Class Layer2Handler

java.lang.Object

Layer2Handler

All Implemented Interfaces:

BitListener

Direct Known Subclasses:

Layer2Endpoint, SwitchPort

public abstract class Layer2Handler
extends java.lang.Object
implements BitListener

This abstract class represents a Layer2 object that can send and receive layer 2 frames.

Constructor Summary

Constructors

Constructor and Description
Layer2Handler() Create an object, using "localhost" and DEFAULT_PORT, for the IP host and TCP port that this object's BitHandler will connect to (i.e., the LightSystem).
Layer2Handler(java.lang.String host, int port) Create an object, and create a BitHandler for it to use in the layer below it.

Method Summary

Modifier and Type	Method and Description
void	bitsReceived(BitHandler handler, java.lang.String bits) Called when the layer below receives bits successfully.
boolean	dropReceivedFrame(Layer2Frame fr, java.lang.String bits) A default implementation that says we do not drop a received frame.
void	send(Layer2Frame frame) Given a frame, convert it to a string of bits and send it using the BitHandler on layer 1 "below".
void	setListener(Layer2Listener l) Allow another object (e.g., a Layer 3 object) to register itself to get called when this object receives a good frame.

Methods inherited from class java.lang.Object

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

Constructor Detail

Layer2Handler

public Layer2Handler()

Create an object, using "localhost" and DEFAULT_PORT, for the IP host and TCP port that this object's BitHandler will connect to (i.e., the LightSystem).

Layer2Handler

public Layer2Handler(java.lang.String host,
                     int port)

Create an object, and create a BitHandler for it to use in the layer below it. Set this object to receive bitStrings when a bit string is received at the BitHandler below it.

Method Detail

send

public void send(Layer2Frame frame)

Given a frame, convert it to a string of bits and send it using the BitHandler on layer 1 "below".

setListener

public void setListener(Layer2Listener l)

Allow another object (e.g., a Layer 3 object) to register itself to get called when this object receives a good frame.

dropReceivedFrame

public boolean dropReceivedFrame(Layer2Frame fr,
                                 java.lang.String bits)

A default implementation that says we do not drop a received frame. Override in a subclass to specify when it should be dropped. The frame is passed in both cooked and raw formats.

bitsReceived

public void bitsReceived(BitHandler handler,
                         java.lang.String bits)

Called when the layer below receives bits successfully. This code drops packets that we sent that were mirrored back to us, parses the bits into a Layer2Frame (making sure they are a legal format), and calls dropReceivedFrame (implemented in subclasses, possibly), to determine if the frame should not be handled here because it isn't for this endpoint. If the frame is for me, then call the upper-layer listener with the received frame.

Specified by:

bitsReceived in interface BitListener