Knowledge section
Patterns
Reusable implementation patterns, failure boundaries, and architecture moves for production systems.
intermediate
Bulkhead Isolation
Isolate resources so one failing dependency, tenant, or workload cannot consume capacity needed by the rest of the system.
foundation
Cache-Aside
A caching pattern where the application reads from cache first, falls back to the database on misses, and then populates the cache.
intermediate
Circuit Breaker
Stop calling an unhealthy dependency for a period of time so failures do not cascade through the system.
intermediate
Connection Registry
Track which realtime gateway currently owns each connected user device so delivery workers can route live events without making gateways durable truth.
intermediate
CQRS Read Model
Separate write models from read-optimized projections so systems can preserve source-of-truth writes while serving efficient queries.
intermediate
Cursor-Based Sync
Let clients recover missed updates by asking for durable records after their last known position instead of trusting live delivery alone.
foundation
Dead-Letter Queue
Isolate messages that repeatedly fail processing so they do not block healthy event processing forever.
intermediate
Idempotent Consumer
Safely process duplicate messages by making consumer side effects converge to the same final result.
advanced
Large Group Fan-Out Isolation
Keep massive group delivery workloads from starving normal messaging by separating queues, worker pools, limits, and backpressure policies.
intermediate
Lease-Based Assignment
Temporarily reserve a scarce resource for one workflow so concurrent workers cannot assign it twice while the final confirmation is still pending.
intermediate
Read Cursor Receipts
Represent read state as a user's latest read sequence in a conversation instead of writing one read receipt per message.
intermediate
Reconciliation Job
Periodically compare source-of-truth data with derived state and repair drift caused by missed, duplicated, or incorrectly processed updates.
foundation
Retry With Exponential Backoff And Jitter
Retry transient failures with increasing delays and randomness so recovery does not create a synchronized traffic spike.
advanced
Saga Pattern
Coordinate a multi-step distributed workflow using local transactions and compensating actions instead of one large distributed transaction.
intermediate
Sharded Counter
Split one logical counter into multiple partial counters to distribute write load for hot aggregates.
intermediate
Transactional Outbox
Reliably publish events that correspond to committed database changes by storing publish intent inside the same local database transaction.
intermediate
Upload-Then-Reference Media
Upload large media outside the message send path, then send a lightweight message that references the stored media object.