Software Design Document

A Software Design Document is a technical design document that captures software design decisions, software component structures, and software implementation approaches.

• AKA: Software Design Specification, SDD, Design Documentation, Software Design Artifact, Technical Design Document, Detailed Design Document.
• Context:
  • It can typically communicate Software Design Intents through design rationale documentations and design principle specifications.
  • It can typically establish Software Component Relationships through component diagrams, class diagrams, and interaction diagrams.
  • It can typically define Software Interfaces through interface specifications, API definitions, and protocol descriptions.
  • It can typically specify Software Behaviors through behavioral descriptions, state diagrams, and sequence diagrams.
  • It can typically document Software Constraints through technical constraint documentations and design limitation specifications.
  • It can typically capture Software Design Patterns through pattern application documentations and pattern relationship mappings.
  • It can typically preserve Software Design Decisions through design choice documentations and alternative analysis records.
  • ...
  • It can often include Software Algorithms through algorithm descriptions, pseudocode specifications, and complexity analysiss.
  • It can often present Software Data Models through data structure definitions, database schemas, and entity relationship diagrams.
  • It can often establish Software Architectures through architectural pattern documentations and system structure overviews.
  • It can often define Software Modules through module specifications, module interfaces, and module dependencys.
  • It can often specify Software Error Handlings through exception strategys and fault tolerance mechanisms.
  • It can often document Software Performance Requirements through performance targets and optimization strategys.
  • It can often include Software Security Designs through security mechanisms and access control specifications.
  • ...
  • It can range from being a High-Level Software Design Document to being a Detailed Software Design Document, depending on its software design abstraction level.
  • It can range from being a Formal Software Design Document to being an Informal Software Design Document, depending on its software design formality level.
  • It can range from being a Waterfall Software Design Document to being an Agile Software Design Document, depending on its software design methodology.
  • It can range from being a Monolithic Software Design Document to being a Modular Software Design Document, depending on its software design structure.
  • It can range from being a Static Software Design Document to being a Living Software Design Document, depending on its software design update frequency.
  • ...
  • It can integrate with Requirements Documents for requirement traceabilitys and design validations.
  • It can connect to Test Plans for test coverage verifications and test case derivations.
  • It can interface with Code Repositorys for implementation trackings and design-code alignments.
  • It can communicate with Project Management Systems for milestone plannings and deliverable trackings.
  • It can synchronize with Review Processes for design approvals and quality assurances.
  • It can reference Coding Standards for implementation guidelines and style consistencys.
  • It can support Development Teams through implementation guidances and technical clarifications.
  • ...
• Example(s):
  • Architecture-Level Software Design Documents capturing software architectures, such as:
    • Software System Architecture Design Documents documenting system-wide architecture decisions through:
      • Enterprise Software System Architecture Design Documents for enterprise-scale system designs.
      • Cloud-Native Software System Architecture Design Documents for cloud-based system designs.
      • Microservices Software System Architecture Design Documents for distributed service architectures.
    • Application Architecture Software Design Documents defining application-level structures through:
      • Web Application Architecture Software Design Documents for web-based system designs.
      • Mobile Application Architecture Software Design Documents for mobile platform designs.
  • Component-Level Software Design Documents specifying software component designs, such as:
    • Module Software Design Documents detailing module implementations:
      • Service Module Software Design Documents for service component designs.
      • Library Module Software Design Documents for reusable library designs.
      • Plugin Module Software Design Documents for extensible component designs.
    • Class Software Design Documents defining object-oriented designs:
      • Domain Model Software Design Documents for business logic designs.
      • Data Access Software Design Documents for persistence layer designs.
  • Interface-Focused Software Design Documents establishing interface specifications, such as:
    • API Software Design Documents for application programming interface designs.
    • Protocol Software Design Documents for communication protocol designs.
    • Message Format Software Design Documents for data exchange designs.
  • Algorithm-Centric Software Design Documents documenting computational approaches, such as:
    • Data Processing Algorithm Software Design Documents for data transformation designs.
    • Machine Learning Algorithm Software Design Documents for ML model implementations.
    • Optimization Algorithm Software Design Documents for performance-critical designs.
  • Methodology-Specific Software Design Documents following development methodologys, such as:
    • Agile Software Design Documents with iterative design evolutions.
    • Waterfall Software Design Documents with comprehensive upfront designs.
    • Domain-Driven Software Design Documents with bounded context definitions.
  • ...
• Counter-Example(s):
  • Requirements Documents, which capture functional requirements and business needs rather than software design decisions.
  • User Manuals, which document system usage instructions rather than software design structures.
  • Code Documentations, which describe implementation-level details rather than software design approaches.
  • Project Plans, which outline project schedules rather than software design specifications.
  • Test Documents, which specify testing procedures rather than software design patterns.
• See: Design Document, Technical Design Document, Software Architecture Design Document, High-Level Design Document (HDD), Design Specification, Software Engineering Document, System Design Document, Architecture Decision Record (ADR), Software Development Artifact, Living Documentation.

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