uk.org.ogsadai.client.toolkit.activity.delivery
Class DataTransportBlockReader

java.lang.Object
  |
  +--uk.org.ogsadai.client.toolkit.activity.delivery.DataTransportBlockReader

All Implemented Interfaces:

BlockReader

public class DataTransportBlockReader

extends java.lang.Object

implements BlockReader

A BlockReader implementation which fetches each block from an output stream exposed by a data service resource exposed by a data service using the service's get operations.

Author:

The OGSA-DAI Project Team

Field Summary

private static java.lang.String	COPYRIGHT_NOTICE Copyright statement
private int	mBlocksToFetch The number of blocks to fetch from a service at once.
private java.lang.Object	mNextBlock The block which will be returned the next time the next method is called.
private DataTransport	mService Object that handles get operations on a service.

Constructor Summary

DataTransportBlockReader(DataTransport service)

DataTransportBlockReader(DataTransport service, int blocksToFetch)
Default constructor.

Method Summary

java.lang.Object	fetchBlock() Obtain a block from the output stream exposed by a data service resource of the service or return null if all the data has been read.
boolean	hasNext() Indicates whether or not there are any more blocks of data to be read from the block reader.
java.lang.Object	next() Gets the next block of data contained in the block reader.

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

mNextBlock

private java.lang.Object mNextBlock

The block which will be returned the next time the next method is called. (We employ a one-block buffer to enable hasNext() to work.)

mBlocksToFetch

private final int mBlocksToFetch

The number of blocks to fetch from a service at once.

mService

private final DataTransport mService

Object that handles get operations on a service.

Constructor Detail

DataTransportBlockReader

public DataTransportBlockReader(DataTransport service)
                         throws StreamDataException

DataTransportBlockReader

public DataTransportBlockReader(DataTransport service,
                                int blocksToFetch)
                         throws StreamDataException

Default constructor. Fetches the first block of data from an output stream exposed by a data service resource exposed by a data service and buffers this locally.

Parameters:

service - Object handling access to the service's output stream.

blocksToFetch - The number of blocks to fetch from the service at once. These are aggregated into a single block service-side.

Throws:

StreamDataException - If there is a problem when streaming the data from the service.

Method Detail

hasNext

public boolean hasNext()

Description copied from interface: BlockReader

Indicates whether or not there are any more blocks of data to be read from the block reader.

Specified by:

hasNext in interface BlockReader

Returns:

true if there are more blocks to be read or false otherwise

next

public java.lang.Object next()

Description copied from interface: BlockReader

Gets the next block of data contained in the block reader.

Specified by:

next in interface BlockReader

Returns:

an Object

fetchBlock

public java.lang.Object fetchBlock()
                            throws StreamDataException

Obtain a block from the output stream exposed by a data service resource of the service or return null if all the data has been read.

Returns:

block

Throws:

StreamDataException - If there is a problem when streaming the data from the service.