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2
Architectural Concepts
This chapter introduces concepts on basic transaction processing
and RTR architecture.
The Three-Layer Model
RTR is based on a three-layer architecture consisting of frontend
(FE) roles, backend (BE) roles and router (TR) roles. The roles
are shown in Figure 2–1. In this and subsequent diagrams,
rectangles represent physical nodes, ovals represent application
software, and DB represents the disks storing the database (and
usually the database software that runs on the server).
Client processes run on nodes defined to have the frontend role.
This layer allows computing power to be provided locally at the
end-user site for transaction acquisition and presentation.
Server processes (represented by ‘‘Server’’ in Figure 2–1) run on
nodes defined to have the backend role. This layer:
• Allows the database to be distributed geographically.
• Permits replication of servers to cope with either network,
node or site failures.
• Allows computer resources to be added to meet performance
requirements.
Architectural Concepts 2–1