Scalability Standards

Standard Metadata

• Area: Performance
• Owner: Technical Leadership group
• Last reviewed: 2026-09-09
• Next review due from: 2026-12-01
• Enforcement: Code review
• Status: Active

Web applications must be stateless by design in order to be horizontally scalable · PERF-02.1 · MUST · DEV

Systems should utilise caching in order to provide more scalable data access · PERF-02.2 · SHOULD · DEV

Caching increases cost and complexity, therefore this must be a consideration rather than a mandate, and the costs and benefits should be communicated to the client where appropriate.

A distributed caching solution should generally be preferred in order to best enable horizontal scalability.

Asynchronous operations should be preferred where possible · PERF-02.3 · SHOULD · DEV

Where an operation does not need to be performed synchronously, technologies like message queues and events should be used in order to process actions asynchronously.

Common examples include:

• Sending an email
• Writing to an audit log
• Notifying an external system of an event