= Async HTTP Client (AHC) Component
:doctitle: Async HTTP Client (AHC)
:shortname: ahc
:artifactid: camel-ahc
:description: Call external HTTP services using Async Http Client.
:since: 2.8
:supportlevel: Stable
:component-header: Only producer is supported
//Manually maintained attributes
:camel-spring-boot-name: ahc

*Since Camel {since}*

*{component-header}*

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
https://github.com/AsyncHttpClient/async-http-client[Async Http Client]
library.

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

[source,xml]
------------------------------------------------------------
<dependency>
    <groupId>org.apache.camel</groupId>
    <artifactId>camel-ahc</artifactId>
    <version>x.x.x</version>
    <!-- use the same version as your Camel core version -->
</dependency>
------------------------------------------------------------

== URI format

---------------------------------------------------
ahc:http://hostname[:port][/resourceUri][?options]
ahc:https://hostname[:port][/resourceUri][?options]
---------------------------------------------------

Will by default use port 80 for HTTP and 443 for HTTPS.

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

// component-configure options: START

// component-configure options: END

// component options: START
include::partial$component-configure-options.adoc[]
include::partial$component-endpoint-options.adoc[]
// component options: END

// endpoint options: START

// endpoint options: END


== Message Headers

[width="100%",cols="10%,10%,80%",options="header",]
|=======================================================================
|Name |Type |Description
|`Exchange.HTTP_URI` |`String` |URI to call. Will override existing URI set directly on the endpoint.

|`Exchange.HTTP_PATH` |`String` |Request URI's path, the header will be used to build the request URI
with the HTTP_URI. If the path is start with "/", 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 onwards:* 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_CHARACTER_ENCODING` |`String` |Character encoding.

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

== 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 code

Camel will handle according to the HTTP response code:

* Response code is in the range 100..299, Camel regards it as a success
response.
* Response code is in the range 300..399, Camel regards it as a
redirection response and will throw a `AhcOperationFailedException` with
the information.
* Response code is 400+, Camel regards it as an external server failure
and will throw a `AhcOperationFailedException` with the 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

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 server provided a body as
response

== 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 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.

[source,java]
----------------------------------
from("direct:start")
        .to("ahc:http://oldhost");
----------------------------------

And the equivalent Spring sample:

[source,xml]
---------------------------------------------------------------------
<camelContext xmlns="http://activemq.apache.org/camel/schema/spring">
  <route>
    <from uri="direct:start"/>
    <to uri="ahc:http://oldhost"/>
  </route>
</camelContext>
---------------------------------------------------------------------

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

[source,java]
-------------------------------------------------------------
from("direct:start")
    .setHeader(Exchange.HTTP_URI, constant("http://newhost"))
    .to("ahc:http://oldhost");
-------------------------------------------------------------

== 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.

[source,java]
---------------------------------------------------------
from("direct:start")
        .to("ahc:http://oldhost?order=123&detail=short");
---------------------------------------------------------

Or options provided in a header:

[source,java]
-------------------------------------------------------------------------------
from("direct:start")
            .setHeader(Exchange.HTTP_QUERY, constant("order=123&detail=short"))
        .to("ahc:http://oldhost");
-------------------------------------------------------------------------------

== How to set the http method to the HTTP producer

The HTTP component provides a way to set the HTTP request method by
setting the message header. Here is an example;

[source,java]
--------------------------------------------------------------
from("direct:start")
            .setHeader(Exchange.HTTP_METHOD, constant("POST"))
        .to("ahc:http://www.google.com")
            .to("mock:results");
--------------------------------------------------------------

And the equivalent Spring sample:

[source,xml]
---------------------------------------------------------------------
<camelContext xmlns="http://activemq.apache.org/camel/schema/spring">
  <route>
    <from uri="direct:start"/>
    <setHeader name="CamelHttpMethod">
        <constant>POST</constant>
    </setHeader>
    <to uri="ahc:http://www.google.com"/>
    <to uri="mock:results"/>
  </route>
</camelContext>
---------------------------------------------------------------------

== Configuring charset

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

[source,java]
----------------------------------------------------------
exchange.setProperty(Exchange.CHARSET_NAME, "iso-8859-1");
----------------------------------------------------------

=== URI Parameters from the endpoint URI

In this sample 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.

[source,java]
--------------------------------------------------------------------
// we query for Camel at the Google page
template.sendBody("ahc:http://www.google.com/search?q=Camel", null);
--------------------------------------------------------------------

=== URI Parameters from the Message

[source,java]
---------------------------------------------------------------------
Map headers = new HashMap();
headers.put(Exchange.HTTP_QUERY, "q=Camel&lr=lang_en");
// we query for Camel and English language at Google
template.sendBody("ahc:http://www.google.com/search", null, headers);
---------------------------------------------------------------------

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`.

[source,java]
----------------------------------------------------------------------------------------------
Exchange exchange = template.send("ahc:http://www.google.com/search", new Processor() {
            public void process(Exchange exchange) throws Exception {
                exchange.getIn().setHeader(Exchange.HTTP_QUERY, constant("hl=en&q=activemq"));
            }
   });
   Message out = exchange.getOut();
   int responseCode = out.getHeader(Exchange.HTTP_RESPONSE_CODE, Integer.class);
----------------------------------------------------------------------------------------------

== Configuring AsyncHttpClient

The `AsyncHttpClient` client uses a `AsyncHttpClientConfig` to configure
the client. See the documentation at +
 http://github.com/sonatype/async-http-client[Async Http Client] for
more details.

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

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.

There is the ability to set configuration
options directly in the URI. URI parameters starting with
"clientConfig." can be used to set the various configurable properties
of `AsyncHttpClientConfig`. The properties specified in the endpoint URI
are merged with those specified in the configuration referenced by the
"clientConfig" URI parameter with those being set using the
"clientConfig." parameter taking priority. The `AsyncHttpClientConfig`
instance referenced is always copied for each endpoint such that
settings on one endpoint will remain independent of settings on any
previously created endpoints. The example below shows how to configure
the AHC component using the "clientConfig." type URI parameters.

[source,java]
---------------------------------------------------------------------------------------------------------
from("direct:start")
    .to("ahc:http://localhost:8080/foo?clientConfig.maxRequestRetry=3&clientConfig.followRedirects=true")
---------------------------------------------------------------------------------------------------------

== SSL Support (HTTPS)

[[AHC-UsingtheJSSEConfigurationUtility]]
Using the JSSE Configuration Utility

The AHC component supports SSL/TLS configuration
through the xref:manual::camel-configuration-utilities.adoc[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.

[[AHC-Programmaticconfigurationofthecomponent]]
Programmatic configuration of the component

[source,java]
-------------------------------------------------------------------------
KeyStoreParameters ksp = new KeyStoreParameters();
ksp.setResource("/users/home/server/keystore.jks");
ksp.setPassword("keystorePassword");

KeyManagersParameters kmp = new KeyManagersParameters();
kmp.setKeyStore(ksp);
kmp.setKeyPassword("keyPassword");

SSLContextParameters scp = new SSLContextParameters();
scp.setKeyManagers(kmp);

AhcComponent component = context.getComponent("ahc", AhcComponent.class);
component.setSslContextParameters(scp));
-------------------------------------------------------------------------

[[AHC-SpringDSLbasedconfigurationofendpoint]]
Spring DSL based configuration of endpoint

[source,xml]
----------------------------------------------------------------------------------
...
  <camel:sslContextParameters
      id="sslContextParameters">
    <camel:keyManagers
        keyPassword="keyPassword">
      <camel:keyStore
          resource="/users/home/server/keystore.jks"
          password="keystorePassword"/>
    </camel:keyManagers>
  </camel:sslContextParameters>...
...
  <to uri="ahc:https://localhost/foo?sslContextParameters=#sslContextParameters"/>
...
----------------------------------------------------------------------------------


include::spring-boot:partial$starter.adoc[]
