Architectural Principles
Higher Level Abstract Principles
- Emergent design over upfront design
- High-level long-term options over detailed long-term design
- Microservices over monoliths
- Data services over databases
- Boundaries of responsibility over shared ownership
Aligning to: MOJ Architecture Principles for Justice
Principles in Practice
- Digital Prison Services (DPS) will be architected as a set of loosely-coupled, “right-sized” (Domains?) services, each owned and supported for their life-time by teams of dedicated professionals. These will be built with a single user experience and to GDS standards.
- Domain Services will be recognised as key authority systems responsible for their own data. Domain service delivery teams must ensure that their domain’s data is available to downstream services as required - both via an API and for reporting and data analytics purposes.
- Core prison data must be retrieved from the appropriate domain API. NOMIS should no-longer be considered the source of truth for prison data. In the short to medium term, data can be synchronised back to NOMIS to satisfy downstream dependencies.
- Domain Services will integrate in a loosely coupled way using Events and APIs. Domains services are responsible keeping themselves aligned to the current prisons state by listening out for event of interest and performing internal processing accordingly.
- Data should not be duplicated data across prison and probation services unless it is absolutely necessary - e.g. for reasons of performance or resilience
Security Principles
HMPPS Digital aims to provide technical solutions that are “Secure By Design” and aligned to MoJ Digital and Justice architecture principles and security guidance.
- Emergent design over upfront design - security needs to be a continuous consideration
- Know the limitations of your architecture - security testing to understand our risks
- Open-source over closed-source - Secure development practices enabling “coding in the open”
- Continuous delivery over change management
- Public cloud by default
- Trust but verify code
- Secure systems over secure zones
- Immutable infrastructure over patch-in-place
- Audit, Audit, Audit