RTR Terminology
Figure 1–3 Roles Symbols
FE
TR
BE
Facility | The mapping between nodes and roles is done using a facility. |
| An RTR facility is the |
| configuration whose definition provides the |
| a given application. Nodes can share several facilities. The role |
| of a node is defined within the scope of a particular facility. The |
| router is the only role that knows about all three roles. A router |
| can run on the same physical node as the frontend or backend, |
| if that is required by configuration constraints, but such a setup |
| would not take full advantage of failover characteristics. |
| Figure |
A facility name is mapped to specific physical nodes and their roles using the CREATE FACILITY command.
Figure
Clients send messages to servers to ask that a piece of work be done. Such requests may be bundled together into transactions. An RTR transaction consists of one or more messages that have been grouped together by a client application, so that the work done as a result of each message can be undone completely, if some part of that work cannot be done. If the system fails or is