Summary
In a large organisation, the same question comes back project after project: which technology may a new project use? The article describes a quarterly technology radar built for such an ecosystem on Zalando’s open-source radar, at the CIO’s request: a top-down initiative, not one that grew from the teams, and one of several the author has set up. The tool is a single HTML page, d3.js and one function, radar_visualization(), configured with four quadrants, four rings and a list of entries, each with its quadrant, its ring and a moved marker. Zalando’s four rings are kept (Adopt, Trial, Assess, Hold); the quadrants are renamed after the organisation’s own concerns: development and integration, infrastructure and cloud, data and storage, security and architecture.
The entries do not live in the page but in a Git repository, as structured JSON or YAML files that give each technology its quadrant, its ring, its rationale and its owner. Each quarter ends with a release tag, from radar-2022-Q1 to radar-2022-Q4, and a pipeline generates and publishes the visualisation on an internal site once the edition is approved. Each tag keeps the decisions that were valid at that date, so anyone can find which rule applied when a project started.
Governance matters more than the drawing. A team or a tech lead proposes a technology or a ring change, with the business need, the alternatives, the risks and the proposed ring; domain architects and specialists review it; the architecture committee approves the significant decisions; a radar owner maintains the repository and publishes. A ring change rests on evidence, maturity and risk, never on popularity, with a written rationale, an accountable owner and a review date. Hold does not shut anything down: it closes the door to new projects, while the owners of existing systems document their dependencies and plan their migration or retirement.
Key ideas
- Zalando’s open-source radar installs as one HTML page and one function, radar_visualization(), with exactly four quadrants and four rings: the organisation keeps Zalando’s rings and renames the quadrants after its own concerns.
- The entries live in Git as structured files, with a quadrant, a ring, a rationale and an owner; the page is generated from them, never edited by hand.
- One release tag per quarter, from radar-2022-Q1 to radar-2022-Q4, keeps the decisions that were valid at that date, and a pipeline publishes the edition only after approval.
- A technology changes ring on evidence, maturity and risk, never on popularity, with a written rationale, an accountable owner and a review date.
- Hold closes the door to new projects without shutting down existing systems, whose owners document their dependencies, obtain exceptions where needed and plan their migration or retirement.