@anabranch/eventlog

Event log with Task/Stream semantics for event-sourced systems with cursor-based consumption.

A high-level event log abstraction that integrates with anabranch's Task and Stream types for composable error handling, concurrent processing, and reliable consumer resumption.

Usage

import { createInMemory, EventLog } from '@anabranch/eventlog'

const connector = createInMemory()
const log = await EventLog.connect(connector).run()

// Append an event
await log.append('users', { type: 'created', userId: 123 }).run()

// Consume events with cursor-based resumption
const { successes, errors } = await log
  .consume('users', 'my-processor', { batchSize: 10 })
  .withConcurrency(5)
  .map(async (batch) => {
    for (const event of batch.events) {
      await handleEvent(event.data)
    }
    // Manual commit for at-least-once delivery
    await log.commit(batch.topic, batch.consumerGroup, batch.cursor).run()
  })
  .partition()

Installation

# JSR
jsr add @anabranch/eventlog

# Deno
deno add @anabranch/eventlog

Features

• Cursor-Based Consumption: Resume processing from any position without data loss
• At-Least-Once Delivery: Manual commit gives you control over processing guarantees
• Task/Stream Integration: Leverage Task's retry/timeout and Stream's error collection
• Multiple Adapters: In-memory implementation included

API Reference

See generated documentation for full API details.

Related

• @anabranch/anabranch - Core Task/Stream primitives