wt.manager
Class ServerManagerImpl

java.lang.Object
  java.rmi.server.RemoteObject
      java.rmi.server.RemoteServer
          wt.util.RMIServer
              wt.manager.ServerManagerImpl

All Implemented Interfaces:

Remote, Serializable, ServerManager, Unreferenced

public class ServerManagerImpl

extends RMIServer

implements ServerManager, Unreferenced

The server manager object. This is an RMI server object that exposes server manager operations to remote clients via the RemoteServerManager class.

See Also:

RemoteServerManager, Serialized Form

Field Summary

private int	activeLaunchCount
private static int	getAllServersCalls
private static int	getInfoCalls
private static Object	getInfoCountLock
private static int	getNextServerCalls
private static int	getServerCalls
private Hashtable	launchLocks
private static int	PING_TIMEOUT
private String	previousClientHost
private static int	registerServerCalls
private static int	reportDeadServerCalls
private static String	RESOURCE
private static int	RMI_OBJ_ID
private static int	SERVER_START_TIMEOUT
private static int	serverLaunchCount
private ServerTable	serverTable
private static Date	startDate
private Object	stopLock
private static boolean	VERBOSE_SERVER
private static boolean	VERIFY_DEAD_SERVERS

Fields inherited from class wt.util.RMIServer

csf, ssf

Fields inherited from class java.rmi.server.RemoteServer

Fields inherited from class java.rmi.server.RemoteObject

ref

Fields inherited from interface wt.manager.ServerManager

SERVER_NAME, versionID

Constructor Summary

ServerManagerImpl()
Construct a RMI Server Manager object.

Method Summary

static boolean	alive(String service_name, ManagedServer server) Test if a given manager server is still alive.
protected void	checkAccess() Method to validate access to secure methods such as registerServer or stop.
Vector	getAllServers(String service_name) Get all servers for the requested service_name
static int	getGetInfoCalls()
static int	getGetServerCalls()
ServerManagerInfo	getInfo() Get usage information.
private Object	getLaunchLock(String service_name)
static ServerManagerInfo	getLocalInfo() Get usage information.
Remote	getNextServer(String service_name, Remote server) Get the next available server for the requested service_name.
static int	getRegisterServerCalls()
static int	getReportDeadServerCalls()
Remote	getServer(String service_name) Get reference to a remote server object.
Remote	getServer(String service_name, int start_num) Get reference to a remote server object.
static int	getServerLaunchCount()
static Date	getStartDate()
void	ping() A no-op method available for testing communication.
void	registerServer(String service_name, Remote server) Register a new server instance.
void	reportDeadServer(String service_name, Remote server) Report a bad remote server reference.
void	reportDeadServer(String service_name, Remote server, Exception report_exception) Report a bad remote server reference.
void	stop() Stop this server manager.
void	stopAllServers() Stop all servers this server manager has started.
void	unreferenced() Called when this RMI server object is no longer referenced by any RMI clients.

Methods inherited from class wt.util.RMIServer

clone, exportObject, exportObject, exportObject, getClientSocketFactory, getPort, getServerSocketFactory, getStub, isHostInList, isLocalHost, setPort, writeReplace

Methods inherited from class java.rmi.server.RemoteServer

getClientHost, getLog, setLog

Methods inherited from class java.rmi.server.RemoteObject

equals, getRef, hashCode, toString, toStub

Methods inherited from class java.lang.Object

finalize, getClass, notify, notifyAll, wait, wait, wait

Field Detail

RESOURCE

private static final String RESOURCE

See Also:

Constant Field Values

SERVER_START_TIMEOUT

private static final int SERVER_START_TIMEOUT

VERBOSE_SERVER

private static final boolean VERBOSE_SERVER

VERIFY_DEAD_SERVERS

private static final boolean VERIFY_DEAD_SERVERS

RMI_OBJ_ID

private static final int RMI_OBJ_ID

PING_TIMEOUT

private static final int PING_TIMEOUT

startDate

private static Date startDate

registerServerCalls

private static int registerServerCalls

getServerCalls

private static int getServerCalls

getNextServerCalls

private static int getNextServerCalls

getAllServersCalls

private static int getAllServersCalls

reportDeadServerCalls

private static int reportDeadServerCalls

getInfoCalls

private static int getInfoCalls

serverLaunchCount

private static int serverLaunchCount

serverTable

private ServerTable serverTable

launchLocks

private Hashtable launchLocks

stopLock

private Object stopLock

activeLaunchCount

private int activeLaunchCount

getInfoCountLock

private static final Object getInfoCountLock

previousClientHost

private String previousClientHost

Constructor Detail

ServerManagerImpl

public ServerManagerImpl()
                  throws RemoteException

Construct a RMI Server Manager object.

Method Detail

registerServer

public void registerServer(String service_name,
                           Remote server)
                    throws RemoteException

Register a new server instance. Called when servers are started and initialized. Only servers on the local host are allowed to register.

Specified by:

registerServer in interface ServerManager

Parameters:

service_name - service name corresponding to this remote server instance

server - the remote server instance

Throws:

RemoteException

getServer

public Remote getServer(String service_name)
                 throws RemoteException,
                        Exception

Get reference to a remote server object. A service name is used to identify the type of server desired. If a server instance is not already available, a new server is started using an instance of the ServerLauncher class.

Specified by:

getServer in interface ServerManager

Parameters:

service_name - the corresponding service name

Returns:

a remote server reference

Throws:

RemoteException

Exception

See Also:

ServerLauncher

getServer

public Remote getServer(String service_name,
                        int start_num)
                 throws RemoteException,
                        Exception

Get reference to a remote server object. A service name is used to identify the type of server desired. If a server instance is not already available, a new server is started using an instance of the ServerLauncher class.

Specified by:

getServer in interface ServerManager

Parameters:

service_name - the corresponding service name

start_num - used in start up of multiple servers for this service

Returns:

a remote server reference

Throws:

RemoteException

Exception

See Also:

ServerLauncher

getLaunchLock

private Object getLaunchLock(String service_name)

getNextServer

public Remote getNextServer(String service_name,
                            Remote server)
                     throws RemoteException

Get the next available server for the requested service_name. The previous server is used for a reference and if no other server is available, null is returned. This method is used by servers that wish to redirect clients to other servers when doing load leveling.

Specified by:

getNextServer in interface ServerManager

Parameters:

service_name - corresponding service name

server - previous server

Returns:

a remote server reference

Throws:

RemoteException

getAllServers

public Vector getAllServers(String service_name)
                     throws RemoteException

Get all servers for the requested service_name

Specified by:

getAllServers in interface ServerManager

Parameters:

service_name - corresponding service name

Returns:

a vector of remote server references

Throws:

RemoteException

reportDeadServer

public void reportDeadServer(String service_name,
                             Remote server,
                             Exception report_exception)
                      throws RemoteException

Report a bad remote server reference. A bad reference is one that is no longer alive or is throwing unexpected exceptions when trying to invoke services. The bad reference is removed from the server table. Subsequent requests for the given service will return a new server.

Specified by:

reportDeadServer in interface ServerManager

Parameters:

service_name - corresponding service name

server - the remote server reference

Throws:

RemoteException

alive

public static boolean alive(String service_name,
                            ManagedServer server)

Test if a given manager server is still alive. Pings the server with a timeout.

Parameters:

server - the remote server reference

reportDeadServer

public void reportDeadServer(String service_name,
                             Remote server)
                      throws RemoteException

Report a bad remote server reference. A bad reference is one that is no longer alive or is throwing unexpected exceptions when trying to invoke services. The bad reference is removed from the server table. Subsequent requests for the given service will return a new server.

Specified by:

reportDeadServer in interface ServerManager

Parameters:

service_name - corresponding service name

server - the remote server reference

Throws:

RemoteException

getInfo

public ServerManagerInfo getInfo()

Get usage information.

Specified by:

getInfo in interface ServerManager

getLocalInfo

public static ServerManagerInfo getLocalInfo()

Get usage information.

getStartDate

public static Date getStartDate()

getRegisterServerCalls

public static int getRegisterServerCalls()

getGetServerCalls

public static int getGetServerCalls()

getReportDeadServerCalls

public static int getReportDeadServerCalls()

getGetInfoCalls

public static int getGetInfoCalls()

getServerLaunchCount

public static int getServerLaunchCount()

ping

public void ping()

A no-op method available for testing communication.

Specified by:

ping in interface ServerManager

stop

public void stop()
          throws RemoteException

Stop this server manager. WTContext.stop is called to signal shutdown. Only calls originating from the local host will be honored.

Specified by:

stop in interface ServerManager

Throws:

RemoteException

stopAllServers

public void stopAllServers()
                    throws RemoteException

Stop all servers this server manager has started. Only calls originating from the local host will be honored.

Specified by:

stopAllServers in interface ServerManager

Throws:

RemoteException

unreferenced

public void unreferenced()

Called when this RMI server object is no longer referenced by any RMI clients. This is a no-op that simply prints a corresponding log message.

Specified by:

unreferenced in interface Unreferenced

checkAccess

protected void checkAccess()

Method to validate access to secure methods such as registerServer or stop. This implementation assumes this is an RMI call and allows access only from clients that are running on the local (server) host.

Throws:

SecurityException - if check fails and/or access is denied