Package eu.webtoolkit.jwt

Class WtServlet

java.lang.Object

javax.servlet.GenericServlet

javax.servlet.http.HttpServlet

eu.webtoolkit.jwt.WtServlet

All Implemented Interfaces:

Serializable, javax.servlet.Servlet, javax.servlet.ServletConfig

public abstract class WtServlet
extends javax.servlet.http.HttpServlet

The abstract JWt servlet class.

This servlet processes all requests for a JWt application. You need to specialize this class to provide an entry point for your web application.

For each new session createApplication(WEnvironment) is called to create a new WApplication object for that session. The web controller that is implemented by this servlet validates each incoming request, and takes the appropriate action by either notifying the application of an event, or serving a WResource.

See Also:

• Serialized Form

Field Summary

Fields

Modifier and Type	Field	Description
static final String	AuthStrings_xml

Constructor Summary

Constructors

Constructor	Description
WtServlet()	Constructor.

Method Summary

Modifier and Type	Method	Description
void	addResource(WResource staticResource, String path)	Binds a resource to a fixed path.
abstract WApplication	createApplication(WEnvironment env)	Creates a new application for a new session.
protected void	doGet(javax.servlet.http.HttpServletRequest req, javax.servlet.http.HttpServletResponse resp)	Implement the GET request.
protected void	doPost(javax.servlet.http.HttpServletRequest req, javax.servlet.http.HttpServletResponse resp)	Implement the POST request.
Configuration	getConfiguration()	Returns the JWt configuration.
static WtServlet	getInstance()
static ServletApi	getServletApi()	This function is only to be used by JWt internals.
void	init(javax.servlet.ServletConfig config)	Initiate the internal servlet api.
static boolean	isAsyncSupported()	Returns whether asynchronous I/O is supported.
void	post(WApplication app, Runnable function, Runnable fallBackFunction)	Posts a task to be run within the scope of a session (and using the session lock).
void	postAll(Runnable function)	Posts a task to be run within the scope of all currently active sessions.
String	readConfigurationProperty(String name, String value)
void	setConfiguration(Configuration configuration)	Sets the JWt configuration.

Methods inherited from class javax.servlet.http.HttpServlet

doDelete, doHead, doOptions, doPut, doTrace, getLastModified, service, service

Methods inherited from class javax.servlet.GenericServlet

destroy, getInitParameter, getInitParameterNames, getServletConfig, getServletContext, getServletInfo, getServletName, init, log, log

Methods inherited from class java.lang.Object

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

Field Details

AuthStrings_xml

public static final String AuthStrings_xml

See Also:

• Constant Field Values

Constructor Details

WtServlet

public WtServlet()

Constructor.

Instantiates the servlet using the default configuration.

See Also:

• getConfiguration()

Method Details

getServletApi

public static ServletApi getServletApi()

This function is only to be used by JWt internals.

Returns:

the servlet API interface

init

public void init(javax.servlet.ServletConfig config)
          throws javax.servlet.ServletException

Initiate the internal servlet api. If you want to override this function, make sure to call the super function, to ensure the initialization of the servlet api.

Specified by:

init in interface javax.servlet.Servlet

Overrides:

init in class javax.servlet.GenericServlet

Throws:

javax.servlet.ServletException

doGet

protected void doGet(javax.servlet.http.HttpServletRequest req,
 javax.servlet.http.HttpServletResponse resp)
              throws javax.servlet.ServletException,
IOException

Implement the GET request.

Overrides:

doGet in class javax.servlet.http.HttpServlet

Throws:

javax.servlet.ServletException

IOException

doPost

protected void doPost(javax.servlet.http.HttpServletRequest req,
 javax.servlet.http.HttpServletResponse resp)
               throws javax.servlet.ServletException,
IOException

Implement the POST request.

Overrides:

doPost in class javax.servlet.http.HttpServlet

Throws:

javax.servlet.ServletException

IOException

getConfiguration

public Configuration getConfiguration()

Returns the JWt configuration.

The Configuration is only definitively constructed after WtServlet#init() is invoked. You should only modify the configuration from this method.

Returns:

the configuration.

setConfiguration

public void setConfiguration(Configuration configuration)

Sets the JWt configuration.

You should only set the configuration from the servlet constructor.

Parameters:

configuration -

createApplication

public abstract WApplication createApplication(WEnvironment env)

Creates a new application for a new session.

Parameters:

env - the environment that describes the new user (agent) and initial parameters

Returns:

a new application object.

isAsyncSupported

public static boolean isAsyncSupported()

Returns whether asynchronous I/O is supported. This is only the case when the servlet container implements the Servlet 3.0 API, and when this application is configured to support asynchronous processing. Asynchronous I/O is required for recursive event loops, and encouraged for scalable server push (although JWt doesn't strictly require it).

Returns:

whether asynchronous I/O is supported.

post

public void post(WApplication app,
 Runnable function,
 Runnable fallBackFunction)

Posts a task to be run within the scope of a session (and using the session lock). Rather than taking an #WApplication.UpdateLock explicitly, which may stall the current thread and also creates the risk of a dead lock scenario, it's usually better to post the task asynchronously to an application session. This will either run the task immediately (within the current thread if the other session is currently unlocked), or queue the event to be run (by the thread currently holding the session lock) when it is releasing the lock. Multiple posted events to the same session are thus guaranteed to be run sequentially in the order they were posted.

Parameters:

app - the application instance which needs to be locked

function - the task to be run

fallBackFunction - the task to be run in case the application has been quit or its session expired.

postAll

public void postAll(Runnable function)

Posts a task to be run within the scope of all currently active sessions.

Parameters:

function - the task to be run

See Also:

• post(eu.webtoolkit.jwt.WApplication,java.lang.Runnable,java.lang.Runnable)

readConfigurationProperty

public String readConfigurationProperty(String name,
 String value)

addResource

public void addResource(WResource staticResource,
 String path)

Binds a resource to a fixed path. Resources may either be private to a single session or public. Use this method to add a public resource with a fixed path. When the path contains the application context's path, the path should start with a '/', if not the '/' should be omitted.

getInstance

public static WtServlet getInstance()