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h2. Netty Component

*Available as of Camel 2.3*

The *netty* component in Camel is a socket communication component, based on the 
JBoss Netty community offering (available under an Apache 2.0 license). 
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:
{code:xml}
<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>
{code}

h3. URI format

The URI scheme for a netty component is as follows

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

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&...}}

h3. Options
{div:class=confluenceTableSmall}
|| Name || Default Value || Description ||
| {{keepAlive}} | {{true}} | Setting to ensure socket is not closed due to inactivity |
| {{tcpNoDelay}} | {{true}} | Setting to improve TCP protocol performance |
| {{broadcast}} | {{false}} | Setting to choose Multicast over UDP |
| {{connectTimeoutMillis}} | {{10 seconds}} | Time to wait for a socket connection to be available |
| {{receiveTimeoutMillis}} | {{10 seconds}} | Time to wait for a response to be received on a connection |
| {{reuseAddress}} | {{true}} | Setting to facilitate socket multiplexing |
| {{sync}} | {{falsetrue}} | Setting to set endpoint as one-way or request-response |
| {{ssl}} | {{false}} | Setting to specify whether SSL encryption is applied to this endpoint |
| {{sendBufferSize}} | {{65536 bytes}} | The TCP/UDP buffer sizes to be used during outbound communication |
| {{receiveBufferSize}} | {{65536 bytes}} | The TCP/UDP buffer sizes to be used during inbound communication |
| {{corePoolSize}} | {{10 threads}} | The number of allocated threads at component startup. Defaults to 10 |
| {{maxPoolSize}} | {{100 threads}} | The maximum number of threads that may be allocated to this endpoint. Defaults to 100 |
| {{disconnect}} | {{false}} | Whether or not to disconnect(close) from Netty Channel right after use. Can be used for both consumer and producer. |
| {{div}

h3. 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:

{div:class=confluenceTableSmall}
|| Name || Description ||
| {{passphrase}} | password setting to use in order to encrypt/decrypt payloads sent using SSH |
| {{keyStoreFormat}} | keystore format to be used for payload encryption. Defaults to "JKS" if not set |
| {{securityProvider}} | Security provider to be used for payload encryption. Defaults to "SunX509" if not set. |
| {{keyStoreFile}} | Client side certificate keystorelazyChannelCreation}} | {{true}} | Channels can be lazily created to avoid exceptions, if the remote server is not up and running when the Camel producer is started. |
{div}

h3. 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:

{div:class=confluenceTableSmall}
|| Name || Description ||
| {{passphrase}} | password setting to use in order to encrypt/decrypt payloads sent using SSH |
| {{keyStoreFormat}} | keystore format to be used for payload encryption. Defaults to "JKS" if not set |
| {{trustStoreFilesecurityProvider}} | Server side certificate keystoreSecurity provider to be used for payload encryption. |
| {{sslHandler}} | Reference to a class that could be used to return an SSL HandlerDefaults to "SunX509" if not set. |
| {{keyStoreFile}} | Client side certificate keystore to be used for encryption |
| {{encodertrustStoreFile}} | AServer customside Handlercertificate classkeystore that canto be used tofor performencryption special marshalling of outbound payloads. Must override {{org.jboss.netty.channel.ChannelDownStreamHandler}}.|
| {{sslHandler}} | Reference to a class that could be used to return an SSL Handler |
| {{encordersencoder}} | A custom listHandler ofclass encoderthat tocan be used to perform special marshalling of outbound payloads. Must override {{org.jboss.netty.channel.ChannelDownStreamHandler}}. |
| {{encorders}} | A list of encoder to be used. You can use a String which have values separated by comma, and have the values be looked up in the [Registry]. Just remember to prefix the value with # so Camel knows it should lookup. |
| {{decoder}} | A custom Handler class that can be used to perform special marshalling of inbound payloads. Must override {{org.jboss.netty.channel.ChannelUpStreamHandler}}. |
| {{decoders}} | A list of decorder to be used. You can use a String which have values separated by comma, and have the values be looked up in the [Registry]. Just remember to prefix the value with # so Camel knows it should lookup. |
| {{handler}} | A custom Handler class that can be used to perform custom processing of Netty events triggered 
during communication. Must override {{org.jboss.netty.channel.SimpleChannelHandler}}. |
{div}

h3. Sending Messages to/from a Netty endpoint

h4.  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.

h4.  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.

h3. Usage Samples

h4. A UDP Netty endpoint using Request-Reply and serialized object payload
{code}
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);
         }
       }
    }
};
{code}

h4. A TCP based Netty consumer endpoint using One-way communication
{code}
RouteBuilder builder = new RouteBuilder() {
  public void configure() {
       from("netty:tcp://localhost:5150")
           .to("mock:result"); 
  }
};
{code}

h4. An SSL/TCP based Netty consumer endpoint using Request-Reply communication 
{code}
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:5150sync=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);                           
          }
       }
  }
});
{code}

h4. 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. 

{snippet:id=registry-beans|lang=java|url=camel/trunk/components/camel-netty/src/test/java/org/apache/camel/component/netty/MultipleCodecsTest.java}

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

{snippet:id=registry-beans|lang=xml|url=camel/trunk/components/camel-netty/src/test/resources/org/apache/camel/component/netty/multiple-codecs.xml}

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

{snippet:id=routes|lang=java|url=camel/trunk/components/camel-netty/src/test/java/org/apache/camel/component/netty/MultipleCodecsTest.java}

or via spring.

{snippet:id=routes|lang=xml|url=camel/trunk/components/camel-netty/src/test/resources/org/apache/camel/component/netty/multiple-codecs.xml}

h3. 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:
{code}
        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);
                }
            }
        });
{code}


{include:Endpoint See Also}
 - [Mina]