communication
Class CommunicationElement

java.lang.Object
  communication.CommunicationElement

All Implemented Interfaces:

ICommunication

Direct Known Subclasses:

ReliableCommElt, UnreliableCommElt

public abstract class CommunicationElement
extends java.lang.Object
implements ICommunication

Communication element for a process to communicate with other processes. The underlying communication support is TCP. Fault and communication delays are simulated through a set of parameters.

Nested Class Summary

protected class

CommunicationElement.Receiver Thread that loops indefinitely for receiving messages through the TCP element associated with the communication element

Field Summary

protected FaultLevel	crashLevel Level of crash of the process
protected boolean	debugFault Precise if debug information, concerning message lost and transmission delays, must be printed on standard output
protected SynchronizedBuffer	msgBuffer Internal buffer for received messages
protected IPProcessIdentifier	myPid Identifier of the process
protected FaultLevel	packetLostLevel Level of lost of packet sent through the network
protected java.util.Random	randGen Generator of random numbers for managing the lost and delays for messages
protected TCPElement	tcp TCP element for physically sending and receiving messages
protected FaultLevel	transmissionDelayLowerBound Level of the minimum delay for a message to join the receiver element
protected FaultLevel	transmissionDelayUpperBound Level of the maximum delay for a message to join the receiver element

Constructor Summary

CommunicationElement()
Create and fully initialize a communication element, using any available TCP port

CommunicationElement(int port)
Create and fully initialize a communication element

Method Summary

Message	asynchReceiveMessage() Return a received message coming from any remote process.
boolean	availableMessage() Check if there is unread received messages
void	crashProcess() Depending of the crash level and a random value generated, crash the process or not
FaultLevel	getCrashLevel()
IPProcessIdentifier	getMyPid() Get the complete process identifier.
FaultLevel	getPacketLostLevel()
FaultLevel	getTransmissionDelayLowerBound()
FaultLevel	getTransmissionDelayUpperBound()
boolean	isDebugFault()
protected boolean	isPacketLost()
protected abstract void	physicalSendMessage(Message msg, ProcessIdentifier id) Method called to "physically" send a message through TCP sockets.
void	sendMessage(Message msg) Send a message to a remote process which address is embedded in the message.
void	sendMessage(ProcessIdentifier id, java.lang.Object data) Send a message to a remote process.
void	setCrashLevel(FaultLevel crashLevel)
void	setDebugFault(boolean debugFault)
void	setMyPid(int id) Modify the (supposed unique) identifier integer value inside the process identifier.
void	setPacketLostLevel(FaultLevel packetLostLevel)
void	setTransmissionDelayLowerBound(FaultLevel transmissionDelayLowerBound)
void	setTransmissionDelayUpperBound(FaultLevel transmissionDelayUpperBound)
Message	synchReceiveMessage() Return a received message coming from any remote process.
protected int	transmissionDelay()

Methods inherited from class java.lang.Object

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

Field Detail

packetLostLevel

protected FaultLevel packetLostLevel

Level of lost of packet sent through the network

transmissionDelayLowerBound

protected FaultLevel transmissionDelayLowerBound

Level of the minimum delay for a message to join the receiver element

transmissionDelayUpperBound

protected FaultLevel transmissionDelayUpperBound

Level of the maximum delay for a message to join the receiver element

crashLevel

protected FaultLevel crashLevel

Level of crash of the process

debugFault

protected boolean debugFault

Precise if debug information, concerning message lost and transmission delays, must be printed on standard output

myPid

protected IPProcessIdentifier myPid

Identifier of the process

msgBuffer

protected SynchronizedBuffer msgBuffer

Internal buffer for received messages

tcp

protected TCPElement tcp

TCP element for physically sending and receiving messages

randGen

protected java.util.Random randGen

Generator of random numbers for managing the lost and delays for messages

Constructor Detail

CommunicationElement

public CommunicationElement()
                     throws CommunicationException

Create and fully initialize a communication element, using any available TCP port

Throws:

CommunicationException - in case of problem (the socket can not be bound to required port)

CommunicationElement

public CommunicationElement(int port)
                     throws CommunicationException

Create and fully initialize a communication element

Parameters:

port - the port on which to bind the TCP socket server of the communication element. 0 for taken any available port

Throws:

CommunicationException - in case of problem (the socket can not be bound to required port)

Method Detail

getTransmissionDelayLowerBound

public FaultLevel getTransmissionDelayLowerBound()

Returns:

the transmissionDelayLowerBound

setTransmissionDelayLowerBound

public void setTransmissionDelayLowerBound(FaultLevel transmissionDelayLowerBound)

Parameters:

transmissionDelayLowerBound - the transmissionDelayLowerBound to set

getTransmissionDelayUpperBound

public FaultLevel getTransmissionDelayUpperBound()

Returns:

the transmissionDelayUpperBound

setTransmissionDelayUpperBound

public void setTransmissionDelayUpperBound(FaultLevel transmissionDelayUpperBound)

Parameters:

transmissionDelayUpperBound - the transmissionDelayUpperBound to set

getPacketLostLevel

public FaultLevel getPacketLostLevel()

Returns:

the packetLostLevel

setPacketLostLevel

public void setPacketLostLevel(FaultLevel packetLostLevel)

Parameters:

packetLostLevel - the packetLostLevel to set

getCrashLevel

public FaultLevel getCrashLevel()

Returns:

the process crash level

setCrashLevel

public void setCrashLevel(FaultLevel crashLevel)

Parameters:

crashLevel - the crash level to set

isDebugFault

public boolean isDebugFault()

Returns:

the debugFault

setDebugFault

public void setDebugFault(boolean debugFault)

Parameters:

debugFault - the debugFault to set

getMyPid

public IPProcessIdentifier getMyPid()

Get the complete process identifier. Notice that the IP and port field are automatically set once the communication element has been created. The identifier integer field is not set and has the value of 0 by default.

Returns:

the process identifier

setMyPid

public void setMyPid(int id)

Modify the (supposed unique) identifier integer value inside the process identifier. The other fields (IP and port) of the complete process identifier have not to be changed because they are initialized when the communication element is created and must not change after that.

Parameters:

id - the identifier of the process

sendMessage

public void sendMessage(Message msg)
                 throws CommunicationException

Description copied from interface: ICommunication

Send a message to a remote process which address is embedded in the message.

Specified by:

sendMessage in interface ICommunication

Parameters:

msg - the message to send

Throws:

CommunicationException - in case of communication error

sendMessage

public void sendMessage(ProcessIdentifier id,
                        java.lang.Object data)
                 throws CommunicationException

Description copied from interface: ICommunication

Send a message to a remote process.

Specified by:

sendMessage in interface ICommunication

Parameters:

id - the identifier, including its physical address, of the remote process

data - the data to send to the remote process

Throws:

CommunicationException - in case of communication error

synchReceiveMessage

public Message synchReceiveMessage()

Description copied from interface: ICommunication

Return a received message coming from any remote process. If no unread message is available wait for the reception of a message.

Specified by:

synchReceiveMessage in interface ICommunication

Returns:

the next unread received message

asynchReceiveMessage

public Message asynchReceiveMessage()

Description copied from interface: ICommunication

Return a received message coming from any remote process. If no unread message is available return directly the null value.

Specified by:

asynchReceiveMessage in interface ICommunication

Returns:

the next unread received message or null if none

availableMessage

public boolean availableMessage()

Description copied from interface: ICommunication

Check if there is unread received messages

Specified by:

availableMessage in interface ICommunication

Returns:

true if there is at least one unread received message, false otherwise

physicalSendMessage

protected abstract void physicalSendMessage(Message msg,
                                            ProcessIdentifier id)
                                     throws CommunicationException

Method called to "physically" send a message through TCP sockets. Will be specialized in ReliableCommElt and UnreliableCommElt depending on the reliability policy.

Parameters:

msg - the message to be sent (including the receiver id)

id - the id of the sender

Throws:

CommunicationException - in case of communication problem

isPacketLost

protected boolean isPacketLost()

Returns:

true if the packet must be lost according to the lost fault level

transmissionDelay

protected int transmissionDelay()

Returns:

the transmission delay to wait before sending the message according to the transmission delay bounds

crashProcess

public void crashProcess()

Description copied from interface: ICommunication

Depending of the crash level and a random value generated, crash the process or not

Specified by:

crashProcess in interface ICommunication