Stratara.Projections
4.0.4
Prefix Reserved
See the version list below for details.
dotnet add package Stratara.Projections --version 4.0.4
NuGet\Install-Package Stratara.Projections -Version 4.0.4
<PackageReference Include="Stratara.Projections" Version="4.0.4" />
<PackageVersion Include="Stratara.Projections" Version="4.0.4" />
<PackageReference Include="Stratara.Projections" />
paket add Stratara.Projections --version 4.0.4
#r "nuget: Stratara.Projections, 4.0.4"
#:package Stratara.Projections@4.0.4
#addin nuget:?package=Stratara.Projections&version=4.0.4
#tool nuget:?package=Stratara.Projections&version=4.0.4
Stratara.Projections
Derived. The behaviour described here is specified under
openspec/specs/. Those specifications are the source; this page explains and illustrates them.
License: MIT.
Projection runtime for the Stratara event-sourced stack. Discovers IProjection implementations in the consumer's application assemblies, dispatches event bundles to them, and applies the resulting change sets atomically via the read-model repository layer.
What's in the box
| Folder | Contents |
|---|---|
Services/ |
The runtime, all internal: ProjectionManager (event-bundle → matching projection-handlers fan-out), ProjectionHandler (invokes a projection's matching methods), ProjectionMethodInvoker (reflection-cached method-pointer dispatch into consumer projections). You implement IProjection; these drive it |
Multitenancy/ |
TenantProjection — the framework's own opinionated tenant aggregate projection. Skip the registration if your application has its own tenancy model |
Diagnostics/Extensions/ |
Source-generated LoggerProjectionExtensions, LoggerChangeSetExtensions, LoggerUpdateExtensions — typed [LoggerMessage] surfaces under the Stratara.Projection.* / Stratara.ChangeSet.* / Stratara.Update.* event-ID bands |
Quick start
// In your EventProjection worker:
builder.Services
.AddProjectionWorker(builder.Configuration) // the runtime + hosted service
.AddProjectionsFromAssemblyContaining<MyAppProjectionMarker>(); // your IProjection implementations
Then implement IProjection in your application assembly. The projection manager picks them up automatically.
Both calls are needed: AddProjectionsFromAssemblyContaining<T>() only registers your projections —
AddProjectionWorker(IConfiguration) registers the manager, the invoker and the hosted service that
consumes the event-bundle subscription. Without it nothing drives your projections. Most hosts get
both from the AddEventProjectionWorkerServices() composite in Stratara.EventSourcing.WorkerDefaults.
No checkpoint store. Projections are driven push-wise off the event bus; the framework keeps no per-projection checkpoint, so there is no consumer-lag metric and no built-in resume-from-sequence. Replay is coordinated separately (see
Stratara.Outbox.RabbitMQ's replay state).
Dependencies
Stratara.Contracts— forEventBundle+IEvent<T>.Stratara.Domain— for the framework'sTenantaggregate (only consumed byTenantProjection).Stratara.Shared— for change-tracking primitives, reflection cache, partitioning helpers, diagnostics base.Microsoft.Extensions.Hosting.Abstractions+Microsoft.Extensions.Options.ConfigurationExtensions— for projection-worker checkpointing options.JetBrains.Annotations— for static-analysis attributes on projection-handler conventions.
| Product | Versions Compatible and additional computed target framework versions. |
|---|---|
| .NET | net10.0 is compatible. net10.0-android was computed. net10.0-browser was computed. net10.0-ios was computed. net10.0-maccatalyst was computed. net10.0-macos was computed. net10.0-tvos was computed. net10.0-windows was computed. |
-
net10.0
- JetBrains.Annotations (>= 2026.2.0)
- Microsoft.Extensions.Hosting.Abstractions (>= 10.0.11)
- Microsoft.Extensions.Options.ConfigurationExtensions (>= 10.0.11)
- Stratara.Contracts (>= 4.0.4)
- Stratara.Domain (>= 4.0.4)
- Stratara.Shared (>= 4.0.4)
NuGet packages (3)
Showing the top 3 NuGet packages that depend on Stratara.Projections:
| Package | Downloads |
|---|---|
|
Stratara.EventSourcing.EntityFrameworkCore
EF Core persistence for the Stratara event-sourced stack on PostgreSQL — write-store, read-store, ASP.NET Identity store, shared conventions, value generators, and UnitOfWork primitives. Targets Npgsql; maps pgvector types for a model that uses them, and needs no database extension otherwise. |
|
|
Stratara.EventSourcing.WorkerDefaults
Worker-host wiring composites for the Stratara event-sourced stack. IHostApplicationBuilder extensions (AddBackendServices, AddCommandWorkerServices, AddHeavyCommandWorkerServices, AddEventProjectionWorkerServices, AddEventStreamHashWorkerServices, AddSagaWorkerServices, AddOutboxWorkerServices, and AddCommandServices, AddEventProjectionServices and AddSagaServices without the bus-fed workers) bundle the per-concern DI calls so each worker host opts in with one line. |
|
|
Stratara.Orleans
The Orleans execution model for the Stratara event-sourced stack — one activation per aggregate across the cluster, commands recorded before the call returns and resumed after a crash, projections and sagas that read the store in commit order from a checkpoint, singleton work, owner-checked durable timers and heavy work bounded across the cluster. |
GitHub repositories
This package is not used by any popular GitHub repositories.
| Version | Downloads | Last Updated |
|---|---|---|
| 4.2.0 | 67 | 9/18/2026 |
| 4.1.1 | 106 | 9/16/2026 |
| 4.1.0 | 110 | 9/16/2026 |
| 4.0.4 | 696 | 9/14/2026 |
| 4.0.3 | 192 | 9/3/2026 |
| 4.0.2 | 627 | 9/3/2026 |
| 4.0.1 | 250 | 9/2/2026 |
| 4.0.0 | 178 | 8/31/2026 |
| 4.0.0-preview.1 | 77 | 8/31/2026 |
| 3.4.0 | 167 | 8/28/2026 |
| 3.3.0 | 140 | 8/25/2026 |
| 3.2.3 | 159 | 8/22/2026 |
| 3.2.2 | 156 | 8/14/2026 |
| 3.2.1 | 168 | 8/2/2026 |
| 3.2.0 | 155 | 7/18/2026 |
| 3.1.7 | 440 | 7/1/2026 |
| 3.1.6 | 579 | 6/22/2026 |
| 3.1.5 | 164 | 6/22/2026 |
| 3.1.4 | 178 | 6/15/2026 |
| 3.1.3 | 168 | 6/10/2026 |
Three findings from a proof of concept of an alternative execution model, each fixed on the shipped
path. A message a handler cannot take is now redelivered a bounded number of times and then
dead-lettered on both brokers instead of being dropped on one of them; an opt-in closes the window
in which a committed fact could be lost between the commit and its publication; and a version
collision is a concurrency conflict on every supported database provider, not only on PostgreSQL.
Additive on every published surface, with one operator step on RabbitMQ: the worker queues change
name and type, and the old ones are deleted once drained.
### Added
- `Outbox:DurableBundles` (`OutboxOptions.DurableBundles`, default `false`): an event bundle is
written to the outbox table in the transaction that commits its events, published after the
commit, and removed once the bus has accepted it — so a process that ends between the commit and
the publish no longer loses the bundle for every subscription. `IEventBundleOutboxDispatcher`
gains `StoresBundlesWithCommit` and `StoreEventBundleAsync`, and `IOutboxRepository` an
`AddAsync(Guid id, …)` overload, all default-implemented so a consumer's own implementations keep
compiling and keep bus-first. `AddOutboxDispatcher()` now binds the `Outbox` section when the host
carries a configuration. Log event `106_108` records a stored copy the bus accepted but the
framework could not remove. The default path is unchanged; the specification now names its window.
- `IStoreConflictDetector` in `Stratara.Abstractions.EventSourcing`: recognises a database
provider's refusal of a duplicate stream version, so the event source can surface it as a
`ConcurrencyException` on that provider. `AddNpgsqlWriteDbContextFactory<T>()` registers the
PostgreSQL detector and `AddStrataraTestingEventStore<T>()` the SQLite one; detectors accumulate,
so a host on another provider adds its own without displacing the framework's. A host that
registers its write context without `AddNpgsqlWriteDbContextFactory<T>()` gets no detector and
no longer sees a `ConcurrencyException` on a version collision: it switches to that registration,
or registers an `IStoreConflictDetector` of its own that recognises PostgreSQL's SQL state
`23505` in the exception chain (the framework's implementations are not public).
- `MessageRetryOptions` (`Stratara.Abstractions.Messaging`, section `MessageRetry`):
`MaxDeliveryAttempts` (default 3) and `MaxConflictRequeues` (default 100), bound and validated by
`AddMessaging()` and by both `AddAzureServiceBus*` registrations. `MessageRetryPolicy` is the
decision both transports apply. Log event `108_110` and counter `messaging.dead_lettered`
(tags `messaging.topic`, `messaging.subscription`, `reason`) record every dead-lettering; `108_111`
warns when a Service Bus subscription's `MaxDeliveryCount` is below the bounds.
### Changed
- A save now maps and signs its event bundle before the transaction opens, so a save with no
session context — or a signer that fails — fails before anything is committed rather than after
the commit with the events stranded unpublished.
- **RabbitMQ worker subscriptions are quorum queues with a dead-letter queue, under a new name.**
A message whose handler throws is redelivered up to `MaxDeliveryAttempts` times (a concurrency
conflict up to `MaxConflictRequeues` times) and then moved to `<subscription>.dead-letter`; it was
rejected and dropped by the broker before (conflicts were requeued without bound). Because a
classic queue cannot be redeclared as a quorum queue, the worker queue is now
`<subscription>.v2`. **Rollout:** deploy — old and new consumers share the exchange and both
receive every message — then delete the old `<subscription>` queue once it is drained, or it fills
forever. Needs RabbitMQ 3.8+.
- **Azure Service Bus applies the same bounds.** A handler failure is abandoned for redelivery until
`MaxDeliveryAttempts` and then dead-lettered with reason `failure` (it was dead-lettered on the
first failure with the exception type as reason); a conflict is dead-lettered by the framework
past `MaxConflictRequeues` with reason `conflict` (it was left to the broker's `MaxDeliveryCount`).
Set the subscription's `MaxDeliveryCount` at least one above the larger bound.
- `AddAzureServiceBus` and `AddAzureServiceBusWithManagedIdentity` also register a
`ServiceBusAdministrationClient` (try-add) for the advisory limit check.
### Fixed
- The `MediatorCommandWorker` remark said a failing command was dead-lettered; on RabbitMQ it was
dropped. It is now dead-lettered on both brokers, and the remark and the
`BusEnvelopeIntegrityMode.Strict` remark say what happens.
- A duplicate stream version on the SQLite test store (`Stratara.Testing.EntityFrameworkCore`) now
surfaces as `ConcurrencyException`, as it does on PostgreSQL, instead of a bare
`DbUpdateException`. A test that asserted the old exception type needs the new one.