org.jlab.coda.cMsg.cMsgDomain.server

Class cMsgNameServer

java.lang.Object

java.lang.Thread

org.jlab.coda.cMsg.cMsgDomain.server.cMsgNameServer

All Implemented Interfaces:

java.lang.Runnable, IExecutorThread

public class cMsgNameServer
extends java.lang.Thread
implements IExecutorThread

This class implements a cMsg name server in the cMsg domain. A word of caution. If multiple cMsgNameServer objects exist in a single JVM and they both service clients in the cMsg subdomain, then there will be undesirable effects. In other words, the cMsg subdomain uses static data in some of its implementing classes (cMsgServerBridge and cMsg).

Version:

1.0

Author:

Carl Timmer

Nested Class Summary

Nested classes/interfaces inherited from class java.lang.Thread

java.lang.Thread.State, java.lang.Thread.UncaughtExceptionHandler

Field Summary

Fields

Modifier and Type	Field and Description
(package private) java.util.concurrent.CountDownLatch	allowConnectionsCloudSignal Use this to signal the point at which other servers and clients are allowed to connect to this server due to server cloud issues.
(package private) java.util.List<cMsgDomainServerSelect>	availableDomainServers List of all cMsgDomainServerSelect objects that have room for more clients.
(package private) static byte	BECOMINGCLOUD Server is in the process of becoming a part of the server cloud.
(package private) cMsgServerBridge	bridgeBeingCreated Server this name server is in the middle of or starting to connect to.
(package private) java.util.concurrent.ConcurrentHashMap<java.lang.String,cMsgServerBridge>	bridges Keep track of all the cMsgServerBridge objects in the cMsg subdomain.
(package private) java.lang.String	clientPassword Password that clients need to match before being allowed to connect.
(package private) java.lang.String	cloudPassword Password that this server needs to join a cloud and the password that another server needs to join this one.
(package private) static int	domainPortMax The maximum value for the cMsgDomainServer's listening port number.
(package private) static int	domainServerPort The value of the TCP listening port for establishing permanent client connections.
(package private) java.util.concurrent.ConcurrentHashMap<cMsgDomainServer,java.lang.String>	domainServers Set of all active cMsgDomainServer objects.
(package private) java.util.concurrent.ConcurrentHashMap<cMsgDomainServerSelect,java.lang.String>	domainServersSelect Set of all active cMsgDomainServerSelect objects.
(package private) java.lang.String	fullMonitorXML String which contains the entire monitor data of the server cloud (xml format).
(package private) static byte	INCLOUD Server is in the server cloud.
(package private) java.util.concurrent.CountDownLatch	listeningThreadsStartedSignal Use this to signal that this server's listening threads have been started so bridges may be created and clients may connect.
(package private) boolean	monitoringOff If true, this server does NOT send an XML string containing its state to all clients.
(package private) java.util.concurrent.ConcurrentHashMap<java.lang.String,cMsgClientData>	nameServers Keep track of all name servers which have connected to this server.
(package private) static byte	NONCLOUD Server is NOT in the server cloud.
(package private) java.lang.String	nsMonitorXML String which contains the monitor data of this particular name server (xml format).
(package private) java.util.concurrent.CountDownLatch	postConnectionThreadsStartedSignal There are 2 threads which must be running before client connections are allowed.
(package private) java.util.concurrent.CountDownLatch	preConnectionThreadsStartedSignal There are 3 threads which must be running before client connections are allowed.
(package private) java.lang.String	serverName This server's name.
(package private) boolean	standAlone Does this server stand alone and NOT allow bridges to/from other cMsg subdomain servers?
(package private) java.util.concurrent.locks.ReentrantLock	subscribeLock Lock to ensure all access to subscriptions is sequential.
(package private) java.util.HashSet<cMsgServerSubscribeInfo>	subscriptions Set of all subscriptions (including the subAndGets) of all clients on this server.
(package private) static byte	UNKNOWNCLOUD Server cloud status is unknown.

Fields inherited from class java.lang.Thread

MAX_PRIORITY, MIN_PRIORITY, NORM_PRIORITY

Constructor Summary

Constructors

Constructor and Description
cMsgNameServer(int port, int domainPort, int udpPort, boolean standAlone, boolean monitoringOff, java.lang.String clientPassword, java.lang.String cloudPassword, java.lang.String serverToJoin, int debug, int clientsMax) Constructor which reads environmental variables and opens listening sockets.

Method Summary

Modifier and Type	Method and Description
void	cleanUp() Implement IExecutorThread interface so cMsgNameServer can be run using the Commander/Executor framework.
(package private) void	cloudLock() This method locks a lock used in adding servers to the server cloud and in adding clients to servers.
(package private) boolean	cloudLock(int delay) This method locks a lock used in adding servers to the server cloud and in adding clients to servers.
(package private) void	cloudUnlock() This method unlocks a lock used in adding servers to the server cloud and in adding clients to servers.
int	getCloudStatus() Get the status of the relationship of this server to the cMsg subdomain server cloud.
int	getDomainPort() Get the domain server's listening port.
java.lang.String	getHost() Get the host this server is running on.
int	getMulticastPort() Get name server's multicast listening port.
int	getPort() Get the name server's listening port.
java.lang.String	getServerName() Get this server's name (host:port).
static void	main(java.lang.String[] args) Run as a stand-alone application.
void	printSizes() This method prints out the sizes of all objects which store other objects.
void	run() This method is executed as a thread.
(package private) void	setCloudStatus(int status) Set the status of the relationship of this server to the cMsg subdomain server cloud.
(package private) void	shutdown() Method to gracefully shutdown all threads associated with this server and to clean up.
void	shutItDown() When a class implementing this interface is run by an Executor, eventually a Commander may want to stop it.
void	startItUp() When a class implementing this interface is run by an Executor, it calls this method to do so.
void	startServer() Method to start up this server and join the cMsg server cloud that serverToJoin is a part of.
void	waitUntilDone() When a class implementing this interface is run by an Executor, a Commander may want to wait until it finished running.

Methods inherited from class java.lang.Thread

activeCount, checkAccess, clone, countStackFrames, currentThread, destroy, dumpStack, enumerate, getAllStackTraces, getContextClassLoader, getDefaultUncaughtExceptionHandler, getId, getName, getPriority, getStackTrace, getState, getThreadGroup, getUncaughtExceptionHandler, holdsLock, interrupt, interrupted, isAlive, isDaemon, isInterrupted, join, join, join, resume, setContextClassLoader, setDaemon, setDefaultUncaughtExceptionHandler, setName, setPriority, setUncaughtExceptionHandler, sleep, sleep, start, stop, stop, suspend, toString, yield

Methods inherited from class java.lang.Object

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

Field Detail

serverName

java.lang.String serverName

This server's name.

domainPortMax

static int domainPortMax

The maximum value for the cMsgDomainServer's listening port number.

domainServerPort

static int domainServerPort

The value of the TCP listening port for establishing permanent client connections.

preConnectionThreadsStartedSignal

java.util.concurrent.CountDownLatch preConnectionThreadsStartedSignal

There are 3 threads which must be running before client connections are allowed. Use this object to signal the point at which both of these threads have been successfully started (during startServer()) .

postConnectionThreadsStartedSignal

java.util.concurrent.CountDownLatch postConnectionThreadsStartedSignal

There are 2 threads which must be running before client connections are allowed. Use this object to signal the point at which both of these threads have been successfully started (during startServer()) .

domainServers

java.util.concurrent.ConcurrentHashMap<cMsgDomainServer,java.lang.String> domainServers

Set of all active cMsgDomainServer objects. It is implemented as a HashMap but that is only to take advantage of the concurrency protection. The values are all null. This set will be used to call the active domain servers' handleServerShutdown methods when this name server is being shutdown or also when creating monitoring data strings.

domainServersSelect

java.util.concurrent.ConcurrentHashMap<cMsgDomainServerSelect,java.lang.String> domainServersSelect

Set of all active cMsgDomainServerSelect objects. It is implemented as a HashMap but that is only to take advantage of the concurrency protection. The values are all null. This set will be used to call the active domain servers' handleServerShutdown methods when this name server is being shutdown or also when creating monitoring data strings.

availableDomainServers

java.util.List<cMsgDomainServerSelect> availableDomainServers

List of all cMsgDomainServerSelect objects that have room for more clients.

subscriptions

java.util.HashSet<cMsgServerSubscribeInfo> subscriptions

Set of all subscriptions (including the subAndGets) of all clients on this server. This is mutex protected by subscribeLock.

subscribeLock

final java.util.concurrent.locks.ReentrantLock subscribeLock

Lock to ensure all access to subscriptions is sequential.

fullMonitorXML

java.lang.String fullMonitorXML

String which contains the entire monitor data of the server cloud (xml format).

nsMonitorXML

java.lang.String nsMonitorXML

String which contains the monitor data of this particular name server (xml format).

monitoringOff

boolean monitoringOff

If true, this server does NOT send an XML string containing its state to all clients.

clientPassword

java.lang.String clientPassword

Password that clients need to match before being allowed to connect. This is subdomain independent and applies to the server as a whole. If this is null and the client supplies a password anyway, that is also forbidden. In this way, this password acts as a unique name for this cMsg server.

cloudPassword

java.lang.String cloudPassword

Password that this server needs to join a cloud and the password that another server needs to join this one. This is cMsg subdomain specific.

standAlone

boolean standAlone

Does this server stand alone and NOT allow bridges to/from other cMsg subdomain servers?

bridgeBeingCreated

volatile cMsgServerBridge bridgeBeingCreated

Server this name server is in the middle of or starting to connect to.

listeningThreadsStartedSignal

java.util.concurrent.CountDownLatch listeningThreadsStartedSignal

Use this to signal that this server's listening threads have been started so bridges may be created and clients may connect.

allowConnectionsCloudSignal

java.util.concurrent.CountDownLatch allowConnectionsCloudSignal

Use this to signal the point at which other servers and clients are allowed to connect to this server due to server cloud issues.

INCLOUD

static final byte INCLOUD

Server is in the server cloud.

See Also:

Constant Field Values

NONCLOUD

static final byte NONCLOUD

Server is NOT in the server cloud.

See Also:

Constant Field Values

BECOMINGCLOUD

static final byte BECOMINGCLOUD

Server is in the process of becoming a part of the server cloud.

See Also:

Constant Field Values

UNKNOWNCLOUD

static final byte UNKNOWNCLOUD

Server cloud status is unknown.

See Also:

Constant Field Values

nameServers

java.util.concurrent.ConcurrentHashMap<java.lang.String,cMsgClientData> nameServers

Keep track of all name servers which have connected to this server. This hashmap stores the server name (host:port) as the index and the cMsgClientData object as the value.

bridges

java.util.concurrent.ConcurrentHashMap<java.lang.String,cMsgServerBridge> bridges

Keep track of all the cMsgServerBridge objects in the cMsg subdomain. A bridge is a connection from this cMsg server to another. The server name (host:port) is the key and the bridge object is the value.

Constructor Detail

cMsgNameServer

public cMsgNameServer(int port,
                      int domainPort,
                      int udpPort,
                      boolean standAlone,
                      boolean monitoringOff,
                      java.lang.String clientPassword,
                      java.lang.String cloudPassword,
                      java.lang.String serverToJoin,
                      int debug,
                      int clientsMax)

Constructor which reads environmental variables and opens listening sockets.

Parameters:

port - TCP listening port for communication from clients

domainPort - listening port for receiving 2 permanent connections from each client

udpPort - UDP listening port for receiving multicasts from clients

standAlone - if true no other cMsg servers are allowed to attached to this one and form a cloud

monitoringOff - if true clients are NOT sent monitoring data

clientPassword - password client needs to provide to connect to this server

cloudPassword - password server needs to provide to connect to this server to become part of a cloud

serverToJoin - server whose cloud this server is to be joined to

debug - desired level of debug output

clientsMax - max number of clients per cMsgDomainServerSelect object for regime = low

Method Detail

cloudLock

void cloudLock()

This method locks a lock used in adding servers to the server cloud and in adding clients to servers. This is used only in the cMsg subdomain.

cloudLock

boolean cloudLock(int delay)

This method locks a lock used in adding servers to the server cloud and in adding clients to servers. This is used only in the cMsg subdomain.

Parameters:

delay - time in milliseconds to wait for the lock before timing out

Returns:

true if locked, false otherwise

cloudUnlock

void cloudUnlock()

This method unlocks a lock used in adding servers to the server cloud and in adding clients to servers. This is used only in the cMsg subdomain.

getCloudStatus

public int getCloudStatus()

Get the status of the relationship of this server to the cMsg subdomain server cloud.

Returns:

status which is one of INCLOUD, NONCLOUD, or BECOMINGCLOUD

setCloudStatus

void setCloudStatus(int status)

Set the status of the relationship of this server to the cMsg subdomain server cloud. The status may only be one of INCLOUD, NONCLOUD, or BECOMINGCLOUD.

Parameters:

status - status of the relationship of this server to the cMsg subdomain server cloud

getServerName

public java.lang.String getServerName()

Get this server's name (host:port).

Returns:

server's name

getHost

public java.lang.String getHost()

Get the host this server is running on.

Returns:

server's name

getPort

public int getPort()

Get the name server's listening port.

Returns:

name server's listening port

getDomainPort

public int getDomainPort()

Get the domain server's listening port.

Returns:

domain server's listening port

getMulticastPort

public int getMulticastPort()

Get name server's multicast listening port.

Returns:

name server's multicast listening port

printSizes

public void printSizes()

This method prints out the sizes of all objects which store other objects.

main

public static void main(java.lang.String[] args)

Run as a stand-alone application.

Parameters:

args - arguments.

startItUp

public void startItUp()

Description copied from interface: IExecutorThread

When a class implementing this interface is run by an Executor, it calls this method to do so. This method does everything that needs doing in order to get this application running. In a Thread object, this can be used to wrap start();

Specified by:

startItUp in interface IExecutorThread

shutItDown

public void shutItDown()

Description copied from interface: IExecutorThread

When a class implementing this interface is run by an Executor, eventually a Commander may want to stop it. In that case, this method can be run so things can be shut down and cleaned up. In a Thread object, this can be used to wrap some user method to gracefully shut the thread down;

Specified by:

shutItDown in interface IExecutorThread

waitUntilDone

public void waitUntilDone()
                   throws java.lang.InterruptedException

Description copied from interface: IExecutorThread

When a class implementing this interface is run by an Executor, a Commander may want to wait until it finished running. In that case, this method can be run so things to wait for it to finish. In a Thread object, this can be used to wrap join();

Specified by:

waitUntilDone in interface IExecutorThread

Throws:

java.lang.InterruptedException - if thread interrupted.

startServer

public void startServer()

Method to start up this server and join the cMsg server cloud that serverToJoin is a part of. If the serverToJoin is null, this server is the nucleus of a new server cloud.

cleanUp

public void cleanUp()

Implement IExecutorThread interface so cMsgNameServer can be run using the Commander/Executor framework.

shutdown

void shutdown()

Method to gracefully shutdown all threads associated with this server and to clean up.

run

public void run()

This method is executed as a thread.

Specified by:

run in interface java.lang.Runnable

Overrides:

run in class java.lang.Thread