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Listener Class

The Listener class encapsulates the ability to listen for Messages, on behalf of registered Agents, at specified queues.

Table 10-20 Summary of Listener Methods

Method	Summary
Listener()	Listener class constructor.
getAgentList()	Retrieve the list of Agents for which the Listener provides its services.
getTimeOutForListen()	Retrieve the time out for a call.
listen()	Listens for Messages and returns the name of the Agent for whom a Message is intended.
setAgentList()	Specifies the list of Agents for which the Listener provides its services.
setTimeOutForListen()	Specifies the time out for a listen() call.

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Listener()

Listener class constructor.

Syntax	Description
Listener( const Connection* conn);	Creates a Listener object.
Listener( const Connection* conn vector<Agent> &aglist, int waitTime=0);	Creates a Listener object and sets the list of Agents on behalf of which it listens on queues. Also sets the waiting time; default: no waiting.

Parameter	Description
conn	The connection of the new Listener object.
aglist	The list of agents on behalf of which the Listener object waits on queues; clients of this Listener.
waitTime	The time to wait on queues for messages of interest for the clients; in seconds.

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getAgentList()

Retrieve the list of Agents for which the Listener provides its services.

Syntax

vector<Agent> getAgentList() const;

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getTimeOutForListen()

Retrieve the time out for a call.

Syntax

int getTimeOutForListen() const;

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listen()

Listens for Messages on behalf of specified Agents for the amount of time specified by a previous setTimeOutForListen() call. Returns the Agent for which there is a Message.

Syntax

Agent listen();

Note: This is a blocking call. Prior to this call, the following steps should be completed: Each Agent must be registered with the listener using setAgentList() method. The time out parameter should be set using the setTimeOutForListen() method. This is a blocking call that returns when a Message for one of the Agents on the list arrives. If no Messages arrive before the wait time expires, the call returns an error.

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setAgentList()

Specifies the list of Agents for which the Listener provides its services.

Syntax

void setAgentList(
   vector<Agent>& list);

Parameter	Description
list	The list of Agents.

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setTimeOutForListen()

Specifies the time out for a listen() call.

Syntax

void setTimeOutForListen(
   int timeOut);

Parameter	Description
timeOut	The time interval, in seconds, during which the Listener is waiting for Messages at specified queues.