Page 150 - DCAP308_OBJECT_ORIENTED_ANALYSIS_AND_DESIGN
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Object Oriented Analysis and Design
Notes Properties of Layered Architectures
Top and bottom layers specified by the problem statement
Top layer is the desired system
Bottom layer is defined by available resources (e.g. HW, OS, libraries)
Easier to port to other HW/SW platforms
Task Make distinction between closed architecture and open architecture.
Partitions
Partitions vertically divide a system into several independent or weakly subsystems, each
providing one kind of service. One difference between layers and partitions is that layers vary
in their level of abstraction, but partitions merely divide a system into pieces, all of which have
a similar level of abstraction.
You can decompose a system into subsystems by combining layers and partitions. Layers can be
partitioned and partitions can be layered. Most large systems require a mixture of layers and
partitions.
Partitioned Architectures divide system into weakly-coupled subsystems.
Each provides specific services
Vertical decomposition of problem
Example: Partitioned Architecture
Figure 12.2: Partitioned Architecture
File Process Virtual Device
System Control Memory Control
Management
Typical Application Architecture
Figure 12.3: Application Architecture
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