HTTP4 Component

Available as of Camel 2.3

The http4: component provides HTTP based endpoints for consuming external HTTP resources (as a client to call external servers using HTTP).

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

<dependency>
    <groupId>org.apache.camel</groupId>
    <artifactId>camel-http4</artifactId>
    <version>x.x.x</version>
    <!-- use the same version as your Camel core version -->
</dependency>
camel-http4 vs camel-http
Camel-http4 uses HttpClient 4.x while camel-http uses HttpClient 3.x.

URI format

http4: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&...

camel-http4 vs camel-jetty
You can only produce to endpoints generated by the HTTP4 component. Therefore it should never be used as input into your camel Routes. To bind/expose an HTTP endpoint via a HTTP server as input to a camel route, you can use the Jetty Component

HttpEndpoint Options

Name Default Value Description
x509HostnameVerifier BrowserCompatHostnameVerifier Camel 2.7: You can refer to a different org.apache.http.conn.ssl.X509HostnameVerifier instance in the Registry such as org.apache.http.conn.ssl.StrictHostnameVerifier or org.apache.http.conn.ssl.AllowAllHostnameVerifier.
throwExceptionOnFailure true Option to disable throwing the HttpOperationFailedException in case of failed responses from the remote server. This allows you to get all responses regardless of the HTTP status code.
bridgeEndpoint false If the option is true , HttpProducer will ignore the Exchange.HTTP_URI header, and use the endpoint's URI for request. You may also set the throwExcpetionOnFailure to be false to let the HttpProducer send all the fault response back. If the option is true, HttpProducer and CamelServlet will skip the gzip processing if the content-encoding is "gzip".
disableStreamCache false DefaultHttpBinding will copy the request input stream into a stream cache and put it into message body if this option is false to support read it twice, otherwise DefaultHttpBinding will set the request input stream direct into the message body.
httpBindingRef null Reference to a org.apache.camel.component.http.HttpBinding in the Registry. Prefer to use the httpBinding option.
httpBinding null Reference to a org.apache.camel.component.http.HttpBinding in the Registry.
httpClientConfigurerRef null Reference to a org.apache.camel.component.http.HttpClientConfigurer in the Registry. Prefer to use the httpClientConfigurer option.
httpClientConfigurer null Reference to a org.apache.camel.component.http.HttpClientConfigurer in the Registry.
httpClient.XXX null Setting options on the BasicHttpParams. For instance httpClient.soTimeout=5000 will set the SO_TIMEOUT to 5 seconds. Look on the setter methods of the following parameter beans for a complete reference: AuthParamBean, ClientParamBean, ConnConnectionParamBean, ConnRouteParamBean, CookieSpecParamBean, HttpConnectionParamBean and HttpProtocolParamBean
clientConnectionManager null To use a custom org.apache.http.conn.ClientConnectionManager.
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 HttpOperationFailedException. The caused exception is required to be serialized.
maxTotalConnections 200 The maximum number of connections.
connectionsPerRoute 20 The maximum number of connections per route.
sslContextParametersRef
null
Camel 2.8: 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.

The following authentication options can also be set on the HttpEndpoint:

Setting Basic Authentication and Proxy

Before Camel 2.8.0

Name Default Value Description
username null Username for authentication.
password null Password for authentication.
domain null The domain name for authentication.
host null The host name authentication.
proxyHost null The proxy host name
proxyPort null The proxy port number
proxyUsername null Username for proxy authentication
proxyPassword null Password for proxy authentication
proxyDomain null The proxy domain name
proxyNtHost null The proxy Nt host name

Since Camel 2.8.0

Name Default Value Description
authUsername null Username for authentication
authPassword null Password for authentication
authDomain null The domain name for authentication
authHost null The host name authentication
proxyAuthHost null The proxy host name
proxyAuthPort null The proxy port number
proxyAuthScheme null The proxy scheme, will fallback and use the scheme from the endpoint if not configured.
proxyAuthUsername null Username for proxy authentication
proxyAuthPassword null Password for proxy authentication
proxyAuthDomain null The proxy domain name
proxyAuthNtHost null The proxy Nt host name

HttpComponent Options

Name Default Value Description
httpBinding null To use a custom org.apache.camel.component.http.HttpBinding.
httpClientConfigurer null To use a custom org.apache.camel.component.http.HttpClientConfigurer.
httpConnectionManager null To use a custom org.apache.commons.httpclient.HttpConnectionManager.
x509HostnameVerifier null Camel 2.7: To use a custom org.apache.http.conn.ssl.X509HostnameVerifier.
sslContextParameters
null
Camel 2.8: To configure a custom SSL/TLS configuration options at the component level.  See  Using the JSSE Configuration Utility for more details.

Message Headers

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.
Exchange.HTTP_QUERY String 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 HttpOperationFailedException with the information.
  • Response code is 400+, Camel regards it as an external server failure and will throw a HttpOperationFailedException with the information.
    throwExceptionOnFailure
    The option, throwExceptionOnFailure, can be set to false to prevent the HttpOperationFailedException from being thrown for failed response codes. This allows you to get any response from the remote server.
    There is a sample below demonstrating this.

HttpOperationFailedException

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.

How to get access to HttpServletRequest and HttpServletResponse

You can get access to these two using the Camel type converter system using
NOTE You can get the request and response not just from the processor after the camel-jetty or camel-cxf endpoint.

HttpServletRequest request = exchange.getIn().getBody(HttpServletRequest.class);
HttpServletRequest response = exchange.getIn().getBody(HttpServletResponse.class);

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.

from("direct:start")
	    .to("http4://oldhost");

And the equivalent Spring sample:

<camelContext xmlns="http://activemq.apache.org/camel/schema/spring">
  <route>
    <from uri="direct:start"/>
    <to uri="http4://oldhost"/>
  </route>
</camelContext>

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

from("direct:start")
            .setHeader(HttpConstants.HTTP_URI, constant("http://newhost"))
	    .to("http4://oldhost");

In the sample above Camel will call the http://newhost despite the endpoint is configured with http4://oldhost.
Where Constants is the class, org.apache.camel.component.http4.Constants.

Configuring URI Parameters

The http 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.

from("direct:start")
	    .to("http4://oldhost?order=123&detail=short");

Or options provided in a header:

from("direct:start")
            .setHeader(Exchange.HTTP_QUERY, constant("order=123&detail=short"))
	    .to("http4://oldhost");

How to set the http method (GET/POST/PUT/DELETE/HEAD/OPTIONS/TRACE) to the HTTP producer

The HTTP4 component provides a way to set the HTTP request method by setting the message header. Here is an example;

from("direct:start")
            .setHeader(Exchange.HTTP_METHOD, constant(org.apache.camel.component.http4.HttpMethods.POST))
	    .to("http4://www.google.com")
            .to("mock:results");

The method can be written a bit shorter using the string constants:

.setHeader("CamelHttpMethod", constant("POST"))

And the equivalent Spring sample:

<camelContext xmlns="http://activemq.apache.org/camel/schema/spring">
  <route>
    <from uri="direct:start"/>
    <setHeader headerName="CamelHttpMethod">
        <constant>POST</constant>
    </setHeader>
    <to uri="http4://www.google.com"/>
    <to uri="mock:results"/>
  </route>
</camelContext>

Using client tineout - SO_TIMEOUT

See the HttpSOTimeoutTest unit test.

Configuring a Proxy

The HTTP4 component provides a way to configure a proxy.

from("direct:start")
	    .to("http4://oldhost?proxyAuthHost=www.myproxy.com&proxyAuthPort=80");

There is also support for proxy authentication via the proxyAuthUsername and proxyAuthPassword options.

Using proxy settings outside of URI

To avoid the System properties conflicts, you can only set the proxy configure from CameContext or URI.
Java DSL :

 context.getProperties().put("http.proxyHost", "172.168.18.9");
 context.getProperties().put("http.proxyPort" "8080");

Spring XML

   <camelContext>
       <properties>
           <property key="http.proxyHost" value="172.168.18.9"/>
           <property key="http.proxyPort" value="8080"/>
      </properties>
   </camelContext>

Camel will first set the settings from Java System or CamelContext Properties and then the endpoint proxy options if provided.
So you can override the system properties with the endpoint options.

Notice in Camel 2.8 there is also a http.proxyScheme property you can set to explicit configure the scheme to use.

Configuring charset

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

exchange.setProperty(Exchange.CHARSET_NAME, "ISO-8859-1");

Sample with scheduled poll

The sample polls the Google homepage every 10 seconds and write the page to the file message.html:

from("timer://foo?fixedRate=true&delay=0&period=10000")
    .to("http4://www.google.com")
    .setHeader(FileComponent.HEADER_FILE_NAME, "message.html")
    .to("file:target/google");

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.

// we query for Camel at the Google page
template.sendBody("http4://www.google.com/search?q=Camel", null);

URI Parameters from the Message

Map headers = new HashMap();
headers.put(HttpProducer.QUERY, "q=Camel&lr=lang_en");
// we query for Camel and English language at Google
template.sendBody("http4://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 HTTP4 component by getting the value from the Out message header with HttpProducer.HTTP_RESPONSE_CODE.

Exchange exchange = template.send("http4://www.google.com/search", new Processor() {
            public void process(Exchange exchange) throws Exception {
                exchange.getIn().setHeader(HttpProducer.QUERY, constant("hl=en&q=activemq"));
            }
   });
   Message out = exchange.getOut();
   int responseCode = out.getHeader(HttpProducer.HTTP_RESPONSE_CODE, Integer.class);

Disabling Cookies

To disable cookies you can set the HTTP Client to ignore cookies by adding this URI option:
httpClient.cookiePolicy=ignoreCookies

Advanced Usage

If you need more control over the HTTP producer you should use the HttpComponent where you can set various classes to give you custom behavior.

Using HTTPS to authenticate gotchas

An end user reported that he had problem with authenticating with HTTPS. The problem was eventually resolved when he discovered the HTTPS server did not return a HTTP code 401 Authorization Required. The solution was to set the following URI option: httpClient.authenticationPreemptive=true

Setting up SSL for HTTP Client

Using the JSSE Configuration Utility

As of Camel 2.8, the HTTP4 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 HTTP4 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");

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

HttpComponent httpComponent = getContext().getComponent("http4", HttpComponent.class);
httpComponent.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:sslContextParameters>...
...
  <to uri="https4://127.0.0.1/mail/?sslContextParametersRef=sslContextParameters"/>...
Configuring Apache HTTP Client Directly

Basically camel-http4 component is built on the top of Apache HTTP client. Please refer to SSL/TLS customization for details or have a look into the org.apache.camel.component.http4.HttpsServerTestSupport unit test base class.
You can also implement a custom org.apache.camel.component.http4.HttpClientConfigurer to do some configuration on the http client if you need full control of it.

However if you just want to specify the keystore and truststore you can do this with Apache HTTP HttpClientConfigurer, for example:

KeyStore keystore = ...;
KeyStore truststore = ...;

SchemeRegistry registry = new SchemeRegistry();
registry.register(new Scheme("https", 443, new SSLSocketFactory(keystore, "mypassword", truststore)));

And then you need to create a class that implements HttpClientConfigurer, and registers https protocol providing a keystore or truststore per example above. Then, from your camel route builder class you can hook it up like so:

HttpComponent httpComponent = getContext().getComponent("http4", HttpComponent.class);
httpComponent.setHttpClientConfigurer(new MyHttpClientConfigurer());

If you are doing this using the Spring DSL, you can specify your HttpClientConfigurer using the URI. For example:

<bean id="myHttpClientConfigurer"
 class="my.https.HttpClientConfigurer">
</bean>

<to uri="https4://myhostname.com:443/myURL?httpClientConfigurer=myHttpClientConfigurer"/>

As long as you implement the HttpClientConfigurer and configure your keystore and truststore as described above, it will work fine.

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