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Chapter 63. HTTP4
HTTP4 Component
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.
HttpComponent Options
Name | Default Value | Description |
---|---|---|
maxTotalConnections
|
200
|
The maximum number of connections. |
connectionsPerRoute
|
20
|
The maximum number of connections per route. |
cookieStore
|
null
|
Camel 2.11.2/2.12.0: 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 cookies shouldn't be stored as we are just bridging (eg acting as a proxy).
|
httpClientConfigurer
|
null
|
Reference to a org.apache.camel.component.http.HttpClientConfigurer in the Registry.
|
clientConnectionManager
|
null
|
To use a custom org.apache.http.conn.ClientConnectionManager .
|
httpBinding
|
null
|
To use a custom org.apache.camel.component.http.HttpBinding .
|
httpContext
|
null
|
Camel 2.9.2: To use a custom org.apache.http.protocol.HttpContext when executing requests.
|
sslContextParameters
|
null
|
Camel 2.8: To use a custom org.apache.camel.util.jsse.SSLContextParameters . See Using the JSSE Configuration Utility.
|
x509HostnameVerifier
|
BrowserCompatHostnameVerifier
|
Camel 2.7: You can refer to a different org.apache.http.conn.ssl.X509HostnameVerifier instance in the Registry such as org.apache.http.conn.ssl.StrictHostnameVerifier or org.apache.http.conn.ssl.AllowAllHostnameVerifier .
|
connectionTimeToLive
|
-1
|
Camel 2.11.0: The time for connection to live, the time unit is millisecond, the default value is always keep alive. |
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 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 fault responses back. Also if set to true HttpProducer and CamelServlet will skip the gzip processing if the content-encoding is "gzip". |
clearExpiredCookies
|
true
|
Camel 2.11.2/2.12.0: 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. |
cookieStore
|
null
|
Camel 2.11.2/2.12.0: 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 cookies shouldn't be stored as we are just bridging (eg acting as a proxy).
|
disableStreamCache
|
false
|
DefaultHttpBinding will copy the request input stream into a stream cache and put it into the message body if this option is false to support multiple reads, otherwise DefaultHttpBinding will set the request input stream directly in the message body. |
headerFilterStrategy
|
null
|
Camel 2.10.4: Reference to a instance of org.apache.camel.spi.HeaderFilterStrategy in the Registry. t will be used to apply the custom headerFilterStrategy on the new create HttpEndpoint.
|
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
|
To use a custom org.apache.camel.component.http.HttpBinding .
|
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
|
Reference to a org.apache.camel.component.http.HttpClientConfigurer in the Registry.
|
httpContextRef
|
null
|
Deprecated and will be removed in Camel 3.0:Camel 2.9.2: Reference to a custom org.apache.http.protocol.HttpContext in the Registry. Use the httpContext option instead.
|
httpContext
|
null
|
Camel 2.9.2: To use a custom org.apache.http.protocol.HttpContext when executing requests.
|
httpClient.XXX
|
null
|
Setting options on the BasicHttpParams. For instance
httpClient.soTimeout=5000 will set the SO_TIMEOUT to 5 seconds. Look on the setter methods of the following parameter beans for a complete reference: AuthParamBean, ClientParamBean, ConnConnectionParamBean, ConnRouteParamBean, CookieSpecParamBean, HttpConnectionParamBean and HttpProtocolParamBean
Since Camel 2.13.0:
httpClient is changed to configure the HttpClientBuilder and RequestConfig.Builder, please check out API document for a complete reference.
|
clientConnectionManager
|
null
|
To use a custom org.apache.http.conn.ClientConnectionManager .
|
transferException
|
false
|
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.
|
sslContextParametersRef
|
null
|
Deprecated and will be removed in Camel 3.0:Camel 2.8: Reference to a org.apache.camel.util.jsse.SSLContextParameters in the Registry. 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. See further below for more details. See Using the JSSE Configuration Utility. Use the sslContextParameters option instead.
|
sslContextParameters
|
null
|
Camel 2.11.1: Reference to a org.apache.camel.util.jsse.SSLContextParameters in the Registry. 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. See further below for more details. See Using the JSSE Configuration Utility.
|
x509HostnameVerifier
|
BrowserCompatHostnameVerifier
|
Camel 2.7: You can refer to a different org.apache.http.conn.ssl.X509HostnameVerifier instance in the Registry such as org.apache.http.conn.ssl.StrictHostnameVerifier or org.apache.http.conn.ssl.AllowAllHostnameVerifier .
|
urlRewrite
|
null
|
Camel 2.11:Producer only Refers to a custom org.apache.camel.component.http4.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.
|
maxTotalConnections
|
null
|
Camel 2.14: The maximum number of total connections that the connection manager has. If this option is not set, camel will use the component's setting instead.
|
connectionsPerRoute
|
null
|
Camel 2.14: The maximum number of connections per route. If this option is not set, camel will use the component's setting instead.
|
authenticationPreemptive
|
false
|
Camel 2.11.3/2.12.2: If this option is true, camel-http4 sends preemptive basic authentication to the server.
|
The following authentication options can also be set on the HttpEndpoint:
Setting Basic Authentication and Proxy
Before Camel 2.8.0
Name | Default Value | 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 |
Name | Default Value | Description |
authUsername
|
null
|
Username for authentication |
authPassword
|
null
|
Password for authentication |
authDomain
|
null
|
The domain name for authentication |
authHost
|
null
|
The host name authentication |
proxyAuthHost
|
null
|
The proxy host name |
proxyAuthPort
|
null
|
The proxy port number |
proxyAuthScheme
|
null
|
The proxy scheme, will fallback and use the scheme from the endpoint if not configured. |
proxyAuthUsername
|
null
|
Username for proxy authentication |
proxyAuthPassword
|
null
|
Password for proxy authentication |
proxyAuthDomain
|
null
|
The proxy domain name |
proxyAuthNtHost
|
null
|
The proxy Nt host name |
Message Headers
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. |
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 .
|
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.throwExceptionOnFailureThe option,throwExceptionOnFailure
, can be set tofalse
to prevent theHttpOperationFailedException
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/POST/PUT/DELETE/HEAD/OPTIONS/TRACE) to the HTTP producer
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.
Configuring a Proxy
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
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
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.
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>