exactly-once

High-performance transactional message broker for applications that need an ordered stream per entity.

Example gaming leaderboard application covering streaming ingestion, CDC enrichment, processing and visualisation including demo of advance real-time analytics concepts like late data arrival, exactly-once, dynamic config, archival and on-demand replay

Safe request retries for Spring Boot REST APIs — @idempotent + Idempotency-Key header, Redis and JDBC stores.

Stateful actors on Apache Flink 2.x and Java 21 — durable per-key state, exactly-once messaging, Kafka and Kinesis I/O, Kubernetes-native deployment. Continues the Apache Stateful Functions programming model on the modern Flink line.

The Inbox Pattern/Process for Laravel apps. Ensure the ordering, uniqueness, and reliable handling of webhook requests.

Exactly-once + circuit breaker for agent tool calls (loops, retries, duplicate side effects)

Transactional Two-Phase Commit (2PC) stream sink coordinator guaranteeing end-to-end exactly-once delivery across failure recoveries.

Transactional Two-Phase Commit (2PC) stream sink coordinator guaranteeing end-to-end exactly-once delivery across failure recoveries.

Stream processing for Kafka pipelines that must stay correct when processes die. SQL, event time, keyed state and exactly-once delivery in modern C++: one process on a laptop, embedded, or a cluster. No JVM.

Lightweight Python message queuing with Redis and built-in publish-side deduplication.

Riffl - generic streaming data ingestion framework

Vibe-code durable AI workflows over sensitive data. The compiler refuses to build one that leaks, loops forever, or pays twice; the runtime makes every external action durable and exactly-once.

Self-hosted control plane for AI video production: an exactly-once job ledger, a documented remote-worker protocol, TTS narration, subtitle alignment and FFmpeg assembly, with pluggable providers.

Interactive browser simulator that visualizes delivery guarantees, idempotency, DLQ, Outbox and Inbox patterns across Azure Service Bus, Event Hubs, Event Grid, Kafka, RabbitMQ and more. Built for teaching Event-Driven Architecture.

Wrappers for Apache Kafka java clients

Observer/Learner replicas for Apache Kafka — sync without joining the ISR; promote in seconds with zero data movement. Reference implementation with real-cluster evidence.

A full agent framework on the Vercel AI SDK, durable from the core: exactly-once tool calls, deterministic replay, time-travel.

3 Problems from SP04 to be solved using HashMap/ HashSet instead of TreeMap/ TreeSet.

Verified Effect Commit Protocol for AI agents — seal the intended effect, witness the actual outcome.

Robust, Stripe-grade idempotency key middleware & decorator for FastAPI / Starlette with pluggable backends (Memory, SQLite, Redis)