com.nt.udc.oi.transport

Class TcpOITransport

java.lang.Object

com.nt.udc.ndk.node.OITransport

com.nt.udc.oi.transport.TcpOITransport

All Implemented Interfaces:

DataReceiverIfc, DCTransport, FileDataReceiverIfc, StateBufferSaveable, java.lang.Runnable

public class TcpOITransport
extends OITransport
implements StateBufferSaveable

This class will create a socket on the given host/port for sending data via TCP. The data will be extracted from the incoming OIRecord() objects via their toByteArray() method.
The recommended use of this transport is for it to be run within its own thread so it can 'pull' the data from its DataProvider. This will allow the transport to control the flow of data it receives and stop that flow if the TCP connection is lost.
If the TCP connection is lost, the current state of the node is saved to mark the current input record being processed, should some form of recovery be needed at a later time. Meanwhile, a thread will be spawned to periodically attempt to re-establish the connection. Until the connection is made, the transport will block and stop processing and requesting data, unless the transport has been configured to drop the records while the connection is down.
If the transport is instructed to shutdown while the connection is down and processing has been stopped, the current state of the node is saved. At the next startup of the transport, processing will begin where it previously stopped.

Field Summary

Fields inherited from class com.nt.udc.ndk.node.OITransport

dataProvider, filedataProvider, node, pollingInterval

Constructor Summary

Constructors

Constructor and Description
TcpOITransport(OINode oinode, java.lang.String host, int prt) Construct a new TcpOITransport to be used within the specified OINode.
TcpOITransport(OINode oinode, java.lang.String host, int prt, boolean wait) Construct a new TcpOITransport to be used within the specified OINode.

Method Summary

Modifier and Type	Method and Description
protected void	close() Close the socket and its output stream.
protected void	connect() Create the socket and attempt to establish a connection.
void	dataIsAvailable() This method allows the transport's DataProvider to tell the transport that data is waiting to be 'picked up'.
boolean	isConnected() Indicates whether this TcpOITransport is connected to the TCP socket
boolean	isDataAvailable() Indicates whether data is available from the transport's DataProvider
boolean	isHealthy() Indicates whether the transport is fully functional
boolean	isProcessingData() Indicates whether this TcpOITransport is currently processing data
boolean	isRunning() Indicates whether this TcpOITransport is running
boolean	isWaitForReconnect() Indicates whether this TcpOITransport is configured to, in the event of a lost connection, wait for the connection to be re-established before sending the data.
void	processData(DCFieldContainer record) Accept an OIRecord to be transmitted via TCP.
void	processData(DCFieldContainer[] records) Accept some OIRecord objects to be transmitted via TCP.
protected void	reconnect() Attempt to re-establish the connection.
void	restoreState(StateBuffer buffer) Restore the Object's state from the given buffer.
void	run() This method is used when the OITransport runs within its own thread.
void	saveState(StateBuffer buffer) Save the Object's state to the given buffer.
protected void	setProcessingData(boolean value) Sets the boolean indicating whether the transport is currently processing data.
protected void	setRunning(boolean run) Sets the boolean which indicates whether the transport is running
void	setWaitForReconnect(boolean value) Sets the boolean indicating whether the transport should, in the event of a lost connection, wait for the connection to be re-established before sending the current record or drop the current record and move on to processing the next record.
void	shutdown() Stop the transport.
protected void	write(byte[] bytes) Write the given bytes to the socket's output stream.

Methods inherited from class com.nt.udc.ndk.node.OITransport

fileDataIsAvailable, getDataProvider, getFileDataProvider, getNode, getPollingInterval, getRealNarsOut, incrementOut, processEndOfFileData, processFileData, processFileData, processRejectFile, processStartOfFileData, setDataProvider, setFileDataProvider, setNode, setPollingInterval, setTransactionID

Methods inherited from class java.lang.Object

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

Constructor Detail

TcpOITransport

public TcpOITransport(OINode oinode,
                      java.lang.String host,
                      int prt)
               throws NodeStartException

Construct a new TcpOITransport to be used within the specified OINode. The transport will create a socket on the given host/port and transmit via TCP the data contained within the incoming OIRecord objects(). The data will be extracted from the records via their toByteArray() method. If the socket connection cannot be established during the construction of the transport, a NodeStartException is thrown.

Parameters:

oinode - Reference to the OINode containing the transport

host - The host name / IP address to which to connect

port - The port number to which to connect

Throws:

NodeStartException

TcpOITransport

public TcpOITransport(OINode oinode,
                      java.lang.String host,
                      int prt,
                      boolean wait)
               throws NodeStartException

Construct a new TcpOITransport to be used within the specified OINode. The transport will create a socket on the given host/port and transmit via TCP the data contained within the incoming OIRecord objects(). The data will be extracted from the records via their toByteArray() method. If the socket connection cannot be established during the construction of the transport, a NodeStartException is thrown unless the 'wait' flag is set to false. If records are to be dropped during a lost connection, this constructor will spawn a thread to periodically attempt to establish the connection while data is 'processed' and dropped. This allows the node to be started without establishing the socket connection.

Parameters:

oinode - Reference to the OINode containing the transport

host - The host name / IP address to which to connect

port - The port number to which to connect

wait - true, if transport should hold the current record until the connection has been re-established. Otherwise, the current record will be dropped and processing will continue with the next record.

Throws:

NodeStartException

Method Detail

dataIsAvailable

public void dataIsAvailable()

This method allows the transport's DataProvider to tell the transport that data is waiting to be 'picked up'. It is then the responsibility of the transport to retrieve the data via the provider's getData() method and process it via the receiver's processData() method.

Specified by:

dataIsAvailable in interface DataReceiverIfc

Specified by:

dataIsAvailable in class OITransport

processData

public void processData(DCFieldContainer record)
                 throws NodeProcessingException

Accept an OIRecord to be transmitted via TCP. This method will block until the data can be successfully transmitted, unless the transport is configured to drop records while the connection is lost.

Specified by:

processData in interface DataReceiverIfc

Specified by:

processData in class OITransport

Parameters:

record - OIRecord containing the data.

Throws:

NodeProcessingException

processData

public void processData(DCFieldContainer[] records)
                 throws NodeProcessingException

Accept some OIRecord objects to be transmitted via TCP. This method will block until the data can be successfully transmitted, unless the transport is configured to drop records while the connection is lost.

Specified by:

processData in interface DataReceiverIfc

Parameters:

records - An array of OIRecord objects.

Throws:

NodeProcessingException

saveState

public void saveState(StateBuffer buffer)
               throws StateException

Save the Object's state to the given buffer.

Specified by:

saveState in interface StateBufferSaveable

Parameters:

buffer - Buffer for writing

Throws:

StateException

restoreState

public void restoreState(StateBuffer buffer)
                  throws StateException

Restore the Object's state from the given buffer.

Specified by:

restoreState in interface StateBufferSaveable

Parameters:

buffer - Buffer for reading

Throws:

StateException

run

public void run()

This method is used when the OITransport runs within its own thread. The method will retrieve the data from the transport's DataProvider pass the DCFieldContainer() objects on to the processData() method.

Specified by:

run in interface java.lang.Runnable

Specified by:

run in class OITransport

shutdown

public void shutdown()

Stop the transport. To ensure no loss of data, this method will wait for the transport to obtain and process all pending data from its DataProvider, unless it is shutting down due to a processing error.

If the TCP connection has been lost and processing has been stoppped until the connection has been re-established, an indicator will be written to the node's scratch directory, marking the position in the current NAR file. When the transport is restarted, this marker will be read and processing will resume at that point in the NAR file.

Specified by:

shutdown in interface DCTransport

Specified by:

shutdown in class OITransport

isHealthy

public boolean isHealthy()

Indicates whether the transport is fully functional

Specified by:

isHealthy in interface DCTransport

Overrides:

isHealthy in class OITransport

Returns:

true if the transport is healthy, false otherwise

isConnected

public boolean isConnected()

Indicates whether this TcpOITransport is connected to the TCP socket

isDataAvailable

public boolean isDataAvailable()

Indicates whether data is available from the transport's DataProvider

isRunning

public boolean isRunning()

Indicates whether this TcpOITransport is running

setRunning

protected void setRunning(boolean run)

Sets the boolean which indicates whether the transport is running

isProcessingData

public boolean isProcessingData()

Indicates whether this TcpOITransport is currently processing data

setProcessingData

protected void setProcessingData(boolean value)

Sets the boolean indicating whether the transport is currently processing data.

isWaitForReconnect

public boolean isWaitForReconnect()

Indicates whether this TcpOITransport is configured to, in the event of a lost connection, wait for the connection to be re-established before sending the data. The default is to wait.

Returns:

true, if transport will hold the current record until the connection has been re-established. Otherwise, the current record will be dropped and processing will continue with the next record.

setWaitForReconnect

public void setWaitForReconnect(boolean value)

Sets the boolean indicating whether the transport should, in the event of a lost connection, wait for the connection to be re-established before sending the current record or drop the current record and move on to processing the next record.

connect

protected void connect()
                throws java.io.IOException

Create the socket and attempt to establish a connection.

Throws:

java.io.IOException

write

protected void write(byte[] bytes)
              throws java.io.IOException

Write the given bytes to the socket's output stream.

Parameters:

bytes - Bytes to be written to the socket's output stream.

Throws:

java.io.IOException

close

protected void close()

Close the socket and its output stream.

reconnect

protected void reconnect()

Attempt to re-establish the connection.