04-08-2012, 02:16 PM
3-Tier Architecture
NTierArchitecture.pdf (Size: 573.41 KB / Downloads: 426)
Traditional Host Systems
A Central Processing System (Mainframe) provides all processing.
Local Terminals are responsible for display and keyboard for user input and viewing capabilities. Local Terminals do not contain any intelligent processing capabilities.
Server Model
• Complements distributed systems
• Responds to limitations found in the two host data processing models:
1. The traditional mainframe host model, in which a single mainframe provides shared data access to many dumb terminals, and;
2. The local area network (LAN) model, in which many isolated systems access a file server that provides no central processing power.
Inter-process Communication
• Basis for client/server computing
• Client process communicates with server process
• Each process performs separate functions
• Data is passed between processes using IPC functions
Middleware
Simplifies 3-tier application development and administration by providing an extra application server layer to manage communication between components.
Middleware Characteristics:
o Simplifies partitioning of application processing among clients and servers
o Manages distributed transactions among multiple databases
o Communicates with heterogeneous database products within a single application.
o Supports application scalability
o Supports service requests prioritization, load-balancing, data dependant routing and queuing.