org.apache.nifi.remote

Class AbstractTransaction

java.lang.Object

org.apache.nifi.remote.AbstractTransaction

All Implemented Interfaces:

Transaction

Direct Known Subclasses:

HttpClientTransaction, SocketClientTransaction

public abstract class AbstractTransaction
extends Object
implements Transaction

Nested Class Summary

Nested classes/interfaces inherited from interface org.apache.nifi.remote.Transaction

Transaction.TransactionState

Field Summary

Fields

Modifier and Type	Field and Description
protected FlowFileCodec	codec
private boolean	compress
private long	contentBytes
private CRC32	crc
private long	creationNanoTime
protected boolean	dataAvailable
protected String	destinationId
protected TransferDirection	direction
protected EventReporter	eventReporter
protected org.slf4j.Logger	logger
protected Peer	peer
private int	penaltyMillis
protected int	protocolVersion
protected Transaction.TransactionState	state
private int	transfers

Constructor Summary

Constructors

Constructor and Description
AbstractTransaction(Peer peer, TransferDirection direction, boolean useCompression, FlowFileCodec codec, EventReporter eventReporter, int protocolVersion, int penaltyMillis, String destinationId)

Method Summary

Modifier and Type	Method and Description
void	cancel(String explanation) Cancels this transaction, indicating to the sender that the data has not been successfully received so that the sender can retry or handle however is appropriate.
protected void	close()
TransactionCompletion	complete() Completes the transaction and indicates to both the sender and receiver that the data transfer was successful.
void	confirm() Confirms the data that was sent or received by comparing CRC32's of the data sent and the data received.
void	error() Sets the TransactionState of the Transaction to Transaction.TransactionState.ERROR, and closes the Transaction.
Peer	getCommunicant()
Transaction.TransactionState	getState()
protected abstract Response	readTransactionResponse()
DataPacket	receive() Retrieves information from the remote NiFi instance, if any is available.
void	send(byte[] content, Map<String,String> attributes) Sends the given byte array as the content of a DataPacket along with the provided attributes
void	send(DataPacket dataPacket) Sends information to the remote NiFi instance.
String	toString()
protected void	writeTransactionResponse(ResponseCode response)
protected void	writeTransactionResponse(ResponseCode response, String explanation)
protected abstract void	writeTransactionResponse(ResponseCode response, String explanation, boolean flush)

Methods inherited from class java.lang.Object

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

Field Detail

logger

protected final org.slf4j.Logger logger

peer

protected final Peer peer

direction

protected final TransferDirection direction

crc

private final CRC32 crc

compress

private final boolean compress

codec

protected final FlowFileCodec codec

eventReporter

protected final EventReporter eventReporter

protocolVersion

protected final int protocolVersion

penaltyMillis

private final int penaltyMillis

destinationId

protected final String destinationId

state

protected Transaction.TransactionState state

dataAvailable

protected boolean dataAvailable

creationNanoTime

private final long creationNanoTime

transfers

private int transfers

contentBytes

private long contentBytes

Constructor Detail

AbstractTransaction

public AbstractTransaction(Peer peer,
                           TransferDirection direction,
                           boolean useCompression,
                           FlowFileCodec codec,
                           EventReporter eventReporter,
                           int protocolVersion,
                           int penaltyMillis,
                           String destinationId)

Method Detail

close

protected void close()
              throws IOException

Throws:

IOException

send

public void send(byte[] content,
                 Map<String,String> attributes)
          throws IOException

Description copied from interface: Transaction

Sends the given byte array as the content of a DataPacket along with the provided attributes

Specified by:

send in interface Transaction

Parameters:

content - to send

attributes - of the content

Throws:

IOException - if unable to send

error

public void error()

Description copied from interface: Transaction

Sets the TransactionState of the Transaction to Transaction.TransactionState.ERROR, and closes the Transaction. The underlying connection should not be returned to a connection pool in this case.

Specified by:

error in interface Transaction

getState

public Transaction.TransactionState getState()

Specified by:

getState in interface Transaction

Returns:

the current state of the Transaction.

getCommunicant

public Peer getCommunicant()

Specified by:

getCommunicant in interface Transaction

Returns:

a Communicant that represents the other side of this Transaction (i.e., the remote NiFi instance)

receive

public final DataPacket receive()
                         throws IOException

Description copied from interface: Transaction

Retrieves information from the remote NiFi instance, if any is available. If no data is available, will return null. It is important to consume all data from the remote NiFi instance before attempting to call Transaction.confirm(). This is because the sender is always responsible for determining when the Transaction has finished. This is done in order to prevent the need for a round-trip network request to receive data for each data packet.

Specified by:

receive in interface Transaction

Returns:

the DataPacket received, or null if there is no more data to receive.

Throws:

IOException - if unable to receive

readTransactionResponse

protected abstract Response readTransactionResponse()
                                             throws IOException

Throws:

IOException

writeTransactionResponse

protected final void writeTransactionResponse(ResponseCode response)
                                       throws IOException

Throws:

IOException

writeTransactionResponse

protected void writeTransactionResponse(ResponseCode response,
                                        String explanation)
                                 throws IOException

Throws:

IOException

writeTransactionResponse

protected abstract void writeTransactionResponse(ResponseCode response,
                                                 String explanation,
                                                 boolean flush)
                                          throws IOException

Throws:

IOException

confirm

public final void confirm()
                   throws IOException

Description copied from interface: Transaction

Confirms the data that was sent or received by comparing CRC32's of the data sent and the data received.

Even if the protocol being used to send the data is reliable and guarantees ordering of packets (such as TCP), it is still required that we confirm the transaction before completing the transaction. This is done as "safety net" or a defensive programming technique. Mistakes happen, and this mechanism helps to ensure that if a bug exists somewhere along the line that we do not end up sending or receiving corrupt data. If the CRC32 of the sender and the CRC32 of the receiver do not match, an IOException will be thrown and both the sender and receiver will cancel the transaction automatically.

If the TransferDirection of this Transaction is RECEIVE, this method will throw an Exception unless all data from the remote instance has been consumed (i.e., a call to Transaction.receive() returns null).

If the TransferDirection of this Transaction is SEND, calling this method dictates that no more data will be sent in this transaction. I.e., there will be no more calls to Transaction.send(DataPacket).

Specified by:

confirm in interface Transaction

Throws:

IOException - if unable to confirm transaction

complete

public final TransactionCompletion complete()
                                     throws IOException

Description copied from interface: Transaction

Completes the transaction and indicates to both the sender and receiver that the data transfer was successful.

Specified by:

complete in interface Transaction

Returns:

a TransactionCompletion that contains details about the Transaction

Throws:

IOException - if unable to complete

cancel

public final void cancel(String explanation)
                  throws IOException

Description copied from interface: Transaction

Cancels this transaction, indicating to the sender that the data has not been successfully received so that the sender can retry or handle however is appropriate.

Specified by:

cancel in interface Transaction

Parameters:

explanation - an explanation to tell the other party why the transaction was canceled.

Throws:

IOException - if unable to cancel

toString

public final String toString()

Overrides:

toString in class Object

send

public final void send(DataPacket dataPacket)
                throws IOException

Description copied from interface: Transaction

Sends information to the remote NiFi instance.

Specified by:

send in interface Transaction

Parameters:

dataPacket - the data packet to send

Throws:

IOException - if unable to send