Available as of Camel 2.3
The netty component in Apache 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 Apache 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 Apache Camel route.
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&...
Maven users 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>
Table 65 list the Netty uri options:
Table 65. URI options
Name | Default | Description |
---|---|---|
keepAlive
|
true
| Setting to ensure socket is not closed due to inactivity |
tcpNoDelay
|
true
| Setting to improve TCP protocol performance |
backlog
| If not set, depends on OS setting | Camel 2.9.6/2.10.4/2.11: Enables you to configure a backlog for netty consumer (server). The backlog is just a best effort, depending on the OS. Setting this option to a value, such as |
broadcast
|
false
| Setting to choose Multicast over UDP |
connectTimeout
|
10000
| Time to wait for a socket connection to be available. Value is in millis. |
reuseAddress
|
true
| Setting to facilitate socket multiplexing |
sync
|
true
| Setting to set endpoint as one-way or request-response |
synchronous
|
false
|
Camel 2.10: Specifies whether Asynchronous Routing Engine is not in use.
|
ssl
|
false
| Setting to specify whether SSL encryption is applied to this endpoint |
sslClientCertHeaders
|
false
| Camel 2.12: When enabled and in SSL mode, the Netty consumer enrichs the Camel Message with headers having information about the client certificate—such as subject name, issuer name, serial number, and the valid date range. |
sendBufferSize
|
65536 bytes
| The TCP/UDP buffer sizes to be used during outbound communication. Size is bytes. |
receiveBufferSize
|
65536 bytes
| The TCP/UDP buffer sizes to be used during inbound communication. Size is bytes. |
option.XXX
|
null
| Camel 2.11/2.10.4: Allows configuring additional netty
options using For example, See the Netty documentation for other options. |
corePoolSize
|
10
| Specifies the number of allocated threads at component startup. Defaults to 10. Note: This option is removed from Camel 2.9.2 onwards, as we rely on Netty's default settings. |
maxPoolSize
|
100
| Specifies the maximum number of threads that may be allocated to this endpoint. Defaults to 100. Note: This option is removed from Camel 2.9.2 onwards. As we rely on Nettys default settings. |
disconnect
|
false
| Specifies whether to disconnect (close) from Netty Channel right after use. Can be used for both consumer and producer. |
lazyChannelCreation
|
true
| Channels can be lazily created to avoid exceptions, if the remote server is not up and running when the Camel producer is started. |
transferExchange
|
false
| Only used for TCP. You can transfer the exchange over the wire instead of just the body. These fields are transferred:
This feature requires that the objects be serializable. Camel excludes any non-serializable object and logs it at WARN level. |
disconnectOnNoReply
|
true
| If sync is enabled, this option dictates whether NettyConsumer should disconnect when there is no reply. |
noReplyLogLevel
|
WARN
| If sync is enabled, this option dictates which logging level NettyConsumer should use for logging when there is no reply. Values are:
|
serverExceptionCaught LogLevel
|
WARN
| Camel 2.11.1: When the server (NettyConsumer) catches an exception, it is logged using this logging level. |
serverClosedChannel ExceptionCaughtLogLevel
|
DEBUG
| Camel 2.11.1: When the server
(NettyConsumer) catches an
This is used to avoid logging the closed channel exceptions, as clients can disconnect abruptly, then cause a flood of closed exceptions in the Netty server. |
allowDefaultCodec
|
true
|
Camel 2.4: The netty component
installs a default codec if encoder/decoder is null and
Setting |
textline
|
false
| Camel 2.4: Only used for TCP. If no codec is specified, you can use this flag to indicate a text line based codec; if not specified or the value is false, then Object Serialization is assumed over TCP. |
delimiter
|
LINE
| Camel 2.4: pecifies the delimiter to use for the textline codec. Possible values are |
decoderMaxLineLength
|
1024
| Camel 2.4: Specifies the max line length to use for the textline codec. |
autoAppendDelimiter
|
true
| Camel 2.4: Specifies whether to auto append a missing end delimiter when sending using the textline codec. |
encoding
|
null
| Camel 2.4: The encoding (a charset name) to use for the textline codec. If not provided, Camel will use the JVM default Charset. |
workerCount
|
null
| Camel 2.9: When netty works in nio
mode, it uses default workerCount parameter from Netty, which is
You can use this operation to override Netty's default workerCount. |
sslContextParameters
|
null
| Camel 2.9: Specifies the SSL configuration using
an |
receiveBufferSize Predictor
|
null
| Camel 2.9: Configures the buffer size predictor. See details at Jetty documentation and this mail thread. |
requestTimeout
|
0
| Camel 2.11.1: Allows using a timeout, in milliseconds, for the Netty producer when calling a remote server. By default ( |
needClientAuth
|
false
| Camel 2.11: Configures whether the server needs client authentication when using SSL. |
orderedThreadPool Executor
|
true
| Camel 2.10.2: Specifies whether to use ordered thread pool to ensure events are processed orderly on the same channel. For more details, see the netty javadoc. |
maximumPoolSize
|
16
| Camel 2.10.2: Specifies the core pool size for the ordered thread pool, when it is used. |
producerPoolEnabled
|
true
| Camel 2.10.4/Camel 2.11: Producer only. Enables/disables the producer pool. Important: Do not turn this off, as pooling is needed for handling concurrency and reliable request/reply messaging. |
producerPoolMaxActive
|
-1
| Camel 2.10.3: Producer only. Sets the cap on the number of objects that can be allocated by the pool (checked out to clients, or idle awaiting checkout) at a given time. Use a negative value for no limit. |
producerPoolMinIdle
|
0
| Camel 2.10.3: Producer only. Sets the minimum number of instances allowed in the producer pool before the evictor thread (if active) spawns new objects. |
producerPoolMaxIdle
|
100
| Camel 2.10.3: Producer only. Sets the cap on the number of "idle" instances in the pool. |
producerPoolMin EvictableIdle
|
30000
| Camel 2.10.3: Producer only. Sets the minimum amount of time (in milliseconds) an object may sit idle in the pool before it is eligible for eviction by the idle object evictor. |
bootstrapConfiguration
|
null
| Camel 2.12: Consumer only. Allows configuring the Netty ServerBootstrap options using a Netty Server Bootstrap Configuration instance. Use this option to reuse the same configuration for multiple consumers and align their configuration more easily. |
bossPoll
|
null
| Camel 2.12: Specifies to use an explicit
By default, each consumer has their own boss pool with one core thread. You can use this option, for example, to share a thread pool with multiple consumers. |
workerPool
|
null
|
Camel 2.12: Specifies to use
an explicit By default, each consumer has their own worker pool with 2 You can use this option, for example, to share a thread pool with multiple consumers. |
networkInterface
|
null
| Camel 2.12: Consumer only. When
using UDP, this option can be used to specify a network interface by
its name, such as eth0 to join a multicast group.
|
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:
Table 66. Registry-based options
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
| deprecated: Client side certificate keystore to be used for encryption |
trustStoreFile
| deprecated: Server side certificate keystore to be used for encryption |
keyStoreResource
| Camel 2.11.1: Client side
certificate keystore to be used for encryption. Is loaded by default
from classpath, but you can prefix with "classpath:" ,
"file:" , or "http:" to load
the resource from different systems. |
trustStoreResource
| Camel 2.11.1: Server side
certificate keystore to be used for encryption. Is loaded by default
from classpath, but you can prefix with "classpath:" ,
"file:" , or "http:" to load
the resource from different systems. |
sslHandler
| Reference to a class that could be used to return an SSL Handler |
encoder
| A custom ChannelHandler class that can be used to
perform special marshalling of outbound payloads. Must override
org.jboss.netty.channel.ChannelDownStreamHandler .
|
encorders
| A list of encoders 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 ChannelHandler class that can be used to
perform special marshalling of inbound payloads. Must override
org.jboss.netty.channel.ChannelUpStreamHandler .
|
decoders
| A list of decoders 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. |
If your encoders or decoders are not shareable (for example, they do not have the
@Shareable
class annotation), they must implement the
org.apache.camel.component.netty.ChannelHandlerFactory
interface, and return a new instance in the newChannelHandler
method. This is required to ensure that the encoder/decoder can be used safely. If not,
the Netty component will log a WARN
when an endpoint is
created.
![]() | Note |
---|---|
The Netty component offers an
|
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.
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.
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); } } } };
RouteBuilder builder = new RouteBuilder() { public void configure() { from("netty:tcp://localhost:5150") .to("mock:result"); } };
![]() | Note |
---|---|
As of Camel 2.9, the Netty component supports SSL/TLS configuration through the Using the 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. |
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); } } } });
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 the 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"/> ...
Available as of Camel 2.12
You can get access to the javax.net.ssl.SSLSession
if you eg need
to get details about the client certificate. When ssl=true
, the
Netty component stores the
SSLSession
as a header on the Camel Message as shown below:
SSLSession session = exchange.getIn().getHeader(NettyConstants.NETTY_SSL_SESSION, SSLSession.class); // get the first certificate which is client certificate javax.security.cert.X509Certificate cert = session.getPeerCertificateChain()[0]; Principal principal = cert.getSubjectDN();
Remember to set needClientAuth=true
to authenticate the client,
otherwise SSLSession
cannot access information about the client
certificate, and you may get an exception
javax.net.ssl.SSLPeerUnverifiedException: peer not authenticated
.
You may also get this exception if the client certificate is expired or not valid
etc.
![]() | Note |
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The option |
In certain cases it may be necessary to add chains of encoders and decoders to the netty pipeline. To add multpile codecs to a Apache 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 Apache Camel's registry so they can be resolved when the endpoint is created.
ChannelHandlerFactory lengthDecoder=channelHandlerFactories.newLengthFieldBasedFrameDecoder(1048576, 0, 4, 0, 4); StringDecoder stringDecoder = new StringDecoder(); registry.bind("length-decoder", lengthDecoder); registry.bind("string-decoder", stringDecoder); LengthFieldPrepender lengthEncoder = new LengthFieldPrepender(4); StringEncoder stringEncoder = new StringEncoder(); registry.bind("length-encoder", lengthEncoder); registry.bind("string-encoder", stringEncoder); List<ChannelUpstreamHandler> decoders = new ArrayList<ChannelUpstreamHandler>(); decoders.add(lengthDecoder); decoders.add(stringDecoder); List<ChannelDownstreamHandler> encoders = new ArrayList<ChannelDownstreamHandler>(); encoders.add(lengthEncoder); encoders.add(stringEncoder); registry.bind("encoders", encoders); registry.bind("decoders", decoders);
Spring's native collections support can be used to specify the codec lists in an application context
<util:list id="decoders" list-class="java.util.LinkedList"> <bean class="org.jboss.netty.handler.codec.frame.LengthFieldBasedFrameDecoder"> <constructor-arg value="1048576"/> <constructor-arg value="0"/> <constructor-arg value="4"/> <constructor-arg value="0"/> <constructor-arg value="4"/> </bean> <bean class="org.jboss.netty.handler.codec.string.StringDecoder"/> </util:list> <util:list id="encoders" list-class="java.util.LinkedList"> <bean class="org.jboss.netty.handler.codec.frame.LengthFieldPrepender"> <constructor-arg value="4"/> </bean> <bean class="org.jboss.netty.handler.codec.string.StringEncoder"/> </util:list> <bean id="length-encoder" class="org.jboss.netty.handler.codec.frame.LengthFieldPrepender"> <constructor-arg value="4"/> </bean> <bean id="string-encoder" class="org.jboss.netty.handler.codec.string.StringEncoder"/> <bean id="length-decoder" class="org.jboss.netty.handler.codec.frame.LengthFieldBasedFrameDecoder"> <constructor-arg value="1048576"/> <constructor-arg value="0"/> <constructor-arg value="4"/> <constructor-arg value="0"/> <constructor-arg value="4"/> </bean> <bean id="string-decoder" class="org.jboss.netty.handler.codec.string.StringDecoder"/> </beans>
The bean names can then be used in netty endpoint definitions either as a comma separated list or contained in a List e.g.
from("direct:multiple-codec").to("netty:tcp://localhost:{{port}}?encoders=#encoders&sync=false"); from("netty:tcp://localhost:{{port}}?decoders=#length-decoder,#string-decoder&sync=false").to("mock:multiple-codec"); } }; } }
or via Spring:
<camelContext id="multiple-netty-codecs-context" xmlns="http://camel.apache.org/schema/spring"> <route> <from uri="direct:multiple-codec"/> <to uri="netty:tcp://localhost:5150?encoders=#encoders&ync=false"/> </route> <route> <from uri="netty:tcp://localhost:5150?decoders=#length-decoder,#string-decoder&ync=false"/> <to uri="mock:multiple-codec"/> </route> </camelContext>
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 Apache Camel on a per message basis as follows. To
instruct Apache 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); } } });
Available as of Apache Camel 2.5
Custom channel pipelines provide complete control to the user over the handler/interceptor chain by inserting custom handler(s), encoder(s) and 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 through the context registry
(JNDIRegistry
,or the 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 can optionally 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 as follows:
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); } } } });
Available as of Camel 2.12
Netty has two kind of thread pools: boss and worker. By default each Netty consumer and producer has their private thread pools. If you want to reuse these thread pools among multiple consumers or producers then the thread pools must be created and enlisted in the Registry.
For example using Spring XML we can create a shared worker thread pool using the
NettyWorkerPoolBuilder
with 2 worker threads as shown
below:
<!-- use the worker pool builder to create to help create the shared thread pool --> <bean id="poolBuilder" class="org.apache.camel.component.netty.NettyWorkerPoolBuilder"> <property name="workerCount" value="2"/> </bean> <!-- the shared worker thread pool --> <bean id="sharedPool" class="org.jboss.netty.channel.socket.nio.WorkerPool" factory-bean="poolBuilder" factory-method="build" destroy-method="shutdown"> </bean>
![]() | Note |
---|---|
For boss thread pool there is a
|
Then in the Camel routes we can refer to this worker pools by configuring the
workerPool
option in the URI as shown
below:
<route> <from uri="netty:tcp://localhost:5021?textline=true&ync=true&orkerPool=#sharedPool&rderedThreadPoolExecutor=false"/> <to uri="log:result"/> ... </route>
And if we have another route we can refer to the shared worker pool:
<route> <from uri="netty:tcp://localhost:5022?textline=true&ync=true&orkerPool=#sharedPool&rderedThreadPoolExecutor=false"/> <to uri="log:result"/> ... </route>
... and so forth.