ikr.simlib.ports

Class Port

java.lang.Object

ikr.simlib.ports.Port

Direct Known Subclasses:

InputPort, OutputPort

public abstract class Port
extends java.lang.Object

Ports are the main abstraction used for communication between entities. Ports use a handshake protocol to exchange messages. Ports of different entities or ports belonging to the same entity may be connected using the Connect()-method of the Entity class. Ports always belong to one entity. Input and output ports are only conceptionally different to make type checking easier. They have the same functionality.

Every port may have several message filters attached to it. They may be used to filter messages, or to get information about messages, e.g. for counting or statistics.
A port may also have one input message handler and one output message handler. Message handlers are the interface between ports and entities. Whenever a message has to be sent, the corresponding message handler is called by the port.

The following protocol is used to exchange messages: If an entity has prepared a new message to send, it calls the MessageIndication()-method of its output port. The message then travels along the connected ports to the destination input port. Finally, the HandleMsgIndication()-method of the input message handler is responsible of handling the message. If it can handle the message, it immediately calls the GetMessage()-method of the input port, which passes the call to the output handler of the source port. The HandleGetMessage()-method of this port must then supply the message (active sender).
If GetMessage() is not called, the sender is blocked. A receiver port may call IsMessageAvailable() which is passed from the input port to the corresponding output port. There, the HandleIsMessageAvailable()-method of the output message handler is called (active receiver). GetMessage() may only be called within HandleMsgIndication() or after a successful IsMessageAvaialbale()-call!
The port registers itself automatically at the port manager.

The difference between input and output ports is implemented by the introduction of two special port classes InputPort and OutputPort.

Field Summary

Fields

Modifier and Type	Field and Description
protected static java.util.logging.Logger	LOG
protected Entity	owner
protected java.lang.String	portName

Constructor Summary

Constructors

Constructor and Description
Port(Entity owner, java.lang.String portName)

Method Summary

Methods

Modifier and Type	Method and Description
void	addPortMonitor(PortMonitor monitor)
abstract Port	getConnectedPort() Returns the connected port.
java.lang.String	getDelimiter()
java.lang.String	getLocalName()
Message	getMessage()
java.lang.String	getName()
Entity	getOwner()
protected abstract Message	handleGetMessage()
protected abstract boolean	handleIsMessageAvailable()
protected abstract void	handleMessageIndication(Message msg)
boolean	isConnected() Returns whether this port is connected to another port.
boolean	isMessageAvailable()
void	messageIndication(Message message)
void	removePortMonitor(PortMonitor monitor)

Methods inherited from class java.lang.Object

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

Field Detail

LOG

protected static final java.util.logging.Logger LOG

portName

protected final java.lang.String portName

owner

protected final Entity owner

Constructor Detail

Port

public Port(Entity owner,
    java.lang.String portName)

Method Detail

isConnected

public boolean isConnected()

Returns whether this port is connected to another port.

getConnectedPort

public abstract Port getConnectedPort()

Returns the connected port.

messageIndication

public void messageIndication(Message message)

isMessageAvailable

public boolean isMessageAvailable()

getMessage

public Message getMessage()

handleGetMessage

protected abstract Message handleGetMessage()

handleIsMessageAvailable

protected abstract boolean handleIsMessageAvailable()

handleMessageIndication

protected abstract void handleMessageIndication(Message msg)

addPortMonitor

public void addPortMonitor(PortMonitor monitor)

removePortMonitor

public void removePortMonitor(PortMonitor monitor)

getOwner

public Entity getOwner()

getDelimiter

public java.lang.String getDelimiter()

getLocalName

public java.lang.String getLocalName()

getName

public final java.lang.String getName()