Cometd Component

Table of Contents

URI format
Examples
Options
Authentication
Setting up SSL for Cometd Component
See Also

The cometd: component is a transport for working with the jetty implementation of the cometd/bayeux protocol. Using this component in combination with the dojo toolkit library it’s possible to push Camel messages directly into the browser using an AJAX based mechanism.

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

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

URI format

cometd://host:port/channelName[?options]

The channelName represents a topic that can be subscribed to by the Camel endpoints.

Examples

cometd://localhost:8080/service/mychannel
cometds://localhost:8443/service/mychannel

where cometds: represents an SSL configured endpoint.

Options

The CometD component supports 6 options which are listed below.

{% raw %}

Name	Java Type	Description
sslKeyPassword	`String`	The password for the keystore when using SSL.
sslPassword	`String`	The password when using SSL.
sslKeystore	`String`	The path to the keystore.
securityPolicy	`SecurityPolicy`	To use a custom configured SecurityPolicy to control authorization
extensions	`List`	To use a list of custom BayeuxServer.Extension that allows modifying incoming and outgoing requests.
sslContextParameters	`SSLContextParameters`	To configure security using SSLContextParameters

{% endraw %}

The CometD component supports 19 endpoint options which are listed below:

{% raw %}

Name	Group	Default	Java Type	Description
host	common		`String`	Required Hostname
port	common		`int`	Required Host port number
channelName	common		`String`	Required The channelName represents a topic that can be subscribed to by the Camel endpoints.
allowedOrigins	common	`*`	`String`	The origins domain that support to cross if the crosssOriginFilterOn is true
baseResource	common		`String`	The root directory for the web resources or classpath. Use the protocol file: or classpath: depending if you want that the component loads the resource from file system or classpath. Classpath is required for OSGI deployment where the resources are packaged in the jar
crossOriginFilterOn	common	`false`	`boolean`	If true the server will support for cross-domain filtering
filterPath	common		`String`	The filterPath will be used by the CrossOriginFilter if the crosssOriginFilterOn is true
interval	common		`int`	The client side poll timeout in milliseconds. How long a client will wait between reconnects
jsonCommented	common	`true`	`boolean`	If true the server will accept JSON wrapped in a comment and will generate JSON wrapped in a comment. This is a defence against Ajax Hijacking.
logLevel	common	`1`	`int`	Logging level. 0=none 1=info 2=debug.
maxInterval	common	`30000`	`int`	The max client side poll timeout in milliseconds. A client will be removed if a connection is not received in this time.
multiFrameInterval	common	`1500`	`int`	The client side poll timeout if multiple connections are detected from the same browser.
timeout	common	`240000`	`int`	The server side poll timeout in milliseconds. This is how long the server will hold a reconnect request before responding.
bridgeErrorHandler	consumer	`false`	`boolean`	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/ERROR level and ignored.
sessionHeadersEnabled	consumer	`false`	`boolean`	Whether to include the server session headers in the Camel message when creating a Camel Message for incoming requests.
exceptionHandler	consumer (advanced)		`ExceptionHandler`	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/ERROR level and ignored.
exchangePattern	consumer (advanced)		`ExchangePattern`	Sets the exchange pattern when the consumer creates an exchange.
disconnectLocalSession	producer	`false`	`boolean`	Whether to disconnect local sessions after publishing a message to its channel. Disconnecting local session is needed as they are not swept by default by CometD and therefore you can run out of memory.
synchronous	advanced	`false`	`boolean`	Sets whether synchronous processing should be strictly used or Camel is allowed to use asynchronous processing (if supported).

{% endraw %}

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

Here is some examples on How to pass the parameters

For file (for webapp resources located in the Web Application directory -→ cometd://localhost:8080?resourceBase=file./webapp For classpath (when by example the web resources are packaged inside the webapp folder -→ cometd://localhost:8080?resourceBase=classpath:webapp

Authentication

Available as of Camel 2.8

You can configure custom SecurityPolicy and Extension’s to the `CometdComponent which allows you to use authentication as documented here

Setting up SSL for Cometd Component

Table of Contents

Using the JSSE Configuration Utility

Using the JSSE Configuration Utility

As of Camel 2.9, the Cometd 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 Cometd component. You need to configure SSL on the CometdComponent.

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");

TrustManagersParameters tmp = new TrustManagersParameters();
tmp.setKeyStore(ksp);

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

CometdComponent commetdComponent = getContext().getComponent("cometds", CometdComponent.class);
commetdComponent.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:trustManagers>
      <camel:keyStore
          resource="/users/home/server/keystore.jks"
          password="keystorePassword"/>
    </camel:keyManagers>
  </camel:sslContextParameters>...
 
  <bean id="cometd" class="org.apache.camel.component.cometd.CometdComponent">
    <property name="sslContextParameters" ref="sslContextParameters"/>
  </bean>
...
  <to uri="cometds://127.0.0.1:443/service/test?baseResource=file:./target/test-classes/webapp&timeout=240000&interval=0&maxInterval=30000&multiFrameInterval=1500&jsonCommented=true&logLevel=2"/>...