Key Software Architecture Characteristics and Techniques to Improve Them

Software architecture characteristics, often ending with "‑ility" (e.g., scalability, deployability), are non‑functional requirements (NFR) or quality attributes. While there is no fixed checklist, the ISO‑25010 standard provides a reference.

1 Performance

Performance is the system's responsiveness, measured by latency, throughput, usable capacity, schedulable utilization, data loss, etc. Techniques to improve performance include analyzing demand, optimizing hardware (CPU, memory, I/O, network), improving software (framework choice, caching, avoiding reflection), using vertical scaling, concurrency, and applying Amdahl's law.

2 Reliability

Reliability means consistent quality or performance and can be expressed by MTBF (Mean Time Between Failures). It is measured through fault intervals, code coverage, fitness functions, and ISO‑9001 compliance. Techniques include best engineering practices, mutation testing, and chaos engineering.

3 Availability

Availability is the ratio of uptime to total time, building on reliability. It is often expressed using MTBF and MTTR. Improving availability involves fault detection, rapid intervention, and robust monitoring.

4 Resilience

Resilience (or fault tolerance) allows a system to degrade gracefully rather than crash when problems occur, often using circuit‑breaker patterns. It is hard to quantify numerically.

5 Trustworthiness

Trustworthiness aggregates reliability, availability, resilience, sustainability, recoverability, and robustness, and should be considered as a whole.

6 Scalability

Scalability is the ability to handle increased load within acceptable thresholds, including manual and automatic (elastic) scaling. Techniques involve monitoring CPU/memory, horizontal scaling (adding/removing instances), and vertical scaling (adding resources).

7 Security

Security comprises confidentiality, integrity, authentication, authorization (RBAC, ACL, ABAC), and non‑repudiation. Enhancing security starts with detection, then applying flexible response strategies, preferably using mature security solutions.

8 Interoperability

Interoperability is the ability of a system to communicate with external systems, relying on well‑defined contracts and error handling.

9 Adjustability

Adjustability (or mutability) describes how easily a system can accommodate change. Architects should identify high‑change areas and apply SOLID principles, fitness functions, and modular design.

10 Deployability

Deployability means packaging the system into artifacts (WAR, JAR, Docker image, etc.) that can be deployed in appropriate environments, often facilitated by containerization.

11 Testability

Testability requires controlling component inputs/outputs, keeping components small, and applying practices like TDD.

12 Simplicity

Simplicity is hard to achieve but essential for rapid MVP development; it should not be confused with proof‑of‑concept or R&D prototypes. Reusability also matters.

13 Portability

Portability is the ability to move a system across operating systems, often aided by languages like Java (JVM) or Go (static binaries) and containerization.

14 Usability

Usability includes configurability, localization (i18n), accessibility, and supportability, aiming for intuitive and learnable systems.

15 Extensibility

Extensibility describes how easily plug‑in components can be added, exemplified by OSGi or Eclipse platforms.

16 Antifragility

Antifragility is the system's ability to thrive under stress, errors, or attacks, often achieved through CI/CD, defensive mechanisms, and tools like Netflix's Simian Army.

17 Upgradability

Upgradability is the ability to upgrade a system seamlessly, using version control, blue‑green or canary deployments for zero‑downtime releases.

18 Compliance

Compliance ensures legal use of third‑party tools, adherence to licenses, GDPR, ISO standards, and avoids restrictive licenses like GPL.

19 Cost

Cost considerations cover tool licensing, cloud services, personnel, technical debt, testing, and code quality, emphasizing the need to treat many expenses as investments.

20 Archival

Archival (or auditability support) involves timestamping data, moving old records to history tables, or soft‑deleting with consideration of query performance.

21 Auditability / Traceability

Auditability requires recording critical operations, often using ELK stack or Sleuth‑Zipkin, to enable reconstruction of events and legal evidence.