The servlet: component provides HTTP based endpoints for consuming HTTP requests that arrive at a HTTP endpoint that is bound to a published Servlet.
Maven users will need to add the following dependency to their
pom.xml for this component:
Servlet is stream based, which means the input it receives is submitted to Camel as a stream. That means you will only be able to read the content of the stream once. If you find a situation where the message body appears to be empty or you need to access the data multiple times (eg: doing multicasting, or redelivery error handling) you should use Stream caching or convert the message body to a
String which is safe to be read multiple times.
You can append query options to the URI in the following format,
Reference to an
|Camel 2.16: Reference to an |
Whether or not the
Specifies the servlet name that the servlet endpoint will bind to. This name should match the name you define in
|Camel 2.11: Consumer only: Used to only allow consuming if the HttpMethod matches, such as GET/POST/PUT etc. From Camel 2.15 onwards multiple methods can be specified separated by comma.|
Camel will apply the same Message Headers as the HTTP component.
Camel will also populate all
request.headers. For example, if a client request has the URL,
http://myserver/myserver?orderid=123, the exchange will contain a header named
orderid with the value 123.
You can consume only from endpoints generated by the Servlet component. Therefore, it should be used only as input into your Camel routes. To issue HTTP requests against other HTTP endpoints, use the HTTP Component
Available as of Camel 2.18
You can configure the servlet with an init-param to turn on async mode when using a Servlet 3.x container. There is a sample XML configuration below:
If you put the Camel JARs such as
camel-servlet, etc. in the boot classpath of your application server (eg usually in its lib directory), then mind that the servlet mapping list is now shared between multiple deployed Camel application in the app server.
Mind that putting Camel JARs in the boot classpath of the application server is generally not best practice!
So in those situations you must define a custom and unique servlet name in each of your Camel application, eg in the
And in your Camel endpoints then include the servlet name as well
From Camel 2.11 onwards Camel will detect this duplicate and fail to start the application. You can control to ignore this duplicate by setting the servlet init-parameter ignoreDuplicateServletName to true as follows:
But its strongly advised to use unique servlet-name for each Camel application to avoid this duplication clash, as well any unforeseen side-effects.
From Camel 2.7 onwards it's easier to use Servlet in Spring web applications. See Servlet Tomcat Example for details.
In this sample, we define a route that exposes a HTTP service at
First, you need to publish the CamelHttpTransportServlet through the normal Web Container, or OSGi Service.
Web.xml file to publish the CamelHttpTransportServlet as follows:
Since we are binding the Http transport with a published servlet, and we don't know the servlet's application context path, the
camel-servlet endpoint uses the relative path to specify the endpoint's URL. A client can access the
camel-servlet endpoint through the servlet publish address:
("http://localhost:8080/camel/services") + RELATIVE_PATH("/hello").
See Servlet Tomcat Example
When using the Servlet component in a Camel/Spring application it's often required to load the Spring ApplicationContext after the Servlet component has started. This can be accomplished by using Spring's
ContextLoaderServlet instead of
ContextLoaderListener. In that case you'll need to start
ContextLoaderServlet after CamelHttpTransportServlet like this:
From Camel 2.6.0, you can publish the CamelHttpTransportServlet as an OSGi service with help of SpringDM like this.
Activator to publish the CamelHttpTransportServlet on the OSGi platform