Async HTTP Client (AHC) Websocket

Since Camel 2.14

Both producer and consumer are supported

The AHC-WS component provides Websocket based endpoints for a client communicating with external servers over Websocket (as a client opening a websocket connection to an external server).
The component uses the AHC component that in turn uses the Async Http Client library.

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

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

URI Format

ahc-ws://hostname[:port][/resourceUri][?options]
ahc-wss://hostname[:port][/resourceUri][?options]

Will by default use port 80 for ahc-ws and 443 for ahc-wss.

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 as a type safe way of configuring endpoints.

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 Async HTTP Client (AHC) Websocket component supports 10 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 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.

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.

boolean

allowJavaSerializedObject (advanced)

Whether to allow java serialization when a request uses context-type=application/x-java-serialized-object This is by default turned off. If you enable this then be aware that Java will deserialize the incoming data from the request to Java and that can be a potential security risk.

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.

boolean

binding (advanced)

To use a custom AhcBinding which allows to control how to bind between AHC and Camel.

AhcBinding

client (advanced)

To use a custom AsyncHttpClient.

AsyncHttpClient

clientConfig (advanced)

To configure the AsyncHttpClient to use a custom com.ning.http.client.AsyncHttpClientConfig instance.

AsyncHttpClientConfig

headerFilterStrategy (filter)

To use a custom org.apache.camel.spi.HeaderFilterStrategy to filter header to and from Camel message.

HeaderFilterStrategy

sslContextParameters (security)

Reference to a org.apache.camel.support.jsse.SSLContextParameters in the Registry. Note that configuring this option will override any SSL/TLS configuration options provided through the clientConfig option at the endpoint or component level.

SSLContextParameters

useGlobalSslContextParameters (security)

Enable usage of global SSL context parameters.

boolean

Endpoint Options

The Async HTTP Client (AHC) Websocket endpoint is configured using URI syntax:

ahc-ws:httpUri

with the following path and query parameters:

Path Parameters (1 parameters)

Name Description Default Type

httpUri (common)

Required The URI to use such as http://hostname:port/path.

URI

Query Parameters (18 parameters)

Name Description Default Type

bridgeEndpoint (common)

If the option is true, then the Exchange.HTTP_URI header is ignored, and use the endpoint’s URI for request. You may also set the throwExceptionOnFailure to be false to let the AhcProducer send all the fault response back.

boolean

bufferSize (common)

The initial in-memory buffer size used when transferring data between Camel and AHC Client.

int

headerFilterStrategy (common)

To use a custom HeaderFilterStrategy to filter header to and from Camel message.

HeaderFilterStrategy

throwExceptionOnFailure (common)

Option to disable throwing the AhcOperationFailedException in case of failed responses from the remote server. This allows you to get all responses regardless of the HTTP status code.

boolean

transferException (common)

If enabled and an Exchange failed processing on the consumer side, and if the caused Exception was send back serialized in the response as a application/x-java-serialized-object content type (for example using Jetty or Servlet Camel components). On the producer side the exception will be deserialized and thrown as is, instead of the AhcOperationFailedException. The caused exception is required to be serialized. This is by default turned off. If you enable this then be aware that Java will deserialize the incoming data from the request to Java and that can be a potential security risk.

boolean

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.

boolean

sendMessageOnError (consumer)

Whether to send an message if the web-socket listener received an error.

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

  • InOptionalOut

ExchangePattern

connectionClose (producer)

Define if the Connection Close header has to be added to HTTP Request. This parameter is false by default.

boolean

cookieHandler (producer)

Configure a cookie handler to maintain a HTTP session.

CookieHandler

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.

boolean

useStreaming (producer)

To enable streaming to send data as multiple text fragments.

boolean

binding (advanced)

To use a custom AhcBinding which allows to control how to bind between AHC and Camel.

AhcBinding

clientConfig (advanced)

To configure the AsyncHttpClient to use a custom com.ning.http.client.AsyncHttpClientConfig instance.

AsyncHttpClientConfig

clientConfigOptions (advanced)

To configure the AsyncHttpClientConfig using the key/values from the Map.

Map

clientConfigRealmOptions (security)

To configure the AsyncHttpClientConfig Realm using the key/values from the Map.

Map

sslContextParameters (security)

Reference to a org.apache.camel.support.jsse.SSLContextParameters in the Registry. This reference overrides any configured SSLContextParameters at the component level. See Using the JSSE Configuration Utility. Note that configuring this option will override any SSL/TLS configuration options provided through the clientConfig option at the endpoint or component level.

SSLContextParameters

Writing and Reading Data over Websocket

An ahc-ws endpoint can either write data to the socket or read from the socket, depending on whether the endpoint is configured as the producer or the consumer, respectively.

Configuring URI to Write or Read Data

In the route below, Camel will write to the specified websocket connection.

from("direct:start")
        .to("ahc-ws://targethost");

And the equivalent Spring sample:

<camelContext xmlns="http://camel.apache.org/schema/spring">
  <route>
    <from uri="direct:start"/>
    <to uri="ahc-ws://targethost"/>
  </route>
</camelContext>

In the route below, Camel will read from the specified websocket connection.

from("ahc-ws://targethost")
        .to("direct:next");

And the equivalent Spring sample:

<camelContext xmlns="http://camel.apache.org/schema/spring">
  <route>
    <from uri="ahc-ws://targethost"/>
    <to uri="direct:next"/>
  </route>
</camelContext>

Spring Boot Auto-Configuration

When using ahc-ws with Spring Boot make sure to use the following Maven dependency to have support for auto configuration:

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

The component supports 11 options, which are listed below.

Name Description Default Type

camel.component.ahc-ws.allow-java-serialized-object

Whether to allow java serialization when a request uses context-type=application/x-java-serialized-object This is by default turned off. If you enable this then be aware that Java will deserialize the incoming data from the request to Java and that can be a potential security risk.

false

Boolean

camel.component.ahc-ws.autowired-enabled

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

camel.component.ahc-ws.binding

To use a custom AhcBinding which allows to control how to bind between AHC and Camel. The option is a org.apache.camel.component.ahc.AhcBinding type.

AhcBinding

camel.component.ahc-ws.bridge-error-handler

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

camel.component.ahc-ws.client

To use a custom AsyncHttpClient. The option is a org.asynchttpclient.AsyncHttpClient type.

AsyncHttpClient

camel.component.ahc-ws.client-config

To configure the AsyncHttpClient to use a custom com.ning.http.client.AsyncHttpClientConfig instance. The option is a org.asynchttpclient.AsyncHttpClientConfig type.

AsyncHttpClientConfig

camel.component.ahc-ws.enabled

Whether to enable auto configuration of the ahc-ws component. This is enabled by default.

Boolean

camel.component.ahc-ws.header-filter-strategy

To use a custom org.apache.camel.spi.HeaderFilterStrategy to filter header to and from Camel message. The option is a org.apache.camel.spi.HeaderFilterStrategy type.

HeaderFilterStrategy

camel.component.ahc-ws.lazy-start-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

camel.component.ahc-ws.ssl-context-parameters

Reference to a org.apache.camel.support.jsse.SSLContextParameters in the Registry. Note that configuring this option will override any SSL/TLS configuration options provided through the clientConfig option at the endpoint or component level. The option is a org.apache.camel.support.jsse.SSLContextParameters type.

SSLContextParameters

camel.component.ahc-ws.use-global-ssl-context-parameters

Enable usage of global SSL context parameters.

false

Boolean