SOFTWARE DESIGN

'Software design' is a process of problem-solving and planning for a software solution. After the purpose and specifications of software is determined, software developers will design or employ designers to develop a plan for a solution. It includes low-level component and algorithm implementation issues as well as the architectural view.
The software requirements analysis (SRA) step of a software development process yields specifications that are used in software engineering. If the software is "semiautomated" or user centered, software design may involve user experience design yielding a story board to help determine those specifications. If the software is completely automated (meaning no user or user interface), a software design may be as simple as a flow chart or text describing a planned sequence of events. There are also semi-formal methods like Unified Modeling Language and Fundamental modeling concepts. In either case some documentation of the plan is usually the product of the design.
A software design may be platform-independent or platform-specific, depending on the availability of the technology called for by the design.

Contents

Design Considerations

Design Patterns

Usage

See also

Design Considerations

There are many aspects to consider in the design of a piece of software. The importance of each should reflect the goals the software is trying to achieve. Some of these aspects are:

★ Extensibility - New capabilities can be added to the software without major changes to the underlying architecture.

★ Robustness - The software is able to operate under stress or tolerate unpredictable or invalid input. For example, it can be designed with a resilience to low memory conditions.

★ Reliability - The software is able to perform a required function under stated conditions for a specified period of time.

★ Fault-tolerance - The software is resistant to and able to recover from component failure.

★ Security - The software is able to withstand hostile acts and influences.

★ Maintainability - The software can be restored to a specified condition withing a specified period of time. For example, virus software may include the ability to periodically receive virus definition updates in order to maintain the software's effectiveness.

★ Compatibility - The software is able to operate with other products that are designed for interoperability with another product. For example, a piece of software may be backward-compatible with an older version of itself.

Design Patterns

A software designer or architect may identify a design problem which has been solved by others before. A template or pattern describing a solution to a common problem is known as a design pattern. (Design pattern (computer science)). The reuse of such patterns can speed up the software development process, having been tested and proved in the past.

Usage

Software design documentation may be reviewed or presented to allow constraints, specifications and even requirements to be adjusted prior to programming. Redesign may occur after review of a programmed simulation or prototype. It is possible to design software in the process of programming, without a plan or requirement analysis, but for more complex projects this would not be considered a professional approach. A separate design prior to programming allows for multidisciplinary designers and Subject Matter Experts (SMEs) to collaborate with highly-skilled programmers for software that is both useful and technically sound.

See also

★ Software development

★ Software architecture

★ Search Based Software Engineering

★ User experience

★ Experience design

★ Model-driven architecture

★ Software Design Description (IEEE 1016)

★ Design pattern (computer science)