> For the complete documentation index, see [llms.txt](https://docs.eventoframework.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.eventoframework.com/evento-3.md). # Evento 3 Everything Evento 3 gives you, in one page **Evento 3 is available.** It is the complete toolkit to build RECQ systems in Java: seven component types to write your domain with, a server that routes and stores everything they exchange, a console that turns your code into a living map of the system, and a cluster mode that runs it from one site to three continents. Every feature is public: the client libraries under Apache-2.0, the server and console under Apache-2.0 with the Commons Clause ([Licensing](/licensing.md)). ## Write your domain * **Seven RECQ components**, each an annotated Java class: [Aggregates](/evento-framework/component/aggregate.md), [Services](/evento-framework/component/service.md), [Projectors](/evento-framework/component/projector.md), [Projections](/evento-framework/component/projection.md), [Sagas](/evento-framework/component/saga.md), [Observers](/evento-framework/component/observer.md) and [Invokers](/evento-framework/component/invoker.md). Bundles announce their components to the server on their own: no deployment descriptors. * **Commands, events and queries** as plain payload classes, with [versioning and upcasting](/evento-framework/payload-and-messages/payload-versioning.md): a class can change shape or name and the history written with the old one is still read. * **Several events from one command**, stored atomically ([returning several events](/evento-framework/component/aggregate/aggregatecommandhandler.md#returning-several-events)). * **Any Java stack**: plain Java, Spring, Micronaut or Quarkus; a [Spring Boot starter](/evento-framework/eventobundle/spring-boot-starter.md) for Boot 4 and 3.5. Everything runs on Java 25 with virtual threads. ## Correct under failure * **Exactly-once commands**: idempotency keys make a retry safe on whichever server it lands, and sagas, projectors and observers derive theirs automatically ([Exactly-once Commands](/evento-server/evento-server-cluster/exactly-once-commands.md)). * **No forked aggregates**: every event carries its aggregate's version under a unique index, so two commands that decided from the same state can never both be stored; commands run without a lock and retry on the new state when they lose. * **Consumers you can trust**: projector, saga and observer progress on [PostgreSQL or MySQL](/evento-framework/eventobundle/consumerstatestore.md), [dead event queues](/evento-framework/dead-event-queues.md), [parallel consumption](/evento-framework/eventobundle/parallel-consumers.md) with per-aggregate ordering when you need it. * **Consumers that wait instead of poll**: the server tells the bundles when events of the kinds they handle arrive; an idle system costs the event store almost nothing. ## Run it as a cluster * **Several servers, one PostgreSQL event store**: from a hot standby next to your server to a cell per region ([Evento Server Cluster](/evento-server/evento-server-cluster.md)). * **Failover and fail-back**: bundles move to another server when theirs dies and come back on their own when it is healthy again ([Bundle Failover and Fail-back](/evento-server/evento-server-cluster/bundle-failover-and-failback.md)). * **Cells and locality**: requests are answered close to the caller ([Cells and Locality](/evento-server/evento-server-cluster/cells-and-locality.md)). * **Highly available consumers**: run each consumer, per context, in as many replicas as you like; one replica holds the lane and another takes over when it goes, without losing or repeating an event. * **Correctness lives in the database**: servers never call one another, so adding one is just starting it. ## Query at any size * **Streamed and paged answers** with flow control, even directly from bundle to bundle; a bundle answers its own queries in process ([Streamed and Paged Queries](/evento-framework/component/projection/streaming-and-paged-queries.md)). * **Read your writes**: a query can wait until the projections reflect a command ([Read Your Writes](/evento-framework/component/projection/read-your-writes.md)). ## Secure and compliant * **Secure by default**: in production the server requires a bus token, TLS, a payload allowlist, real passwords and explicit CORS origins ([Security](/evento-server/setup-evento-server/security.md)). * **Single sign-on and audit trail** for the console ([GUI Auth](/evento-gui/gui-auth.md)). * **Personal data and the right to erasure**: personal fields are encrypted per data subject, and deleting the subject's key erases them from the whole history ([Personal Data](/evento-framework/personal-data.md)). * **Multi-tenancy** patterns ([Multi-Tenancy](/evento-framework/multi-tenancy.md)). ## See and measure * **A console generated from your code**: catalog of payloads, components and bundles, flows, application graph, what-if performance analysis ([Evento GUI](/evento-gui/explore-recq-systems-visually.md)). * **OpenTelemetry tracing and Prometheus metrics** ([OpenTelemetry](/evento-framework/eventobundle/tracingagend-and-track/opentelemetry.md)). ## Test it * **Fixtures, an in-process broker and a containerised server** to test components alone or a whole system ([Testing with Fixtures](/evento-framework/testing-with-fixtures.md)). And Evento itself is tested hard: see [How Evento Is Tested](/testing-and-verification.md).