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Chapter 339. Jetty Websocket Component
Available as of Camel version 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
Camel 2.18 uses Jetty 9
339.1. URI format
websocket://hostname[:port][/resourceUri][?options]
You can append query options to the URI in the following format, ?option=value&option=value&…
339.2. Websocket Options
The Jetty Websocket component supports 14 options which are listed below.
| Name | Description | Default | Type |
|---|---|---|---|
| staticResources (consumer) | Set a resource path for static resources (such as .html files etc). The resources can be loaded from classpath, if you prefix with classpath:, otherwise the resources is loaded from file system or from JAR files. For example to load from root classpath use classpath:., or classpath:WEB-INF/static If not configured (eg null) then no static resource is in use. | String | |
| host (common) | The hostname. The default value is 0.0.0.0 | 0.0.0.0 | String |
| port (common) | The port number. The default value is 9292 | 9292 | Integer |
| sslKeyPassword (security) | The password for the keystore when using SSL. | String | |
| sslPassword (security) | The password when using SSL. | String | |
| sslKeystore (security) | The path to the keystore. | String | |
| enableJmx (advanced) | If this option is true, Jetty JMX support will be enabled for this endpoint. See Jetty JMX support for more details. | false | boolean |
| minThreads (advanced) | To set a value for minimum number of threads in server thread pool. MaxThreads/minThreads or threadPool fields are required due to switch to Jetty9. The default values for minThreads is 1. | Integer | |
| maxThreads (advanced) | To set a value for maximum number of threads in server thread pool. MaxThreads/minThreads or threadPool fields are required due to switch to Jetty9. The default values for maxThreads is 1 2 noCores. | Integer | |
| threadPool (advanced) | To use a custom thread pool for the server. MaxThreads/minThreads or threadPool fields are required due to switch to Jetty9. | ThreadPool | |
| sslContextParameters (security) | To configure security using SSLContextParameters | SSLContextParameters | |
| useGlobalSslContext Parameters (security) | Enable usage of global SSL context parameters. | false | boolean |
| socketFactory (common) | To configure a map which contains custom WebSocketFactory for sub protocols. The key in the map is the sub protocol. The default key is reserved for the default implementation. | Map | |
| 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 Jetty Websocket endpoint is configured using URI syntax:
websocket:host:port/resourceUri
with the following path and query parameters:
339.2.1. Path Parameters (3 parameters):
| Name | Description | Default | Type |
|---|---|---|---|
| host | The hostname. The default value is 0.0.0.0. Setting this option on the component will use the component configured value as default. | 0.0.0.0 | String |
| port | The port number. The default value is 9292. Setting this option on the component will use the component configured value as default. | 9292 | Integer |
| resourceUri | Required Name of the websocket channel to use | String |
339.2.2. Query Parameters (18 parameters):
| Name | Description | Default | Type |
|---|---|---|---|
| maxBinaryMessageSize (common) | 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) | -1 | Integer |
| 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 |
| sessionSupport (consumer) | Whether to enable session support which enables HttpSession for each http request. | false | boolean |
| staticResources (consumer) | Set a resource path for static resources (such as .html files etc). The resources can be loaded from classpath, if you prefix with classpath:, otherwise the resources is loaded from file system or from JAR files. For example to load from root classpath use classpath:., or classpath:WEB-INF/static If not configured (eg null) then no static resource is in use. | String | |
| 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 | |
| sendTimeout (producer) | Timeout in millis when sending to a websocket channel. The default timeout is 30000 (30 seconds). | 30000 | Integer |
| sendToAll (producer) | 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. | Boolean | |
| bufferSize (advanced) | Set the buffer size of the websocketServlet, which is also the max frame byte size (default 8192) | 8192 | Integer |
| maxIdleTime (advanced) | Set the time in ms that the websocket created by the websocketServlet may be idle before closing. (default is 300000) | 300000 | Integer |
| maxTextMessageSize (advanced) | Can be used to set the size in characters that the websocket created by the websocketServlet may be accept before closing. | Integer | |
| minVersion (advanced) | Can be used to set the minimum protocol version accepted for the websocketServlet. (Default 13 - the RFC6455 version) | 13 | Integer |
| synchronous (advanced) | Sets whether synchronous processing should be strictly used, or Camel is allowed to use asynchronous processing (if supported). | false | boolean |
| allowedOrigins (cors) | The CORS allowed origins. Use to allow all. | String | |
| crossOriginFilterOn (cors) | Whether to enable CORS | false | boolean |
| filterPath (cors) | Context path for filtering CORS | String | |
| enableJmx (monitoring) | If this option is true, Jetty JMX support will be enabled for this endpoint. See Jetty JMX support for more details. | false | boolean |
| sslContextParameters (security) | To configure security using SSLContextParameters | SSLContextParameters |
339.3. Message Headers
The websocket component uses 2 headers to indicate to either send messages back to a single/current client, or to all clients.
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. |
|---|---|
|
| Sends the message to the client with the given connection key. |
339.4. 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.
from("activemq:topic:newsTopic")
.routeId("fromJMStoWebSocket")
.to("websocket://localhost:8443/newsTopic?sendToAll=true&staticResources=classpath:webapp");339.5. Setting up SSL for WebSocket Component
339.5.1. 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
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:trustManagers>
</camel:sslContextParameters>...
...
<to uri="websocket://127.0.0.1:8443/test?sslContextParameters=#sslContextParameters"/>...Java DSL based configuration of endpoint
...
protected RouteBuilder createRouteBuilder() throws Exception {
return new RouteBuilder() {
public void configure() {
String uri = "websocket://127.0.0.1:8443/test?sslContextParameters=#sslContextParameters";
from(uri)
.log(">>> Message received from WebSocket Client : ${body}")
.to("mock:client")
.loop(10)
.setBody().constant(">> Welcome on board!")
.to(uri);
...