Software Engineering (2160701)

• Large systems are decomposed into subsystems
• Sub-systems provide related services
• Initial design process includes
• Identifying sub-systems
• Establishing a framework for sub-system control and communication

Why to document the Architecture?

• Stakeholder Communication: High-level presentation of system
• System Analysis: Big effect on performance, reliability, maintainability and other -ilities
• Large-scale Reuse: Similar requirements similar architecture

Architectural Styles

• Data-centered architecture style
• Data-flow architectures
• Call and return architecture
• Object-oriented architecture
• Layered architecture

Data-centered architecture style

• A data store (Ex., a file or database) resides at the center of this architecture and is accessed frequently by other components.
• Client software accesses a central repository.
• In some cases the data repository is passive.
• That is, client software accesses the data independent of any changes to the data or the actions of other client software.

Data-flow architectures

• This architecture is applied when input data are to be transformed.
• A set of components (called filters) connected by pipes that transmit data from one component to the next.
• Each filter works independently of those components upstream and downstream, is designed to expect data input of a certain form, and produces data output (to the next filter) of a specified form.

Call and return architecture

• This architectural style enables a software designer (system architect) to achieve a program structure that is relatively easy to modify and scale.
• A number of sub styles exist within this category as below.
• Main program/subprogram architectures
• This classic program structure decomposes function into a control hierarchy where a “main” program invokes a number of program components, which in turn may invoke still other components.
• Remote procedure call architectures
• The components of a main program/subprogram architecture are distributed across multiple computers on a network.

Object-oriented architecture

• The components of a system encapsulate data and the operations that must be applied to manipulate the data.
• Communication and coordination between components is accomplished via message passing.

Layered architecture

• A number of different layers are defined, each accomplishing operations that progressively become closer to the machine instruction set.
• At the outer layer, components service user interface operations.
• At the inner layer, components perform operating system interfacing.
• Intermediate layers provide utility services and application software functions.