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Chapter 33. HTTP

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

http: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&...

[Important]camel-http vs camel-jetty

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

Name Default Value Description
throwExceptionOnFailure true Apache Camel 2.0: Option to disable throwing the HttpOperationFailedException in case of failed responses from the remote server. This allows you to get all responses regardles of the HTTP status code.
bridgeEndpoint false

Camel 2.1: 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. Camel 2.3: If the option is true, HttpProducer and CamelServlet will skip the gzip processing if the content-encoding is "gzip".

disableStreamCache false Camel 2.3: 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.
httpBinding null Camel 2.3: 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. From Camel 2.3 onwards prefer to use the httpClientConfigurer option.
httpClientConfigurer null Camel 2.3: Reference to a org.apache.camel.component.http.HttpClientConfigurer in the Registry.
httpClient.XXX null Setting options on the HttpClientParams. For instance httpClient.soTimeout=5000 will set the SO_TIMEOUT to 5 seconds.
clientConnectionManager null Camel 2.3: To use a custom org.apache.http.conn.ClientConnectionManager.

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

Name Default Value Description
authMethod null Authentication method, either as Basic, Digest or NTLM.
authMethodPriority null Priority of authentication methods. Is a list separated with comma. For example: Basic,Digest to exclude NTLM.
authUsername null Username for authentication
authPassword null Password for authentication
authDomain null Domain for NTML authentication
authHost null Optional host for NTML authentication
proxyHost null The proxy host name
proxyPort null The proxy port number
proxyAuthMethod null Authentication method for proxy, either as Basic, Digest or NTLM.
proxyAuthUsername null Username for proxy authentication
proxyAuthPassword null Password for proxy authentication
proxyAuthDomain null Domain for proxy NTML authentication
proxyAuthHost null Optional host for proxy NTML authentication

When using authentication you must provide the choice of method for the authMethod or authProxyMethod options. You can configure the proxy and authentication details on either the HttpComponent or the HttpEndoint. Values provided on the HttpEndpoint will take precedence over HttpComponent. Its most likely best to configure this on the HttpComponent which allows you to do this once.

The Http component uses convention over configuration which means that if you have not explicit set a authMethodPriority then it will fallback and use the select(ed) authMethod as priority as well. So if you use authMethod.Basic then the auhtMethodPriority will be Basic only.

The following Exchange properties are recognized by HTTP endpoints:

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. Camel 2.3.0: 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 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.
Exchange.HTTP_SERVLET_REQUEST HttpServletRequest Apache Camel 2.3: The HttpServletRequest object.
Exchange.HTTP_SERVLET_RESPONSE HttpServletResponse Apache Camel 2.3: The HttpServletResponse object.
Exchange.HTTP_PROTOCOL_VERSION String Camel 2.5: You can set the http protocol version with this header, eg. "HTTP/1.0". If you didn't specify the header, HttpProducer will use the default value "HTTP/1.1"

Apache 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 Apache Camel will add the HTTP response headers as well to the OUT message headers.

Apache Camel will handle according to the HTTP response code:

This exception contains the following information:

From Apache Camel 1.5 onwards, the following algorithm is used to determine if either GET or POST HTTP method should be used:

Available as of Apache Camel 2.0

You can get access to these two using the Camel type converter system using NOTE from Camel 2.3.0 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);

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

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

And the equivalent Spring sample:

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

In Apache Camel 1.5.1 you can override the HTTP endpoint URI by adding a header with the key, HttpProducer.HTTP_URI, on the message.

from("direct:start")
            .setHeader(org.apache.camel.component.http.HttpProducer.HTTP_URI, constant("http://newhost"))
	    .to("http://oldhost");

In the sample above Apache Camel will call the http://newhost despite the endpoint is configured with http://oldhost .

In Apache Camel 2.0, you can override the HTTP endpoint URI by setting the Exchange.HTTP_URI header, as follows:

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

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, as follows:

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

Or as a header with the key, Exchange.HTTP_QUERY, on the message, as follows:

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

The HTTP 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.http.HttpMethods.POST))
	    .to("http://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="http://www.google.com"/>
    <to uri="mock:results"/>
  </route>
</camelContext>

See the unit test in this link

Only for >= Apache Camel 1.6.2 The HTTP component provides a way to configure a proxy.

from("direct:start")
	    .to("http://oldhost?proxyHost=www.myproxy.com&proxyPort=80");

There is also support for proxy authentication via the proxyUsername and proxyPassword options.

Only for >= Apache Camel 1.6.2 The HTTP component will detect Java System Properties for http.proxyHost and http.proxyPort and use them if provided. See more at SUN http proxy documentation.

To avoid the System properties conflicts, from Apache Camel 2.2.0 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>

Apache 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.

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");

Or the httpClient options: httpClient.contentCharset=iso-8859-1

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("http://www.google.com")
    .setHeader(FileComponent.HEADER_FILE_NAME, "message.html").to("file:target/google");

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. Apache Camel does no tricks here.

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

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

Exchange exchange = template.send("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);

Available as of Apache Camel 2.0 In the route below we want to route a message that we enrich with data returned from a remote HTTP call. As we want any response from the remote server, we set the throwExceptionOnFailure option to false so we get any response in the AggregationStrategy. As the code is based on a unit test that simulates a HTTP status code 404, there is some assertion code etc.

// We set throwExceptionOnFailure to false to let Apache Camel return any response from the remove HTTP server without thrown
// HttpOperationFailedException in case of failures.
// This allows us to handle all responses in the aggregation strategy where we can check the HTTP response code
// and decide what to do. As this is based on an unit test we assert the code is 404
from("direct:start").enrich("http://localhost:8222/myserver?throwExceptionOnFailure=false&user=Camel", new AggregationStrategy() {
    public Exchange aggregate(Exchange original, Exchange resource) {
        // get the response code
        Integer code = resource.getIn().getHeader(Exchange.HTTP_RESPONSE_CODE, Integer.class);
        assertEquals(404, code.intValue());
        return resource;
    }
}).to("mock:result");

// this is our jetty server where we simulate the 404
from("jetty://http://localhost:8222/myserver")
        .process(new Processor() {
            public void process(Exchange exchange) throws Exception {
                exchange.getOut().setBody("Page not found");
                exchange.getOut().setHeader(Exchange.HTTP_RESPONSE_CODE, 404);
            }
        });

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

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.

The Http Component has a org.apache.commons.httpclient.HttpConnectionManager where you can configure various global configuration for the given component. By global, we mean that any endpoint the component creates has the same shared HttpConnectionManager. So, if we want to set a different value for the max connection per host, we need to define it on the HTTP component and not on the endpoint URI that we usually use. So here comes:

First, we define the http component in Spring XML. Yes, we use the same scheme name, http, because otherwise Apache Camel will auto-discover and create the component with default settings. What we need is to overrule this so we can set our options. In the sample below we set the max connection to 5 instead of the default of 2.

<bean id="http" class="org.apache.camel.component.http.HttpComponent">
    <property name="camelContext" ref="camel"/>
    <property name="httpConnectionManager" ref="myHttpConnectionManager"/>
</bean>

<bean id="myHttpConnectionManager" class="org.apache.commons.httpclient.MultiThreadedHttpConnectionManager">
    <property name="params" ref="myHttpConnectionManagerParams"/>
</bean>

<bean id="myHttpConnectionManagerParams" class="org.apache.commons.httpclient.params.HttpConnectionManagerParams">
    <property name="defaultMaxConnectionsPerHost" value="5"/>
</bean>

And then we can just use it as we normally do in our routes:

<camelContext id="camel" xmlns="http://camel.apache.org/schema/spring" trace="true">
    <route>
        <from uri="direct:start"/>
        <to uri="http://www.google.com"/>
        <to uri="mock:result"/>
    </route>
</camelContext>

Some HTTPS servers do not return a HTTP code 401 Authorization Required, which can cause HTTPS connections to fail. The solution to this problem is to set the following URI option: httpClient.authenticationPreemptive=true.

Basically camel-http component is built on the top of Apache HTTP client, and you can implement a custom org.apache.camel.component.http.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:

Protocol authhttps = new Protocol("https", new AuthSSLProtocolSocketFactory(
  new URL("file:my.keystore"), "mypassword",
  new URL("file:my.truststore"), "mypassword"), 443);

Protocol.registerProtocol("https", authhttps);

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 Apache Camel route builder class you can hook it up like so:

HttpComponent httpComponent = getContext().getComponent("http", 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="https://myhostname.com:443/myURL?httpClientConfigurerRef=myHttpClientConfigurer"/> 

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

See also: