jade.core

Class Filter

java.lang.Object

jade.core.Filter

public abstract class Filter
extends java.lang.Object

Base class for command filters, that allow to set up an open-ended chain of platform services to process commands coming from the upper JADE layers. Filters process commands when their accept() method and postProcess methods are invoked; Filters in the filter chain are nested. The accept() method is called before the command is processed by successive filters in the chain. It should be used to take proper actions before the command consumption. On the other hand the postProcess() method is called after the command has been processed by successive filters in the chain. It should be used to take proper actions after the command consumption.

Author:

Giovanni Rimassa - FRAMeTech s.r.l., Giovanni Caire - TILAB

See Also:

jade.core.CommandProcessor

Field Summary

Fields

Modifier and Type	Field and Description
static int	FIRST The constant indicating the first position in the filter chain
static boolean	INCOMING A constant indicating a filter for incoming commands
static int	LAST The constant indicating the last position in the filter chain
static boolean	OUTGOING A constant indicating a filter for outgoing commands

Constructor Summary

Constructors

Constructor and Description
Filter()

Method Summary

Modifier and Type	Method and Description
protected boolean	accept(VerticalCommand cmd) Process a command before it is processed by successive filters in the filter-chain.
int	getPreferredPosition() Retrieve the preferred position for this filter in the filter chain
boolean	isBlocking() Inquires the blocking state of this filter.
boolean	isSkipping() Inquires the skipping state of this filter.
protected void	postProcess(VerticalCommand cmd) Post-process a command object after it has been processed by the successive filters in the filter chain.
void	setBlocking(boolean newState) Sets the blocking state of this filter.
void	setPreferredPosition(int pos) Sets the preferred position for this filter in the filter chain
void	setSkipping(boolean newState) Sets the skipping state of this filter.

Methods inherited from class java.lang.Object

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

Field Detail

FIRST

public static final int FIRST

The constant indicating the first position in the filter chain

See Also:

Constant Field Values

LAST

public static final int LAST

The constant indicating the last position in the filter chain

See Also:

Constant Field Values

INCOMING

public static final boolean INCOMING

A constant indicating a filter for incoming commands

See Also:

Constant Field Values

OUTGOING

public static final boolean OUTGOING

A constant indicating a filter for outgoing commands

See Also:

Constant Field Values

Constructor Detail

Filter

public Filter()

Method Detail

accept

protected boolean accept(VerticalCommand cmd)

Process a command before it is processed by successive filters in the filter-chain.

Parameters:

cmd - A VerticalCommand describing what operation has been requested from previous layers (that can be the actual prime source of the command or previous filters in the chain).

Returns:

A boolean value, telling whether the filtered command has been accepted or not. A filter can veto a command by returning false from this method. A vetoed command is not propagated in the filter chain.

postProcess

protected void postProcess(VerticalCommand cmd)

Post-process a command object after it has been processed by the successive filters in the filter chain.

Parameters:

cmd - A VerticalCommand describing what operation has been requested from previous layers (that can be the actual prime source of the command or previous filters in the chain).

getPreferredPosition

public final int getPreferredPosition()

Retrieve the preferred position for this filter in the filter chain

setPreferredPosition

public final void setPreferredPosition(int pos)

Sets the preferred position for this filter in the filter chain

setBlocking

public void setBlocking(boolean newState)

Sets the blocking state of this filter. A blocked filter does not process commands, and also prevents subsequent filters to process them.

Parameters:

newState - The boolean value to set the blocking state to.

isBlocking

public boolean isBlocking()

Inquires the blocking state of this filter. A blocked fliter does not process commands, and also prevents subsequent filters to process them.

Returns:

The current blocking state of this filter.

setSkipping

public void setSkipping(boolean newState)

Sets the skipping state of this filter. A skipped filter does not process commands, but passes them directly to subsequent filters.

Parameters:

blocked - The boolean value to set the skipping state to.

isSkipping

public boolean isSkipping()

Inquires the skipping state of this filter. A skipped filter does not process commands, but passes them directly to subsequent filters.

Returns:

The current skipping state of this filter.