can be enlisted in the Registry, such as in the Spring XML file.
The values that could be passed in, are the following:

Important: Read below about using non shareable encoders/decoders.

Using non shareable encoders or decoders

If your encoders or decoders is not shareable (eg they have the @Shareable class annotation), then your encoder/decoder must implement the org.apache.camel.component.netty.ChannelHandlerFactory interface, and return a new instance in the newChannelHandler method. This is to ensure the encoder/decoder can safely be used. If this is not the case, then the Netty component will log a WARN when
an endpoint is created.

The Netty component offers a org.apache.camel.component.netty.ChannelHandlerFactories factory class, that has a number of commonly used methods.

Sending Messages to/from a Netty endpoint

Netty Producer

In Producer mode, the component provides the ability to send payloads to a socket endpoint
using either TCP or UDP protocols (with optional SSL support).

The producer mode supports both one-way and request-response based operations.

Netty Consumer

In Consumer mode, the component provides the ability to:

• listen on a specified socket using either TCP or UDP protocols (with optional SSL support),
• receive requests on the socket using text/xml, binary and serialized object based payloads and
• send them along on a route as message exchanges.

The consumer mode supports both one-way and request-response based operations.

Usage Samples

A UDP Netty endpoint using Request-Reply and serialized object payload

RouteBuilder builder = new RouteBuilder() {
  public void configure() {
    from("netty:udp://localhost:5155?sync=true")
      .process(new Processor() {
         public void process(Exchange exchange) throws Exception {
           Poetry poetry = (Poetry) exchange.getIn().getBody();
           poetry.setPoet("Dr. Sarojini Naidu");
           exchange.getOut().setBody(poetry);
         }
       }
    }
};

A TCP based Netty consumer endpoint using One-way communication

RouteBuilder builder = new RouteBuilder() {
  public void configure() {
       from("netty:tcp://localhost:5150")
           .to("mock:result");
  }
};

An SSL/TCP based Netty consumer endpoint using Request-Reply communication

Using the JSSE Configuration Utility

As of Camel 2.9, the Netty component supports SSL/TLS configuration through the Camel JSSE Configuration Utility.  This utility greatly decreases the amount of component specific code you need to write and is configurable at the endpoint and component levels.  The following examples demonstrate how to use the utility with the Netty component.

Programmatic configuration of the component

KeyStoreParameters ksp = new KeyStoreParameters();
ksp.setResource("/users/home/server/keystore.jks");
ksp.setPassword("keystorePassword");

KeyManagersParameters kmp = new KeyManagersParameters();
kmp.setKeyStore(ksp);
kmp.setKeyPassword("keyPassword");

SSLContextParameters scp = new SSLContextParameters();
scp.setKeyManagers(kmp);

NettyComponent nettyComponent = getContext().getComponent("netty", NettyComponent.class);
nettyComponent.setSslContextParameters(scp);

Spring DSL based configuration of endpoint

...
  <camel:sslContextParameters
      id="sslContextParameters">
    <camel:keyManagers
        keyPassword="keyPassword">
      <camel:keyStore
          resource="/users/home/server/keystore.jks"
          password="keystorePassword"/>
    </camel:keyManagers>
  </camel:sslContextParameters>...
...
  <to uri="netty:tcp://localhost:5150?sync=true&ssl=true&sslContextParameters=#sslContextParameters"/>
...

Using Basic SSL/TLS configuration on the Jetty Component

JndiRegistry registry = new JndiRegistry(createJndiContext());
registry.bind("password", "changeit");
registry.bind("ksf", new File("src/test/resources/keystore.jks"));
registry.bind("tsf", new File("src/test/resources/keystore.jks"));

context.createRegistry(registry);
context.addRoutes(new RouteBuilder() {
  public void configure() {
      String netty_ssl_endpoint =
         "netty:tcp://localhost:5150?sync=true&ssl=true&passphrase=#password"
         + "&keyStoreFile=#ksf&trustStoreFile=#tsf";
      String return_string =
         "When You Go Home, Tell Them Of Us And Say,"
         + "For Your Tomorrow, We Gave Our Today.";

      from(netty_ssl_endpoint)
       .process(new Processor() {
          public void process(Exchange exchange) throws Exception {
            exchange.getOut().setBody(return_string);
          }
       }
  }
});

Using Multiple Codecs

In certain cases it may be necessary to add chains of encoders and decoders to the netty pipeline. To add multpile codecs to a camel netty endpoint the 'encoders' and 'decoders' uri parameters should be used. Like the 'encoder' and 'decoder' parameters they are used to supply references (to lists of ChannelUpstreamHandlers and ChannelDownstreamHandlers) that should be added to the pipeline. Note that if encoders is specified then the encoder param will be ignored, similarly for decoders and the decoder param.

The lists of codecs need to be added to the Camel's registry so they can be resolved when the endpoint is created.

Spring's native collections support can be used to specify the codec lists in an application context

The bean names can then be used in netty endpoint definitions either as a comma separated list or contained in a List e.g.

or via spring.

Closing Channel When Complete

When acting as a server you sometimes want to close the channel when, for example, a client conversion is finished.
You can do this by simply setting the endpoint option disconnect=true.

However you can also instruct Camel on a per message basis as follows.
To instruct Camel to close the channel, you should add a header with the key CamelNettyCloseChannelWhenComplete set to a boolean true value.
For instance, the example below will close the channel after it has written the bye message back to the client:

        from("netty:tcp://localhost:8080").process(new Processor() {
            public void process(Exchange exchange) throws Exception {
                String body = exchange.getIn().getBody(String.class);
                exchange.getOut().setBody("Bye " + body);
                // some condition which determines if we should close
                if (close) {
                    exchange.getOut().setHeader(NettyConstants.NETTY_CLOSE_CHANNEL_WHEN_COMPLETE, true);
                }
            }
        });

Adding custom channel pipeline factories to gain complete control over a created pipeline

Available as of Camel 2.5

Custom channel pipelines provide complete control to the user over the handler/interceptor chain by inserting custom handler(s), encoder(s) & decoders without having to specify them in the Netty Endpoint URL in a very simple way.

In order to add a custom pipeline, a custom channel pipeline factory must be created and registered with the context via the context registry (JNDIRegistry,or the camel-spring ApplicationContextRegistry etc).

A custom pipeline factory must be constructed as follows

• A Producer linked channel pipeline factory must extend the abstract class ClientPipelineFactory.
• A Consumer linked channel pipeline factory must extend the abstract class ServerPipelineFactory.
• The classes should override the getPipeline() method in order to insert custom handler(s), encoder(s) and decoder(s). Not overriding the getPipeline() method creates a pipeline with no handlers, encoders or decoders wired to the pipeline.

The example below shows how ServerChannel Pipeline factory may be created

public class SampleServerChannelPipelineFactory extends ServerPipelineFactory {
    private int maxLineSize = 1024;

    public ChannelPipeline getPipeline() throws Exception {
        ChannelPipeline channelPipeline = Channels.pipeline();

        channelPipeline.addLast("encoder-SD", new StringEncoder(CharsetUtil.UTF_8));
        channelPipeline.addLast("decoder-DELIM", new DelimiterBasedFrameDecoder(maxLineSize, true, Delimiters.lineDelimiter()));
        channelPipeline.addLast("decoder-SD", new StringDecoder(CharsetUtil.UTF_8));
        // here we add the default Camel ServerChannelHandler for the consumer, to allow Camel to route the message etc.
        channelPipeline.addLast("handler", new ServerChannelHandler(consumer));

        return channelPipeline;
    }
}

The custom channel pipeline factory can then be added to the registry and instantiated/utilized on a camel route in the following way

Registry registry = camelContext.getRegistry();
serverPipelineFactory = new TestServerChannelPipelineFactory();
registry.bind("spf", serverPipelineFactory);
context.addRoutes(new RouteBuilder() {
  public void configure() {
      String netty_ssl_endpoint =
         "netty:tcp://localhost:5150?serverPipelineFactory=#spf"
      String return_string =
         "When You Go Home, Tell Them Of Us And Say,"
         + "For Your Tomorrow, We Gave Our Today.";

      from(netty_ssl_endpoint)
       .process(new Processor() {
          public void process(Exchange exchange) throws Exception {
            exchange.getOut().setBody(return_string);
          }
       }
  }
});

See Also

• Configuring Camel
• Component
• Endpoint
• Getting Started

• MINA