Apache EventMesh Documentation

Welcome to the Apache EventMesh documentation. EventMesh is a stateless application-layer event mesh for cloud-native, serverless, and AI-agent workloads: it connects applications to messaging backends (RocketMQ, Kafka, …) through an HTTP + CloudEvents API while owning subscription, offset, and delivery semantics itself — the broker is used purely as a write-ahead log.

Maturity tags (GA / Beta / Experimental / Legacy) for every capability live in the capability status table in the project README — that table is the single source of truth.

Where to start

I want to…	Read
Understand what EventMesh is and when to use it	Introduction
Get a runtime running and send my first event	Quickstart
Use the Java SDK in my application	Java client guide
Understand the architecture	Architecture overview
Operate a deployment	Deployment & operations

Documentation map

Quickstart

• Getting started — zero to a running runtime (Docker or source), first publish, subscribe and receive.
• Configuration reference — every runtime key: storage backends, ports, security, connector scheduling.

Feature guides

One page per capability — what it does, why it matters, how to use it, where the code lives. Reference material (APIs, protocols, operations) lives here too.

Core features

• Publish & subscribe — topics, distribution modes (LOAD_BALANCE / BROADCAST / MULTICAST), filtering, batching, request-reply.

• Reliable delivery — the at-least-once model: ACK tracking, retries, dead-letter queue, crash recovery, fencing.

• Streaming & push transports — long-poll, SSE, WebSocket, LLM streaming sessions (Mode 1 / Mode 2).

• Lite Topic (RocketMQ 5.x) — hierarchical messaging inside a parent topic; publish/poll semantics and checkpoints.

• A2A — Agent-to-Agent — the agent collaboration protocol: task lifecycle, JSON-RPC/MCP bridge, REST + SDK usage; pairs with the streaming agent runtime for agent-to-LLM sessions (Experimental).

• Agent tools & event triggers — the agent extension points (LLM client, conversation memory, function-calling tools) and connector plugins as the agent tool library; event-driven agents (Experimental).

• Connectors — bridge EventMesh with external systems (Kafka, RocketMQ, RabbitMQ, databases, chat platforms): the connector model, running a worker, and a per-plugin guide for all 23 shipped plugins.

Internals & mechanisms

• Offset management — the two offset layers, per-backend mechanics, deferred ACK, monotonic writes, takeover.
• Load balancing — full-stickiness model, self-reported instance load, the recommend loop, trade-offs.
• Frame protocol conversion — EventMeshFrame wire format, the FrameAdaptor / WireCodec SPIs, per-protocol conversion chains.
• Control plane — delivery topology, the unified state control plane (L1/L2/L3 stores), and the per-backend state store failure matrix.
• Architecture guard — the ArchUnit rulebook keeping module boundaries enforced in CI (contributors).
• Connector API split plan — the eventmesh-connector-api module split design (contributors).

Reference

• Java client guide — the complete CloudEventsClient / A2AClient API surface: builders, pub/sub patterns, request-reply, transports, security, reliability, backends.
• HTTP API — every traffic endpoint on port 10105: methods, request/response shapes, error codes.
• Admin API — the operational surface on port 10106, including the fail-closed bearer-token guard.
• Observability — metrics (Prometheus + JSON), traces, health checks, SLOs and alert rules.
• Deployment & operations — deployment modes, Docker, multi-instance coordination, runbooks, known limitations.
• Protocols & SDKs — wire protocol inventory (CloudEvents, EventMeshFrame, A2A, TCP/gRPC/OpenMessaging) and SDK status per language.
• Storage SPI — the MeshStoragePlugin contract, capability matrix, TCK.

Architecture

• Architecture overview — the three planes (data / control / agent), module decomposition, the publish wire path.
• Security — the unified SecurityGate: auth filters, per-tenant quota, audit; TLS/mTLS; admin token guard.
• Unified architecture redesign — the original rewrite design record (English rewrite): iron rules, target architecture, decision log, semantics boundaries.
• Architecture review evidence — PR/test evidence behind every closed review issue.
• Production HA acceptance plan

Conventions

• File naming: lowercase, hyphen-separated (delivery-reliability.md); one topic per page; pages are written to render standalone as HTML (website conversion pulls this tree directly).
• Every page starts with a one-paragraph summary of who it is for and what it covers, followed by a --- separator.
• Status banners reference the README capability table instead of restating maturity levels.