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System Design Document (SDD) Template

It follows industry-standard practices inspired by IEEE 1016

Table 1 — Summary of design viewpoints

Design viewpointDesign concernsExample design languages
Context (5.2)Systems services and usersIDEF0, UML use case diagram, Structured Analysis context diagram
Composition (5.3)
Can be refined into new viewpoints, such as: functional (logical) decomposition, and run-time (physical) decomposition.		Composition and modular assembly of systems in terms of subsystems and (pluggable) components, buy vs. build, reuse of componentsLogical: UML package diagram, UML component diagram, Architecture Description Languages, IDEF0, Structure chart, HIPO
Physical: UML deployment diagram
Logical (5.4)Static structure (classes, interfaces, and their relationships)
Reuse of types and implementations (classes, data types)		UML class diagram, UML object diagram
Dependency (5.5)Interconnection, sharing, and parameterizationUML package diagram and component diagram
Information (5.6) with data distribution overlay and physical volumetric overlayPersistent informationIDEF1X, entity-relation diagram, UML class diagram
Patterns (5.7)Reuse of patterns and available Framework templateUML composite structure diagram
Interface (5.8)Service definition, service accessInterface definition languages (IDL), UML component diagram
Structure (5.9)Internal constituents and organization of design subjects, components and classesUML structure diagram, class diagram
Interaction (5.10)Object communication, messagingUML sequence diagram, UML communication diagram
State dynamics (5.11)Dynamic state transformationUML state machine diagram, statechart (Harel’s), state transition table (matrix), automata, Petri net
Algorithm (5.12)Procedural logicDecision table, Warnier diagram, JSP, PDL
Resources (5.13)
May be refined into resource based viewpoints with possible overlays		Resource utilizationUML Real-time Profile, UML class diagram, UML Object Constraint Language (OCL)

1. Document Control​

  • Document Version:
  • Date:
  • Author(s):
  • Reviewed by:
  • Approved by:
  • Status: Draft / Final

2. Introduction​

2.1 Purpose​

Explain the purpose of this document, its intended audience, and scope.

2.2 Scope​

Describe the system’s overall goals, business context, and key functionalities.

2.3 References​

List all referenced documents, standards, or related designs.

2.4 Definitions & Acronyms​

Provide a glossary of terms and abbreviations.

3. System Overview​

3.1 System Context​

  • High-level description of the system.
  • Include System Context Diagram (showing external systems and actors).

3.2 Objectives & Success Criteria​

Define measurable goals for the system.

4. Architectural Design​

4.1 Architecture Overview​

  • Describe chosen architectural style (e.g., microservices, layered, event-driven).
  • Show high-level architecture diagram.

4.2 Design Principles​

List guiding principles (e.g., scalability, availability, security).

4.3 Subsystems & Components​

Break down into major components/modules:

  • Name
  • Responsibility
  • Interfaces
  • Dependencies

4.4 Data Design​

  • Database schema diagrams
  • Data flow diagrams
  • Key data entities & relationships

4.5 Technology Stack​

Specify technologies chosen (languages, frameworks, infra, databases, messaging, etc.)

5. Detailed Design​

For each component/subsystem:

  • Name
  • Purpose
  • Inputs / Outputs
  • Interfaces (APIs, protocols, message formats)
  • Internal Processing
  • Data Storage
  • Dependencies
  • Error Handling & Logging

Use UML diagrams where helpful:

  • Class diagrams
  • Sequence diagrams
  • State diagrams

6. Integration & Interfaces​

6.1 External Interfaces​

  • APIs, services, third-party integrations.

6.2 Internal Interfaces​

  • Communication between modules.

6.3 Data Migration / Legacy System Considerations​

7. Security Design​

  • Authentication & Authorization
  • Data protection (encryption, secure storage)
  • Network security (firewalls, TLS, etc.)
  • Compliance considerations (GDPR, HIPAA, PCI DSS, etc.)

8. Performance & Scalability​

  • Expected loads and throughput
  • Latency requirements
  • Scalability strategies (sharding, caching, load balancing)

9. Reliability & Availability​

  • Fault tolerance strategies
  • Backup & disaster recovery plan
  • High availability design

10. Deployment & Infrastructure​

  • Environment setup (Dev, Staging, Prod)
  • Infrastructure design (cloud/on-prem, containers, orchestration)
  • CI/CD pipeline overview
  • Monitoring & logging strategy

11. Non-Functional Requirements​

  • Security
  • Performance
  • Usability
  • Maintainability
  • Extensibility
  • Compliance

12. Risks & Mitigations​

  • Technical risks
  • Business risks
  • Mitigation strategies

13. Appendix​

  • Supporting diagrams, extra notes, calculations, POCs.