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Chapter 227. Netty Component (deprecated)
Available as of Camel version 2.3
This component is deprecated. You should use Netty4.
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>
227.1. 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&…
227.2. Options
The Netty component supports 4 options which are listed below.
Name | Description | Default | Type |
---|---|---|---|
configuration (advanced) | To use the NettyConfiguration as configuration when creating endpoints. | NettyConfiguration | |
maximumPoolSize (advanced) | The core pool size for the ordered thread pool, if its in use. The default value is 16. | 16 | int |
useGlobalSslContext Parameters (security) | Enable usage of global SSL context parameters. | false | boolean |
resolveProperty Placeholders (advanced) | Whether the component should resolve property placeholders on itself when starting. Only properties which are of String type can use property placeholders. | true | boolean |
The Netty endpoint is configured using URI syntax:
netty:protocol:host:port
with the following path and query parameters:
227.2.1. Path Parameters (3 parameters):
Name | Description | Default | Type |
---|---|---|---|
protocol | Required The protocol to use which can be tcp or udp. | String | |
host | Required The hostname. For the consumer the hostname is localhost or 0.0.0.0 For the producer the hostname is the remote host to connect to | String | |
port | Required The host port number | int |
227.2.2. Query Parameters (67 parameters):
Name | Description | Default | Type |
---|---|---|---|
disconnect (common) | Whether or not to disconnect(close) from Netty Channel right after use. Can be used for both consumer and producer. | false | boolean |
keepAlive (common) | Setting to ensure socket is not closed due to inactivity | true | boolean |
reuseAddress (common) | Setting to facilitate socket multiplexing | true | boolean |
sync (common) | Setting to set endpoint as one-way or request-response | true | boolean |
tcpNoDelay (common) | Setting to improve TCP protocol performance | true | boolean |
bridgeErrorHandler (consumer) | Allows for bridging the consumer to the Camel routing Error Handler, which mean any exceptions occurred while the consumer is trying to pickup incoming messages, or the likes, will now be processed as a message and handled by the routing Error Handler. By default the consumer will use the org.apache.camel.spi.ExceptionHandler to deal with exceptions, that will be logged at WARN or ERROR level and ignored. | false | boolean |
broadcast (consumer) | Setting to choose Multicast over UDP | false | boolean |
clientMode (consumer) | If the clientMode is true, netty consumer will connect the address as a TCP client. | false | boolean |
backlog (consumer) | Allows to configure a backlog for netty consumer (server). Note the backlog is just a best effort depending on the OS. Setting this option to a value such as 200, 500 or 1000, tells the TCP stack how long the accept queue can be If this option is not configured, then the backlog depends on OS setting. | int | |
bossCount (consumer) | When netty works on nio mode, it uses default bossCount parameter from Netty, which is 1. User can use this operation to override the default bossCount from Netty | 1 | int |
bossPool (consumer) | To use a explicit org.jboss.netty.channel.socket.nio.BossPool as the boss thread pool. For example to share a thread pool with multiple consumers. By default each consumer has their own boss pool with 1 core thread. | BossPool | |
channelGroup (consumer) | To use a explicit ChannelGroup. | ChannelGroup | |
disconnectOnNoReply (consumer) | If sync is enabled then this option dictates NettyConsumer if it should disconnect where there is no reply to send back. | true | boolean |
exceptionHandler (consumer) | To let the consumer use a custom ExceptionHandler. Notice if the option bridgeErrorHandler is enabled then this options is not in use. By default the consumer will deal with exceptions, that will be logged at WARN or ERROR level and ignored. | ExceptionHandler | |
exchangePattern (consumer) | Sets the exchange pattern when the consumer creates an exchange. | ExchangePattern | |
maxChannelMemorySize (consumer) | The maximum total size of the queued events per channel when using orderedThreadPoolExecutor. Specify 0 to disable. | 10485760 | long |
maxTotalMemorySize (consumer) | The maximum total size of the queued events for this pool when using orderedThreadPoolExecutor. Specify 0 to disable. | 209715200 | long |
nettyServerBootstrapFactory (consumer) | To use a custom NettyServerBootstrapFactory | NettyServerBootstrap Factory | |
networkInterface (consumer) | When using UDP then this option can be used to specify a network interface by its name, such as eth0 to join a multicast group. | String | |
noReplyLogLevel (consumer) | If sync is enabled this option dictates NettyConsumer which logging level to use when logging a there is no reply to send back. | WARN | LoggingLevel |
orderedThreadPoolExecutor (consumer) | Whether to use ordered thread pool, to ensure events are processed orderly on the same channel. See details at the netty javadoc of org.jboss.netty.handler.execution.OrderedMemoryAwareThreadPoolExecutor for more details. | true | boolean |
serverClosedChannel ExceptionCaughtLogLevel (consumer) | If the server (NettyConsumer) catches an java.nio.channels.ClosedChannelException then its logged using this logging level. This is used to avoid logging the closed channel exceptions, as clients can disconnect abruptly and then cause a flood of closed exceptions in the Netty server. | DEBUG | LoggingLevel |
serverExceptionCaughtLog Level (consumer) | If the server (NettyConsumer) catches an exception then its logged using this logging level. | WARN | LoggingLevel |
serverPipelineFactory (consumer) | To use a custom ServerPipelineFactory | ServerPipelineFactory | |
workerCount (consumer) | When netty works on nio mode, it uses default workerCount parameter from Netty, which is cpu_core_threads2. User can use this operation to override the default workerCount from Netty | int | |
workerPool (consumer) | To use a explicit org.jboss.netty.channel.socket.nio.WorkerPool as the worker thread pool. For example to share a thread pool with multiple consumers. By default each consumer has their own worker pool with 2 x cpu count core threads. | WorkerPool | |
connectTimeout (producer) | Time to wait for a socket connection to be available. Value is in millis. | 10000 | long |
requestTimeout (producer) | Allows to use a timeout for the Netty producer when calling a remote server. By default no timeout is in use. The value is in milli seconds, so eg 30000 is 30 seconds. The requestTimeout is using Netty’s ReadTimeoutHandler to trigger the timeout. | long | |
clientPipelineFactory (producer) | To use a custom ClientPipelineFactory | ClientPipelineFactory | |
lazyChannelCreation (producer) | Channels can be lazily created to avoid exceptions, if the remote server is not up and running when the Camel producer is started. | true | boolean |
producerPoolEnabled (producer) | Whether producer pool is enabled or not. Important: Do not turn this off, as the pooling is needed for handling concurrency and reliable request/reply. | true | boolean |
producerPoolMaxActive (producer) | 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. | -1 | int |
producerPoolMaxIdle (producer) | Sets the cap on the number of idle instances in the pool. | 100 | int |
producerPoolMinEvictable Idle (producer) | Sets the minimum amount of time (value in millis) an object may sit idle in the pool before it is eligible for eviction by the idle object evictor. | 300000 | long |
producerPoolMinIdle (producer) | Sets the minimum number of instances allowed in the producer pool before the evictor thread (if active) spawns new objects. | int | |
udpConnectionlessSending (producer) | This option supports connection less udp sending which is a real fire and forget. A connected udp send receive the PortUnreachableException if no one is listen on the receiving port. | false | boolean |
useChannelBuffer (producer) | If the useChannelBuffer is true, netty producer will turn the message body into ChannelBuffer before sending it out. | false | boolean |
bootstrapConfiguration (advanced) | To use a custom configured NettyServerBootstrapConfiguration for configuring this endpoint. | NettyServerBootstrap Configuration | |
options (advanced) | Allows to configure additional netty options using option. as prefix. For example option.child.keepAlive=false to set the netty option child.keepAlive=false. See the Netty documentation for possible options that can be used. | Map | |
receiveBufferSize (advanced) | The TCP/UDP buffer sizes to be used during inbound communication. Size is bytes. | 65536 | long |
receiveBufferSizePredictor (advanced) | Configures the buffer size predictor. See details at Jetty documentation and this mail thread. | int | |
sendBufferSize (advanced) | The TCP/UDP buffer sizes to be used during outbound communication. Size is bytes. | 65536 | long |
synchronous (advanced) | Sets whether synchronous processing should be strictly used, or Camel is allowed to use asynchronous processing (if supported). | false | boolean |
transferExchange (advanced) | Only used for TCP. You can transfer the exchange over the wire instead of just the body. The following fields are transferred: In body, Out body, fault body, In headers, Out headers, fault headers, exchange properties, exchange exception. This requires that the objects are serializable. Camel will exclude any non-serializable objects and log it at WARN level. | false | boolean |
allowDefaultCodec (codec) | The netty component installs a default codec if both, encoder/deocder is null and textline is false. Setting allowDefaultCodec to false prevents the netty component from installing a default codec as the first element in the filter chain. | true | boolean |
autoAppendDelimiter (codec) | Whether or not to auto append missing end delimiter when sending using the textline codec. | true | boolean |
decoder (codec) | Deprecated A custom ChannelHandler class that can be used to perform special marshalling of inbound payloads. Must override org.jboss.netty.channel.ChannelUpStreamHandler. | ChannelHandler | |
decoderMaxLineLength (codec) | The max line length to use for the textline codec. | 1024 | int |
decoders (codec) | 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. | String | |
delimiter (codec) | The delimiter to use for the textline codec. Possible values are LINE and NULL. | LINE | TextLineDelimiter |
encoder (codec) | Deprecated A custom ChannelHandler class that can be used to perform special marshalling of outbound payloads. Must override org.jboss.netty.channel.ChannelDownStreamHandler. | ChannelHandler | |
encoders (codec) | 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. | String | |
encoding (codec) | The encoding (a charset name) to use for the textline codec. If not provided, Camel will use the JVM default Charset. | String | |
textline (codec) | 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. | false | boolean |
enabledProtocols (security) | Which protocols to enable when using SSL | TLSv1,TLSv1.1,TLSv1.2 | String |
keyStoreFile (security) | Client side certificate keystore to be used for encryption | File | |
keyStoreFormat (security) | Keystore format to be used for payload encryption. Defaults to JKS if not set | JKS | String |
keyStoreResource (security) | 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. | String | |
needClientAuth (security) | Configures whether the server needs client authentication when using SSL. | false | boolean |
passphrase (security) | Password setting to use in order to encrypt/decrypt payloads sent using SSH | String | |
securityProvider (security) | Security provider to be used for payload encryption. Defaults to SunX509 if not set. | SunX509 | String |
ssl (security) | Setting to specify whether SSL encryption is applied to this endpoint | false | boolean |
sslClientCertHeaders (security) | When enabled and in SSL mode, then the Netty consumer will enrich the Camel Message with headers having information about the client certificate such as subject name, issuer name, serial number, and the valid date range. | false | boolean |
sslContextParameters (security) | To configure security using SSLContextParameters | SSLContextParameters | |
sslHandler (security) | Reference to a class that could be used to return an SSL Handler | SslHandler | |
trustStoreFile (security) | Server side certificate keystore to be used for encryption | File | |
trustStoreResource (security) | 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. | String |
227.3. 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:
Name | Description |
---|---|
| password setting to use in order to encrypt/decrypt payloads sent using SSH |
| keystore format to be used for payload encryption. Defaults to "JKS" if not set |
| Security provider to be used for payload encryption. Defaults to "SunX509" if not set. |
| deprecated: Client side certificate keystore to be used for encryption |
| deprecated: Server side certificate keystore to be used for encryption |
|
Camel 2.11.1: Client side certificate keystore to be used for encryption. Is loaded by default from classpath, but you can prefix with |
|
Camel 2.11.1: Server side certificate keystore to be used for encryption. Is loaded by default from classpath, but you can prefix with |
| Reference to a class that could be used to return an SSL Handler |
|
A custom |
| 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. |
|
A custom |
| 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. |
Important: Read below about using non shareable encoders/decoders.
227.4. Sending Messages to/from a Netty endpoint
227.4.1. 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.
227.4.2. 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.
227.5. Headers
The following headers are filled for the exchanges created by the Netty consumer:
Header key | Class | Description |
---|---|---|
|
| `ChannelHandlerContext `instance associated with the connection received by netty. |
|
| `MessageEvent `instance associated with the connection received by netty. |
|
| Remote address of the incoming socket connection. |
|
| Local address of the incoming socket connection. |
227.6. Usage Samples
227.6.1. 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); } } } };
227.6.2. 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"); } };
227.6.3. 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); } } } });
Getting access to SSLSession and the client certificate
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
then the Netty component will store 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.
The option sslClientCertHeaders
can be set to true
which then enriches the Camel Message with headers having details about the client certificate. For example the subject name is readily available in the header CamelNettySSLClientCertSubjectName
.
227.6.4. 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.
INFO: Read further above about using non shareable encoders/decoders.
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.
227.7. 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); } } });
227.8. 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
Using custom pipeline factory
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); } } } });
227.9. Reusing Netty boss and worker thread pools
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 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>
For boss thread pool there is a org.apache.camel.component.netty.NettyServerBossPoolBuilder
builder for Netty consumers, and a org.apache.camel.component.netty.NettyClientBossPoolBuilder
for the Netty producers.
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&sync=true&workerPool=#sharedPool&orderedThreadPoolExecutor=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&sync=true&workerPool=#sharedPool&orderedThreadPoolExecutor=false"/> <to uri="log:result"/> ... </route>
- and so forth.
227.10. See Also
- Configuring Camel
- Component
- Endpoint
- Getting Started
- Netty HTTP
- MINA