The difference between software design and software architecture mainly lies in their level of abstraction and scope within the software development process.
1. Software Architecture
Software architecture focuses on the overall view of a software system. It defines the main components of the system and how they interact with each other. Architecture is often described as a “macro” view of the system, addressing high-level design decisions while considering non-functional constraints like performance, security, scalability, and maintainability.
Key aspects of software architecture:
- Overall structure of the software (components, subsystems, modules).
- Interaction between components (e.g., via interfaces, APIs, data buses).
- Major technological choices (choice of frameworks, languages, databases, protocols).
- Compliance with non-functional requirements (scalability, performance, security, reliability).
Example: In a web application, the architecture defines that the system will be divided into three layers: presentation (user interface), business logic, and data (database).
2. Software Design
Software design is more detailed and operates at a “micro” level. It focuses on how the various components or modules defined by the architecture will be implemented. It involves specific decisions about algorithms, data structures, class interfaces, detailed object interactions, and error handling.
Key aspects of software design:
- Internal organization of modules or components (e.g., classes, methods, and objects in an object-oriented model).
- Design patterns such as Singleton, Factory, Observer, etc.
- Algorithms and data structures used to solve specific problems.
- Implementation details of internal functions, class interactions, etc.
Example: In the “business logic” layer of a web application, design will detail how business objects (e.g., a User class) will interact with services (e.g., a UserService for managing users), and which design pattern (like MVC or Observer pattern) will be used.
To sum up :
- Level of Abstraction: Software architecture is at a higher level, while software design is more detailed and focused on implementation.
- Scope: Architecture deals with the entire system and its broad structure, while design is concerned with implementation details of individual elements.
- Focus: Architecture focuses on overall structure and major technical choices, while design focuses on internal components and programming logic.
Software architecture is like the blueprint of a building: it describes the major sections, how the rooms will be laid out, and the basic materials. Software design, on the other hand, is like the detailed description of how each room will be furnished, how the electrical wiring will be installed, or how the plumbing will be handled.