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Chapter 150. HTTP Component (deprecated)

Available as of Camel version 1.0

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: 

<dependency>
    <groupId>org.apache.camel</groupId>
    <artifactId>camel-http</artifactId>
    <version>x.x.x</version>
    <!-- use the same version as your Camel core version -->
</dependency>

150.1. URI format

http:hostname[:port][/resourceUri][?param1=value1][&param2=value2]

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

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 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

150.2. 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 

from("direct:start")
  .to("http://myhost/mypath");
<from uri="direct:start"/>
<to uri="http://oldhost"/>

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 

from("direct:start")
  .setHeader(Exchange.HTTP_URI, simple("http://myserver/orders/${header.orderId}"))
  .to("http://dummyhost");

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

Java DSL 

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

Set the HTTP request method to POST

Java DSL

Spring DSL 

from("direct:start")
  .setHeader(Exchange.HTTP_METHOD, constant("POST"))
  .to("http://www.google.com");
<from uri="direct:start"/>
<setHeader headerName="CamelHttpMethod">
  <constant>POST</constant>
</setHeader>
<to uri="http://www.google.com"/>
<to uri="mock:results"/>

150.3. Http Options

The HTTP component supports 8 options, which are listed below.

NameDescriptionDefaultType

httpClientConfigurer (advanced)

To use the custom HttpClientConfigurer to perform configuration of the HttpClient that will be used.

 

HttpClientConfigurer

httpConnectionManager (advanced)

To use a custom HttpConnectionManager to manage connections

 

HttpConnectionManager

httpBinding (producer)

To use a custom HttpBinding to control the mapping between Camel message and HttpClient.

 

HttpBinding

httpConfiguration (producer)

To use the shared HttpConfiguration as base configuration.

 

HttpConfiguration

allowJavaSerialized Object (producer)

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.

false

boolean

useGlobalSslContext Parameters (security)

Enable usage of global SSL context parameters.

false

boolean

headerFilterStrategy (filter)

To use a custom org.apache.camel.spi.HeaderFilterStrategy to filter header to and from Camel message.

 

HeaderFilterStrategy

resolveProperty Placeholders (advanced)

Whether the component should resolve property placeholders on itself when starting. Only properties which are of String type can use property placeholders.

true

boolean

The HTTP endpoint is configured using URI syntax: 

http:httpUri

with the following path and query parameters:

150.3.1. Path Parameters (1 parameters):

NameDescriptionDefaultType

httpUri

Required The url of the HTTP endpoint to call.

 

URI

150.3.2. Query Parameters (38 parameters):

NameDescriptionDefaultType

disableStreamCache (common)

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.

false

boolean

headerFilterStrategy (common)

To use a custom HeaderFilterStrategy to filter header to and from Camel message.

 

HeaderFilterStrategy

httpBinding (common)

To use a custom HttpBinding to control the mapping between Camel message and HttpClient.

 

HttpBinding

bridgeEndpoint (producer)

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.

false

boolean

chunked (producer)

If this option is false the Servlet will disable the HTTP streaming and set the content-length header on the response

true

boolean

connectionClose (producer)

Specifies whether a Connection Close header must be added to HTTP Request. By default connectionClose is false.

false

boolean

copyHeaders (producer)

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).

true

boolean

httpMethod (producer)

Configure the HTTP method to use. The HttpMethod header cannot override this option if set.

 

HttpMethods

ignoreResponseBody (producer)

If this option is true, The http producer won’t read response body and cache the input stream

false

boolean

preserveHostHeader (producer)

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

false

boolean

throwExceptionOnFailure (producer)

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.

true

boolean

transferException (producer)

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.

false

boolean

cookieHandler (producer)

Configure a cookie handler to maintain a HTTP session

 

CookieHandler

okStatusCodeRange (producer)

The status codes which are considered a success response. The values are inclusive. Multiple ranges can be defined, separated by comma, e.g. 200-204,209,301-304. Each range must be a single number or from-to with the dash included.

200-299

String

urlRewrite (producer)

Deprecated 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

 

UrlRewrite

httpClientConfigurer (advanced)

Register a custom configuration strategy for new HttpClient instances created by producers or consumers such as to configure authentication mechanisms etc

 

HttpClientConfigurer

httpClientOptions (advanced)

To configure the HttpClient using the key/values from the Map.

 

Map

httpConnectionManager (advanced)

To use a custom HttpConnectionManager to manage connections

 

HttpConnectionManager

httpConnectionManager Options (advanced)

To configure the HttpConnectionManager using the key/values from the Map.

 

Map

mapHttpMessageBody (advanced)

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.

true

boolean

mapHttpMessageFormUrl EncodedBody (advanced)

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.

true

boolean

mapHttpMessageHeaders (advanced)

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.

true

boolean

synchronous (advanced)

Sets whether synchronous processing should be strictly used, or Camel is allowed to use asynchronous processing (if supported).

false

boolean

proxyAuthDomain (proxy)

Proxy authentication domain to use with NTML

 

String

proxyAuthHost (proxy)

Proxy authentication host

 

String

proxyAuthMethod (proxy)

Proxy authentication method to use

 

String

proxyAuthPassword (proxy)

Proxy authentication password

 

String

proxyAuthPort (proxy)

Proxy authentication port

 

int

proxyAuthScheme (proxy)

Proxy authentication scheme to use

 

String

proxyAuthUsername (proxy)

Proxy authentication username

 

String

proxyHost (proxy)

Proxy hostname to use

 

String

proxyPort (proxy)

Proxy port to use

 

int

authDomain (security)

Authentication domain to use with NTML

 

String

authHost (security)

Authentication host to use with NTML

 

String

authMethod (security)

Authentication methods allowed to use as a comma separated list of values Basic, Digest or NTLM.

 

String

authMethodPriority (security)

Which authentication method to prioritize to use, either as Basic, Digest or NTLM.

 

String

authPassword (security)

Authentication password

 

String

authUsername (security)

Authentication username

 

String

150.4. Spring Boot Auto-Configuration

The component supports 9 options, which are listed below.

NameDescriptionDefaultType

camel.component.http.allow-java-serialized-object

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.

false

Boolean

camel.component.http.enabled

Enable http component

true

Boolean

camel.component.http.header-filter-strategy

To use a custom org.apache.camel.spi.HeaderFilterStrategy to filter header to and from Camel message. The option is a org.apache.camel.spi.HeaderFilterStrategy type.

 

String

camel.component.http.http-binding

To use a custom HttpBinding to control the mapping between Camel message and HttpClient. The option is a org.apache.camel.http.common.HttpBinding type.

 

String

camel.component.http.http-client-configurer

To use the custom HttpClientConfigurer to perform configuration of the HttpClient that will be used. The option is a org.apache.camel.component.http.HttpClientConfigurer type.

 

String

camel.component.http.http-configuration

To use the shared HttpConfiguration as base configuration. The option is a org.apache.camel.http.common.HttpConfiguration type.

 

String

camel.component.http.http-connection-manager

To use a custom HttpConnectionManager to manage connections. The option is a org.apache.commons.httpclient.HttpConnectionManager type.

 

String

camel.component.http.resolve-property-placeholders

Whether the component should resolve property placeholders on itself when starting. Only properties which are of String type can use property placeholders.

true

Boolean

camel.component.http.use-global-ssl-context-parameters

Enable usage of global SSL context parameters.

false

Boolean

150.5. Message Headers

NameTypeDescription

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_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.

150.6. 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.

150.7. 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.

150.8. 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

150.9. Which HTTP method will be used

The following algorithm is used to determine what HTTP method should be used:
1. Use method provided as endpoint configuration (httpMethod).
2. Use method provided in header (Exchange.HTTP_METHOD).
3. GET if query string is provided in header.
4. GET if endpoint is configured with a query string.
5. POST if there is data to send (body is not null).
6. GET otherwise.

150.10. How to get access to HttpServletRequest and HttpServletResponse

You can get access to these two using the Camel type converter system using 

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

150.11. Using client timeout - SO_TIMEOUT

See the unit test in Camel Jetty repository

150.12. More Examples

150.12.1. Configuring a Proxy

Java DSL 

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.

150.12.2. Using proxy settings outside of URI

Java DSL

Spring DSL 

 context.getProperties().put("http.proxyHost", "172.168.18.9");
 context.getProperties().put("http.proxyPort" "8080");
   <camelContext>
       <properties>
           <property key="http.proxyHost" value="172.168.18.9"/>
           <property key="http.proxyPort" value="8080"/>
      </properties>
   </camelContext>

Options on Endpoint will override options on the context.

150.13. Configuring charset

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

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

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

150.15. 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. 

   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);

150.16. 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.

150.17. Disabling Cookies

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

150.18. 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.

150.18.1. 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:

150.18.2. 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

150.18.3. 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.

150.18.4. 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. 

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);

ProtocolSocketFactory factory =
    new SSLContextParametersSecureProtocolSocketFactory(scp);

Protocol.registerProtocol("https",
        new Protocol(
        "https",
        factory,
        443));

from("direct:start")
        .to("https://mail.google.com/mail/").to("mock:results");

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: 

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 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.

150.19. See Also

  • Configuring Camel
  • Component
  • Endpoint
  • Getting Started
  • Jetty
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