org.lsst.ccs.messaging

Interface MessagingLayer

All Known Subinterfaces:

BusMessagingLayer

public interface MessagingLayer

Interface providing methods to connect/disconnect MessagingAccessLayer objects to/from the CCS buses and to send messages over the buses. An instance of a MessagingLayer is created via the MessagingManager. When connecting a MessagingAccessLayer, its name is used to uniquely identify it on the buses. If such name is not unique, a DuplicateAgentNameException is thrown.

Author:

emarin

Method Summary

Modifier and Type	Method and Description
void	connect(MessagingAccessLayer accessLayer) Connects a MessagingAccessLayer object on the buses by using its name as a unique identifier.
void	disconnect(MessagingAccessLayer accessLayer) Remove the entry point to the buses for the given MessagingAccessLayer.
<T extends BusMessage> void	sendMessage(String senderAgent, Bus bus, T msg) Sends a message on a bus for a given MessagingAccessLayer.

Method Detail

sendMessage

<T extends BusMessage> void sendMessage(String senderAgent,
                                        Bus bus,
                                        T msg)
                                 throws IOException

Sends a message on a bus for a given MessagingAccessLayer. The name of the MessagingAccessLayer determines the origin of the bus message. note : that BusMessage should have sender and destination information but it is not the role of the communication layer to parse destination information such as "subsystem1, subsystem2" or "subsystem3/module"a.

Type Parameters:

T - the type of message sent on the bus

Parameters:

senderAgent - provides the name as the origin of the message

bus - the bus on which to send the message

msg - the message

Throws:

IOException - this could have a list of causes if some destinations fail. as much as possible implementers will ensure that all correct destinationa are adressed: if some fail it is not mandatory to report with a special subclass of IOexception that lists all destination that failed.

See Also:

org.lsst.ccs.bus.DestinationsException

connect

void connect(MessagingAccessLayer accessLayer)
      throws DuplicateAgentNameException,
             IOException

Connects a MessagingAccessLayer object on the buses by using its name as a unique identifier. Upon creation, if needed, all needed buses are created. Depending on the underlying implementation, the MessagingLayer allows this method to be called more than once, or throws a RuntimeException. TBD : should all the buses be created or just the ones specified by the MessagingAccessLayer ?

Parameters:

accessLayer - The layer to be connected on the buses

Throws:

DuplicateAgentNameException - if the name of MessagingAccessLayer is not unique on the buses

IOException

disconnect

void disconnect(MessagingAccessLayer accessLayer)

Remove the entry point to the buses for the given MessagingAccessLayer. At this point, the CCS buses might be closed.

Parameters:

accessLayer - The layer to be connected on the buses