[[cometd-component]]
= CometD Component
:docTitle: CometD
:artifactId: camel-cometd
:description: Offers publish/subscribe, peer-to-peer (via a server), and RPC style messaging using the CometD/Bayeux protocol.
:since: 2.0
:supportLevel: Stable
:component-header: Both producer and consumer are supported

*Since Camel {since}*

*{component-header}*

The Cometd component is a transport for working with the
http://www.mortbay.org/jetty[jetty] implementation of the
http://docs.codehaus.org/display/JETTY/Cometd+%28aka+Bayeux%29[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:

[source,xml]
------------------------------------------------------------
<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

[source,java]
----------------------------------------
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




// component options: START
The CometD component supports 10 options, which are listed below.



[width="100%",cols="2,5,^1,2",options="header"]
|===
| Name | Description | Default | Type
| *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
| *lazyStartProducer* (producer) | Whether the producer should be started lazy (on the first message). By starting lazy you can use this to allow CamelContext and routes to startup in situations where a producer may otherwise fail during starting and cause the route to fail being started. By deferring this startup to be lazy then the startup failure can be handled during routing messages via Camel's routing error handlers. Beware that when the first message is processed then creating and starting the producer may take a little time and prolong the total processing time of the processing. | false | boolean
| *basicPropertyBinding* (advanced) | Whether the component should use basic property binding (Camel 2.x) or the newer property binding with additional capabilities | false | boolean
| *extensions* (advanced) | To use a list of custom BayeuxServer.Extension that allows modifying incoming and outgoing requests. |  | List
| *securityPolicy* (security) | To use a custom configured SecurityPolicy to control authorization |  | SecurityPolicy
| *sslContextParameters* (security) | To configure security using SSLContextParameters |  | SSLContextParameters
| *sslKeyPassword* (security) | The password for the keystore when using SSL. |  | String
| *sslKeystore* (security) | The path to the keystore. |  | String
| *sslPassword* (security) | The password when using SSL. |  | String
| *useGlobalSslContextParameters* (security) | Enable usage of global SSL context parameters. | false | boolean
|===
// component options: END






// endpoint options: START
The CometD endpoint is configured using URI syntax:

----
cometd:host:port/channelName
----

with the following path and query parameters:

=== Path Parameters (3 parameters):


[width="100%",cols="2,5,^1,2",options="header"]
|===
| Name | Description | Default | Type
| *host* | *Required* Hostname |  | String
| *port* | *Required* Host port number |  | int
| *channelName* | *Required* The channelName represents a topic that can be subscribed to by the Camel endpoints. |  | String
|===


=== Query Parameters (18 parameters):


[width="100%",cols="2,5,^1,2",options="header"]
|===
| Name | Description | Default | Type
| *allowedOrigins* (common) | The origins domain that support to cross, if the crosssOriginFilterOn is true | * | String
| *baseResource* (common) | 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 |  | String
| *crossOriginFilterOn* (common) | If true, the server will support for cross-domain filtering | false | boolean
| *filterPath* (common) | The filterPath will be used by the CrossOriginFilter, if the crosssOriginFilterOn is true |  | String
| *interval* (common) | The client side poll timeout in milliseconds. How long a client will wait between reconnects |  | int
| *jsonCommented* (common) | 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. | true | boolean
| *logLevel* (common) | Logging level. 0=none, 1=info, 2=debug. The value can be one of: 0, 1, 2 | 1 | int
| *maxInterval* (common) | The max client side poll timeout in milliseconds. A client will be removed if a connection is not received in this time. | 30000 | int
| *multiFrameInterval* (common) | The client side poll timeout, if multiple connections are detected from the same browser. | 1500 | int
| *timeout* (common) | The server side poll timeout in milliseconds. This is how long the server will hold a reconnect request before responding. | 240000 | int
| *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
| *sessionHeadersEnabled* (consumer) | Whether to include the server session headers in the Camel message when creating a Camel Message for incoming requests. | false | boolean
| *exceptionHandler* (consumer) | To let the consumer use a custom ExceptionHandler. Notice if the option bridgeErrorHandler is enabled then this option 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. The value can be one of: InOnly, InOut, InOptionalOut |  | ExchangePattern
| *disconnectLocalSession* (producer) | 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. | false | boolean
| *lazyStartProducer* (producer) | Whether the producer should be started lazy (on the first message). By starting lazy you can use this to allow CamelContext and routes to startup in situations where a producer may otherwise fail during starting and cause the route to fail being started. By deferring this startup to be lazy then the startup failure can be handled during routing messages via Camel's routing error handlers. Beware that when the first message is processed then creating and starting the producer may take a little time and prolong the total processing time of the processing. | false | boolean
| *basicPropertyBinding* (advanced) | Whether the endpoint should use basic property binding (Camel 2.x) or the newer property binding with additional capabilities | false | boolean
| *synchronous* (advanced) | Sets whether synchronous processing should be strictly used, or Camel is allowed to use asynchronous processing (if supported). | false | boolean
|===
// endpoint options: END




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

*Since Camel 2.8*

You can configure custom `SecurityPolicy` and `Extension`'s to the
`CometdComponent` which allows you to use authentication as
http://cometd.org/documentation/howtos/authentication[documented here]

== Setting up SSL for Cometd Component

=== Using the JSSE Configuration Utility

The Cometd component supports SSL/TLS configuration
through the xref:manual::camel-configuration-utilities.adoc[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.

[[Cometd-Programmaticconfigurationofthecomponent]]
Programmatic configuration of the component

[source,java]
-----------------------------------------------------------------------------------------------
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);
-----------------------------------------------------------------------------------------------

[[Cometd-SpringDSLbasedconfigurationofendpoint]]
Spring DSL based configuration of endpoint

[source,xml]
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
...
  <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"/>...
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------


include::camel-spring-boot::page$cometd-starter.adoc[]
