biz.chitec.quarterback.gjsa
Class SessionedServerConnector

java.lang.Object
  biz.chitec.quarterback.gjsa.SessionedServerConnector

Direct Known Subclasses:

CBServerConnector, DirectSessionedServerConnector

public abstract class SessionedServerConnector

extends java.lang.Object

Low level communication with GJSA server Keeps connection to server one way or the other. Gets all data from server and passes it to the appropriate SessionConnector object. All ServerConnectors are connected to this one and send and receive data from here. SessionedServerConnector tells interested party through PropertyChangeEvents what is happening with the connection. The following property names and values can be sent during normal operation:

• CONNECTED (false|true): sent after a connection could be established or was closed normally.
• OBJECTMODE (false|true): indicates change in object transmission mode. By default, data is transferred between client and server as Latin1-coded strings. If both parties agree, however, at the beginning of the connection that version numbers of protocols and virtual machines are equal enough, data transfer is switched to serialized Java objects. Such a change is indicated by this property. Note that the transfer mode is fully transparent to all higher layers. This property is sent for documentation purposes only. Note that this property will at maximum change once and that this will happen during the connection initialisation phase.
• ENCRYPTED (false|true): indicates whether the connection is SSL-encrypted or not. At the beginning, the connection is always unencrypted. If client and server agree that encryption would be nice and find a common encryption protocol, they turn on encryption. Note that this property will at maximum change once and that this will happen during the connection initialisation phase.
• TRANSMITTING (false|true): indicates that a transmission is currently happening. Before sending any query to the server, this property is changed from false to true. After the answer has been received, it changes back to false.
• DESASTER (true): Sent if a so-called "connection desaster" occurred. Normally, this means an unexpected shutdown of the connection. This can happen if there is a problem with the connection itself or if the server has been shut down. After this property has been sent, the connection is closed and all transmissions have been aborted. This property is only sent once and its new value is always true.

A connection to a GJSA server can be opened by either calling openConnection() or openConnectionAsynchonously(). The first call blocks until either the connection could have been established or the socket did timeout. The second one detaches into a seperate thread which tries to open the connection in the background. That thread can be stopped by calling stopOpenConnectionAsynchonously(). Asynchronous connection establishing indicates mode changes also via property events. The following ones can occur:

• BACKGROUNDCONNECT (false|true): Indicates that the background connecting thread has been started or stopped. Stopping of this thread does not indicate that the connection has actually been established.
• BGCEXCEPTION (Exception): An exception occured while attempting to connect to the server. The thread will continue, however.
• BGDESASTER (error message): An internal problem occured. The connection could not be opened. This should not happen. Which is the best guarantee that it actually will...
• SESSION0 (SessionConnector): Sent after the connection has been established successfully. The property contains the initial SessionConnector object which can be used to send commands to the server. Receiving this property event means that the connection has been established successfully. It is the same which would have been returned by the synchronous openConnection()-method.

Version:

$Id: cdc0efc936f95584cc573f0f185e7523c1a4dc63 $

Author:

cantamen/Dirk Hillbrecht 2003-2004. Distributed under the terms of the GNU LGPL.

Nested Class Summary

private class

SessionedServerConnector.BackgroundConnectionOpener Seperate thread for connection opening in the background.

Field Summary

private SessionedServerConnector.BackgroundConnectionOpener	bco
protected boolean	connected
protected int	connectionport
protected int	encodingmode
protected boolean	encrypted
private java.util.List	freefloatingreceivers
protected Logger	mess
protected int	myscno
protected java.beans.PropertyChangeSupport	pcs
private static int	sccount
private java.util.Map	serverconnectors For passing free floating information.
protected java.lang.String	serverseenclientip
protected java.lang.String	serverseenclientname
private SessionConnector	session0
static int	SOCKET_SO_TIME Timeout for the socket in initialisation phase.
private static boolean	sslavailable
protected java.lang.String[]	sslciphers
protected javax.net.ssl.SSLSocketFactory	sslfactory
protected boolean	transmitting

Constructor Summary

SessionedServerConnector()

Method Summary

void	addFreeFloatingReceiver(ThreadInterface ti) Add a new receiver for free floating messages.
void	addPropertyChangeListener(java.beans.PropertyChangeListener listener)
void	addPropertyChangeListener(java.lang.String propertyname, java.beans.PropertyChangeListener listener)
void	closeConnection() Close the connection.
protected abstract void	doCloseConnection() Perform necessary operations to actually close the connection.
protected abstract void	doOpenConnection() Perform necessary operations to actually open the connection.
protected void	fireDesaster()
protected void	fireFreeFloatingMessage(ServerEnvelope se) Fires a free floating message.
int	getEncodingMode()
protected boolean	getEncryptionAdvice(int clientstrategy, int serverwish) Determines whether the connection should be encrypted or not.
private java.util.List	getFirstAndSecondVersionPart(java.lang.String vers) Puts first and second part of a multipart version number into a list.
java.lang.String	getServerSeenClientIP()
java.lang.String	getServerSeenClientName()
SessionConnector	getSession0()
static SessionedServerConnector	getSessionedServerConnector(java.lang.String host, int port)
static SessionedServerConnector	getSessionedServerConnector(java.lang.String host, int port, java.util.List params)
static SessionedServerConnector	getSessionedServerConnector(java.lang.String host, int port, java.util.Map params)
boolean	isConnected()
boolean	isEncrypted()
boolean	isTransmitting()
SessionConnector	openConnection() Opens the connection to the server.
void	openConnectionAsynchronously() Opens a connection asynchronously without waiting at the beginning.
void	openConnectionAsynchronously(long initialwaittime) Starts a seperate thread which tries to open the connection asynchronously.
java.lang.Object	queryOrBranch(ServerEnvelope se)
protected abstract ServerEnvelope	readEnvelope() Read a reply from the server.
void	removeFreeFloatingReceiver(ThreadInterface ti) Removes a receiver for free floating messages from the internal list.
void	removePropertyChangeListener(java.beans.PropertyChangeListener listener)
void	removePropertyChangeListener(java.lang.String propertyname, java.beans.PropertyChangeListener listener)
protected void	setConnected(boolean newconnected)
protected void	setEncodingMode(int newencodingmode)
protected void	setEncrypted(boolean newencrypted)
void	setMessageLogger(Logger mx)
abstract void	setSendKeepAlive(boolean b) Enables and disables the session connector to/from sending keep alive packets to the server.
protected void	setTransmission(boolean newtransmitting)
protected void	setupConnectionParameters(boolean forcestring, java.util.List clientprotocolversion, int clientencstrategy, java.util.Map serverparams)
void	stopOpenConnectionAsynchronously(boolean waitforstop) Stops an asynchronous connection opening.
void	unregisterServerConnector(SessionConnector sc)
protected abstract void	writeEnvelope(ServerEnvelope se) Write an envelope to the server.

Methods inherited from class java.lang.Object

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

Field Detail

sslavailable

private static boolean sslavailable

SOCKET_SO_TIME

public static final int SOCKET_SO_TIME

Timeout for the socket in initialisation phase.

See Also:

Constant Field Values

sccount

private static int sccount

myscno

protected int myscno

serverconnectors

private java.util.Map serverconnectors

For passing free floating information. Registered automatically, unregistering must be done by ServerConnectors on their own.

encodingmode

protected int encodingmode

encrypted

protected boolean encrypted

connected

protected boolean connected

transmitting

protected boolean transmitting

sslfactory

protected javax.net.ssl.SSLSocketFactory sslfactory

sslciphers

protected java.lang.String[] sslciphers

connectionport

protected int connectionport

mess

protected Logger mess

serverseenclientip

protected java.lang.String serverseenclientip

serverseenclientname

protected java.lang.String serverseenclientname

pcs

protected java.beans.PropertyChangeSupport pcs

freefloatingreceivers

private java.util.List freefloatingreceivers

bco

private SessionedServerConnector.BackgroundConnectionOpener bco

session0

private SessionConnector session0

Constructor Detail

SessionedServerConnector

public SessionedServerConnector()

Method Detail

queryOrBranch

public java.lang.Object queryOrBranch(ServerEnvelope se)
                               throws java.io.IOException

Throws:

java.io.IOException

unregisterServerConnector

public void unregisterServerConnector(SessionConnector sc)

getServerSeenClientIP

public java.lang.String getServerSeenClientIP()

getServerSeenClientName

public java.lang.String getServerSeenClientName()

addPropertyChangeListener

public void addPropertyChangeListener(java.beans.PropertyChangeListener listener)

addPropertyChangeListener

public void addPropertyChangeListener(java.lang.String propertyname,
                                      java.beans.PropertyChangeListener listener)

removePropertyChangeListener

public void removePropertyChangeListener(java.beans.PropertyChangeListener listener)

removePropertyChangeListener

public void removePropertyChangeListener(java.lang.String propertyname,
                                         java.beans.PropertyChangeListener listener)

getEncodingMode

public int getEncodingMode()

isEncrypted

public boolean isEncrypted()

isConnected

public boolean isConnected()

isTransmitting

public boolean isTransmitting()

setEncodingMode

protected void setEncodingMode(int newencodingmode)

setEncrypted

protected void setEncrypted(boolean newencrypted)

setConnected

protected void setConnected(boolean newconnected)

setTransmission

protected void setTransmission(boolean newtransmitting)

setMessageLogger

public void setMessageLogger(Logger mx)

fireDesaster

protected void fireDesaster()

openConnection

public SessionConnector openConnection()
                                throws java.io.IOException

Opens the connection to the server. Tries to open the connection to the server which has been given to the factory method. Throws an IOException if the connection cannot be opened, an error occurs during opening attempt of if the connection is already open and has not been closed in advance.

Returns:

SessionConnector to the initial session of the server connection.

Throws:

java.io.IOException - If something goes wrong with opening the connection.

getSession0

public SessionConnector getSession0()

closeConnection

public void closeConnection()

Close the connection. Closing the connection does not render the Connector invalid, the connection can be reopened.

doOpenConnection

protected abstract void doOpenConnection()
                                  throws java.io.IOException

Perform necessary operations to actually open the connection.

Throws:

java.io.IOException

doCloseConnection

protected abstract void doCloseConnection()

Perform necessary operations to actually close the connection.

writeEnvelope

protected abstract void writeEnvelope(ServerEnvelope se)
                               throws java.io.IOException

Write an envelope to the server.

Throws:

java.io.IOException

readEnvelope

protected abstract ServerEnvelope readEnvelope()
                                        throws java.io.IOException

Read a reply from the server.

Throws:

java.io.IOException

setSendKeepAlive

public abstract void setSendKeepAlive(boolean b)

Enables and disables the session connector to/from sending keep alive packets to the server. These packets prevent the server from closing the connection in case of inactivity.

addFreeFloatingReceiver

public void addFreeFloatingReceiver(ThreadInterface ti)

Add a new receiver for free floating messages. The receiver is given as ThreadInterface. It is put into the receiver list (if it is not already in there). This method synchronized with the receiver list, so no delivery of free floating messages takes place while there are receivers to be added.

Parameters:

ti - The ThreadInterface to be removed

removeFreeFloatingReceiver

public void removeFreeFloatingReceiver(ThreadInterface ti)

Removes a receiver for free floating messages from the internal list. The receiver is given as the same ThreadInterface as which it was added. If the receiver is not in the list, noting happens. This method synchronized with the receiver list, so no delivery of free floating messages takes place while there are receivers to be added. Note that a receiver's ThreadInterface is removed automatically if writing to it fails. Therefore, it could be better not to remove the ThreadInterface explicitly but simply to close it on the receiver side. This circumvents the need of an additional synchronization on the receiver list just for the removing task.

Parameters:

ti - The ThreadInterface to be removed

fireFreeFloatingMessage

protected void fireFreeFloatingMessage(ServerEnvelope se)

Fires a free floating message. The message is sent into all ThreadInterfaces registered through addFreeFloatingReceiver. If produce()ing the message into a ThreadInterface fails, that ThreadInterface is removed from the internal list immediately. The complete action is synchronized on the receiver's list. As sending data into a ThreadInterface does never delay, this should be ok.

Parameters:

se - The message to be sent

openConnectionAsynchronously

public void openConnectionAsynchronously(long initialwaittime)

Starts a seperate thread which tries to open the connection asynchronously. Throws exception if an asynchronous attempt to open the connection is already running. Otherwise, instanciates a seperate thread which tries to connect regulary to the server. If the initialwaittime is greater than zero, the background opener will wait for the given amount of milliseconds before the first connection attempt is made.

Parameters:

initialwaittime - Milliseconds to wait before the first connection attempt is done.

openConnectionAsynchronously

public void openConnectionAsynchronously()

Opens a connection asynchronously without waiting at the beginning.

stopOpenConnectionAsynchronously

public void stopOpenConnectionAsynchronously(boolean waitforstop)

Stops an asynchronous connection opening. If an asynchronous connection opening thread is currently running, it is asked to stop. It is not guaranteed that the connection is not established quite between calling this method and stop call to the async thread. The real connection state can only be derived from the events sent by the connector.

Parameters:

waitforstop - If true, method does not return before asynchronous thread has finished.

getFirstAndSecondVersionPart

private java.util.List getFirstAndSecondVersionPart(java.lang.String vers)

Puts first and second part of a multipart version number into a list.

getEncryptionAdvice

protected boolean getEncryptionAdvice(int clientstrategy,
                                      int serverwish)

Determines whether the connection should be encrypted or not. The Server has one of four wishes about encryption while the client follows one of five strategies. The actual result of the connection being encrypted or not or the whole connect process being aborted can be looked up in the following table (client in rows, server in columns):

Client\Server	no encryption	FORBIDDEN	NOTNEEDED	WANTED	REQUIRED
never	clear	clear	clear	clear	fail
onrequire	clear	clear	clear	clear	encrypted
onwanted	clear	clear	clear	encrypted	encrypted
always	clear	clear	encrypted	encrypted	encrypted
alwaysforced	fail	fail	encrypted	encrypted	encrypted

Parameters:

clientstrategy - encryption strategy of the client

serverwish - encryption wish of the server

Returns:

indication whether the connection should be encrypted (true) or not (false)

setupConnectionParameters

protected void setupConnectionParameters(boolean forcestring,
                                         java.util.List clientprotocolversion,
                                         int clientencstrategy,
                                         java.util.Map serverparams)

getSessionedServerConnector

public static SessionedServerConnector getSessionedServerConnector(java.lang.String host,
                                                                   int port,
                                                                   java.util.Map params)

getSessionedServerConnector

public static SessionedServerConnector getSessionedServerConnector(java.lang.String host,
                                                                   int port,
                                                                   java.util.List params)

getSessionedServerConnector

public static SessionedServerConnector getSessionedServerConnector(java.lang.String host,
                                                                   int port)