LWCArchitect (Hardest)lmspub-subarchitecture
Compare LMS versus pub-sub for sibling LWC communication at scale
Real World Scenario
Record page has 12 sibling LWCs; team debates Lightning Message Service vs custom pub-sub module for filter state broadcast.
Expected Answer
• LMS is platform-supported, documented, works across DOM boundaries and some namespace scenarios
• Custom pub-sub breaks when components not in same document or after navigation
• LMS requires message channel metadata — governance and discoverability advantage
• Define message schema version and payload typing in shared module
• Avoid high-frequency LMS messages — throttle or batch filter updates
• Document subscribers in architecture diagram for onboarding
• Fallback when LMS unavailable in certain contexts — document exceptions
Follow-Up Questions & Answers
Click to expand — each follow-up includes a direct, interview-ready answer
Stay within limits by: LMS is platform-supported, documented, works across DOM boundaries and some namespace scenarios. Bulkify everything — never query or DML in loops. LMS requires message channel metadata — governance and discoverability advantage. At scale, communication patterns must be governable — LMS beats anonymous pub-sub for enterprise maintenance. Document the decision in an ADR and align with enterprise standards.
Architect Perspective
At scale, communication patterns must be governable — LMS beats anonymous pub-sub for enterprise maintenance.