HTTP Component

The http: 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:

URI format

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

camel-http vs camel-jetty

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You can only produce to endpoints generated by the HTTP 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 or the Servlet Component

Examples

Call the url with the body using POST and return response as out message. If body is null call URL using GET and return response as out message

Java DSL

Spring DSL

You can override the HTTP endpoint URI by adding a header. Camel will call the http://newhost. This is very handy for e.g. REST urls.

Java DSL

URI parameters can either be set directly on the endpoint URI or as a header

Java DSL

Set the HTTP request method to POST

Java DSL

Spring DSL

HttpEndpoint Options

Name

Default Value

Description

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 * throwExceptionOnFailure* 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

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

Deprecated and will be removed in Camel 3.0: Reference to a org.apache.camel.component.http.HttpBinding in the Registry. Use the httpBinding option instead.

httpBinding

null

Camel 2.3: Reference to a org.apache.camel.component.http.HttpBinding in the Registry.

httpClientConfigurerRef

null

Deprecated and will be removed in Camel 3.0: Reference to a org.apache.camel.component.http.HttpClientConfigurer in the Registry. Use the httpClientConfigurer option instead.

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

To use a custom org.apache.http.conn.ClientConnectionManager.

transferException

false

Camel 2.6: 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.

headerFilterStrategy

null

Camel 2.11: Reference to a instance of org.apache.camel.spi.HeaderFilterStrategy in the Registry. It will be used to apply the custom headerFilterStrategy on the new create HttpEndpoint.

urlRewrite

null

Camel 2.11: Producer only 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 UrlRewrite and How to use Camel as a HTTP proxy between a client and server.

Authentication and Proxy

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.

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.

httpConfiguration

null

To use a custom org.apache.camel.component.http.HttpConfiguration

HttpConfiguration contains all the options listed in the table above under the section HttpConfiguration - Setting Authentication and Proxy.

Message Headers

Name

Type

Description

Exchange.HTTP_URI

String

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

Exchange.HTTP_METHOD

String

HTTP Method / Verb to use (GET/POST/PUT/DELETE/HEAD/OPTIONS/TRACE)

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

The HttpServletRequest object.

Exchange.HTTP_SERVLET_RESPONSE

HttpServletResponse

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"

The header name above are constants. For the spring DSL you have to use the value of the constant instead of the name.

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

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    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

Using client timeout - SO_TIMEOUT

See the unit test in this link

More Examples

Configuring a Proxy

Java DSL

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

Using proxy settings outside of URI

Java DSL

Spring DSL

Options on Endpoint will override options on the context.

Configuring charset

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

Sample with scheduled poll

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

Getting the Response Code

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.

Using throwExceptionOnFailure=false to get any response back

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.

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.

Setting MaxConnectionsPerHost

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 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.

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

Using preemptive authentication

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

Accepting self signed certificates from remote server

See this link from a mailing list discussion with some code to outline how to do this with the Apache Commons HTTP API.

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.

The version of the Apache HTTP client used in this component resolves SSL/TLS information from a global "protocol" registry.  This component provides an implementation, org.apache.camel.component.http.SSLContextParametersSecureProtocolSocketFactory, of the HTTP client's protocol socket factory in order to support the use of the Camel JSSE Configuration utility.  The following example demonstrates how to configure the protocol registry and use the registered protocol information in a route.

Configuring Apache HTTP Client Directly

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:

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:

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

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

See Also

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