Parallel Design System Running

Running design systems in parallel involves maintaining multiple component libraries simultaneously during transition periods. This approach enables gradual migration between design system versions or from legacy systems while maintaining application functionality.

What Is Parallel Running

Parallel running means both old and new design system components are available and functional within the same application. Teams can use components from either system based on migration status, with both rendering correctly and coexisting without conflicts.

This approach is common during major design system version upgrades, migrations from one design system to another, or transitions from legacy implementations to a new design system. It acknowledges that immediate complete migration is often impractical.

How to Run Systems in Parallel

Style isolation prevents CSS conflicts between systems. This might involve scoped styles, CSS modules, CSS-in-JS solutions, or careful selector namespacing. Without isolation, styles from one system may unintentionally affect components from another.

Import path management keeps component sources clear. Distinct import paths for each system prevent accidental imports from the wrong source. Linting rules can enforce intended import patterns.

Dependency management handles potential conflicts between system requirements. Different systems might require different versions of shared dependencies. Package management strategies like aliases or workspaces can resolve conflicts.

Testing covers both systems throughout the parallel period. Test suites should verify components from both systems work correctly, including in combination. Visual regression testing catches unexpected interaction effects.

Naming conventions distinguish components during the parallel period. Clear naming that indicates which system a component comes from reduces confusion for developers working across both.

Key Considerations

• Parallel running increases bundle size; both systems contribute code
• Developer cognitive load increases managing two systems simultaneously
• Documentation should clarify when to use which system
• Parallel periods should be time-bounded to prevent indefinite coexistence
• Monitoring can detect declining usage of the system being phased out

Common Questions

How long should parallel running last?

Duration depends on migration scope and organizational capacity. Small applications might parallel run for weeks; large enterprise applications might take years. Setting milestones for migration completion and tracking progress prevents indefinite parallel states. If parallel running extends beyond planned duration, investigating blockers and adjusting plans helps get migration back on track.

What problems arise from extended parallel running?

Extended parallel running causes bundle size inflation from maintaining both systems, developer confusion about which system to use, maintenance burden of supporting both systems, and potential for forgotten cleanup leaving legacy code indefinitely. These problems compound over time, making time-bounded parallel periods with clear end dates important.

Summary

Parallel design system running enables gradual migration by maintaining multiple component libraries simultaneously. Implementation requires style isolation, import management, dependency handling, comprehensive testing, and clear naming conventions. Time-bounding parallel periods prevents the accumulating costs of extended coexistence.