HTTP4 Component

Table of Contents

URI format
Http4 Component Options
Message Headers
Message Body
Using System Properties
Response code
HttpOperationFailedException
Calling using GET or POST
How to get access to HttpServletRequest and HttpServletResponse
Configuring URI to call
Configuring URI Parameters
How to set the http method (GET/PATCH/POST/PUT/DELETE/HEAD/OPTIONS/TRACE) to the HTTP producer
Using client timeout - SO_TIMEOUT
Configuring a Proxy
Configuring charset
Disabling Cookies
Advanced Usage

Available as of Camel 2.3

The http4: component provides HTTP based endpoints for calling 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 Apache HttpClient 4.x while camel-http uses Apache 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, use the Jetty Component instead.

Http4 Component Options

The HTTP4 component supports 13 options which are listed below.

{% raw %}

Name	Java Type	Description
httpClientConfigurer	`HttpClientConfigurer`	To use the custom HttpClientConfigurer to perform configuration of the HttpClient that will be used.
clientConnectionManager	`HttpClientConnectionManager`	To use a custom HttpClientConnectionManager to manage connections
httpBinding	`HttpBinding`	To use a custom HttpBinding to control the mapping between Camel message and HttpClient.
httpConfiguration	`HttpConfiguration`	To use the shared HttpConfiguration as base configuration.
allowJavaSerializedObject	`boolean`	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.
httpContext	`HttpContext`	To use a custom org.apache.http.protocol.HttpContext when executing requests.
sslContextParameters	`SSLContextParameters`	To configure security using SSLContextParameters. Important: Only one instance of org.apache.camel.util.jsse.SSLContextParameters is supported per HttpComponent. If you need to use 2 or more different instances you need to define a new HttpComponent per instance you need.
x509HostnameVerifier	`X509HostnameVerifier`	To use a custom X509HostnameVerifier such as org.apache.http.conn.ssl.StrictHostnameVerifier or org.apache.http.conn.ssl.AllowAllHostnameVerifier.
maxTotalConnections	`int`	The maximum number of connections.
connectionsPerRoute	`int`	The maximum number of connections per route.
connectionTimeToLive	`long`	The time for connection to live the time unit is millisecond the default value is always keep alive.
cookieStore	`CookieStore`	To use a custom org.apache.http.client.CookieStore. By default the org.apache.http.impl.client.BasicCookieStore is used which is an in-memory only cookie store. Notice if bridgeEndpoint=true then the cookie store is forced to be a noop cookie store as cookie shouldn’t be stored as we are just bridging (eg acting as a proxy).
headerFilterStrategy	`HeaderFilterStrategy`	To use a custom HeaderFilterStrategy to filter header to and from Camel message.

{% endraw %}

The HTTP4 component supports 31 endpoint options which are listed below:

{% raw %}

Name	Group	Default	Java Type	Description
httpUri	producer		`URI`	Required The url of the HTTP endpoint to call.
disableStreamCache	common	`false`	`boolean`	Determines whether or not the raw input stream from Servlet is cached or not (Camel will read the stream into a in memory/overflow to file Stream caching) cache. By default Camel will cache the Servlet input stream to support reading it multiple times to ensure it Camel can retrieve all data from the stream. However you can set this option to true when you for example need to access the raw stream such as streaming it directly to a file or other persistent store. DefaultHttpBinding will copy the request input stream into a stream cache and put it into message body if this option is false to support reading the stream multiple times. If you use Servlet to bridge/proxy an endpoint then consider enabling this option to improve performance in case you do not need to read the message payload multiple times. The http/http4 producer will by default cache the response body stream. If setting this option to true then the producers will not cache the response body stream but use the response stream as-is as the message body.
authenticationPreemptive	producer	`false`	`boolean`	If this option is true camel-http4 sends preemptive basic authentication to the server.
authMethodPriority	producer		`String`	Authentication method for proxy either as Basic Digest or NTLM.
bridgeEndpoint	producer	`false`	`boolean`	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 option throwExceptionOnFailure to be false to let the HttpProducer send all the fault response back.
chunked	producer	`true`	`boolean`	If this option is false the Servlet will disable the HTTP streaming and set the content-length header on the response
clearExpiredCookies	producer	`true`	`boolean`	Whether to clear expired cookies before sending the HTTP request. This ensures the cookies store does not keep growing by adding new cookies which is newer removed when they are expired.
connectionClose	producer	`false`	`boolean`	Specifies whether a Connection Close header must be added to HTTP Request. By default connectionClose is false.
cookieStore	producer		`CookieStore`	To use a custom org.apache.http.client.CookieStore. By default the org.apache.http.impl.client.BasicCookieStore is used which is an in-memory only cookie store. Notice if bridgeEndpoint=true then the cookie store is forced to be a noop cookie store as cookie shouldn’t be stored as we are just bridging (eg acting as a proxy).
copyHeaders	producer	`true`	`boolean`	If this option is true then IN exchange headers will be copied to OUT exchange headers according to copy strategy. Setting this to false allows to only include the headers from the HTTP response (not propagating IN headers).
headerFilterStrategy	producer		`HeaderFilterStrategy`	To use a custom HeaderFilterStrategy to filter header to and from Camel message.
httpBinding	producer		`HttpBinding`	To use a custom HttpBinding to control the mapping between Camel message and HttpClient.
ignoreResponseBody	producer	`false`	`boolean`	If this option is true The http producer won’t read response body and cache the input stream
okStatusCodeRange	producer	`200-299`	`String`	The status codes which is considered a success response. The values are inclusive. The range must be defined as from-to with the dash included.
preserveHostHeader	producer	`false`	`boolean`	If the option is true HttpProducer will set the Host header to the value contained in the current exchange Host header useful in reverse proxy applications where you want the Host header received by the downstream server to reflect the URL called by the upstream client this allows applications which use the Host header to generate accurate URL’s for a proxied service
proxyHost	producer		`String`	The proxy host name
proxyPort	producer		`int`	The proxy port number
throwExceptionOnFailure	producer	`true`	`boolean`	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.
transferException	producer	`false`	`boolean`	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. 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. 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.
urlRewrite	producer (advanced)		`UrlRewrite`	Refers to a custom org.apache.camel.component.http.UrlRewrite which allows you to rewrite urls when you bridge/proxy endpoints. See more details at http://camel.apache.org/urlrewrite.html
clientBuilder	advanced		`HttpClientBuilder`	Provide access to the http client request parameters used on new RequestConfig instances used by producers or consumers of this endpoint.
clientConnectionManager	advanced		`HttpClientConnectionManager`	To use a custom HttpClientConnectionManager to manage connections
httpClient	advanced		`HttpClient`	Gets the HttpClient to be used by org.apache.camel.component.http4.HttpProducer
httpClientConfigurer	advanced		`HttpClientConfigurer`	Register a custom configuration strategy for new HttpClient instances created by producers or consumers such as to configure authentication mechanisms etc
httpClientOptions	advanced		`Map`	To configure the HttpClient using the key/values from the Map.
httpContext	advanced		`HttpContext`	To use a custom HttpContext instance
mapHttpMessageBody	advanced	`true`	`boolean`	If this option is true then IN exchange Body of the exchange will be mapped to HTTP body. Setting this to false will avoid the HTTP mapping.
mapHttpMessageFormUrlEncodedBody	advanced	`true`	`boolean`	If this option is true then IN exchange Form Encoded body of the exchange will be mapped to HTTP. Setting this to false will avoid the HTTP Form Encoded body mapping.
mapHttpMessageHeaders	advanced	`true`	`boolean`	If this option is true then IN exchange Headers of the exchange will be mapped to HTTP headers. Setting this to false will avoid the HTTP Headers mapping.
synchronous	advanced	`false`	`boolean`	Sets whether synchronous processing should be strictly used or Camel is allowed to use asynchronous processing (if supported).
useSystemProperties	advanced	`false`	`boolean`	To use System Properties as fallback for configuration

{% endraw %}

Message Headers

Name	Type	Description
`Exchange.HTTP_URI`	`String`	URI to call. Will override existing URI set directly on the endpoint. This uri is the uri of the http server to call. Its not the same as the Camel endpoint uri, where you can configure endpoint options such as security etc. This header does not support that, its only the uri of the http server.
`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_RESPONSE_TEXT`	`String`	The HTTP response text from the external server.
`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.

Using System Properties

When setting useSystemProperties to true, the HTTP Client will look for the following System Properties and it will use it:

ssl.TrustManagerFactory.algorithm
javax.net.ssl.trustStoreType
javax.net.ssl.trustStore
javax.net.ssl.trustStoreProvider
javax.net.ssl.trustStorePassword
java.home
ssl.KeyManagerFactory.algorithm
javax.net.ssl.keyStoreType
javax.net.ssl.keyStore
javax.net.ssl.keyStoreProvider
javax.net.ssl.keyStorePassword
http.proxyHost
http.proxyPort
http.nonProxyHosts
http.keepAlive
http.maxConnections

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 whether the 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, Exchange.HTTP_URI, on the message.

from("direct:start")
  .setHeader(Exchange.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. If the http4 endpoint is working in bridge mode, it will ignore the message header of Exchange.HTTP_URI.

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/PATCH/POST/PUT/DELETE/HEAD/OPTIONS/TRACE) to the HTTP producer

Using the http PATCH method

The http PATCH method is supported starting with Camel 2.11.3 / 2.12.1.

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 timeout - SO_TIMEOUT

See the HttpSOTimeoutTest unit test.

Since Camel 2.13.0: See the updated HttpSOTimeoutTest unit test.

Configuring a Proxy

Table of Contents

Using proxy settings outside of URI

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 System properties conflicts, you can set proxy configuration only from the CamelContext 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

Table of Contents

Sample with scheduled poll
URI Parameters from the endpoint URI
URI Parameters from the Message
Getting the Response Code

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

This 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(Exchange.HTTP_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 Exchange.HTTP_RESPONSE_CODE.

Exchange exchange = template.send("http4://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);

Disabling Cookies

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

Advanced Usage

Table of Contents

Setting up SSL for HTTP Client

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.

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("https4", 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 HttpClient. 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.

Using HTTPS to authenticate gotchas

An end user reported that he had problem with authenticating with HTTPS. The problem was eventually resolved by providing a custom configured org.apache.http.protocol.HttpContext:

1. Create a (Spring) factory for HttpContexts:

public class HttpContextFactory {

  private String httpHost = "localhost";
  private String httpPort = 9001;

  private BasicHttpContext httpContext = new BasicHttpContext();
  private BasicAuthCache authCache = new BasicAuthCache();
  private BasicScheme basicAuth = new BasicScheme();

  public HttpContext getObject() {
    authCache.put(new HttpHost(httpHost, httpPort), basicAuth);

    httpContext.setAttribute(ClientContext.AUTH_CACHE, authCache);

    return httpContext;
  }

  // getter and setter
}

2. Declare an HttpContext in the Spring application context file:

<bean id="myHttpContext" factory-bean="httpContextFactory" factory-method="getObject"/>

3. Reference the context in the http4 URL:

<to uri="https4://myhostname.com:443/myURL?httpContext=myHttpContext"/>

Using different SSLContextParameters

The HTTP4 component only support one instance of org.apache.camel.util.jsse.SSLContextParameters per component. If you need to use 2 or more different instances, then you need to setup multiple HTTP4 components as shown below. Where we have 2 components, each using their own instance of sslContextParameters property.

<bean id="http4-foo" class="org.apache.camel.component.http4.HttpComponent">
   <property name="sslContextParameters" ref="sslContextParams1"/>
   <property name="x509HostnameVerifier" ref="hostnameVerifier"/>
</bean>

<bean id="http4-bar" class="org.apache.camel.component.http4.HttpComponent">
   <property name="sslContextParameters" ref="sslContextParams2"/>
   <property name="x509HostnameVerifier" ref="hostnameVerifier"/>
</bean>