Component relationships when using MDBs

Component relationships when using MDBs

Relationship Meaning
1 to 1 For the first component to operate there has to be one of the second component available.
For example a listener port session requires a message listener thread. A message listener thread is always associated to a listener port session.
1 to 0 .. 1 The first component can optionally be associated to the second component.
For example, one QueueSession can have 0 or 1 listener port sessions associated to it.
0 .. 1 to 1 Reads the same as 1 to 1. See 1 to 1.
1 to * Component one has many instances of component two associated to it. On this diagram a 1 to * is showing control. Component one is in charge of multiple component two's.
For example, the message listener service has many message listener threads.
* to 1 Reads the same as 1 to 1, except that when it is a * to 1 relationship it showing a child - parent relationship.
For example, one QueueSession is managed by one QueueConnection.

Some of the boxes on the diagram represent configurable components that can be altered, changing the number of them that exist. These relationships become important when configuration changes are made as each change could have a knock on effect.

Scenario Requirements
Increase the number of QueueSessions by one. As there is only a single 1 to 1 relationship for a QueueSession the only requirements to be able to do this are to make sure there are enough queue manager connections available. Remember though, by increasing the number of QueueSessions in the session pool by one, it is affecting all the session pools for all the QueueConnections established from that QCF. So it will in fact allow QueueConnections * 1 more sessions, not just one more session.
The setting for the max sessions in the session pool will be determined by the QueueConnection that needs the most sessions.
Increase listener port sessions by one. Reading the diagram shows that a listener port session is reliant on a QueueSession and a message listener thread. This means that there needs to be enough of these available for it to be increased. Increasing the message listener threads has no impact on any other component, except that there need to be enough message listener threads for all listener port's sessions. Increasing the QueueSessions is described above.
Add a new listener port with one listener port session. To do this there needs to be enough message listener threads, QueueConnections and QueueSessions available. Increasing the number of QueueSessions will not be necessary as this new QueueConnection has its own pool of QueueSessions, which has at least one in the pool.

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Relationship	Meaning
1 to 1	For the first component to operate there has to be one of the second component available. For example a listener port session requires a message listener thread. A message listener thread is always associated to a listener port session.
1 to 0 .. 1	The first component can optionally be associated to the second component. For example, one QueueSession can have 0 or 1 listener port sessions associated to it.
0 .. 1 to 1	Reads the same as 1 to 1. See 1 to 1.
1 to *	Component one has many instances of component two associated to it. On this diagram a 1 to * is showing control. Component one is in charge of multiple component two's. For example, the message listener service has many message listener threads.
* to 1	Reads the same as 1 to 1, except that when it is a * to 1 relationship it showing a child - parent relationship. For example, one QueueSession is managed by one QueueConnection.

Scenario	Requirements
Increase the number of QueueSessions by one.	As there is only a single 1 to 1 relationship for a QueueSession the only requirements to be able to do this are to make sure there are enough queue manager connections available. Remember though, by increasing the number of QueueSessions in the session pool by one, it is affecting all the session pools for all the QueueConnections established from that QCF. So it will in fact allow QueueConnections * 1 more sessions, not just one more session. The setting for the max sessions in the session pool will be determined by the QueueConnection that needs the most sessions.
Increase listener port sessions by one.	Reading the diagram shows that a listener port session is reliant on a QueueSession and a message listener thread. This means that there needs to be enough of these available for it to be increased. Increasing the message listener threads has no impact on any other component, except that there need to be enough message listener threads for all listener port's sessions. Increasing the QueueSessions is described above.
Add a new listener port with one listener port session.	To do this there needs to be enough message listener threads, QueueConnections and QueueSessions available. Increasing the number of QueueSessions will not be necessary as this new QueueConnection has its own pool of QueueSessions, which has at least one in the pool.