The software design phase starts as soon as the requirements document for the software to be produced is available. Design is the initial step in turning a problem into a solution, whereas requirement definition deals only with the problem domain. A product or system is developed during the design phase by combining technical concerns with business and client requirements.
The principles, concepts, and techniques that make up the design process enable a software engineer to model the system or product that will be created. This model, called the design model, is examined and evaluated for quality before code generation and testing. The software data structures, architecture, interfaces, and other components needed to implement the system are all described in detail in the design model.
Fundamentals of Software Design:
In the software engineering process, software design is the creation of a blueprint that will be used as the foundation for building the software system. “Both a process of defining, the architecture, components, interfaces, and other characteristics of a system or component and the result of that process,” according to IEEE, is what software design is.
Several important and strategic decisions must be made throughout the design phase to achieve the intended functionality and quality of the system. These choices are considered to successfully design the software and maintain it in a way that enhances the final product’s quality.
Software Design Principle:
Design development is a laborious procedure because this is where the majority of widespread faults are typically introduced. Furthermore, it gets harder to fix these mistakes if they get undiscovered until later stages. As such, some guidelines are complied with in the software’s design.
The designers can adhere to excellent design practices by using these principles as a foundation.
Software architecture and the analysis model should work together:
Since a design element frequently relates to several needs, we need to understand how the design model satisfies every demand that the analysis model represents.
Select the appropriate programming paradigm:
A programming paradigm explains the software system’s architecture. Programming paradigms such as procedural, object-oriented, and prototyping can be applied, depending on the application’s nature and type. The paradigm should be selected with consideration for limitations including time, resource availability, and user requirements.
Software design needs to be consistent and cohesive:
When interfaces between design components are appropriately defined, software design is deemed consistent and cohesive. For this reason, before the design team begins creating the software, guidelines, formats, and styles are decided upon.
Software design ought to be adaptable:
It ought to be sufficiently flexible to accommodate modifications with ease. Basic design principles like abstraction, refinement, and modularity must be used successfully to gain flexibility.
Software design should guarantee a minimum of conceptual (semantic) errors:
Before addressing the syntactical faults found in the design model, the design team must make sure that significant conceptual problems, such as ambiguity and inconsistency, are handled beforehand.
Software should be designed to handle unexpected changes and circumstances:
If termination becomes necessary, it should be handled properly to ensure that the software’s functioning is not compromised. Software design should be constructed to degrade gracefully.
Software design should show how the program and the real-world issue correspond:
The structure of the software design should be such that it consistently connects to the real-world issue.
Software reuse:
The adage “do not reinvent the wheel” holds for software engineers. Consequently, to maximize productivity, software components should be developed with effective reuse in mind.
Considering testability while designing:
It has long been standard procedure to keep the testing stage distinct from the design and implementation stages. In other words, the software is created (planned and implemented) first, and then it is sent to the testers, who decide whether or not it is suitable for distribution and consumer use. But it’s become clear that the technique of separate testing is significantly problematic because the program has to be rewritten entirely or in large part if any kind of design or implementation error is discovered after it’s been put into use. As a result, the test engineers ought to be involved right away. They must collaborate with analysts, for instance, to create tests that will ascertain whether the user requirements are being met.
Prototyping:
When requirements are not fully specified at the outset, prototyping should be used. As the development process moves forward, the user and developer collaborate to enhance and improve the requirements. Prototyping can be used to quickly create a “mock-up” of the system. This mock-up can be a useful tool for showing users the features that will be included in the final system and giving them an idea of how the system will look. Additionally, prototyping lowers the possibility of creating software that does not meet the needs of the client.
Concepts of Software Design:
Every software process is defined by a set of fundamental ideas and procedures. Methods are how the ideas are put into practice. Many changes take place in the ways that the principles employed in software development are applied as newer technologies replace older ones. Nonetheless, some of the basic ideas that guide the software design process are still relevant today.
Abstraction:
The process of abstraction entails keeping the module’s intricate implementation details hidden and providing its users with only the information they require. This makes interacting with the module easier and permits modifications to the underlying implementation without impacting the system as a whole.
In software design, functional abstraction, data abstraction, and control abstraction are the three most often utilized abstraction methods. By methodically moving from the abstract to the concrete design model, all of these techniques enable us to regulate the complexity of the design process.
- Functional abstraction: Under functional abstraction, parameterized subprograms are used. A generalization of functional abstraction would be “groups,” which are collections of subprograms. There are rituals inside these groupings that can be seen or unseen. While hidden routines are only available for usage within the containing group and are concealed from other groups, visible procedures can be utilized both inside and outside of the containing group.
- Data abstraction: Defining data that characterizes a data entity is known as data abstraction. For instance, the data object window includes a collection of properties (such as window type and window dimension) that provide a concise description of the window object. Details of representation and manipulation are disregarded in this abstraction method.
- Control abstraction: This expresses the intended outcome but leaves out the precise control method. For instance, in programming languages such as C and C++, the if and while statements are abstractions of machine code implementations that contain conditional instructions. This abstraction approach allows the defining of exception handlers and sequential subprograms at the architectural design level without requiring precise implementation details.
Architecture:
The structure of the system, which is made up of different program/system components, their qualities (properties), and their relationships with one another, is referred to as software architecture. The software engineers can effectively analyze the program design thanks to the software architecture. They also benefit from it when making decisions and managing risks. The following is done by the software architecture.
- Gives all interested parties a clear understanding so they can interact with one another and emphasizes early design choices that have a significant influence on software engineering tasks (such as coding and testing) that come after the design phase.
- Builds conceptual representations of the system’s breakdown into its constituent parts and their interactions.