org.restlet

Class Component

java.lang.Object

org.restlet.Restlet

org.restlet.Component

All Implemented Interfaces:

Uniform

public class Component
extends Restlet

Restlet managing a set of Connectors, VirtualHosts, Services and Applications. Applications are expected to be directly attached to virtual hosts or to the internal router (see RIAP pseudo-protocol for usage). Components also expose several services: access logging and status setting.

From an architectural point of view, here is the REST definition: "A component is an abstract unit of software instructions and internal state that provides a transformation of data via its interface." Roy T. Fielding

The configuration of a Component can be done programmatically or by using a XML document. There are dedicated constructors that accept either an URI reference to such XML document or a representation of such XML document, allowing easy configuration of the list of supported client and server connectors as well as services. In addition, you can add and configure virtual hosts (including the default one). Finally, you can attach applications either using their fully qualified class name or by pointing to a descriptor document (at this time only WADL description are supported, see the WADL Restlet extension for details).

The XML Schema of the configuration files is available both online and inside the API JAR under the "org.restlet.Component.xsd" name. Here is a sample of XML configuration:

 <?xml version="1.0"?>
 <component xmlns="http://restlet.org/schemas/2.0/Component">
    <client protocol="CLAP" />
    <client protocol="FILE" />
    <client protocols="HTTP HTTPS" />
    <server protocols="HTTP HTTPS" />
 
    <defaultHost>
       <attach uriPattern="/abcd/{xyz}" 
                  targetClass="org.restlet.test.MyApplication" />
       <attach uriPattern="/efgh/{xyz}"
                  targetDescriptor="clap://class/org/restlet/test/MyApplication.wadl" />
    </defaultHost>
 </component>
 

Components also have useful services associated. They are all enabled by default and are available as properties that can be eventually overridden:

• "logService" to configure access logging.
• "statusService" to provide common representations for exception status.
• "taskService" to run tasks asynchronously.

Concurrency note: instances of this class or its subclasses can be invoked by several threads at the same time and therefore must be thread-safe. You should be especially careful when storing state in member variables.

Author:

Jerome Louvel

See Also:

Source dissertation

Constructor Summary

Constructors

Constructor and Description
Component() Constructor.
Component(Reference xmlConfigRef) Deprecated. Use XML support in the Spring extension instead.
Component(Representation xmlConfigRepresentation) Deprecated. Use XML support in the Spring extension instead.
Component(java.lang.String xmlConfigurationRef) Deprecated. Use XML support in the Spring extension instead.

Method Summary

Modifier and Type	Method and Description
ClientList	getClients() Returns a modifiable list of client connectors.
VirtualHost	getDefaultHost() Returns the default virtual host.
java.util.List<VirtualHost>	getHosts() Returns the modifiable list of virtual hosts.
Router	getInternalRouter() Returns the private internal router where Restlets like Applications can be attached.
LogService	getLogService() Returns the global log service.
Realm	getRealm(java.lang.String name) Finds the realm with the given name.
java.util.List<Realm>	getRealms() Returns the modifiable list of security realms.
ServerList	getServers() Returns the modifiable list of server connectors.
ServiceList	getServices() Returns the modifiable list of services.
StatusService	getStatusService() Deprecated. Use Application.getStatusService() instead.
TaskService	getTaskService() Returns a task service to run concurrent tasks.
void	handle(Request request, Response response) Handles a call.
static void	main(java.lang.String[] args) Deprecated. Use XML support in the Spring extension instead.
void	setClients(ClientList clients) Sets the modifiable list of client connectors.
void	setContext(Context context) Sets the context.
void	setDefaultHost(VirtualHost defaultHost) Sets the default virtual host.
void	setHosts(java.util.List<VirtualHost> hosts) Sets the modifiable list of virtual hosts.
void	setInternalRouter(Router internalRouter) Sets the private internal router were Restlets like Applications can be attached.
void	setLogService(LogService logService) Sets the global log service.
void	setRealms(java.util.List<Realm> realms) Sets the list of realms.
void	setServers(ServerList servers) Sets the modifiable list of server connectors.
void	setStatusService(StatusService statusService) Deprecated. Use Application.setStatusService(StatusService) instead.
void	setTaskService(TaskService taskService) Sets the task service.
void	start() Starts the component.
protected void	startClients() Starts the client connectors.
protected void	startHelper() Starts the internal helper allowing incoming requests to be served.
protected void	startRealms() Starts the realms.
protected void	startRouters() Starts the virtual hosts and the internal router.
protected void	startServers() Starts the server connectors.
protected void	startServices() Starts the associated services.
void	stop() Stops the component.
protected void	stopClients() Stops the client connectors.
protected void	stopHelper() Stops the internal helper allowing incoming requests to be served.
protected void	stopRealms() Stops the realms.
protected void	stopRouters() Stops the virtual hosts and the internal router.
protected void	stopServers() Stops the server connectors.
protected void	stopServices() Stops the associated services.
void	updateHosts() Updates the component to take into account changes to the virtual hosts.

Methods inherited from class org.restlet.Restlet

createFinder, finalize, getApplication, getAuthor, getContext, getDescription, getFinderClass, getLogger, getName, getOwner, handle, handle, handle, isStarted, isStopped, setAuthor, setDescription, setFinderClass, setName, setOwner

Methods inherited from class java.lang.Object

clone, equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

Component

public Component()

Constructor.

Component

@Deprecated
public Component(Reference xmlConfigRef)

Deprecated. Use XML support in the Spring extension instead.

Constructor with the reference to the XML configuration file.

Parameters:

xmlConfigRef - The URI reference to the XML configuration file.

Component

@Deprecated
public Component(Representation xmlConfigRepresentation)

Deprecated. Use XML support in the Spring extension instead.

Constructor with the representation of the XML configuration file.

Parameters:

xmlConfigRepresentation - The representation of the XML configuration file.

Component

@Deprecated
public Component(java.lang.String xmlConfigurationRef)

Deprecated. Use XML support in the Spring extension instead.

Constructor with the URI reference to the XML configuration file.

Parameters:

xmlConfigurationRef - The URI reference to the XML configuration file.

Method Detail

main

@Deprecated
public static void main(java.lang.String[] args)
                             throws java.lang.Exception

Deprecated. Use XML support in the Spring extension instead.

Used as bootstrap for configuring and running a component in command line. Just provide as first and unique parameter the URI to the XML file. Note that relative paths are accepted.

Parameters:

args - The list of in-line parameters.

Throws:

java.lang.Exception

getClients

public ClientList getClients()

Returns a modifiable list of client connectors.

Returns:

A modifiable list of client connectors.

getDefaultHost

public VirtualHost getDefaultHost()

Returns the default virtual host.

Returns:

The default virtual host.

getHosts

public java.util.List<VirtualHost> getHosts()

Returns the modifiable list of virtual hosts. Note that the order of virtual hosts in this list will be used to check the first one that matches.

Returns:

The modifiable list of virtual hosts.

getInternalRouter

public Router getInternalRouter()

Returns the private internal router where Restlets like Applications can be attached. Those Restlets can be addressed via the Protocol.RIAP (Restlet Internal Access Protocol) client connector. This is used to manage private, internal and optimized access to local applications.

The first use case is the modularization of a large application into modules or layers. This can also be achieved using the Context.getServerDispatcher() method, but the internal router is easily addressable via an URI scheme and can be fully private to the current Component.

The second use case is the composition/mash-up of several representations via the org.restlet.ext.xml.Transformer class for example. For this you can leverage the XPath's document() function or the XSLT's include and import elements with RIAP URIs.

Returns:

The private internal router.

getLogService

public LogService getLogService()

Returns the global log service. On the first call, if no log service was defined via the setLogService(LogService) method, then a default logger service is created. This service will be enabled by default and has a logger name composed the "org.restlet." prefix followed by the simple component class name (without packages), followed by the ".LogService" suffix.

Returns:

The global log service.

getRealm

public Realm getRealm(java.lang.String name)

Finds the realm with the given name.

Parameters:

name - The name.

Returns:

The realm found or null.

getRealms

public java.util.List<Realm> getRealms()

Returns the modifiable list of security realms.

Returns:

The modifiable list of security realms.

getServers

public ServerList getServers()

Returns the modifiable list of server connectors.

Returns:

The modifiable list of server connectors.

getServices

public ServiceList getServices()

Returns the modifiable list of services.

Returns:

The modifiable list of services.

getStatusService

@Deprecated
public StatusService getStatusService()

Deprecated. Use Application.getStatusService() instead.

Returns the status service, enabled by default.

Returns:

The status service.

getTaskService

public TaskService getTaskService()

Returns a task service to run concurrent tasks. The service is enabled by default.

Returns:

A task service.

handle

public void handle(Request request,
                   Response response)

Description copied from class: Restlet

Handles a call. The default behavior is to initialize the Restlet by setting the current context using the Context.setCurrent(Context) method and by attempting to start it, unless it was already started. If an exception is thrown during the start action, then the response status is set to Status.SERVER_ERROR_INTERNAL.

Subclasses overriding this method should make sure that they call super.handle(request, response) before adding their own logic.

Specified by:

handle in interface Uniform

Overrides:

handle in class Restlet

Parameters:

request - The request to handle.

response - The response to update.

setClients

public void setClients(ClientList clients)

Sets the modifiable list of client connectors. This method clears the current list and adds all entries in the parameter list.

Parameters:

clients - A list of client connectors.

setContext

public void setContext(Context context)

Description copied from class: Restlet

Sets the context.

Overrides:

setContext in class Restlet

Parameters:

context - The context.

setDefaultHost

public void setDefaultHost(VirtualHost defaultHost)

Sets the default virtual host.

Parameters:

defaultHost - The default virtual host.

setHosts

public void setHosts(java.util.List<VirtualHost> hosts)

Sets the modifiable list of virtual hosts. Note that the order of virtual hosts in this list will be used to check the first one that matches. This method clears the current list and adds all entries in the parameter list.

Parameters:

hosts - A list of virtual hosts.

setInternalRouter

public void setInternalRouter(Router internalRouter)

Sets the private internal router were Restlets like Applications can be attached.

Parameters:

internalRouter - The private internal router.

See Also:

getInternalRouter()

setLogService

public void setLogService(LogService logService)

Sets the global log service.

Parameters:

logService - The global log service.

setRealms

public void setRealms(java.util.List<Realm> realms)

Sets the list of realms. This method clears the current list and adds all entries in the parameter list.

Parameters:

realms - A list of realms.

setServers

public void setServers(ServerList servers)

Sets the modifiable list of server connectors. This method clears the current list and adds all entries in the parameter list.

Parameters:

servers - A list of server connectors.

setStatusService

@Deprecated
public void setStatusService(StatusService statusService)

Deprecated. Use Application.setStatusService(StatusService) instead.

Sets the status service.

Parameters:

statusService - The status service.

setTaskService

public void setTaskService(TaskService taskService)

Sets the task service.

Parameters:

taskService - The task service.

start

public void start()
           throws java.lang.Exception

Starts the component. First it starts all the connectors (clients then servers), the routers, the services, the realms and then the component's internal helper. Finally it calls the start method of the super class.

Overrides:

start in class Restlet

Throws:

java.lang.Exception

See Also:

startClients(), startServers(), startRouters(), startServices(), startRealms(), startHelper()

startClients

protected void startClients()
                     throws java.lang.Exception

Starts the client connectors.

Throws:

java.lang.Exception

startHelper

protected void startHelper()
                    throws java.lang.Exception

Starts the internal helper allowing incoming requests to be served.

Throws:

java.lang.Exception

startRealms

protected void startRealms()
                    throws java.lang.Exception

Starts the realms.

Throws:

java.lang.Exception

startRouters

protected void startRouters()
                     throws java.lang.Exception

Starts the virtual hosts and the internal router.

Throws:

java.lang.Exception

startServers

protected void startServers()
                     throws java.lang.Exception

Starts the server connectors.

Throws:

java.lang.Exception

startServices

protected void startServices()
                      throws java.lang.Exception

Starts the associated services.

Throws:

java.lang.Exception

stop

public void stop()
          throws java.lang.Exception

Stops the component. First it stops the component's internal helper, the realms, the services, the routers and then stops all the connectors (servers then clients) Finally it calls the stop method of the super class.

Overrides:

stop in class Restlet

Throws:

java.lang.Exception

See Also:

stopHelper(), stopRealms(), stopServices(), stopRouters(), stopServers(), stopClients()

stopClients

protected void stopClients()
                    throws java.lang.Exception

Stops the client connectors.

Throws:

java.lang.Exception

stopHelper

protected void stopHelper()
                   throws java.lang.Exception

Stops the internal helper allowing incoming requests to be served.

Throws:

java.lang.Exception

stopRealms

protected void stopRealms()
                   throws java.lang.Exception

Stops the realms.

Throws:

java.lang.Exception

stopRouters

protected void stopRouters()
                    throws java.lang.Exception

Stops the virtual hosts and the internal router.

Throws:

java.lang.Exception

stopServers

protected void stopServers()
                    throws java.lang.Exception

Stops the server connectors.

Throws:

java.lang.Exception

stopServices

protected void stopServices()
                     throws java.lang.Exception

Stops the associated services.

Throws:

java.lang.Exception

updateHosts

public void updateHosts()
                 throws java.lang.Exception

Updates the component to take into account changes to the virtual hosts. This method doesn't stop the connectors or the applications or Restlets attached to the virtual hosts. It just updates the internal routes between the virtual hosts and the attached Restlets or applications.

Throws:

java.lang.Exception