uk.org.ogsadai.activity.transform
Class IncrementalProcessorInputStream

java.lang.Object
  |
  +--java.io.InputStream
        |
        +--uk.org.ogsadai.activity.transform.IncrementalProcessorInputStream

public class IncrementalProcessorInputStream

extends java.io.InputStream

An InputStream designed to read the output of some kind of process in incremental stages. An IncrementalProcessor is used to perform this actual processing.

There are many cases where a process writes to an output stream and it is necessary to retrieve this data produced in stages during the processing, rather than in a single block when the processing is complete. This class together with the IncrementalProcessor interface provides a solution to this problem.

This class contains an inner class, which extends OutputStream. An instance of this can write to the same buffer that the read method reads from. The IncrementalProcessorInputStream must be constructed using an IncrementalProcessor that uses an instance of this OutputStream. Whenever a read method is invoked, processing is performed using the IncrementalProcessor, to generate some output that can be returned.

Author:

The OGSA-DAI Project Team

Nested Class Summary

private class

IncrementalProcessorInputStream.QueueSharingOutputStream An inner class OutputStream that writes to the same byte buffer that the surrounding class reads from.

Field Summary

private static java.lang.String	COPYRIGHT_NOTICE Copyright statement
private static int	DEFAULT_BUFFER_SIZE Default buffer size.
private byte[]	mByte Used to optimise the read and write methods.
private IncrementalProcessor	mProcessor Used to generate the output that will be read, in incremental stages.
private ByteQueue	mQueue The internal byte buffer, written to and read from.

Fields inherited from class java.io.InputStream

Constructor Summary

IncrementalProcessorInputStream(IncrementalProcessor processor)
Constructs an instance using the specified parameters and the default internal buffer size.

IncrementalProcessorInputStream(IncrementalProcessor processor, int bufferSize)
Constructs an instance using the specified parameters.

Method Summary

int	read()
int	read(byte[] bytes, int start, int length)

Methods inherited from class java.io.InputStream

available, close, mark, markSupported, read, reset, skip

Methods inherited from class java.lang.Object

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

Field Detail

COPYRIGHT_NOTICE

private static final java.lang.String COPYRIGHT_NOTICE

Copyright statement

See Also:

Constant Field Values

DEFAULT_BUFFER_SIZE

private static final int DEFAULT_BUFFER_SIZE

Default buffer size.

See Also:

Constant Field Values

mQueue

private ByteQueue mQueue

The internal byte buffer, written to and read from.

mProcessor

private IncrementalProcessor mProcessor

Used to generate the output that will be read, in incremental stages.

mByte

private byte[] mByte

Used to optimise the read and write methods.

Constructor Detail

IncrementalProcessorInputStream

public IncrementalProcessorInputStream(IncrementalProcessor processor)
                                throws java.io.IOException

Constructs an instance using the specified parameters and the default internal buffer size.

Parameters:

processor - The IncrementalProcessor used to perform the processing. This should be constructed but not initialised.

Throws:

java.io.IOException - If there is an I/O problem.

IncrementalProcessorInputStream

public IncrementalProcessorInputStream(IncrementalProcessor processor,
                                       int bufferSize)
                                throws java.io.IOException

Constructs an instance using the specified parameters.

Parameters:

processor - The IncrementalProcessor used to perform the processing. This should be constructed but not initialised.

bufferSize - The internal buffer size.

Throws:

java.io.IOException - If there is an I/O problem.

Method Detail

read

public int read()
         throws java.io.IOException

Specified by:

read in class java.io.InputStream

java.io.IOException

read

public int read(byte[] bytes,
                int start,
                int length)
         throws java.io.IOException

Overrides:

read in class java.io.InputStream

java.io.IOException