Vert.x WebSocket

Since Camel 3.5

Both producer and consumer are supported

The Vert.x WebSocket component provides WebSocket capabilities as a WebSocket server, or as a client to connect to an existing WebSocket.

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

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

URI format

vertx-websocket://hostname[:port][/resourceUri][?options]

Configuring Options

Camel components are configured on two separate levels:

  • component level

  • endpoint level

Configuring Component Options

The component level is the highest level which holds general and common configurations that are inherited by the endpoints. For example a component may have security settings, credentials for authentication, urls for network connection and so forth.

Some components only have a few options, and others may have many. Because components typically have pre configured defaults that are commonly used, then you may often only need to configure a few options on a component; or none at all.

Configuring components can be done with the Component DSL, in a configuration file (application.properties|yaml), or directly with Java code.

Configuring Endpoint Options

Where you find yourself configuring the most is on endpoints, as endpoints often have many options, which allows you to configure what you need the endpoint to do. The options are also categorized into whether the endpoint is used as consumer (from) or as a producer (to), or used for both.

Configuring endpoints is most often done directly in the endpoint URI as path and query parameters. You can also use the Endpoint DSL and DataFormat DSL as a type safe way of configuring endpoints and data formats in Java.

A good practice when configuring options is to use Property Placeholders, which allows to not hardcode urls, port numbers, sensitive information, and other settings. In other words placeholders allows to externalize the configuration from your code, and gives more flexibility and reuse.

The following two sections lists all the options, firstly for the component followed by the endpoint.

Component Options

The Vert.x WebSocket component supports 11 options, which are listed below.

Name Description Default Type

bridgeErrorHandler (consumer)

Allows for bridging the consumer to the Camel routing Error Handler, which mean any exceptions (if possible) occurred while the Camel consumer is trying to pickup incoming messages, or the likes, will now be processed as a message and handled by the routing Error Handler. Important: This is only possible if the 3rd party component allows Camel to be alerted if an exception was thrown. Some components handle this internally only, and therefore bridgeErrorHandler is not possible. In other situations we may improve the Camel component to hook into the 3rd party component and make this possible for future releases. 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

allowOriginHeader (advanced)

Whether the WebSocket client should add the Origin header to the WebSocket handshake request.

true

boolean

autowiredEnabled (advanced)

Whether autowiring is enabled. This is used for automatic autowiring options (the option must be marked as autowired) by looking up in the registry to find if there is a single instance of matching type, which then gets configured on the component. This can be used for automatic configuring JDBC data sources, JMS connection factories, AWS Clients, etc.

true

boolean

defaultHost (advanced)

Default value for host name that the WebSocket should bind to.

0.0.0.0

String

defaultPort (advanced)

Default value for the port that the WebSocket should bind to.

0

int

originHeaderUrl (advanced)

The value of the Origin header that the WebSocket client should use on the WebSocket handshake request. When not specified, the WebSocket client will automatically determine the value for the Origin from the request URL.

String

router (advanced)

To provide a custom vertx router to use on the WebSocket server.

Router

vertx (advanced)

To use an existing vertx instead of creating a new instance.

Vertx

vertxOptions (advanced)

To provide a custom set of vertx options for configuring vertx.

VertxOptions

useGlobalSslContextParameters (security)

Enable usage of global SSL context parameters.

false

boolean

Endpoint Options

The Vert.x WebSocket endpoint is configured using URI syntax:

vertx-websocket:host:port/path

with the following path and query parameters:

Path Parameters (3 parameters)

Name Description Default Type

host (common)

Required WebSocket hostname, such as localhost or a remote host when in client mode.

String

port (common)

Required WebSocket port number to use.

int

path (common)

WebSocket path to use.

String

Query Parameters (18 parameters)

Name Description Default Type

allowedOriginPattern (consumer)

Regex pattern to match the origin header sent by WebSocket clients.

String

allowOriginHeader (consumer)

Whether the WebSocket client should add the Origin header to the WebSocket handshake request.

true

boolean

consumeAsClient (consumer)

When set to true, the consumer acts as a WebSocket client, creating exchanges on each received WebSocket event.

false

boolean

fireWebSocketConnectionEvents (consumer)

Whether the server consumer will create a message exchange when a new WebSocket peer connects or disconnects.

false

boolean

maxReconnectAttempts (consumer)

When consumeAsClient is set to true this sets the maximum number of allowed reconnection attempts to a previously closed WebSocket. A value of 0 (the default) will attempt to reconnect indefinitely.

0

int

originHeaderUrl (consumer)

The value of the Origin header that the WebSocket client should use on the WebSocket handshake request. When not specified, the WebSocket client will automatically determine the value for the Origin from the request URL.

String

reconnectInitialDelay (consumer)

When consumeAsClient is set to true this sets the initial delay in milliseconds before attempting to reconnect to a previously closed WebSocket.

0

int

reconnectInterval (consumer)

When consumeAsClient is set to true this sets the interval in milliseconds at which reconnecting to a previously closed WebSocket occurs.

1000

int

router (consumer)

To use an existing vertx router for the HTTP server.

Router

serverOptions (consumer)

Sets customized options for configuring the HTTP server hosting the WebSocket for the consumer.

HttpServerOptions

bridgeErrorHandler (consumer (advanced))

Allows for bridging the consumer to the Camel routing Error Handler, which mean any exceptions (if possible) occurred while the Camel consumer is trying to pickup incoming messages, or the likes, will now be processed as a message and handled by the routing Error Handler. Important: This is only possible if the 3rd party component allows Camel to be alerted if an exception was thrown. Some components handle this internally only, and therefore bridgeErrorHandler is not possible. In other situations we may improve the Camel component to hook into the 3rd party component and make this possible for future releases. 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

exceptionHandler (consumer (advanced))

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 (advanced))

Sets the exchange pattern when the consumer creates an exchange.

Enum values:

  • InOnly

  • InOut

ExchangePattern

clientOptions (producer)

Sets customized options for configuring the WebSocket client used in the producer.

HttpClientOptions

clientSubProtocols (producer)

Comma separated list of WebSocket subprotocols that the client should use for the Sec-WebSocket-Protocol header.

String

sendToAll (producer)

To send to all websocket subscribers. Can be used to configure at the endpoint level, instead of providing the VertxWebsocketConstants.SEND_TO_ALL header on the message. Note that when using this option, the host name specified for the vertx-websocket producer URI must match one used for an existing vertx-websocket consumer. Note that this option only applies when producing messages to endpoints hosted by the vertx-websocket consumer and not to an externally hosted WebSocket.

false

boolean

lazyStartProducer (producer (advanced))

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

sslContextParameters (security)

To configure security using SSLContextParameters.

SSLContextParameters

Message Headers

The Vert.x WebSocket component supports 4 message header(s), which is/are listed below:

Name Description Default Type

CamelVertxWebsocket.connectionKey (common)

Constant: CONNECTION_KEY

Sends the message to the client with the given connection key. You can use a comma separated list of keys to send a message to multiple clients. Note that this option only applies when producing messages to endpoints hosted by the vertx-websocket consumer and not to an externally hosted WebSocket.

String

CamelVertxWebsocket.sendToAll (producer)

Constant: 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. Note that this option only applies when producing messages to endpoints hosted by the vertx-websocket consumer and not to an externally hosted WebSocket.

boolean

CamelVertxWebsocket.remoteAddress (consumer)

Constant: REMOTE_ADDRESS

The remote address.

SocketAddress

CamelVertxWebsocket.event (consumer)

Constant: EVENT

The WebSocket event that triggered the message exchange.

Enum values:

  • CLOSE

  • ERROR

  • MESSAGE

  • OPEN

VertxWebsocketEvent

Usage

The following example shows how to expose a WebSocket on http://localhost:8080/echo and returns an 'echo' response back to the same channel:

from("vertx-websocket:localhost:8080/echo")
    .transform().simple("Echo: ${body}")
    .to("vertx-websocket:localhost:8080/echo");

It’s also possible to configure the consumer to connect as a WebSocket client on a remote address with the consumeAsClient option:

from("vertx-websocket:my.websocket.com:8080/chat?consumeAsClient=true")
    .log("Got WebSocket message ${body}");

Path & query parameters

The WebSocket server consumer supports the configuration of parameterized paths. The path parameter value will be set as a Camel exchange header:

from("vertx-websocket:localhost:8080/chat/{user}")
    .log("New message from ${header.user} >>> ${body}")

Similarly you can retrieve any query parameter values that were used by the WebSocket client to connect to the server endpoint:

from("direct:sendChatMessage")
    .to("vertx-websocket:localhost:8080/chat/camel?role=admin");

from("vertx-websocket:localhost:8080/chat/{user}")
    .log("New message from ${header.user} (${header.role}) >>> ${body}")

Sending messages to peers connected to the vertx-websocket server consumer

This section only applies when producing messages to a WebSocket hosted by the camel-vertx-websocket consumer. It is not relevant when producing messages to an externally hosted WebSocket.

To send a message to all peers connected to a WebSocket hosted by the vertx-websocket server consumer, use the sendToAll=true endpoint option, or the CamelVertxWebsocket.sendToAll header.

from("vertx-websocket:localhost:8080/chat")
    .log("Got WebSocket message ${body}");

from("direct:broadcastMessage")
    .setBody().constant("This is a broadcast message!")
    .to("vertx-websocket:localhost:8080/chat?sendToAll=true");

Alternatively, you can send messages to specific peers by using the CamelVertxWebsocket.connectionKey header. Multiple peers can be specified as a comma separated list.

The value of the connectionKey can be determined whenever a peer triggers an event on the vertx-websocket consumer, where a unique key identifying the peer will be propagated via the CamelVertxWebsocket.connectionKey header.

from("vertx-websocket:localhost:8080/chat")
    .log("Got WebSocket message ${body}");

from("direct:broadcastMessage")
    .setBody().constant("This is a broadcast message!")
    .setHeader(VertxWebsocketConstants.CONNECTION_KEY).constant("key-1,key-2,key-3")
    .to("vertx-websocket:localhost:8080/chat");

SSL

By default, the ws:// protocol is used, but secure connections with wss:// are supported by configuring the consumer or producer via the sslContextParameters URI parameter and the Camel JSSE Configuration Utility