## Name

HTTP4 — provides endpoints for consuming external HTTP resources using Apache HttpClient 4.x

## Overview

The HTTP4 component provides HTTP based endpoints for consuming external HTTP resources as a client to call external servers using HTTP.

The HTTP4 component can only send messages to external resources. It should never be used as input into a route. To expose an HTTP endpoint via a HTTP server as input to a route, you can use the Jetty Component.

| Important
HTTP4 uses HttpClient 4.x while HTTP uses HttpClient 3.x.

## URI format

The URI format for an HTTP4 endpoint is:

    http(s)4:hostname[:port][/resourceUri][?options]

By default the port is set to `80` for HTTP and to `443` for HTTPS.

## Dependencies

Maven users will need to add a dependency on `camel-http4` 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>

## HttpEndpoint options

Table 24, “HTTP4 endpoint options” lists the options for an HTTP4 endpoint.

Table 24. HTTP4 endpoint options

Name | Default | Description
--- | --- | ---
`x509HostnameVerifier` | `BrowserCompatHostnameVerifier` [a] | Specifies an `X509HostnameVerifier`[a] instance in the registry.
`throwExceptionOnFailure` | `true` | Specifies if you want 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` | Specifies if the HttpProducer ignores the `Exchange.HTTP_URI` header, and use the endpoint's URI for request. If the option is `true`, HttpProducer and CamelServlet will skip the gzip processing if the content-encoding is `gzip`.
`disableStreamCache` | `false` | Specifies if the DefaultHttpBinding copies the request input stream directly into the message body. The default setting is to copy the request input stream into a stream cache and into the message body to support reading the message twice.
`httpBinding` | `null` | Specifies a reference to a `HttpBinding`[b] in the registry.
`httpClientConfigurer` | `null` | Specifies a reference to a `HttpClientConfigurer` [b] in the registry.
`httpClient.`XXX`` |  | Specifies options to set on the BasicHttpParams. For instance, `httpClient.soTimeout=5000` will set the `SO_TIMEOUT` to 5 seconds.
`clientConnectionManager` | `null` | Specifies a custom `ClientConnectionManager` [c].
`transferException` | `false` | Specifies if a producer will throw the received exception if the received exception was serialized in the response as a `application/x-java-serialized-object` content type.
`maxTotalConnections` | `200` | Specifies the maximum number of connections.
`connectionsPerRoute` | `20` | Specifies the maximum number of connections per route.
[a] In the package org.apache.http.conn.ssl. [b] In the org.apache.camel.component.http package. [c] In the org.apache.http.conn package.

## Authentication and proxy options

The following authentication options can also be set on the HTTP4 endpoint:

Name | Default | 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

## HttpComponent options

The following options can be set on the HttpComponent:

Name | Default | 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` | To use a custom `org.apache.http.conn.ssl.X509HostnameVerifier`

## Message headers

The following `Exchange` properties are recognized by HTTP4 endpoints:

Table 25. HTTP Exchange properties

Name | Type | Description
--- | --- | ---
`CamelHttpUri` | `String` | Specifies the URI to call. The value if this header will override the URI set directly on the endpoint.
`CamelHttpPath` | `String` | Specifies the Request URI's path. The header will be used to build the request URI with the HTTP_URI. If the path is start with `/`, the HTTP producer will try to find the relative path based on the `HTTP_BASE_URI` header or the `exchange.getFromEndpoint().getEndpointUri()` method.
`CamelHttpQuery` | `String` | Specifies the URI parameters. The value of this header overrides the URI parameters set directly on the endpoint.
`CamelHttpResponseCode` | `int` | Specifies the HTTP response code from the external server.
`CamelHttpCharacterEncoding` | `String` | Specifies the character encoding.
`Content-Type` | `String` | Specifies the HTTP content type. This header is populated on both the IN and OUT message to provide a content type, such as `text/html`.
`Content-Encoding` | `String` | Specifies the HTTP content encoding. This header is populated on both the IN and OUT message to provide a content encoding, such as `gzip`.
`CamelHttpServletRequest` | `String` | Specifies the `HttpServletRequest` object.
`CamelHttpServletResponse` | `String` | Specifies the `HttpServletResponse` object.
`CamelHttpProtocolVersion` | `String` | Specifies the HTTP protocol version. If you do not specify the header, HttpProducer will use the default value `HTTP/1.1`.

## Message Body

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.

## Response code

Apache Camel will handle according to the HTTP response code:

- Response code is in the range 100..299, Apache Camel regards it as a success response.

- Response code is in the range 300..399, Apache Camel regards it as a redirection response and will throw a `HttpOperationFailedException` with the information.

- Response code is 400+, Apache Camel regards it as an external server failure and will throw a `HttpOperationFailedException` with the information.

  | Note
  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.

## Related topics

HTTP
Jetty
BasicHttpParams