9.x Capabilities in V10

Use this page to find out, before you migrate, what happens to each 9.x capability your service uses. Each row says where the capability went:

• Kept: V10 has it.
• Replaced: V10 provides it another way. The note says how; the wow-migrate Skill rewrites code that uses it.
• Dropped: V10 does not provide it, on purpose. The note says what to do instead.
• 10.x: not in 10.0; planned for a later 10.x release.

Commands

9.x capability	In V10	Notes
Command gateway: send, wait, execute	Kept	Coroutine-based; results arrive as a flow of command results.
Reactor-shaped command gateway	Dropped	Call the gateway from coroutines, or from Java through the client's CompletableFuture facade. Handlers may still return Mono or Flux.
Wait stages SENT, PROCESSED, SNAPSHOT, PROJECTED, EVENT_HANDLED, SAGA_HANDLED	Replaced	Three stages, ACCEPTED, COMMITTED and HANDLED(subscription), with snapshot as the default. See Waiting for outcomes.
Wait chain tail headers (Command-Wait-Tail-*)	Replaced	A multi-hop Wow-Wait plan.
Waiting across contexts	Kept	Signals go straight to the originating node.
Server-sent events for results	Kept	One event per hop reached.
Request id idempotency	Kept	The request id is unique per tenant and aggregate type; a reuse with another command type is refused.
Bloom filter idempotency checker	Replaced	Each cached aggregate keeps its most recent requests, derived from the log; storage answers the rest.
Command rewriter (CommandBuilderRewriter)	Replaced	A command transformer at admission; it may not change the command's identity.
Commands mounted on another aggregate (@AggregateRoot(commands))	Replaced	@MountedCommand, and @Unaddressed for commands that do not name their aggregate.
Command validation (Jakarta Bean Validation)	Replaced	Validation at admission, with Jakarta validation as one validator.
@VoidCommand	Dropped	Send the command and do not wait past ACCEPTED.
Custom routes (@CommandRoute, @AggregateRoute)	Dropped	Routes are derived from the Manifest: POST /{context}/{aggregate}/{id}/{command}, or without {id} for a creation.
Command-* request headers	Replaced	Wow-Wait, Wow-Wait-Timeout, Wow-Request-Id, If-Match, Wow-Scope, Wow-Space.
Request header aliases	Dropped	Rewrite the headers in your gateway.
Request facts copied from headers	Kept	A configured list of headers, plus the authenticated application, the remote address and the user agent.
Operator of a command	Kept	Recorded with every commit.
Global and per-aggregate id generation, CosId	Kept	Also available to decide through the decide scope.
Command batching	Replaced	The partition owner commits in batches.
Extra command results (CommandResultAccessor)	Replaced	Decide returns extra results through the decide scope; they are not stored, so a duplicate does not get them.
Unique keys across aggregates (PrepareKey, @PreparableKey)	Replaced	Reserved keys through the decide scope, stored beside the log; the data tool imports the confirmed 9.x keys.
Looking up a PrepareKey, its value, its time to live	10.x	A read-only lookup of reservations is planned. Time to live is dropped: schedule a command that releases the key.
Expected version	Kept	If-Match; a mismatch answers 412.
Command buses: in-memory, local-first, Kafka	Replaced	Partitioned routing over the cluster channel by default; Kafka routing per aggregate type for durable intake.
Redis command bus	Dropped	—
One command endpoint (/wow/command/send)	Replaced	One route per command.
Command filters and instrumentation	Replaced	An observation port, implemented by the OpenTelemetry module.
Error code to HTTP status mapping	Kept	Declared with @ErrorCode, or configured per code.
Domain exceptions converted to ErrorInfo	Replaced	A decision returns a rejection with a declared error code.

Domain model

9.x capability	In V10	Notes
Core annotations	Kept	A smaller, redesigned set in the same package.
Event revisions and upgraders (EventUpgrader)	Replaced	@Revision, @Upgrade and @Alias.
Dropped events (DroppedEvent)	Replaced	Retired events, listed on the aggregate.
Fixed tenant (@StaticTenantId)	Replaced	A fixed tenant per aggregate type in configuration.
Fixed aggregate id (@StaticAggregateId)	Dropped	—
Owner and space policies (@AggregateOwner, @Spaced)	Replaced	Ownership per aggregate type, owner or tenant; scope comes from the caller. See Identity, tenancy and access.
Identity annotations on command fields (@AggregateId and others)	Dropped	The aggregate comes from the route or the message; command bodies hold business data only.
Tags derived from state (StateAggregateTagsExtractor)	Replaced	@Tags on the state.
Applying tags	Kept	The ApplyTags lifecycle command.
Lifecycle commands: delete, restore, transfer owner or space	Kept	—
@EntityObject, @ValueObject, @Order	Dropped	—
@OnError	Dropped	Return a rejection from decide; put compensation in a saga.
Domain models written in Java	Kept	The compiler reads Java sources. A Java-friendly test API is planned for 10.x.
Domain services injected into command functions	Kept	Bound once, through the generated model factory.
Error events (IgnoreSourcing)	Replaced	A rejection, or an evolve function that changes nothing.
Aggregate with a separate state class	Kept	—
@AfterCommand, @Blocking, @CreateAggregate, @AllowCreate	Kept	—
Snapshot system fields eventId, snapshotTime, eventTime	Replaced	firstEventTime, lastEventTime, operator, firstOperator and the other snapshot fields.

Events and storage

9.x capability	In V10	Notes
MongoDB event store	Kept	A first-class log backend; PostgreSQL is the other.
Redis event and snapshot stores	Dropped	The data tool reads only the 9.x MongoDB store: move Redis data to MongoDB in 9.x first.
Elasticsearch event store	Dropped	Elasticsearch receives copies of snapshots and event streams for search; it never holds the log. Move 9.x data to MongoDB before migrating.
MongoDB and Elasticsearch snapshot stores	Kept	PostgreSQL as well.
Snapshot strategy (every n versions)	Replaced	A snapshot is written for every version, batched per aggregate.
Turning snapshots off for an aggregate	Kept	New in V10.
Storage per aggregate (storage-routing)	Kept	Named stores, chosen per aggregate for the log and the snapshots.
Regenerating snapshots, one or in bulk	Kept	A system command, and automatic rebuilds when the state revision rises.
Historical state: by version, by time, traced	Kept	GET …/state?version=, ?at= and …/state/trace.
Reading one aggregate's event stream	Kept	The events query model.
Recovering or skipping failed processing	Replaced	Parking and the failure ledger, operated through the ops service.
Targeted replay of a version range; resending state events in bulk	10.x	Until then, resume parked aggregates or rebuild a whole subscription.
Domain and state event buses	Replaced	The log is the bus; other contexts read published streams on Kafka. See The log is the bus.
Creating collections and indexes	Kept	Managed by the stores' DDL setting.

Processors and subscriptions

9.x capability	In V10	Notes
Sagas, projections, event processors	Replaced	@Saga, @Projection and @Reactor; each handler function is its own subscription.
@OnStateEvent, @OnMessage	Replaced	@OnEvent, taking the state event, or one event type of it.
Handling another context's events	Kept	Through its published stream.
Decoding another context's events into shared classes	Kept	With the other context's API jar on the classpath.
@Retry: attempts, backoff, timeout	Replaced	V10's @Retry, configurable per subscription, then long-horizon retries of parked aggregates.
Recoverable and unrecoverable exception classes	Kept	On @Retry, plus pluggable failure classifiers.
Where a subscription starts	Kept	New in V10: declared on the handler or configured.
Processor filters, interceptors, @Order	Dropped	—
Skipping Kafka messages that do not decode	10.x	V10 parks them.
Reading other aggregates' state or querying in a handler	Replaced	The typed query API, available to handlers.

Queries

9.x capability	In V10	Notes
Single, list, paged, cursor, count and aggregation queries	Kept	—
Filter expressions, relative time, metadata filters, aggregation windows	Kept	—
The Condition protocol	Dropped	Use filter expressions; the Skill rewrites conditions.
Kotlin query DSL and generated <State>Properties	Kept	—
Query field annotations (@Sensitive, @QueryAlias, @QueryReference, …)	Kept	—
Masking sensitive fields, in queries and state reads	Kept	—
ABAC query policies, CoSec abac. attributes	Kept	Off by default.
Query policy SPI and scopes	Kept	—
Snapshot queries on MongoDB and Elasticsearch	Kept	PostgreSQL as well.
Event stream queries and aggregation across aggregates	Kept	One query engine for snapshots, events and datasets.
HTTP query routes (snapshot/list and others)	Replaced	POST /{context}/{aggregate}/{model}/query, with the query kind in the body.
Streaming a list	Kept	Server-sent events that resume where they stopped.
Query schema routes and refresh	Replaced	GET on the query route describes what the model can do; the schema comes from the Manifest.
Datasets: catalog, gateway, routes	Kept	—
Dataset registration (dataset-registry)	Replaced	The analytics catalog, a platform service.
ClickHouse dataset backend	Kept	—
Query budgets, bounded counts, cursors	Kept	Plus a query bulkhead per store.

Messaging, BI and external stores

9.x capability	In V10	Notes
Kafka transport	Replaced	A sink for published streams, subscriptions to other contexts' streams, command topics and receipts.
Kafka topic prefix and topic management	Kept	—
Separate producer and consumer settings	10.x	One wow.kafka.properties until then.
BI sync scripts (/wow/bi/script)	Replaced	The ClickHouse sink writes the warehouse directly, with flattened views for datasets.
Nested expansion of state in BI tables	10.x	—
External consumers of 9.x topics	Dropped	Move each consumer to the V10 published stream at the cut-over. There is no 9.x-format sink.

Tenancy and security

9.x capability	In V10	Notes
CoSec integration	Kept	—
Tenant and owner route prefixes	Dropped	Identity comes from the caller; a caller allowed to act elsewhere names the scope in Wow-Scope.
Propagating the CoSec principal to messages	Replaced	The operator and the propagated request facts travel with every command a saga sends.
Contexts across tenants	Kept	—

Contract, OpenAPI and HTTP

9.x capability	In V10	Notes
wow-metadata.json and /wow/metadata	Replaced	The Manifest and GET /wow/manifest. See One contract.
JSON Schema generation	Replaced	Schemas generated at build time from Jackson's own view of the classes.
Registering custom Jackson modules	Dropped	Wow's JSON registers a fixed set of modules, so the wire form does not depend on the host.
OpenAPI document	Kept	Derived from the Manifest; also a Gradle task.
springdoc integration	Kept	—
Error bodies (ErrorInfo)	Replaced	application/problem+json (RFC 9457) with the error code.

Observability

9.x capability	In V10	Notes
OpenTelemetry tracing	Kept	—
Metrics	Kept	—
Health indicators	Kept	New in V10: readiness and liveness groups for Actuator.

Testing

9.x capability	In V10	Notes
Aggregate tests	Kept	The V10 test DSL, artifact wow-test.
fork, givenState, expectError by type	Kept	—
Saga, projection and reactor tests	Kept	—
Java test API	10.x	The test DSL is Kotlin-only until then.
TestValidator	Dropped	—
TCK and Testcontainers fixtures	Kept	—
wow-mock	Dropped	—

Platform services

9.x capability	In V10	Notes
Compensation service	Replaced	The ops service and console over the services' failure ledgers. The data tool imports unresolved executions.
Long-horizon automatic retries	Kept	—
Resume, skip, mark recoverable, apply a retry spec	Kept	—
Changing an execution's function; forced prepare	Dropped	—
WeCom (WeChat Work) webhook	Kept	And a generic webhook.
Console links and templates in notifications	10.x	—
Stack traces in the console	Dropped	—
Daily trend analysis in the console	10.x	—
Editable boards in the console	Dropped	—
View store	Kept	—
Dataset registry and analytics service	Replaced	The analytics catalog.

Extension modules

9.x capability	In V10	Notes
wow-models	Kept	—
wow-cocache	Dropped	—
wow-apiclient	Replaced	Typed command and query clients that run in-process for the service's own contexts and over HTTP for others. See Between contexts.
CosId	Kept	—
Spring integration and starter features	Replaced	One Spring Boot host module, wiring each backend by classpath.

Configuration and operations

9.x capability	In V10	Notes
wow.* configuration	Replaced	New keys. An unknown wow.* key is logged as a warning; an unknown key of a security setting stops the service from starting.
Graceful shutdown	Kept	—
Failing fast without a durable store	Kept	—
Maven builds	Dropped	V10 needs Gradle for its compile-time binding.
TypeScript client generator	Kept	It reads the Manifest.

TypeScript

9.x capability	In V10	Notes
Command client and waiting over SSE	Kept	—
Snapshot, event, dataset and description clients	Kept	—
Condition and localized operators	Dropped	—
Reading state by owner path	Dropped	Identity comes from the caller.
React query hooks (wow-react)	Kept	—
View engine and view store clients	Kept	—

Data migration

9.x source	In V10	Notes
MongoDB event store: import, follow, compare, snapshots	Kept	See Migrate the data.
Redis event store	Dropped	Move it to MongoDB in 9.x first.
Elasticsearch event store	Dropped	Move it to MongoDB in 9.x first.
PrepareKey keys	Kept	Imported as confirmed reservations.
Unresolved compensation executions	Kept	Imported as parked aggregates.