org.smartfrog.examples.dynamicwebserver.balancer
Class BalancerImpl

java.lang.Object
  org.smartfrog.sfcore.reference.RemoteReferenceResolverHelperImpl
      org.smartfrog.sfcore.prim.PrimImpl
          org.smartfrog.examples.dynamicwebserver.balancer.BalancerImpl

All Implemented Interfaces:

java.rmi.Remote, Balancer, DataSource, MessageKeys, Diagnostics, Liveness, Prim, RemoteReferenceResolver, RemoteReferenceResolverHelper

public class BalancerImpl
extends PrimImpl
implements Prim, Balancer, DataSource

Title: BalancerImpl.

Description: BalancerImpl is the main class for a software load balancer for socket connections between a set of clients and a set of servers. The clients connect to a specific port on the balancer host and the balancer selects a server to handle the client session. The balancer opens a socket connection to the selected server and relays data between the client and the server. The balancer listens for client connections on a well-known port, specified by the "port" SmartFrog parameter.

The Balancer maintains a set of servers that are included in the selection algorithm for balancing. The curent selection algorithm is round-robin. An initial set of servers can be specified via the "hosts" SmartFrog parameter; if "hosts" is specified, the parameter "hostsPort" is used to specify the port number to connect to on the servers. Subsequent changes to the set of servers can be made at run-time via the Balancer remote interface; in this case the port number for each host can be specified individually.

Field Summary

Fields inherited from class org.smartfrog.sfcore.prim.PrimImpl

refLivenessDelay, refLivenessFactor, sfCompleteName, sfContext, sfDeployHooks, sfDeployWithHooks, sfExportRef, sfIsDeployed, sfIsStarted, sfIsTerminated, sfIsTerminating, sfLivenessCount, sfLivenessDelay, sfLivenessFactor, sfLivenessSender, sfParent, sfStartHooks, sfTerminateWithHooks, termLock

Fields inherited from interface org.smartfrog.examples.dynamicwebserver.balancer.Balancer

HOSTS, HOSTSPORT, LOGTO, NAME, PORT

Fields inherited from interface org.smartfrog.sfcore.common.MessageKeys

CANNOT_LINK_TO_PREDICATE, COMPONENT_TERMINATED, COPY_FAILED, COPY_SERIALIZE_FAILED, ERROR_NO_SECURITY_BUT_REQUIRED, ILLEGAL_BOOLEAN_PARAMETER, ILLEGAL_NUMERIC_PARAMETER, ILLEGAL_STRING_PARAMETER, ILLEGAL_VECTOR_PARAMETER, LIVENESS_SEND_FAILURE, LIVENESS_SEND_FAILURE_IN, MISSING_PARAMETER, MSG_CLASS_NOT_FOUND, MSG_CONNECT_ERR, MSG_CONT_OTHER_DEPLOY, MSG_DEPLOY_COMP_TERMINATED, MSG_DEPLOY_SUCCESS, MSG_DEPLOYWITH_PHASE_FAILED, MSG_DETACH_SUCCESS, MSG_DETACH_TERMINATE_SUCCESS, MSG_ERR_DEPLOY_FROM_URL, MSG_ERR_PARSE, MSG_ERR_RESOLVE_PHASE, MSG_ERR_SF_RUNNING, MSG_ERR_TERM, MSG_FAILED_INET_ADDRESS_LOOKUP, MSG_FAILED_TO_CONTACT_PARENT, MSG_FILE_NOT_FOUND, MSG_HOOK_ACTION_FAILED, MSG_ILLEGAL_ACCESS, MSG_ILLEGAL_CLASS_TYPE, MSG_ILLEGAL_CLASS_TYPE_EXPECTING_GOT, MSG_ILLEGAL_REFERENCE, MSG_INPUTSTREAM_NULL, MSG_INSTANTIATION_ERROR, MSG_INVALID_OBJECT_TYPE, MSG_INVOCATION_TARGET, MSG_LANG_NOT_FOUND, MSG_LIVENESS_START_FAILED, MSG_LOADING_URL, MSG_METHOD_NOT_FOUND, MSG_NON_REP_ATTRIB, MSG_NOT_COMPONENT_REFERENCE, MSG_NOT_FOUND_ATTRIBUTE, MSG_NOT_FOUND_REFERENCE, MSG_NOT_VALUE_REFERENCE, MSG_NULL_DEF_METHOD, MSG_NULL_URL, MSG_OBJECT_REGISTRATION_FAILED, MSG_PARENT_LOCATION_FAILED, MSG_PING_SUCCESS, MSG_RANDM_ERR, MSG_REMOTE_CONNECT_ERR, MSG_REPEATED_ATTRIBUTE, MSG_SF_DEAD, MSG_SF_READY, MSG_SF_TERMINATED, MSG_STACKTRACE_FOLLOWS, MSG_START_COMP_TERMINATED, MSG_TERMINATE_SUCCESS, MSG_UNHANDLED_EXCEPTION, MSG_UNKNOWN_HOST, MSG_UNRESOLVED_REFERENCE, MSG_UNRESOLVED_REFERENCE_IN, MSG_UPDATE_SUCCESS, MSG_URL_NOT_FOUND, MSG_URL_TO_PARSE_NOT_FOUND, MSG_WARNING_LIVENESS_ENABLED, MSG_WARNING_STACKTRACE_DISABLED, MSG_WARNING_STACKTRACE_ENABLED, ROOT_MUST_BE_COMPONENT, WARN_NO_SECURITY

Constructor Summary

BalancerImpl()
Constructor for the Balancer component

Method Summary

void	addServer(java.lang.String hostname) Implementation of the Balancer interface
void	addServer(java.lang.String hostname, int port) Implementation of the Balancer interface
int	getData() implementation of DataSource interface resets the data after every request - so only suited to single requestor
static void	main(java.lang.String[] args) Used to start the component from the command line.
void	removeServer(java.lang.String hostname) Implementation of the Balancer interface
void	sfDeploy() Standard sfDeploy().
void	sfStart() Standard sfStart().
void	sfTerminateWith(TerminationRecord tr) Standard sfTerminateWith()
void	stop() Stop the load balancer.
java.lang.String	toString() Returns textual representation.

Methods inherited from class org.smartfrog.sfcore.prim.PrimImpl

equals, hashCode, registerWithProcessCompound, sfAddAttribute, sfAttributeKeyFor, sfAttributes, sfCompleteName, sfCompleteNameSafe, sfContainsAttribute, sfContainsValue, sfContext, sfDeployedHost, sfDeployedProcessName, sfDeployWith, sfDetach, sfDetachAndTerminate, sfDiagnosticsReport, sfDumpState, sfExport, sfExportRef, sfExportRef, sfGetApplicationLog, sfGetCoreLog, sfGetLog, sfIsDeployed, sfIsRemote, sfIsStarted, sfIsTerminated, sfIsTerminating, sfLivenessFailure, sfLog, sfParent, sfParentageChanged, sfPing, sfRemoveAttribute, sfReplaceAttribute, sfResolve, sfResolve, sfResolveHere, sfResolveHere, sfResolveParent, sfSetLog, sfStartLivenessSender, sfStopLivenessSender, sfTerminate, sfTerminatedWith, sfTerminateQuietlyWith, sfValues, terminateComponent, terminateNotifying

Methods inherited from class org.smartfrog.sfcore.reference.RemoteReferenceResolverHelperImpl

sfResolve, sfResolve, sfResolve, sfResolve, sfResolve, sfResolve, sfResolve, sfResolve, sfResolve, sfResolve, sfResolve, sfResolve, sfResolve, sfResolve, sfResolve, sfResolve, sfResolve, sfResolve, sfResolve, sfResolve, sfResolve, sfResolve, sfResolve, sfResolve, sfResolve, sfResolve, sfResolve, sfResolve, sfResolve, sfResolve, sfResolve, sfResolve, sfResolve, sfResolve, sfResolve, sfResolve, sfResolve, sfResolve, sfResolve, sfResolve, sfResolve, sfResolve, sfResolve, sfResolveWithParser

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.smartfrog.sfcore.prim.Prim

sfAddAttribute, sfAttributeKeyFor, sfAttributes, sfCompleteName, sfContainsAttribute, sfContainsValue, sfContext, sfDeployedHost, sfDeployedProcessName, sfDeployWith, sfDetach, sfDetachAndTerminate, sfDumpState, sfIsDeployed, sfIsStarted, sfIsTerminated, sfIsTerminating, sfParent, sfParentageChanged, sfRemoveAttribute, sfReplaceAttribute, sfTerminate, sfTerminatedWith, sfTerminateQuietlyWith, sfValues

Methods inherited from interface org.smartfrog.sfcore.prim.Liveness

sfPing

Methods inherited from interface org.smartfrog.sfcore.reference.RemoteReferenceResolver

sfResolve, sfResolve, sfResolveHere, sfResolveHere, sfResolveParent

Methods inherited from interface org.smartfrog.sfcore.reference.RemoteReferenceResolverHelper

sfResolve, sfResolve, sfResolve, sfResolve, sfResolve, sfResolve, sfResolve, sfResolve, sfResolve, sfResolve, sfResolve, sfResolve, sfResolve, sfResolve, sfResolve, sfResolve, sfResolve, sfResolve, sfResolve, sfResolve, sfResolve, sfResolve, sfResolve, sfResolve, sfResolve, sfResolve, sfResolve, sfResolve, sfResolve, sfResolve, sfResolve, sfResolve, sfResolve, sfResolve, sfResolve, sfResolve, sfResolve, sfResolve, sfResolve, sfResolve, sfResolve, sfResolve, sfResolve, sfResolveWithParser

Methods inherited from interface org.smartfrog.sfcore.prim.Diagnostics

sfDiagnosticsReport

Constructor Detail

BalancerImpl

public BalancerImpl()
             throws java.rmi.RemoteException

Constructor for the Balancer component

Throws:

java.rmi.RemoteException - in case of Remote/network error

Method Detail

addServer

public void addServer(java.lang.String hostname,
                      int port)

Implementation of the Balancer interface

Specified by:

addServer in interface Balancer

Parameters:

hostname - The host name of the new server

port - The port number on the new server used open the connection from the balancer

addServer

public void addServer(java.lang.String hostname)

Implementation of the Balancer interface

Specified by:

addServer in interface Balancer

Parameters:

hostname - The host name of the new server

removeServer

public void removeServer(java.lang.String hostname)

Implementation of the Balancer interface

Specified by:

removeServer in interface Balancer

Parameters:

hostname - The host name of the server to remove from the set

getData

public int getData()
            throws java.rmi.RemoteException

implementation of DataSource interface resets the data after every request - so only suited to single requestor

Specified by:

getData in interface DataSource

Returns:

the number of connections since last request

Throws:

java.rmi.RemoteException - in case of Remote/network error

stop

public void stop()

Stop the load balancer.

main

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

Used to start the component from the command line.

Parameters:

args - command line arguments

toString

public java.lang.String toString()

Returns textual representation.

Overrides:

toString in class PrimImpl

Returns:

textual representation

sfDeploy

public void sfDeploy()
              throws SmartFrogException,
                     java.rmi.RemoteException

Standard sfDeploy().

Specified by:

sfDeploy in interface Prim

Overrides:

sfDeploy in class PrimImpl

Throws:

SmartFrogException - error while deploying

java.rmi.RemoteException - In case of network/rmi error

sfStart

public void sfStart()
             throws SmartFrogException,
                    java.rmi.RemoteException

Standard sfStart().

Specified by:

sfStart in interface Prim

Overrides:

sfStart in class PrimImpl

Throws:

SmartFrogException - error while starting

java.rmi.RemoteException - In case of network/rmi error

sfTerminateWith

public void sfTerminateWith(TerminationRecord tr)

Standard sfTerminateWith()

Overrides:

sfTerminateWith in class PrimImpl

Parameters:

tr - TerminationRecord object