Websocket Component

Available as of Camel 2.10

The websocket component provides websocket endpoints for communicating with clients using websocket. The component uses Eclipse Jetty Server which implements the IETF specification (drafts and RFC 6455). It supports the protocols ws:// and wss://. To use wss:// protocol, the SSLContextParameters must be defined.

Version currently supported

Icon

As Camel 2.10 uses Jetty 7.5.4.v20111024, only the D00 to D13 IETF implementations are available.
Camel 2.11 uses Jetty 7.6.7.

URI format

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

Component Options

The WebsocketComponent can be configured prior to use, to setup host, to act as a websocket server.

Option

Default

Description

host

0.0.0.0

The hostname.

port

9292

The port number.

staticResources

null

Path for static resources such as index.html files etc. If this option has been configured, then a server is started on the given hostname and port, to service the static resources, eg such as an index.html file. If this option has not been configured, then no server is started.

sslContextParameters

 

Reference to a org.apache.camel.util.jsse.SSLContextParameters in the Registry. This reference overrides any configured SSLContextParameters at the component level.  See Using the JSSE Configuration Utility.

enableJmx

false

If this option is true, Jetty JMX support will be enabled for this endpoint. See Jetty JMX support for more details.

sslKeyPassword

null

Consumer only: The password for the keystore when using SSL.

sslPassword

null

Consumer only: The password when using SSL.

sslKeystore

null

Consumer only: The path to the keystore.

minThreads

null

Consumer only: To set a value for minimum number of threads in server thread pool.

maxThreads

null

Consumer only: To set a value for maximum number of threads in server thread pool.

threadPool

null

Consumer only: To use a custom thread pool for the server.

Endpoint Options

The WebsocketEndpoint can be configured prior to use

Option

Default

Description

sslContextParametersRef

 

Deprecated and will be removed in Camel 3.0: Reference to a org.apache.camel.util.jsse.SSLContextParameters in the Registry.  This reference overrides any configured SSLContextParameters at the component level. See Using the JSSE Configuration Utility. Use the sslContextParameters option instead

sslContextParameters

 

Camel 2.11.1: Reference to a org.apache.camel.util.jsse.SSLContextParameters in the Registry. This reference overrides any configured SSLContextParameters at the component level.  See Using the JSSE Configuration Utility.

sendToAll

null

Producer only: To send to all websocket subscribers. Can be used to configure on endpoint level, instead of having to use the WebsocketConstants.SEND_TO_ALL header on the message.

staticResources

null

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.

 bufferSize

null

Camel 2.12.3: set the buffer size of the websocketServlet, which is also the max frame byte size (default 8192)

maxIdleTime

null

Camel 2.12.3: set the time in ms that the websocket created by the websocketServlet may be idle before closing. (default is 300000)

maxTextMessageSize

null

Camel 2.12.3: can be used to set the size in characters that the websocket created by the websocketServlet may be accept before closing.

maxBinaryMessageSize

null

Camel 2.12.3: can be used to set the size in bytes that the websocket created by the websocketServlet may be accept before closing. (Default is -1 - or unlimited)

minVersion

null

Camel 2.12.3: can be used to set the minimum protocol version accepted for the websocketServlet. (Default 13 - the RFC6455 version)

 

Message Headers

The websocket component uses 2 headers to indicate to either send messages back to a single/current client, or to all clients.

Key

Description

WebsocketConstants.SEND_TO_ALL

Sends the message to all clients which are currently connected. You can use the sendToAll option on the endpoint instead of using this header.

WebsocketConstants.CONNECTION_KEY

Sends the message to the client with the given connection key.

Usage

In this example we let Camel exposes a websocket server which clients can communicate with. The websocket server uses the default host and port, which would be 0.0.0.0:9292.
The example will send back an echo of the input. To send back a message, we need to send the transformed message to the same endpoint "websocket://echo". This is needed
because by default the messaging is InOnly.

This example is part of an unit test, which you can find here. As a client we use the AHC library which offers support for web socket as well.

Here is another example where webapp resources location have been defined to allow the Jetty Application Server to not only register the WebSocket servlet but also to expose web resources for the browser. Resources should be defined under the webapp directory.

Setting up SSL for WebSocket Component

Using the JSSE Configuration Utility

As of Camel 2.10, the WebSocket 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.

Programmatic configuration of the component
Spring DSL based configuration of endpoint
Java DSL based configuration of endpoint

See Also

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