org.licas.server

Class MessageMediator

java.lang.Object

java.lang.Thread

org.licas.server.MessageMediator

All Implemented Interfaces:

java.lang.Runnable, BusDef, PublishSubscribeDef

public class MessageMediator
extends java.lang.Thread
implements BusDef, PublishSubscribeDef

This class mediates the process of passing messages between the server and the services

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
protected ESB	esb The parent ESB server
protected MessageStore	messageStore Communication IDs to identify the calling components and replies for stored method results.
protected MonitorServer	monitorServer To monitor the server resource allocation
protected PasswordHandler	passwordHandler The parent password handler
protected PublishSubscribeDef	pubSub The publish-subscribe facility for registering and notifying about service work.

Fields inherited from class java.lang.Thread

MAX_PRIORITY, MIN_PRIORITY, NORM_PRIORITY

Constructor Summary

Constructors

Constructor and Description
MessageMediator(ESB theESB, PasswordHandler thePasswordHandler, MessageStore theMessageStore) Create a new instance of MessageMediator.

Method Summary

Modifier and Type	Method and Description
void	cancelMessage(java.lang.String ticket) Remove the message with the specified ticket number from the queue.
protected org.licas_xml.abs.Element	executeServerService(java.lang.String serviceType, MethodInfo methodInfo) Execute a method on the server or a type of service owned by the server.
org.licas_xml.abs.Element	executeServiceType(java.lang.String serviceType, MethodInfo methodInfo) Execute a synchronous method on a service type known by the server and probably stored locally.
void	executeServiceTypeAsync(java.lang.String serviceType, MethodInfo methodInfo) Execute an asynchronous method on the server, or a service type owned by the server.
java.util.ArrayList<java.lang.String>	getServiceNames() Get a list of current services on the server that allow ptp comm.
java.util.ArrayList<java.lang.String>	getServiceTypeNames(java.lang.String serviceType) Get a list of current services on the server for a service type that allow subscribe comm.
java.lang.Object	messageBus(MethodInfo methodInfo) Execute a call on the system message bus.
boolean	messageToBus(MessageInfo ro) Add the message to the message bus queue for subsequent processing.
boolean	publish(WorkInfo workInfo) Publish to do work.
void	run() Run the thread loop to process the message bus queue.
boolean	subscribe(WorkInfo workInfo) Subscribe for a service.
void	unpublish(KeywordInfo keyInfo, org.licas_xml.abs.Element serviceURI) Un-publish to do work.
void	unsubscribe(KeywordInfo keyInfo, org.licas_xml.abs.Element clientURI) Un-subscribe for a service.

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

monitorServer

protected MonitorServer monitorServer

To monitor the server resource allocation

pubSub

protected PublishSubscribeDef pubSub

The publish-subscribe facility for registering and notifying about service work.

messageStore

protected MessageStore messageStore

Communication IDs to identify the calling components and replies for stored method results.

passwordHandler

protected PasswordHandler passwordHandler

The parent password handler

esb

protected ESB esb

The parent ESB server

Constructor Detail

MessageMediator

public MessageMediator(ESB theESB,
                       PasswordHandler thePasswordHandler,
                       MessageStore theMessageStore)

Create a new instance of MessageMediator.

Parameters:

theESB - the parent ESB server.

thePasswordHandler - the parent password handler.

theMessageStore - the message store.

Method Detail

run

public void run()

Run the thread loop to process the message bus queue.

Specified by:

run in interface java.lang.Runnable

Overrides:

run in class java.lang.Thread

messageToBus

public boolean messageToBus(MessageInfo ro)

Add the message to the message bus queue for subsequent processing.

Parameters:

ro - the request object to add.

Returns:

true if added, false otherwise.

cancelMessage

public void cancelMessage(java.lang.String ticket)

Remove the message with the specified ticket number from the queue.

Parameters:

ticket - unique ticket number, equivalent to a communication ID.

getServiceNames

public java.util.ArrayList<java.lang.String> getServiceNames()
                                                      throws LicasException

Get a list of current services on the server that allow ptp comm.

Returns:

list of current service IDs.

Throws:

LicasException - licas error.

getServiceTypeNames

public java.util.ArrayList<java.lang.String> getServiceTypeNames(java.lang.String serviceType)
                                                          throws LicasException

Get a list of current services on the server for a service type that allow subscribe comm.

Parameters:

serviceType - the service type to check for.

Returns:

list of current service IDs.

Throws:

LicasException - licas error.

messageBus

public java.lang.Object messageBus(MethodInfo methodInfo)
                            throws java.lang.Exception

Execute a call on the system message bus. This passes the message to a queue on the server from where it gets selected for processing by a service.

Specified by:

messageBus in interface BusDef

Parameters:

methodInfo - the method call description with all of the required information.

Returns:

Object the reply to the call.

Throws:

java.lang.Exception - any error.

executeServiceTypeAsync

public void executeServiceTypeAsync(java.lang.String serviceType,
                                    MethodInfo methodInfo)
                             throws java.lang.Exception

Execute an asynchronous method on the server, or a service type owned by the server. This method calls executeServerService to invoke the methodInfo spec. The asynchronous call does not return a value, thereby freeing the client sooner. After executing the method, it instead saves any reply to a messageStore under the methodInfo's communicationID. This method forces a return type of Element on the method it invokes or void return type. If that is not correct the method to invoke will not be found.

Parameters:

serviceType - the service type on the server.

methodInfo - this is the actual method call as it would be invoked from any place. It requires the correct method name and parameter list.

Throws:

java.lang.Exception - any error.

executeServiceType

public org.licas_xml.abs.Element executeServiceType(java.lang.String serviceType,
                                                    MethodInfo methodInfo)
                                             throws java.lang.Exception

Execute a synchronous method on a service type known by the server and probably stored locally. This method calls executeServerService to invoke the parameter methodInfo spec. This method forces a return type of Element on the method it invokes. If that is not correct the method to invoke will not be found.

Parameters:

serviceType - the service type on the server.

methodInfo - this is the actual method description as it would be invoked from any place. It requires the correct method name and parameter list. It is not restricted to the two query types, but the further programming might be required to add other ones. The invoked method is assumed to return XML elements only.

Returns:

the reply as an Element.

Throws:

java.lang.Exception - any error.

executeServerService

protected org.licas_xml.abs.Element executeServerService(java.lang.String serviceType,
                                                         MethodInfo methodInfo)
                                                  throws java.lang.Exception

Execute a method on the server or a type of service owned by the server. The service password is not required and so the server itself should have more control over the execution of these methods.

Parameters:

serviceType - the service type on the server.

methodInfo - this is the actual method call as it would be made from a remote server. It requires the correct method name and parameter list. The service itself is replaced by a direct reference to one of the specified type, if one exists. The method is assumed to return XML elements only.

Returns:

the reply as an Element, or null if a void reply type.

Throws:

java.lang.Exception - any error.

subscribe

public boolean subscribe(WorkInfo workInfo)
                  throws java.lang.Exception

Subscribe for a service.

Specified by:

subscribe in interface PublishSubscribeDef

Parameters:

workInfo - new client details. It must include the keyword list and the method to reply with.

1. A list of descriptive keywords and topic to match with.
2. Details of the client method to reply with if a service work matches with the keywords request.

If getClientURI() is empty, then the request is ignored. It must also contain a parameter list of size 1, that is either an Object or a WorkInfo object, as that is what will be sent as a reply.

Returns:

true if service request registered, false if keyword overlap.

Throws:

java.lang.Exception - any error.

unsubscribe

public void unsubscribe(KeywordInfo keyInfo,
                        org.licas_xml.abs.Element clientURI)
                 throws java.lang.Exception

Un-subscribe for a service.

Specified by:

unsubscribe in interface PublishSubscribeDef

Parameters:

keyInfo - list of descriptive keywords to uniquely identify the service.

clientURI - the client URI defines the request client.

Throws:

java.lang.Exception - any error.

publish

public boolean publish(WorkInfo workInfo)
                throws java.lang.Exception

Publish to do work.

Specified by:

publish in interface PublishSubscribeDef

Parameters:

workInfo - full work details, including an optional contract. The method description must include the client URI as this is what identifies the request. If getClientURI() is empty, then the request is ignored.

Returns:

true if work request registered, false if keyword overlap.

Throws:

java.lang.Exception - any error.

unpublish

public void unpublish(KeywordInfo keyInfo,
                      org.licas_xml.abs.Element serviceURI)
               throws java.lang.Exception

Un-publish to do work.

Specified by:

unpublish in interface PublishSubscribeDef

Parameters:

keyInfo - list of descriptive keywords to uniquely identify the work.

serviceURI - the client URI defines the request service.

Throws:

java.lang.Exception - any error.