Stratara.Projections
4.0.1
Prefix Reserved
See the version list below for details.
dotnet add package Stratara.Projections --version 4.0.1
NuGet\Install-Package Stratara.Projections -Version 4.0.1
<PackageReference Include="Stratara.Projections" Version="4.0.1" />
<PackageVersion Include="Stratara.Projections" Version="4.0.1" />
<PackageReference Include="Stratara.Projections" />
paket add Stratara.Projections --version 4.0.1
#r "nuget: Stratara.Projections, 4.0.1"
#:package Stratara.Projections@4.0.1
#addin nuget:?package=Stratara.Projections&version=4.0.1
#tool nuget:?package=Stratara.Projections&version=4.0.1
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 (>= 4.0.1)
- Stratara.Domain (>= 4.0.1)
- Stratara.Shared (>= 4.0.1)
NuGet packages (2)
Showing the top 2 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 with pgvector. |
|
|
Stratara.EventSourcing.WorkerDefaults
Worker-host wiring composites for the Stratara event-sourced stack. IHostApplicationBuilder extensions (AddBackendServices, AddCommandWorkerServices, AddHeavyCommandWorkerServices, AddEventProjectionWorkerServices, AddEventStreamHashWorkerServices, AddSagaWorkerServices, AddOutboxWorkerServices) bundle the per-concern DI calls so each worker host opts in with one line. |
GitHub repositories
This package is not used by any popular GitHub repositories.
| Version | Downloads | Last Updated |
|---|---|---|
| 4.0.3 | 46 | 9/3/2026 |
| 4.0.2 | 239 | 9/3/2026 |
| 4.0.1 | 125 | 9/2/2026 |
| 4.0.0 | 161 | 8/31/2026 |
| 4.0.0-preview.1 | 62 | 8/31/2026 |
| 3.4.0 | 155 | 8/28/2026 |
| 3.3.0 | 129 | 8/25/2026 |
| 3.2.3 | 143 | 8/22/2026 |
| 3.2.2 | 143 | 8/14/2026 |
| 3.2.1 | 161 | 8/2/2026 |
| 3.2.0 | 151 | 7/18/2026 |
| 3.1.7 | 364 | 7/1/2026 |
| 3.1.6 | 578 | 6/22/2026 |
| 3.1.5 | 163 | 6/22/2026 |
| 3.1.4 | 177 | 6/15/2026 |
| 3.1.3 | 166 | 6/10/2026 |
| 3.1.2 | 173 | 6/5/2026 |
| 3.1.1 | 239 | 6/1/2026 |
| 3.1.0 | 158 | 5/30/2026 |
| 3.0.23 | 146 | 5/28/2026 |
### Added
- **Bundles about one aggregate are now applied one at a time within a process, a handler can say
"not yet", and the workers' parallelism is configurable.** The projection worker and the saga
worker open one consumer per processor on a shared queue, so two bundles published milliseconds
apart — the fact that creates an entity and the first fact about it — landed on two consumers and
ran at the same time, and whichever finished first won. A projection that then found no row for
the follow-up could only warn and acknowledge a fact it never applied, or throw and have the
bundle discarded; either way the read model lost the fact until a replay. The command worker has
never had this problem, because it takes a per-aggregate lock before it runs a command.
Both workers now take the same lock, keyed on the streams the bundle's events belong to. Bundles
about different aggregates still run in parallel; bundles about one aggregate queue behind each
other. The guarantee is per process — two replicas consuming the same subscription do not
serialise against each other — and the delivery guarantee now says so explicitly.
The lock serialises but does not order, so the residual case gets a second chance:
`PrecedingFactMissingException(streamId, eventTypeName)` in `Stratara.Abstractions` is the one
exception the workers retry — five attempts from 100 ms doubling, about three seconds in all,
under the new named policy `ResilienceNames.PrecedingFact`, with every aggregate lock released
between attempts so the creating fact can land in the gap. Once the retries are exhausted the
bundle fails as any unhandled failure does, and the warning logged on each attempt
(`104_010` for projections, `110_005` for sagas) names the stream and the event type. Any other
exception fails the bundle on the first attempt, as before.
`Projections:DegreeOfParallelism` and `Sagas:DegreeOfParallelism` set the number of consumers each
worker opens; a value that is not a positive number means the processor count, and `1` gives a
worker that applies every bundle in the order the transport delivers it.
A consumer that changes nothing gets the serialisation and the default parallelism it had. A
consumer that implements `IMessageBus` itself is unaffected: the retry runs inside the worker
before the transport sees an outcome. `BucketLockPool`, previously internal to the mediator, is
now public in `Stratara.Abstractions` so that every worker takes the same lock from the same
place; the mediator's own copy is gone.
### Changed
- **A published version now announces itself in the repository.** The release workflow gained a
third job that creates the GitHub release entry for the tag once the packages have reached
nuget.org, with the changelog section for that version as its notes — the same section the
packages already carry as their release notes. A prerelease tag is marked as one, so it does not
displace the current stable version. Until now the release list was maintained by hand and had
fallen behind: 4.0.0 was on nuget.org while the repository still presented 3.4.0 as current.
Nothing about what publishes, when, or on whose approval has changed.