br.shob
Class AbstractCommLayer

java.lang.Object
  |
  +--br.shob.AbstractCommLayer

Direct Known Subclasses:

ClientCommLayer, ServerCommLayer

public abstract class AbstractCommLayer

extends Object

This class contains all common processing for the Communications Layer, which involves connecting to peer machines and sending/receiving signed messages from a socket.

Version:

$Revision: 1.11 $

Author:

crolmos, dukejeffrie

Created:

August 30, 2002

Field Summary

static String	keyPairGeneratorAlgorithm KeyPair generator algorithm name.
protected Logger	logger Description of the Field
protected HostId	myId The HostId of this host.
static String	signatureAlgorithm The algorithm used in all digital signatures in all hosts.

Constructor Summary

protected	AbstractCommLayer() Creates new CommLayer
	AbstractCommLayer(HostId myId, PrivateKey pKey) Constructs a new instance of the communications layer.
	AbstractCommLayer(String hostname, int port) Constructs a new instance of the communications layer.

Method Summary

Socket	connect(String hostname, int port) connects with the peer.
Socket	connect(URL url) connects with the peer.
Logger	getLogger() Gets the logger for this comm layer.
boolean	isOnline() Checks if this commlayer is online (i.e., running and listening).
Message	recvMessage(Socket s, HostId peer) Receives a message using the Root class loader.
Message	recvMessage(Socket s, HostId peer, ClassLoader loader) Reads a message coming from the given socket and verifies its authenticity using the public key from peer.
void	sendMessage(Socket s, Message m) Signs and send a message through the given socket.
void	setLogger(Logger logger) Sets the logger for this instance

Methods inherited from class java.lang.Object

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

Field Detail

keyPairGeneratorAlgorithm

public static final String keyPairGeneratorAlgorithm

KeyPair generator algorithm name. Currently "RSA"

See Also:

Constant Field Values

signatureAlgorithm

public static final String signatureAlgorithm

The algorithm used in all digital signatures in all hosts.

See Also:

Constant Field Values

logger

protected Logger logger

Description of the Field

myId

protected HostId myId

The HostId of this host.

Constructor Detail

AbstractCommLayer

public AbstractCommLayer(HostId myId,
                         PrivateKey pKey)

Constructs a new instance of the communications layer.

Parameters:

myId - HostId of the local host.

pKey - PrivateKey to be used for signing.

AbstractCommLayer

public AbstractCommLayer(String hostname,
                         int port)
                  throws CommLayerException

Constructs a new instance of the communications layer. This constructor generates a HostId and a Key Pair for the instance on the fly.

Parameters:

hostname - Hostname for this host's HostId

port - Listening port for this comm layer

Throws:

CommLayerException - If a URL cannot be formed using the provided hostname and port or if the intended KeyPair Generator Algorithm is not found.

See Also:

keyPairGeneratorAlgorithm

AbstractCommLayer

protected AbstractCommLayer()

Creates new CommLayer

Method Detail

connect

public Socket connect(String hostname,
                      int port)
               throws CommLayerException

connects with the peer.

Parameters:

hostname - the peer hostname

port - the peer's listening port number

Returns:

an open connection to the peer

Throws:

CommLayerException - if any communication error occurs.

connect

public Socket connect(URL url)
               throws CommLayerException

connects with the peer.

Parameters:

url - the url of the peer.

Returns:

an open connection to the peer

Throws:

CommLayerException - if any communication error occurs.

getLogger

public Logger getLogger()

Gets the logger for this comm layer.

Returns:

The logger

isOnline

public boolean isOnline()

Checks if this commlayer is online (i.e., running and listening).

Returns:

true if it is running, false otherwise

recvMessage

public Message recvMessage(Socket s,
                           HostId peer,
                           ClassLoader loader)
                    throws CommLayerException

Reads a message coming from the given socket and verifies its authenticity using the public key from peer.

Parameters:

peer - HostId of the peer.

s - the socket through which the message comes

loader - the class loader used to load remote classes

Returns:

the received and verified Message .

Throws:

CommLayerException - if any communication error occurs.

recvMessage

public Message recvMessage(Socket s,
                           HostId peer)
                    throws CommLayerException

Receives a message using the Root class loader. Equivalent of calling recvMessage(s, peer, null)

Parameters:

s - the socket through which the message comes

peer - HostId of the peer.

Returns:

the received and verified Message

Throws:

CommLayerException - if any communication error occurs.

sendMessage

public void sendMessage(Socket s,
                        Message m)
                 throws CommLayerException

Signs and send a message through the given socket. The message is signed using this host's private key.

Parameters:

s - socket connecting the two hosts.

m - Message to be sent.

Throws:

CommLayerException - if any communication error occurs.

setLogger

public void setLogger(Logger logger)

Sets the logger for this instance

Parameters:

logger - The new logger