AngularJS to Angular migration

Context

Harmonic publishes VOS360/XOS, a video processing and delivery platform. An internal channel monitoring tool, built into the product, lets teams supervise a service’s streams in real time: bitrate, sources, processing and outputs.

This tool relied on AngularJS, an end-of-life framework, and on an architecture that had become hard to maintain. The goal: migrate it to Angular while modernizing the interface and simplifying the architecture, without interrupting the service provided to the teams.

Approach

• Audit of the existing architecture and exhaustive inventory of features
• Comparative study of migration strategies (incremental vs. rewrite), with a reasoned recommendation in favor of a rewrite
• Interactive prototype validated by the technical team and the Product Owners before any development
• Interface redesign that respects the visual language of VOS360/XOS
• Full migration to Angular with functional continuity and higher test coverage

Technical decisions

The choice of migration strategy was decisive from day one: it shaped the long-term maintainability of the product. An incremental migration would have prolonged the coexistence of both frameworks; a rewrite allowed a fresh start on a simpler architecture, provided feature parity was secured.

That parity was guaranteed by the initial feature inventory and by a systematic testing strategy, unit tests with Vitest and end-to-end tests with WebdriverIO, in a business domain, video monitoring, that had to be learned quickly.

Results

• Application fully migrated to Angular, with better maintainability and less technical debt
• Test coverage raised from 40% to 92%
• A modernized, simpler interface, consistent with the product’s identity
• Business needs validated upfront thanks to the prototype