Stratara.Contracts 4.4.3

• net10.0

  • No dependencies.

A release about facts recorded in the wrong place and replays nobody dared to start. A handler can now append
only if the stream is still where it read it, so a fact decided on a stream's earlier state is no longer recorded
after one that contradicts it. A replay request starts one replay instead of one per host, its outcome stays
readable after it ends, and on PostgreSQL a failed replay restores the read models it emptied. A new stream's
owner can be stated at creation, and a subscription nobody consumes is reported. Everything new is opt-in or
additive; no migration is needed. Three optional settings are new — and hosts that run the replay worker are
upgraded together (see *Changed*).

### Added

- **An append can be made on the condition of the version the handler read.** `AppendAsync` numbers an
 event after whatever the stream holds when the append is made, so a write that landed between a
 handler's read and its append went unnoticed and the handler's fact was recorded after it — after a
 stream's end, for example, which then stops every later projection replay. `IEventSource` gains
 `AppendAtVersionAsync<TAggregate>(streamId, expectedVersion, @event)` and
 `AppendRangeAtVersionAsync<TAggregate>(streamId, expectedVersion, events)`: if another writer has moved
 the stream past `expectedVersion`, `SaveChangesAsync` throws `ConcurrencyException` — naming the stream that
 moved — and records nothing, and the bus redelivers as for any conflict. A version the stream has not reached,
 or a negative one, is refused at the append with `ArgumentOutOfRangeException`. The members have default
 implementations that throw `NotSupportedException`, so an implementation of `IEventSource` outside the
 framework still compiles.
- **`EventSourcing:AppendAgainstAggregatedVersion`** (default `false`). With it on, an append to a stream
 the handler rebuilt through `IAggregationService.AggregateAsync` in the same scope is made on the
 condition of the version that rebuild saw — every read-then-write handler gets the protection without a
 code change. The condition is the version of the first rebuild of a stream in the scope; a rebuild bounded
 with `toVersion` sets none; a rebuild that found no stream expects it still not to exist; a successful save
 ends it on the streams it wrote. With the option off nothing is recorded. The cost: a handler appending to a
 stream another writer touches concurrently gets a conflict where it used to succeed, and on the `IMediator`
 path the caller sees it.
- **A new stream's owner can be stated at creation.** `IEventSource.CreateOnBehalfOfAsync<TAggregate>(streamId,
 @event, subject)` creates the stream with the owner the subject states, which every later event keeps. Until
 now the explicit route existed for appends only. A default implementation built on `ExistsAsync` and
 `AppendOnBehalfOfAsync` keeps implementations outside the framework compiling.
- **`EventSourcing:NewStreamOwnerFromSession`** — `Allow` (default), `Warn` or `Refuse` — decides what happens when
 a new stream's first event would take its owner from the session: as before, as before plus a warning `102_007`
 (once per stream and batch), or a refusal before anything is staged. Stated owners, creation events that carry a
 tenant, and appends to existing streams are untouched. A value that names no policy fails the host's start with
 an `OptionsValidationException`.
- **The outcome of the last replay is kept.** After a replay that succeeded, `GetProgress()` answered exactly
 what it answered before any replay, so a status reader that polled saw a short replay only if a poll fell
 inside it, and told the operator it had not begun. `ReplayProgress.LastReplay` is a new `ReplayOutcome` —
 the request's id, when the replay started and ended, how many events it replayed, and whether it
 `Succeeded`, `Failed` or was `Interrupted` — kept until the next replay ends. `ReplayProgress.RequestId`
 names the replay that is running.
- **A replay request has an identity.** `IProjectionReplayState.RequestReplay(Guid requestId)` lets the
 requester choose it and find it again; `Guid.Empty` is refused. `IProjectionReplayState` also gains
 `SubscribeToReplayRequestAsync(Func<Guid, Task>)`, `TryActivate(Guid)` and `Complete(ReplayCompletion)`;
 all four have default implementations, so an implementation outside the framework still compiles and
 behaves as before.
- **A failed replay can restore the read models it emptied.** `AddReadModelRestore<TReadContext>()`
 (PostgreSQL, `Stratara.EventSourcing.EntityFrameworkCore`) copies every table the read context maps — the read
 models, the projection checkpoints and the record of forgotten tenants, as one snapshot — before a replay empties
 anything. A replay that fails writes the copy back in one transaction, one that succeeds drops it, and one whose
 host stopped leaves it for the next host that starts, which writes it back — and, while a replay still marked
 active owns it, checks again every thirty seconds. A replay then ends in the rebuilt read models or exactly the
 ones it started from. `ReplayOutcome.ReadModelsRestored` says it happened. Settings come from
 `ProjectionReplay:Restore` (`Schema`, `ExcludedTables`, `AdditionalTables`, `CommandTimeout`); deployments that
 share a read store give each its own `Schema`. New abstraction `IReadModelPreservation` in `Stratara.Projections`
 for another store; without one registered a replay behaves as before. The copy costs one more read of the read
 store before the replay and the disk to hold it twice while it runs. On a host without the shared Redis state, a
 successful replay whose copy could not be dropped (`104_025`) is restored at the next start, because the outcome
 that would say otherwise does not survive the restart.
- **A subscription nobody consumes is reported.** An established subscription keeps what is published to it until
 something consumes it, so one whose worker is never deployed, or was retired, grows without end — and until now
 nothing said so. On RabbitMQ, `EnsureSubscriptionAsync` logs `108_114` at Warning when the subscription already
 holds at least `Messaging:UnconsumedSubscriptionWarningThreshold` messages (default 10 000; 0 turns it off; a
 negative value fails the host's start) and no consumer is attached. Nothing is capped or discarded, and no queue
 is declared with different arguments.
- **Log events:** `102_007` (Warning, a new stream's owner taken from the session), `104_019` (a request not run
 because a replay is active), `104_020` (replay interrupted), `104_021` (read models preserved), `104_022`
 (Warning, read models restored after a failure), `104_023` (Warning, an abandoned copy restored at start),
 `104_025` (Warning, a copy that could not be dropped), `104_026` (Warning, the marking could not be renewed while
 the replay prepares), `104_121` (Error, an outcome not recorded), `104_124` (Error, a write-back or a check at
 start that failed; the copy is kept), `104_127` (Error, a request that could not be claimed), `108_114` (Warning,
 a subscription nobody consumes).

### Changed

- **`AddEventSourcing()` reads the `EventSourcing` section itself** and validates it at start;
 `AddWriteStore(configuration)` still binds it too, and the later registration wins if the two differ.
- **`CreateAsync` and `CreateRangeAsync` refuse a stream that already has events staged in the same batch** with
 `InvalidOperationException` at the call, where the save used to fail later with a `ConcurrencyException`.
- **A replay renews its marking every second while it prepares** — preserves, empties and counts — so
 `ProjectionReplay:LeaseSeconds` now has to outlast the slowest batch only, not the truncation before the first
 progress report.
- **Rolling upgrade of replay hosts.** A host on an earlier release claims nothing: it runs every replay request it
 receives, records no outcome, and its own requests carry no identity. Upgrade every host that runs the replay
 worker before relying on one request starting one replay, or on `LastReplay`.

### Fixed

- **One replay request starts one replay.** Every host that runs the replay worker subscribes to the
 request channel, and nothing claimed a request: with the coordination state in Redis, one request started
 a full replay in every such host at once, all emptying and rebuilding the same read store, and two
 requests in quick succession did the same within one host. A request is now claimed atomically with the
 replay's marking; the other hosts pass it over, a host that receives it after the replay ended finds it
 claimed, and a request that arrives while a replay is running — or while the host stops — starts nothing. A
 replay that outlived its lease while another started records its outcome without touching the other's marking
 or error message.
- **A replay stopped by its host ends as interrupted.** A replay cancelled between two batches logged
 `104_006` "completed" with its partial count. It now ends as `Interrupted` and logs `104_020`, and the host's
 stop waits, within its shutdown timeout, for the replay to record that. A cancellation that does not come from
 the host stopping — a provider's own timeout — now ends the replay as `Failed` with its message, where it was
 silently treated as a shutdown. Nothing the replay does after claiming a request can escape the coordination
 store's callback any more.
- **The Redis-backed replay state reports `0` of `0` after a failure,** as the in-process one and the guide
 always did; it kept showing the failed run's counters until their lease ran out.
- **A conflict in a batch that spans several streams names the stream another writer moved**, not the batch's first
 entry; the conflict counter is tagged the same way.