HP Reliable Transaction Router - Manual (Page 40)

The Three-Tier Architecture
Figure 2–1 The Multitier Model
VM-0839A-AI
TR
FE
Terminals Frontends Routers Backends Database
BE
Server
application
BE
Server
application
Client
application
TR FE
Client
application
FE
Client
application
FE
Client
application
BE
Server
application
Client application processes run on nodes defined to have the
frontend role. This tier allows computing power to be provided
locally at the end-user site for transaction acquisition and
presentation.
Server application processes (represented by ‘‘Server application’’
in Figure 2–1) run on nodes defined to have the backend role.
This tier:
• Enables the database to be distributed geographically
• Permits replication of servers to cope with network, node or
site failures
• Allows computer resources to be added to meet performance
requirements
2–2 Architectural Concepts