Restlet Component

The Restlet component provides Restlet based endpoints for consuming and producing RESTful resources.

Maven users will need to add the following dependency to their pom.xml for this component:

URI format

Format of restletUrl:

Restlet promotes decoupling of protocol and application concerns. The reference implementation of Restlet Engine supports a number of protocols. However, we have tested the HTTP protocol only. The default port is port 80. We do not automatically switch default port based on the protocol yet.

You can append query options to the URI in the following format, ?option=value&option=value&...

 

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We have received a report about drop in performance in camel-restlet in Camel 2.14.0 and 2.14.1. We have reported this to the Restlet team in issue 996. To remedy the issue then from Camel 2.14.2 onwards you can set synchronous=true as option on the endpoint uris, Or set it on the RestletComponent as a global option so all endpoints inherit this option.

 

Options

Name

Default Value

Description

headerFilterStrategy=#refName

An instance of RestletHeaderFilterStrategy

Use the # notation (headerFilterStrategy=#refName) to reference a header filter strategy in the Camel Registry. The strategy will be plugged into the restlet binding if it is HeaderFilterStrategyAware.

restletBinding=#refName

An instance of DefaultRestletBinding

The bean ID of a RestletBinding object in the Camel Registry.

restletMethod

GET

On a producer endpoint, specifies the request method to use. On a consumer endpoint, specifies that the endpoint consumes only restletMethod requests. The string value is converted to org.restlet.data.Method by the Method.valueOf(String) method.

restletMethods

None

Consumer only Specify one or more methods separated by commas (e.g. restletMethods=post,put) to be serviced by a restlet consumer endpoint. If both restletMethod and restletMethods options are specified, the restletMethod setting is ignored.

restletRealm=#refName

null

The bean ID of the Realm Map in the Camel Registry.

restletUriPatterns=#refName

None

Consumer only Specify one ore more URI templates to be serviced by a restlet consumer endpoint, using the # notation to reference a List<String> in the Camel Registry. If a URI pattern has been defined in the endpoint URI, both the URI pattern defined in the endpoint and the restletUriPatterns option will be honored.

throwExceptionOnFailure (2.6 or later)

true

*Producer only * Throws exception on a producer failure.

connectionTimeout

300000

Since Camel 2.12.3 Producer only The Client will give up connection if the connection is timeout, 0 for unlimited wait.

socketTimeout

300000

Since Camel 2.12.3 Producer only The Client socket receive timeout, 0 for unlimited wait.

disableStreamCachefalseCamel 2.14: Determines whether or not the raw input stream from Jetty 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 Jetty 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. DefaultRestletBinding 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.

Component Options

The Restlet component can be configured with the following options. Notice these are component options and cannot be configured on the endpoint, see further below for an example.

Name

Default Value

Description

controllerDaemon

true

Camel 2.10: Indicates if the controller thread should be a daemon (not blocking JVM exit).

controllerSleepTimeMs

100

Camel 2.10: Time for the controller thread to sleep between each control.

inboundBufferSize

8192

Camel 2.10: The size of the buffer when reading messages.

minThreads

1

Camel 2.10: Minimum threads waiting to service requests.

maxThreads

10

Camel 2.10: Maximum threads that will service requests.

lowThreads8Camel 2.13: Number of worker threads determining when the connector is considered overloaded.
maxQueued0Camel 2.13: Maximum number of calls that can be queued if there aren't any worker thread available to service them. If the value is '0', then no queue is used and calls are rejected if no worker thread is immediately available. If the value is '-1', then an unbounded queue is used and calls are never rejected.

maxConnectionsPerHost

-1

Camel 2.10: Maximum number of concurrent connections per host (IP address).

maxTotalConnections

-1

Camel 2.10: Maximum number of concurrent connections in total.

outboundBufferSize

8192

Camel 2.10: The size of the buffer when writing messages.

persistingConnections

true

Camel 2.10: Indicates if connections should be kept alive after a call.

pipeliningConnections

false

Camel 2.10: Indicates if pipelining connections are supported.

threadMaxIdleTimeMs

60000

Camel 2.10: Time for an idle thread to wait for an operation before being collected.

useForwardedForHeader

false

Camel 2.10: Lookup the "X-Forwarded-For" header supported by popular proxies and caches and uses it to populate the Request.getClientAddresses() method result. This information is only safe for intermediary components within your local network. Other addresses could easily be changed by setting a fake header and should not be trusted for serious security checks.

reuseAddress

true

Camel 2.10.5/2.11.1: Enable/disable the SO_REUSEADDR socket option. See java.io.ServerSocket#reuseAddress property for additional details.

disableStreamCachefalseCamel 2.14: Determines whether or not the raw input stream from Jetty 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 Jetty 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. DefaultRestletBinding 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.

Message Headers

Name

Type

Description

Content-Type

String

Specifies the content type, which can be set on the OUT message by the application/processor. The value is the content-type of the response message. If this header is not set, the content type is based on the object type of the OUT message body. In Camel 2.3 onward, if the Content-Type header is specified in the Camel IN message, the value of the header determine the content type for the Restlet request message.   Otherwise, it is defaulted to "application/x-www-form-urlencoded'. Prior to release 2.3, it is not possible to change the request content type default.

CamelAcceptContentType

String

Since Camel 2.9.3, 2.10.0: The HTTP Accept request header.

CamelHttpMethod

String

The HTTP request method. This is set in the IN message header.

CamelHttpQuery

String

The query string of the request URI. It is set on the IN message by DefaultRestletBinding when the restlet component receives a request.

CamelHttpResponseCode

String or Integer

The response code can be set on the OUT message by the application/processor. The value is the response code of the response message. If this header is not set, the response code is set by the restlet runtime engine.

CamelHttpUri

String

The HTTP request URI. This is set in the IN message header.

CamelRestletLogin

String

Login name for basic authentication. It is set on the IN message by the application and gets filtered before the restlet request header by Camel.

CamelRestletPassword

String

Password name for basic authentication. It is set on the IN message by the application and gets filtered before the restlet request header by Camel.

CamelRestletRequest

Request

Camel 2.8: The org.restlet.Request object which holds all request details.

CamelRestletResponse

Response

Camel 2.8: The org.restlet.Response object. You can use this to create responses using the API from Restlet. See examples below.

org.restlet.*

 

Attributes of a Restlet message that get propagated to Camel IN headers.

cache-control

String or List<CacheDirective>

Camel 2.11: User can set the cache-control with the String value or the List of CacheDirective of Restlet from the camel message header.

Message Body

Camel will store the restlet response from the external server on the OUT body. All headers from the IN message will be copied to the OUT message, so that headers are preserved during routing.

Samples

Restlet Endpoint with Authentication

The following route starts a restlet consumer endpoint that listens for POST requests on http://localhost:8080. The processor creates a response that echoes the request body and the value of the id header.

The restletRealm setting in the URI query is used to look up a Realm Map in the registry. If this option is specified, the restlet consumer uses the information to authenticate user logins. Only authenticated requests can access the resources. In this sample, we create a Spring application context that serves as a registry. The bean ID of the Realm Map should match the restletRealmRef.

The following sample starts a direct endpoint that sends requests to the server on http://localhost:8080 (that is, our restlet consumer endpoint).

That is all we need. We are ready to send a request and try out the restlet component:

The sample client sends a request to the direct:start-auth endpoint with the following headers:

  • CamelRestletLogin (used internally by Camel)
  • CamelRestletPassword (used internally by Camel)
  • id (application header)

Note

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org.apache.camel.restlet.auth.login and org.apache.camel.restlet.auth.password will not be propagated as Restlet header.

The sample client gets a response like the following:

Single restlet endpoint to service multiple methods and URI templates

It is possible to create a single route to service multiple HTTP methods using the restletMethods option. This snippet also shows how to retrieve the request method from the header:

In addition to servicing multiple methods, the next snippet shows how to create an endpoint that supports multiple URI templates using the restletUriPatterns option. The request URI is available in the header of the IN message as well. If a URI pattern has been defined in the endpoint URI (which is not the case in this sample), both the URI pattern defined in the endpoint and the restletUriPatterns option will be honored.

The restletUriPatterns=#uriTemplates option references the List<String> bean defined in the Spring XML configuration.

Using Restlet API to populate response

Available as of Camel 2.8

You may want to use the org.restlet.Response API to populate the response. This gives you full access to the Restlet API and fine grained control of the response. See the route snippet below where we generate the response from an inlined Camel Processor:

Generating response using Restlet Response API

Configuring max threads on component

To configure the max threads options you must do this on the component, such as:

Using the Restlet servlet within a webapp

Available as of Camel 2.8
There are three possible ways to configure a Restlet application within a servlet container and using the subclassed SpringServerServlet enables configuration within Camel by injecting the Restlet Component.

Use of the Restlet servlet within a servlet container enables routes to be configured with relative paths in URIs (removing the restrictions of hard-coded absolute URIs) and for the hosting servlet container to handle incoming requests (rather than have to spawn a separate server process on a new port).

To configure, add the following to your camel-context.xml;

And add this to your web.xml;

You will then be able to access the deployed route at http://localhost:8080/mywebapp/rs/demo/1234 where;

localhost:8080 is the server and port of your servlet container
mywebapp is the name of your deployed webapp
Your browser will then show the following content;

You will need to add dependency on the Spring extension to restlet which you can do in your Maven pom.xml file:

And you would need to add dependency on the restlet maven repository as well:

See Also

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