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Shuttle.Recall.SqlServer.EventProcessing

A Sql Server implementation of the Shuttle.Recall event projection processing mechanism.

Installation

dotnet add package Shuttle.Recall.SqlServer.EventProcessing

Configuration

This package processes projections against events already stored via Shuttle.Recall.SqlServer.Storage — it reuses that package's connection, schema, and database-creation settings, so UseSqlServerEventStorage must be configured alongside UseSqlServerEventProcessing:

services
    .AddRecall()
    .UseSqlServerEventStorage(options =>
    {
        options.ConnectionString = "connection-string";
        options.Schema = "dbo";
    })
    .UseSqlServerEventProcessing(options =>
    {
        options.ProjectionPrefetchCount = 100;
    });

SqlServerEventProcessingOptions has the following properties:

Property Default Description
ProjectionPrefetchCount 100 Number of projection events fetched per round-trip
MaximumCacheSize 1000 Maximum number of entries kept in the event-type cache. Values above 100000 are clamped to 100000
CacheDuration 00:01:00 How long cached entries are retained. Values above 01:00:00 are clamped to 01:00:00
ProjectionLockTimeout 00:00:30 Timeout applied when acquiring a projection's processing lock

ConnectionString, Schema, and ConfigureDatabase are not properties of SqlServerEventProcessingOptions — they come from SqlServerStorageOptions (see Shuttle.Recall.SqlServer.Storage) and are shared between both packages.

SqlServerEventProcessingOptions.SectionName is "Shuttle:Recall:SqlServer:EventProcessing", so the equivalent appsettings.json shape (for the properties that belong to this package) is:

{
  "Shuttle": {
    "Recall": {
      "SqlServer": {
        "EventProcessing": {
          "ProjectionPrefetchCount": 100,
          "MaximumCacheSize": 1000,
          "CacheDuration": "00:01:00",
          "ProjectionLockTimeout": "00:00:30"
        },
        "Storage": {
          "ConnectionString": "connection-string",
          "Schema": "dbo",
          "ConfigureDatabase": true
        }
      }
    }
  }
}

Neither package binds these sections automatically — use services.Configure<SqlServerEventProcessingOptions>(configuration.GetSection(SqlServerEventProcessingOptions.SectionName)) (and the equivalent for SqlServerStorageOptions) if you want to configure from appsettings.json.

Database

In order to create the relevant database structures you can use the Shuttle.Recall.SqlServer.EventProcessing.Database console application and provide the connection-string and (optional) schema arguments:

Shuttle.Recall.SqlServer.EventProcessing.Database --connection-string "connection-string" --schema "dbo"

Alternatively, you can let the library create the structures by setting SqlServerStorageOptions.ConfigureDatabase to true (which is the default).

Immediate Consistency

When a projection is configured for immediate consistency (see the Shuttle.Recall documentation's EventProcessingOptions.ImmediateConsistency options), this package tracks each event that a projection has already handled immediately in an ImmediateProjectionEvent table, via IImmediateProjectionEventRepository. This allows the eventual event processor to skip re-invoking that projection's handler for an event it has already handled immediately, while still advancing the projection's checkpoint over it.

This package provides SequentialProjectionEventService, a Sql Server-backed implementation of Shuttle.Recall's IProjectionEventService, which drives retrieval, acknowledgement, and deferral of projection events against the PrimitiveEvent/Projection/ImmediateProjectionEvent tables.