springs.context
Class Context

java.lang.Object
  |
  +--springs.context.Context

All Implemented Interfaces:

ConfigurationParameters, ContextInterfaceForAgents, Debug

Direct Known Subclasses:

Context_RMIImpl

public abstract class Context

extends java.lang.Object

implements ContextInterfaceForAgents, ConfigurationParameters

A context. An implementation should follow the singleton pattern: only a context is allowed in a given JVM.

Author:

Sergio Ilarri Artigas

Field Summary

protected springs.access.AccessService	_accessService A reference to the access service.
protected springs.context.AgentInfos	_agentInfos Information kept for the agents that execute in the context.
protected static springs.context.Context	_context Singleton pattern.
protected springs.context.ContextAddress	_contextAddress The address of the context.
private java.util.Hashtable	_contexts Table with the contexts in the system, consisting of pairs .
private java.io.BufferedWriter	_logFile The log file.
private static int	_PORT_FOR_CLASS_SERVER
static springs.context.ContextAddress	CONTEXT_ADDRESS_REGION_NAME_SERVER The address of the Region Name Server.
static java.lang.String	CONTEXT_LOG_FILENAME For logs.
static java.lang.String	LOCALHOST
static java.lang.String	LOCALHOST_IP
static boolean	START_CLASS_SERVER Set it to true to enable the remote loading of classes.

Fields inherited from interface springs.common.ConfigurationParameters

_persistence, ACTIVATE_AUTOMATIC_REFERENCES_UPDATES, ACTIVATE_NAMING_SERVICE, AGENT_REFERENCES_UPDATER_NAME, BACKLOG, BLOCK_UNTIL_REFERENCE_UPDATED_IF_NEEDED, COLLECT_LOGS_CALLS, CONTEXT_MANAGER_NAME, CONTEXT_WATCHING_PERIOD, CRASH_WHEN_NOT_ENOUGH_MEMORY, CREATE_AGENTS_IN_BACKGROUND, DEFAULT_PORT_NUMBER_FOR_CONTEXTS, DELAY_DEPARTURES_IF_NEEDED, DISABLE_LOGGER, EXPORT_RETRIAL, FORCE_REMOVALS, HYBRID_STRATEGY_PROXY_UPDATE, INITIAL_SEPARATOR_URL, LAZY_UPDATE_AGENT_OBJECT, LEASE_VALUE, MAX_MILLIS_TO_WAIT_FOR_ARU, MAX_MILLIS_TO_WAIT_FOR_UPDATE_REFERENCE, MAX_TRIES_ASSIGNING_THREAD_TO_AGENT, MAXIMUM_NUMBER_OF_CONSECUTIVE_FAILED_PINGS, MILLIS_TO_KEEP_MARKED_TO_REMOVE_REFERENCES, MILLIS_TO_KEEP_UNUSED_LOCAL_REFERENCES, MILLIS_TO_WAIT_FOR_CLASS_SERVER_READY, MILLIS_TO_WAIT_FOR_RMI_REGISTRY_CREATION, MINIMUM_MILLIS_STAY_AT_CONTEXT, NUM_STAYS_TO_COMPUTE_AVERAGE_STAY, PERIOD_LARC, REBIND_RETRIAL, REGION_NAME_SERVER_NAME, RETRYING_STRATEGY_FOR_AGENT_SEARCHING, RETRYING_STRATEGY_FOR_CREATIONS, RETRYING_STRATEGY_FOR_INVOKATIONS, RETRYING_STRATEGY_FOR_REMOTE_REFERENCE_UPDATING, RETURN_CALL_RESULTS_WITH_STATISTICS, RMI_PROTOCOL, SECURITY_POLICY, TIME_BETWEEN_TRIES_ASSIGNING_THREAD_TO_AGENT, TIMEOUT_CONNECTION_RMI, TIMEOUT_RMI, TRACE_RMI_SERVERS, TRACKING_FACTOR, UPDATE_REFERENCES_IN_BACKGROUND, UPDATE_REFERENCES_WITH_AUXILIARY_THREAD, USE_CACHE_OF_CLASSES, USE_SOCKETS_COUNTING_BYTES, USE_SPECIFIC_SOCKET_FACTORY, WAIT_UNTIL_REFERENCES_UPDATED, WRITE_CONTEXT_LOGS_IN_STDOUT

Fields inherited from interface springs.common.Debug

DEBUG_ACCESS_SERVICE, DEBUG_BASIC, DEBUG_CLASS_LOADING, DEBUG_CONTEXT_MANAGER, DEBUG_CONTEXT_STATUS_WHEN_MEMORY_ERROR, DEBUG_CREATION, DEBUG_DELETING, DEBUG_NAMING_SERVICE, DEBUG_PROBLEMS_WITH_RMI_CLASS_LOADING, DEBUG_REFERENCE_UPDATER, DEBUG_REMOVAL, DEBUG_RMI, DEBUG_RMI_FAILURES, DEBUG_RNS, DEBUG_SEARCHING, DEBUG_SENDING, DEBUG_TIMES, LOG_CONTEXT_INFO, PRINT_EXCEPTION_FAILED_REMOTE_CALLS, PRINT_FAILED_MOVEMENTS, PRINT_FAILED_REMOTE_CALLS, PRINT_FAILED_REMOTE_REFERENCE_UPDATING, PRINT_FAILED_SEARCHINGS, PRINT_RETRYING_TASK_FAILURES, PROXY_QUEUE

Constructor Summary

Context()

Method Summary

void	addAgentInfo(springs.agent.SpringsAgent agent) Adds information about the given agent.
void	addContext(springs.context.ContextAddress context) Adds a context to the list of contexts in the system.
void	createAgent(java.lang.String targetContext, springs.agent.SpringsAgent agent, java.lang.String agentName) Creates an agent.
private springs.access.AgentReference	createAgentReference(springs.agent.SpringsAgent agent) Creates an agent reference.
protected void	ensureMinimumStayTime(java.lang.String agentName) Ensures that the agent will stay in the context at least the minimum amount of time required, delaying the call otherwise.
springs.access.AccessService	getAccessService() Gets a reference to the access service.
springs.agent.SpringsAgent	getAgent(java.lang.String agentName) Obtains the local agent.
springs.context.ContextAddress	getContextAddress() Gets the context address.
springs.context.ContextAddress	getContextAddress(java.lang.String contextName) Obtains the address of the given context.
abstract springs.context.ContextManager	getContextManager(springs.context.ContextAddress contextAddress) Obtains the context manager at a certain address.
java.util.Collection	getContexts() Returns the information about the contexts in the system.
java.lang.String	getContextStatus() Gets a string with information about the context.
java.util.Vector	getLocationServers(java.lang.String agentName)
protected long	getMillisStay(java.lang.String agentName) Gets the number of milliseconds that the given agent has stayed so far in the current context.
java.lang.String	getName() Obtains the name of the context.
int	getNumAgents() Gets the number of agents executing in the context.
int	getNumContexts() Returns the number of contexts in the system.
int	getNumLocationServers(java.lang.String agentName)
int	getNumObservers(java.lang.String agentName)
int	getNumTrackedAndObservedAgents() Obtains the number of tracked agents.
java.util.Vector	getObservers(java.lang.String agentName)
static int	getPortClassServer() Gets the port for the class server.
springs.access.AgentReference	getReferenceToLocalAgent(java.lang.String agentName, boolean addAsObserver) Gets a reference to an agent that it is executing locally.
protected java.lang.String	getStringForReferenceUpdates(java.util.Vector referenceUpdates) Obtains a string with the reference updates.
static void	initializeLocalIP() Initializes the local IP address.
protected static boolean	isLocalContext(springs.context.ContextAddress addr) Checks if the given address refers to the local context.
void	logContextInfo() Logs information about contexts.
void	recordStartStay(java.lang.String agentName) Records the current as the time instant when the agent starts its stay in the current context.
void	referenceUsed(java.lang.String agentName) Notifies the context that a reference to the given agent has been used.
abstract void	releaseReference(java.lang.String agentName) Releases a reference to the given agent, so that it must not be automatically updated anymore
abstract void	removeAgent(springs.agent.SpringsAgent agent, boolean isMoving) Removes an agent.
void	removeAgentInfo(java.lang.String agentName, int seqNumber) Removes the information for the given agent.
void	removeContext(java.lang.String cn) Removes a context from the list of contexts in the system.
void	setContexts(java.util.Hashtable contexts) Records the information about the contexts in the system.
static void	setPortClassServer(int port) Sets the port for the class server.
protected abstract void	start(java.lang.String addressRNS) Starts a context.
protected abstract void	start(java.lang.String addressRNS, int portClassServer) Starts a context.
void	stop() Stops the context.
abstract void	updateRemoteReferences(java.util.Hashtable contextsToReferences) Updates the remote references to local agents.

Methods inherited from class java.lang.Object

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

Methods inherited from interface springs.context.ContextInterfaceForAgents

callAgentMethod, callAgentMethod, callAgentMethod, callAgentMethod, callAgentMethodAsynchronously, callAgentMethodAsynchronously, callAgentMethodAsynchronously, callAgentMethodAsynchronously, checkpoint, createAgent, deleteAgent, isSuspended, moveAgent, sendAgent, sendAsynchronousMessage, sendMessage, sendMessage, suspend

Field Detail

CONTEXT_LOG_FILENAME

public static java.lang.String CONTEXT_LOG_FILENAME

For logs.

START_CLASS_SERVER

public static boolean START_CLASS_SERVER

Set it to true to enable the remote loading of classes.

_PORT_FOR_CLASS_SERVER

private static int _PORT_FOR_CLASS_SERVER

LOCALHOST

public static java.lang.String LOCALHOST

LOCALHOST_IP

public static java.lang.String LOCALHOST_IP

CONTEXT_ADDRESS_REGION_NAME_SERVER

public static springs.context.ContextAddress CONTEXT_ADDRESS_REGION_NAME_SERVER

The address of the Region Name Server.

_context

protected static springs.context.Context _context

Singleton pattern.

See Also:

Context

_agentInfos

protected springs.context.AgentInfos _agentInfos

Information kept for the agents that execute in the context.

See Also:

AgentInfos

_accessService

protected springs.access.AccessService _accessService

A reference to the access service.

See Also:

AccessService

_contextAddress

protected springs.context.ContextAddress _contextAddress

The address of the context.

See Also:

ContextAddress

_contexts

private java.util.Hashtable _contexts

Table with the contexts in the system, consisting of pairs .

See Also:

Hashtable

_logFile

private java.io.BufferedWriter _logFile

The log file.

See Also:

BufferedWriter

Constructor Detail

Context

public Context()

Method Detail

setPortClassServer

public static void setPortClassServer(int port)

Sets the port for the class server.

Parameters:

port - the port.

getPortClassServer

public static int getPortClassServer()

Gets the port for the class server.

Returns:

the port.

initializeLocalIP

public static void initializeLocalIP()

Initializes the local IP address.

getObservers

public java.util.Vector getObservers(java.lang.String agentName)

getNumObservers

public int getNumObservers(java.lang.String agentName)

getLocationServers

public java.util.Vector getLocationServers(java.lang.String agentName)

getNumLocationServers

public int getNumLocationServers(java.lang.String agentName)

logContextInfo

public void logContextInfo()

Logs information about contexts.

getContextStatus

public java.lang.String getContextStatus()

Gets a string with information about the context.

Returns:

a string with information about the context.

See Also:

String

addAgentInfo

public void addAgentInfo(springs.agent.SpringsAgent agent)

Adds information about the given agent.

Parameters:

agent - the agent name.

See Also:

SpringsAgent

recordStartStay

public void recordStartStay(java.lang.String agentName)

Records the current as the time instant when the agent starts its stay in the current context.

Parameters:

agentName - the agent name.

See Also:

String

getMillisStay

protected long getMillisStay(java.lang.String agentName)

Gets the number of milliseconds that the given agent has stayed so far in the current context.

Parameters:

agentName - the agent name.

Returns:

the number of milliseconds.

See Also:

String

ensureMinimumStayTime

protected void ensureMinimumStayTime(java.lang.String agentName)

Ensures that the agent will stay in the context at least the minimum amount of time required, delaying the call otherwise.

Parameters:

agentName - the agent name.

See Also:

String

removeAgentInfo

public void removeAgentInfo(java.lang.String agentName,
                            int seqNumber)

Removes the information for the given agent.

Parameters:

agentName - the name of the agent.

seqNumber - the sequence number for this delete.

See Also:

String

getAgent

public springs.agent.SpringsAgent getAgent(java.lang.String agentName)

Obtains the local agent.

Parameters:

agentName - the name of the agent.

Returns:

the agent.

See Also:

SpringsAgent

getNumTrackedAndObservedAgents

public int getNumTrackedAndObservedAgents()

Obtains the number of tracked agents.

Returns:

the number of tracked agents.

getNumAgents

public int getNumAgents()

Gets the number of agents executing in the context.

Returns:

the number of agents.

getReferenceToLocalAgent

public springs.access.AgentReference getReferenceToLocalAgent(java.lang.String agentName,
                                                              boolean addAsObserver)

Gets a reference to an agent that it is executing locally.

Parameters:

agentName - the name of the agent.

addAsObserver - a boolean indicating whether the requester should add itself as an observer.

Returns:

the reference; null if the agent is not executing locally anymore or has began to move.

Throws:

AgentReferenceException - if error.

See Also:

AgentReference, String, AgentReferenceException

createAgentReference

private springs.access.AgentReference createAgentReference(springs.agent.SpringsAgent agent)

Creates an agent reference.

Parameters:

agent - the agent.

Returns:

the reference.

See Also:

AgentReference, SpringsAgent

getNumContexts

public int getNumContexts()

Returns the number of contexts in the system.

Returns:

the number of contexts.

setContexts

public void setContexts(java.util.Hashtable contexts)

Records the information about the contexts in the system.

Parameters:

contexts - a table consisting of pairs .

See Also:

Hashtable

getContexts

public java.util.Collection getContexts()

Returns the information about the contexts in the system.

Returns:

the pairs .

See Also:

Collection

addContext

public void addContext(springs.context.ContextAddress context)

Adds a context to the list of contexts in the system.

Parameters:

context - the context.

See Also:

ContextAddress

removeContext

public void removeContext(java.lang.String cn)

Removes a context from the list of contexts in the system.

Parameters:

cn - the name of the context.

See Also:

String, RemoteException

getContextAddress

public springs.context.ContextAddress getContextAddress(java.lang.String contextName)

Obtains the address of the given context.

Returns:

the address, or null if unknown.

See Also:

ContextAddress, String

getName

public java.lang.String getName()

Obtains the name of the context.

Returns:

the name.

See Also:

String

getContextAddress

public springs.context.ContextAddress getContextAddress()

Gets the context address.

Specified by:

getContextAddress in interface ContextInterfaceForAgents

Returns:

the context address.

See Also:

ContextAddress

getAccessService

public springs.access.AccessService getAccessService()

Gets a reference to the access service.

Returns:

a reference to the access service.

See Also:

AccessService

isLocalContext

protected static boolean isLocalContext(springs.context.ContextAddress addr)

Checks if the given address refers to the local context.

Parameters:

addr - the address.

Returns:

a boolean indicating that.

See Also:

ContextAddress

referenceUsed

public void referenceUsed(java.lang.String agentName)

Notifies the context that a reference to the given agent has been used.

Parameters:

agentName - the name of the agent.

See Also:

String

stop

public void stop()
          throws ContextStoppingException

Stops the context.

Throws:

ContextStoppingException - if the context cannot be stopped.

See Also:

ContextStoppingException

createAgent

public void createAgent(java.lang.String targetContext,
                        springs.agent.SpringsAgent agent,
                        java.lang.String agentName)
                 throws CreationException

Creates an agent.

Parameters:

targetContext - the name of the target context.

agent - the agent.

agentName - the name of the agent.

Throws:

CreationException - if error.

See Also:

CreationException

getContextManager

public abstract springs.context.ContextManager getContextManager(springs.context.ContextAddress contextAddress)
                                                          throws CommunicationException

Obtains the context manager at a certain address.

Parameters:

contextAddress - the context address.

Returns:

the context manager.

Throws:

CommunicationException - if error.

See Also:

ContextAddress, ContextManager, CommunicationException

start

protected abstract void start(java.lang.String addressRNS)
                       throws ContextStartingException

Starts a context.

Parameters:

addressRNS - the address of the Region Name Server. If any, pass null.

Throws:

ContextStartingException - if the context cannot be started.

See Also:

String, ContextStartingException

start

protected abstract void start(java.lang.String addressRNS,
                              int portClassServer)
                       throws ContextStartingException

Starts a context.

Parameters:

addressRNS - the address of the Region Name Server. If any, pass null.

portClassServer - the port where to launch the class server.

Throws:

ContextStartingException - if the context cannot be started.

See Also:

String, ContextStartingException

updateRemoteReferences

public abstract void updateRemoteReferences(java.util.Hashtable contextsToReferences)
                                     throws CommunicationException

Updates the remote references to local agents.

Parameters:

contextsToReferences - a table that maps from contexts to information about how to update the references.

Throws:

CommunicationException - if error.

See Also:

Hashtable, CommunicationException

releaseReference

public abstract void releaseReference(java.lang.String agentName)
                               throws ContextException

Releases a reference to the given agent, so that it must not be automatically updated anymore

Parameters:

agentName - the name of the agent.

Throws:

ContextException - if error.

See Also:

AgentReference, String, ContextException

removeAgent

public abstract void removeAgent(springs.agent.SpringsAgent agent,
                                 boolean isMoving)
                          throws RemovalException

Removes an agent.

Parameters:

agent - the agent.

isMoving - a boolean indicating if the agent is sent because of a movement from another context.

Throws:

throws - RemovalException if error.

RemovalException

See Also:

SpringsAgent, RemovalException

getStringForReferenceUpdates

protected java.lang.String getStringForReferenceUpdates(java.util.Vector referenceUpdates)

Obtains a string with the reference updates.

Parameters:

referenceUpdates - the updates.

Returns:

the string.

See Also:

String, Vector