org.apache.shale.application.faces
Class ShaleApplicationFilter

java.lang.Object
  org.apache.shale.application.faces.ShaleApplicationFilter

All Implemented Interfaces:

Filter

public class ShaleApplicationFilter
extends Object
implements Filter

ShaleApplicationFilter is a Filter implementation that invokes the required Application Controller functionality on every request. In addition, it performs overall application startup and shutdown operations on behalf of the framework.

The detailed processing to be performed for each request is configured by a Command or Chain defined using the "Chain of Resposibility" design pattern, as implemented by the Commons Chain package. There must exist a Catalog named shale, which contains a Command named standard, that defines the processing to be performed.

At any point, one of the Commands being executed may choose to complete the response itself (such as to perform an HTTP redirect), instead of allowing processing to continue. To indicate this choice, the Command should follow the standard Commons Chain convention of returning true. If you want processing to continue, return false instead.

The default implementation of the standard command processing chain performs the following tasks:

• Invoke a command named preprocess (in the shale catalog), if it exists. This is where you should insert commands to be executed before ShaleApplicationFilter passes the request on to the next filter or servlet.
• Execute the remainder of the filter chain for this request.
• Invokes a command named postprocess (in the shale catalog), if it exists. This is where you should insert commands to be executed after control returns from the invoked filter or servlet. Note that it is no longer possible, at this point, to replace the response content produced by the filter or servlet -- that should be done in a preprocess step.

NOTE - Configuration of the shale catalog, and the commands it contains, may be performed in any manner you desire. One convenient mechanism is to use the ChainListener class that is included in the Commons Chain package. If you do not reconfigure it differently, the standard command (in the shale catalog) will be configured according to the embedded resource org/apache/shale/faces/shale-config.xml in the JAR file containing the core Shale runtime environment, which executes the default request processing described above.

$Id: ShaleApplicationFilter.java 464373 2006-10-16 04:21:54Z rahul $

Field Summary

static String	CATALOG_NAME The name of the Commons Chain Catalog to use.
static String	COMMAND_DESTROY The name of the Command to execute during application shutdown.
static String	COMMAND_INIT The name of the Command to execute during application startup.
static String	COMMAND_POSTPROCESS The name of the Command to execute after the application logic itself is invoked.
static String	COMMAND_PREPROCESS The name of the Command to execute before the application logic itself is invoked.
static String	CONTEXT_ATTR The request scope attribute key under which the Context object used for this chain of command request to be stored, in addition to it being passed in to the command chains.
static String	RESOURCE_NAME The name of the internal resource containing our default configuration of the default command.

Constructor Summary

ShaleApplicationFilter()

Method Summary

void	destroy() Perform application shutdown finalization as necessary.
void	doFilter(ServletRequest request, ServletResponse response, FilterChain chain) Perform per-request application controler functionality.
void	init(FilterConfig config) Perform application startup intiialization as necessary.

Methods inherited from class java.lang.Object

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

Field Detail

CATALOG_NAME

public static final String CATALOG_NAME

The name of the Commons Chain Catalog to use.

See Also:

Constant Field Values

COMMAND_DESTROY

public static final String COMMAND_DESTROY

The name of the Command to execute during application shutdown.

See Also:

Constant Field Values

COMMAND_INIT

public static final String COMMAND_INIT

The name of the Command to execute during application startup.

See Also:

Constant Field Values

COMMAND_PREPROCESS

public static final String COMMAND_PREPROCESS

The name of the Command to execute before the application logic itself is invoked.

See Also:

Constant Field Values

COMMAND_POSTPROCESS

public static final String COMMAND_POSTPROCESS

The name of the Command to execute after the application logic itself is invoked.

See Also:

Constant Field Values

CONTEXT_ATTR

public static final String CONTEXT_ATTR

The request scope attribute key under which the Context object used for this chain of command request to be stored, in addition to it being passed in to the command chains.

See Also:

Constant Field Values

RESOURCE_NAME

public static final String RESOURCE_NAME

The name of the internal resource containing our default configuration of the default command.

See Also:

Constant Field Values

Constructor Detail

ShaleApplicationFilter

public ShaleApplicationFilter()

Method Detail

destroy

public void destroy()

Perform application shutdown finalization as necessary.

Specified by:

destroy in interface Filter

doFilter

public void doFilter(ServletRequest request,
                     ServletResponse response,
                     FilterChain chain)
              throws IOException,
                     ServletException

Perform per-request application controler functionality.

Specified by:

doFilter in interface Filter

Parameters:

request - The request we are processing

response - The response we are creating

chain - The filter chain for this request

Throws:

IOException - if an input/output error occurs

ServletException - if a servlet exception is thrown

init

public void init(FilterConfig config)
          throws ServletException

Perform application startup intiialization as necessary.

Specified by:

init in interface Filter

Parameters:

config - FilterConfig for this filter

Throws:

ServletException - if a servlet exception is thrown