Listener Class

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

Table 13-23 Summary of Listener Methods

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

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 `Agent`s 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.

getAgentList()

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

Syntax

vector<Agent> getAgentList() const;

getTimeOutForListen()

Retrieves the time out for a call.

Syntax

int getTimeOutForListen() const;

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.

Note that this is a blocking call. Before this call, complete the following steps:

Registers each Agent listener through a setAgentList() call.
Make a blocking call to setTimeOutForListen() 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.

Syntax

Agent listen();

setAgentList()

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

Syntax

void setAgentList(
   vector<Agent>& agList);

Parameter	Description
agList	The list of `Agent`s.

setTimeOutForListen()

Specifies the time out for a listen() call.

Syntax

void setTimeOutForListen(
   int waitTime);

Parameter	Description
waitTime	The time interval, in seconds, during which the `Listener` is waiting for `Message`s at specified queues.