Stratara.Projections 4.0.1

Prefix Reserved
There is a newer version of this package available.
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
                    
This command is intended to be used within the Package Manager Console in Visual Studio, as it uses the NuGet module's version of Install-Package.
<PackageReference Include="Stratara.Projections" Version="4.0.1" />
                    
For projects that support PackageReference, copy this XML node into the project file to reference the package.
<PackageVersion Include="Stratara.Projections" Version="4.0.1" />
                    
Directory.Packages.props
<PackageReference Include="Stratara.Projections" />
                    
Project file
For projects that support Central Package Management (CPM), copy this XML node into the solution Directory.Packages.props file to version the package.
paket add Stratara.Projections --version 4.0.1
                    
#r "nuget: Stratara.Projections, 4.0.1"
                    
#r directive can be used in F# Interactive and Polyglot Notebooks. Copy this into the interactive tool or source code of the script to reference the package.
#:package Stratara.Projections@4.0.1
                    
#:package directive can be used in C# file-based apps starting in .NET 10 preview 4. Copy this into a .cs file before any lines of code to reference the package.
#addin nuget:?package=Stratara.Projections&version=4.0.1
                    
Install as a Cake Addin
#tool nuget:?package=Stratara.Projections&version=4.0.1
                    
Install as a Cake Tool

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 — for EventBundle + IEvent<T>.
  • Stratara.Domain — for the framework's Tenant aggregate (only consumed by TenantProjection).
  • 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 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. 
Compatible target framework(s)
Included target framework(s) (in package)
Learn more about Target Frameworks and .NET Standard.

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.