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Async Http Client (AHC) Component

Available from Camel 2.8

The ahc component provides HTTP based endpoints for consuming external HTTP resources (as a client to call external servers using HTTP). The component uses the Async Http Client library.

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

URI format

The default ports are 80 for HTTP and 443 for HTTPS.

Query options can be specified on the URI using the following format: ?option=value&option=value&...

AhcEndpoint Options

Name

Default Value

Description

binding

null

To use a custom org.apache.camel.component.ahc.AhcBinding.

bridgeEndpoint

false

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 throwExcpetionOnFailure to be false to let the AhcProducer send all the fault response back.

bufferSize

4096

Camel 2.10.3: The initial in-memory buffer size used when transferring data between Camel and the ahc Client.

client

null

To use a custom com.ning.http.client.AsyncHttpClient.

clientConfig

null

To configure the AsyncHttpClient to use a custom com.ning.http.client.AsyncHttpClientConfig instance. This instance replaces any instance configured at the component level.

clientConfig.x

null

To configure additional properties of the com.ning.http.client.AsyncHttpClientConfig instance used by the endpoint.

Note: that configuration options set using this parameter will be merged with those set using the clientConfig parameter or the instance set at the component level with properties set using this parameter taking priority.

clientConfig.realm.x

null

Camel 2.11: To configure realm properties of the com.ning.http.client.AsyncHttpClientConfig The options which can be used are the options from com.ning.http.client.Realm.RealmBuilder. e.g., to set the scheme, you should configure clientConfig.realm.scheme=DIGEST

connectionClose

false

Camel 2.18: If this option is true, the producer will add a Connection Close header to HTTP Request

cookieHandler

null

Camel 2.19: Configure a cookie handler to maintain a HTTP session

sslContextParameters

null

Camel 2.9: 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

Note: configuring this option will override any SSL/TLS configuration options provided through the clientConfig option at the endpoint or component level.

throwExceptionOnFailure

true

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.

transferException

false

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.

AhcComponent Options

Name

Default Value

Description

binding

null

To use a custom org.apache.camel.component.ahc.AhcBinding.

client

null

To use a custom com.ning.http.client.AsyncHttpClient.

clientConfig

null

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

sslContextParameters

null

Camel 2.9: To configure custom SSL/TLS configuration options at the component level. 

See  Using the JSSE Configuration Utility for more details. 

Note: configuring this option will override any SSL/TLS configuration options provided through the clientConfig option at the endpoint or component level.

Note: setting any of the options on the AhcComponent will propagate those options to the AhcEndpoint(s) being created. However, the AhcEndpoint can also configure/override a custom option. Options set on endpoints will always take precedence over options from the AhcComponent.

Message Headers

Name

Type

Description

Exchange.CONTENT_ENCODING

String

The HTTP content encoding. Is set on both the IN and OUT message to provide a content encoding, such as gzip.

Exchange.CONTENT_TYPE

String

The HTTP content type. Is set on both the IN and OUT message to provide a content type, such as text/html.

Exchange.HTTP_CHARACTER_ENCODING

String

Character encoding.

Exchange.HTTP_PATH

String

Request URI's path, the header will be used to build the request URI with the HTTP_URI.

However, if the path is start with "/", the HTTP producer will try to find the relative path based on the Exchange.HTTP_BASE_URI header or the exchange.getFromEndpoint().getEndpointUri();

Exchange.HTTP_QUERY

String

Camel 2.11: URI parameters. Will override existing URI parameters set directly on the endpoint.

Exchange.HTTP_RESPONSE_CODE

int

The HTTP response code from the external server. Is 200 for OK.

Exchange.HTTP_URI

String

URI to call. Will override existing URI set directly on the endpoint.

Message Body

Camel will store the HTTP response from the external server on the OUT body. All headers from the IN message will be copied to the OUT message, so headers are preserved during routing. Additionally Camel will add the HTTP response headers as well to the OUT message headers.

Response Codes

The value of the HTTP response code governs how Camel behaves:

  • If in the range 100..299 Camel will regard it as a successful response.

  • If in the range 300..399 Camel will regard it as a redirection response and throw an AhcOperationFailedException containing the relevant information.

  • If greater than 400 Camel regards it as an external server failure and throw an AhcOperationFailedException containing the relevant information.

    throwExceptionOnFailure

    The option, throwExceptionOnFailure, can be set to false to prevent the AhcOperationFailedException from being thrown for failed response codes. This allows you to get any response from the remote server.

AhcOperationFailedException Details

This exception contains the following information:

  • The HTTP status code.

  • The HTTP status line (text of the status code).

  • Redirect location, if server returned a redirect.

  • Response body as a java.lang.String, if the server provides a response body.

Calling using GET or POST

The following algorithm is used to determine if either GET or POST HTTP method should be used:

  1.   Use method provided in header.

  2.   GET if query string is provided in header.

  3.   GET if endpoint is configured with a query string.

  4.   POST if there is data to send (body is not null).

  5.   GET otherwise.

Configuring the URI to Call

You can set the HTTP producer's URI directly form the endpoint URI. In the route below, Camel will call out to the external server, oldhost, using HTTP.

Java DSL:

Spring XML DSL:

You can override the HTTP endpoint URI by adding a header with the key Exchange.HTTP_URI on the message.

Configuring URI Parameters

The ahc producer supports URI parameters to be sent to the HTTP server. The URI parameters can either be set directly on the endpoint URI or as a header with the key Exchange.HTTP_QUERY on the message.

Or options provided via a header:

How to Set the HTTP Method (GET/POST/PUT/DELETE/HEAD/OPTIONS/TRACE) to the HTTP Producer

The HTTP component provides a way to set the HTTP request method by setting the message header.

Example

Java DSL:

Spring XML DSL:

Configuring charset

If you are using POST to send data you can configure the charset using the Exchange property:

URI Parameters From the Endpoint URI

In this example we have the complete URI endpoint that is just what you would have typed in a web browser. Multiple URI parameters can of course be set using the & character as separator, just as you would in the web browser. Camel does no tricks here.

URI Parameters From the Message

In the header value above notice that it should not be prefixed with ? and you can separate parameters as usual with the & char.

Getting the Response Code

You can get the HTTP response code from the ahc component by getting the value from the OUT message header with Exchange.HTTP_RESPONSE_CODE.

Configuring AsyncHttpClient

The AsyncHttpClient client uses a AsyncHttpClientConfig to configure the client. See the documentation at Async Http Client for more details.

In Camel 2.8, configuration is limited to using the builder pattern provided by AsyncHttpClientConfig.Builder. In Camel 2.8, the AsyncHttpClientConfig doesn't support getters/setters so its not easy to create/configure using a Spring bean style e.g., the <bean> tag in the XML file.

The example below shows how to use a builder to create the AsyncHttpClientConfig which we configure on the AhcComponent.

In Camel 2.9, the ahc component uses Async HTTP library 1.6.4. This newer version provides added support for plain bean style configuration. The AsyncHttpClientConfigBean class provides getters and setters for the configuration options available in AsyncHttpClientConfig. An instance of AsyncHttpClientConfigBean may be passed directly to the ahc component or referenced in an endpoint URI using the clientConfig URI parameter.

Also available in Camel 2.9 is the ability to set configuration options directly in the URI. URI options starting with clientConfig can be used to set the various configurable properties of AsyncHttpClientConfig. Options specified in the endpoint URI are merged with those specified by the clientConfig option. These options take precedence over the options specified on the URI endpoint. A copy of the AsyncHttpClientConfig is made for each new endpoint. The example below shows how to configure the ahc component using the clientConfig URI options.

SSL Support (HTTPS)

Using the JSSE Configuration Utility

From Camel 2.9, the ahc 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 ahc component.

Programmatic configuration of the component
Spring DSL based configuration of endpoint

See Also

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