net.kwfgrid.gwes.uiproxy
Class SequenceBuffer

java.lang.Object
  net.kwfgrid.gwes.uiproxy.AbstractBuffer
      net.kwfgrid.gwes.uiproxy.SequenceBuffer

All Implemented Interfaces:

Buffer, Consumer

Direct Known Subclasses:

JDOMSequenceBuffer

public abstract class SequenceBuffer
extends AbstractBuffer

An abstract buffer implementation to order messages with sequence numbers. Subclasses must implement getSequenceNumber(message) to access the sequence number of an incoming message. A SequenceBuffer's client must explicitly initialize the buffer by setting the SequenceBuffer.first property to the first valid sequence number. The buffer will not return any messages on read() before this property has been set. This buffer supports the following properties:

• Buffer.size
• SequenceBuffer.first

Field Summary

protected LinkedList	_content
protected BufferException	_exception
protected int	_first
protected boolean	_initialized
protected LinkedList	_precontent
static String	FIRST_PROPERTY_KEY

Fields inherited from class net.kwfgrid.gwes.uiproxy.AbstractBuffer

_id, _size, DEFAULT_SIZE, SIZE_PROPERTY_KEY

Constructor Summary

SequenceBuffer()

Method Summary

protected abstract int	getSequenceNumber(Object message) Generic method to access the sequence number of the specified message.
void	handle(Object message) Handle a message.
protected void	initialize(int first)
Object[]	read() Will always return messages in correct order.
void	setProperty(String key, String value) This implementation only interprets the Buffer.size property.
protected void	setSize(int size) Size should be set by setting property Buffer.size.
protected abstract boolean	shouldHandle(Object message) Determine if this buffer should handle the specified message.

Methods inherited from class net.kwfgrid.gwes.uiproxy.AbstractBuffer

getID, getSize, setID, setProperties

Methods inherited from class java.lang.Object

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

Field Detail

FIRST_PROPERTY_KEY

public static final String FIRST_PROPERTY_KEY

See Also:

Constant Field Values

_first

protected int _first

_initialized

protected boolean _initialized

_exception

protected BufferException _exception

_content

protected LinkedList _content

_precontent

protected LinkedList _precontent

Constructor Detail

SequenceBuffer

public SequenceBuffer()

Method Detail

getSequenceNumber

protected abstract int getSequenceNumber(Object message)
                                  throws Exception

Generic method to access the sequence number of the specified message. Sequence numbers are expected to be positive integers.

Throws:

Exception

setSize

protected void setSize(int size)
                throws BufferException

Description copied from class: AbstractBuffer

Size should be set by setting property Buffer.size.

Overrides:

setSize in class AbstractBuffer

Throws:

BufferException

initialize

protected void initialize(int first)
                   throws BufferException

Throws:

BufferException

setProperty

public void setProperty(String key,
                        String value)
                 throws BufferException

Description copied from class: AbstractBuffer

This implementation only interprets the Buffer.size property.

Specified by:

setProperty in interface Buffer

Overrides:

setProperty in class AbstractBuffer

Throws:

BufferException

handle

public void handle(Object message)

Description copied from interface: Buffer

Handle a message. The buffer itself determines if it is responsible for buffering the specified Message. Buffer overflows or other exceptions must be remembered internally and notified on forthcoming calls of read().

Specified by:

handle in interface Buffer

Specified by:

handle in interface Consumer

Specified by:

handle in class AbstractBuffer

Parameters:

message - The message.

shouldHandle

protected abstract boolean shouldHandle(Object message)
                                 throws Exception

Determine if this buffer should handle the specified message. Subclasses must override this method in order to sort out messages of interest.

Throws:

Exception

read

public Object[] read()
              throws BufferException

Will always return messages in correct order.

Specified by:

read in interface Buffer

Specified by:

read in class AbstractBuffer

Throws:

BufferException - If a message could not be handled for some reason.