- Comprise software elements, the externally visible properties of those elements, and the relationships among them
- Aids in communicationc with stakeholders
- Defines constraints on implementation
- Dictates organizational structure
- Inhibits or enables quality attributes
- Supports predicting cost, quality, and schedule
- Aids in software evolution and prototyping
- Quality matters
- Performance, Availability, Modifiability, Portability, Scalability, Security, Testability, Usability, Cost to build, Cots to operate
- Architectural decisions affect entire systems, not only individual modules
- Abstract, different abstractions for different scenarios
- Reason about quality attributes early
- Make architectural decisions explicit
- Requirements
- Architecture
- OO-Design
- Code
| Design Questions | Architectural Questions |
|---|---|
| How do I add a menu item in Eclipse? | How do I extend Eclipse with a plugin? |
| How lock protects this data? | What threads exists and how do they coordinate? |
| How does Google rank pages? | How does Google scale to billions of hits per day? |
| What is the interface between objects? | What is the interface between subsystems? |
- Blueprint for the system
- Artifact for early analysis
- Documentation speaks for the architect
- Support traceability
- Static View
- Modules (subsystems, structures) and their relations (dependencies)
- Dynamic View
- Components (processes, runnable entities) and connectors (messages, data flow)
- Physical View (Deployment)
- Hardware structures and their connections
- Selecting a Notation
- Suitable for purpose
- UML possible (semi-formal), but possibly constraining
- Always include a legend
- Supplement graphics with explanation
- Do not try to do too much in one diagram