Snapshot support (as an event)

Directory.Packages.props

@@ -22,7 +22,13 @@
     <TUnitVersion>0.77.3</TUnitVersion>
   </PropertyGroup>
   <ItemGroup>
+    <PackageVersion Include="Aspire.Hosting.MongoDB" Version="13.0.2" />
+    <PackageVersion Include="Aspire.Hosting.PostgreSQL" Version="13.0.2" />
+    <PackageVersion Include="Aspire.Hosting.Redis" Version="13.0.2" />
+    <PackageVersion Include="Aspire.Hosting.SqlServer" Version="13.0.2" />
     <PackageVersion Include="BenchmarkDotNet" Version="0.14.0" />
+    <PackageVersion Include="CommunityToolkit.Aspire.Hosting.KurrentDB" Version="13.0.0" />
+    <PackageVersion Include="CommunityToolkit.Aspire.KurrentDB" Version="13.0.0" />
     <PackageVersion Include="FluentValidation" Version="12.0.0" />
     <PackageVersion Include="KurrentDB.Client" Version="1.2.0" />
     <PackageVersion Include="Microsoft.Extensions.Configuration" Version="$(MicrosoftExtensionsVer)" />

Eventuous.slnx

@@ -114,6 +114,7 @@
     </Folder>
     <Folder Name="/Mongo/" />
     <Folder Name="/Mongo/src/">
+        <Project Path="src/Mongo/src/Eventuous.MongoDB/Eventuous.MongoDB.csproj" />
         <Project Path="src/Mongo/src/Eventuous.Projections.MongoDB/Eventuous.Projections.MongoDB.csproj" />
     </Folder>
     <Folder Name="/Mongo/test/">
@@ -140,6 +141,11 @@
         <Project Path="src/SqlServer/test/Eventuous.Tests.SqlServer/Eventuous.Tests.SqlServer.csproj" />
     </Folder>
     <Folder Name="/Samples/" />
+    <Folder Name="/Samples/Banking/">
+        <Project Path="samples/banking/Banking.Api/Banking.Api.csproj" />
+        <Project Path="samples/banking/Banking.AppHost/Banking.AppHost.csproj" />
+        <Project Path="samples/banking/Banking.Domain/Banking.Domain.csproj" />
+    </Folder>
     <Folder Name="/Samples/Esdb/">
         <Project Path="samples/esdb/Bookings.Domain/Bookings.Domain.csproj" />
         <Project Path="samples/esdb/Bookings.Payments/Bookings.Payments.csproj" />

samples/banking/Banking.Api/Banking.Api.csproj

@@ -0,0 +1,25 @@
+<Project Sdk="Microsoft.NET.Sdk.Web">
+
+  <PropertyGroup>
+    <TargetFramework>net10.0</TargetFramework>
+    <Nullable>enable</Nullable>
+    <ImplicitUsings>enable</ImplicitUsings>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <PackageReference Include="CommunityToolkit.Aspire.KurrentDB" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="$(SrcRoot)\Core\src\Eventuous.Application\Eventuous.Application.csproj" />
+    <ProjectReference Include="$(SrcRoot)\Core\gen\Eventuous.Shared.Generators\Eventuous.Shared.Generators.csproj" OutputItemType="Analyzer" ReferenceOutputAssembly="false" />
+    <ProjectReference Include="$(SrcRoot)\Extensions\src\Eventuous.Extensions.DependencyInjection\Eventuous.Extensions.DependencyInjection.csproj" />
+    <ProjectReference Include="$(SrcRoot)\KurrentDB\src\Eventuous.KurrentDB\Eventuous.KurrentDB.csproj" />
+    <ProjectReference Include="$(SrcRoot)\Postgres\src\Eventuous.Postgresql\Eventuous.Postgresql.csproj" />
+    <ProjectReference Include="$(SrcRoot)\SqlServer\src\Eventuous.SqlServer\Eventuous.SqlServer.csproj" />
+    <ProjectReference Include="$(SrcRoot)\Mongo\src\Eventuous.MongoDB\Eventuous.MongoDB.csproj" />
+    <ProjectReference Include="$(SrcRoot)\Redis\src\Eventuous.Redis\Eventuous.Redis.csproj" />
+    <ProjectReference Include="..\Banking.Domain\Banking.Domain.csproj" />
+  </ItemGroup>
+
+</Project>

samples/banking/Banking.Api/Program.cs

@@ -0,0 +1,65 @@
+using Banking.Api.Services;
+using Banking.Domain.Accounts;
+using Eventuous.KurrentDB;
+using Microsoft.AspNetCore.Mvc;
+
+var builder = WebApplication.CreateBuilder(args);
+
+//----------------------------------------------------------------
+// Snapshot store registration
+
+var postgresSnapshotDbConnectionString = builder.Configuration.GetConnectionString("postgresSnapshotsDb");
+if (postgresSnapshotDbConnectionString == null) {
+    throw new InvalidOperationException("postgres snapshots db conenction string should be not null");
+}
+
+//builder.Services.AddPostgresSnapshotStore(postgresSnapshotDbConnectionString, initializeDatabase: true);
+
+var sqlServerSnapshotsDbConnectionString = builder.Configuration.GetConnectionString("sqlServerSnapshotsDb");
+if (sqlServerSnapshotsDbConnectionString == null) {
+    throw new InvalidOperationException("sqlServer snapshots db connection string should be not null");
+}
+
+//builder.Services.AddSqlServerSnapshotStore(sqlServerSnapshotsDbConnectionString, initializeDatabase: true);
+
+var mongoDbSnapshotsDbConnectionString = builder.Configuration.GetConnectionString("mongoDbSnapshotsDb");
+if (mongoDbSnapshotsDbConnectionString == null) {
+    throw new InvalidOperationException("mongodb snapshots db connection string should be not null");
+}
+
+//builder.Services.AddMongoSnapshotStore(mongoDbSnapshotsDbConnectionString, initializeIndexes: true);
+
+var redisConnectionString = builder.Configuration.GetConnectionString("redis");
+if (redisConnectionString == null) {
+    throw new InvalidOperationException("redis connection string should be not null");
+}
+
+builder.Services.AddRedisSnapshotStore(redisConnectionString, database: 0);
+
+//----------------------------------------------------------------
+// Event store registration
+
+builder.AddKurrentDBClient("kurrentdb");
+builder.Services.AddEventStore<KurrentDBEventStore>();
+
+//----------------------------------------------------------------
+
+builder.Services.AddCommandService<AccountService, AccountState>();
+
+var app = builder.Build();
+
+app.MapGet("/accounts/{id}/deposit/{amount}", async ([FromRoute] string id, [FromRoute] decimal amount, [FromServices] AccountService accountService) => {
+    var cmd = new AccountService.Deposit(id, amount);
+    var res = await accountService.Handle(cmd, default);
+
+    return res.Match<object>(ok => ok, err => err);
+});
+
+app.MapGet("/accounts/{id}/withdraw/{amount}", async ([FromRoute] string id, [FromRoute] decimal amount, [FromServices] AccountService accountService) => {
+    var cmd = new AccountService.Withdraw(id, amount);
+    var res = await accountService.Handle(cmd, default);
+
+    return res.Match<object>(ok => ok, err => err);
+});
+
+app.Run();

samples/banking/Banking.Api/Services/AccountService.cs

@@ -0,0 +1,35 @@
+// Copyright (C) Eventuous HQ OÜ. All rights reserved
+// Licensed under the Apache License, Version 2.0.
+
+using Banking.Domain.Accounts;
+using Eventuous;
+
+namespace Banking.Api.Services;
+
+public class AccountService : CommandService<AccountState> {
+    public record Deposit(string AccountId, decimal Amount);
+    public record Withdraw(string AccountId, decimal Amount);
+
+    public AccountService(IEventStore store, ISnapshotStore snapshotStore) : base(store, snapshotStore: snapshotStore) {
+
+        UseSnapshotStrategy(
+            predicate: (events, _) => events.Count() >= 5,
+            produce: (_, state) => new AccountEvents.V1.Snapshot(state.Balance));
+
+        On<Deposit>()
+            .InState(ExpectedState.Any)
+            .GetStream(cmd => StreamName.ForState<AccountState>(cmd.AccountId))
+            .Act((_, __, cmd) => [new AccountEvents.V1.Deposited(cmd.Amount)]);
+
+        On<Withdraw>()
+            .InState(ExpectedState.Any)
+            .GetStream(cmd => StreamName.ForState<AccountState>(cmd.AccountId))
+            .Act(static (state, __, cmd) => {
+                if (state.Balance < cmd.Amount) {
+                    throw new InvalidOperationException();
+                }
+
+                return [new AccountEvents.V1.Withdrawn(cmd.Amount)];
+            });
+    }
+}

samples/banking/Banking.Api/appsettings.Development.json

@@ -0,0 +1,8 @@
+{
+  "Logging": {
+    "LogLevel": {
+      "Default": "Information",
+      "Microsoft.AspNetCore": "Warning"
+    }
+  }
+}

samples/banking/Banking.Api/appsettings.json

@@ -0,0 +1,9 @@
+{
+  "Logging": {
+    "LogLevel": {
+      "Default": "Information",
+      "Microsoft.AspNetCore": "Warning"
+    }
+  },
+  "AllowedHosts": "*"
+}

samples/banking/Banking.AppHost/AppHost.cs

@@ -0,0 +1,37 @@
+var builder = DistributedApplication.CreateBuilder(args);
+
+var kurrentdb = builder.AddKurrentDB("eventuous-kurrentdb", 2113)
+    .WithEnvironment("EVENTSTORE_ENABLE_ATOM_PUB_OVER_HTTP", "true");
+
+var postgres = builder.AddPostgres("eventuous-postgres")
+    .WithPgWeb();
+
+var postgresSnapshotsDb = postgres.AddDatabase("snapshots");
+
+var sqlServer = builder.AddSqlServer("eventuous-sqlserver");
+var sqlServerSnapshotsDb = sqlServer.AddDatabase("eventuous-sqlserver-snapshotsdb", "snapshots");
+
+var mongodb = builder.AddMongoDB("eventuous-mongodb")
+    .WithMongoExpress();
+
+var mongodbSnapshotsDb = mongodb.AddDatabase("eventuous-mongodb-snapshotsdb", "snapshots");
+
+var redis = builder.AddRedis("eventuous-redis")
+    .WithRedisInsight();
+
+builder
+    .AddProject<Projects.Banking_Api>("banking-api")
+    .WithReference(kurrentdb, "kurrentdb")
+    .WaitFor(kurrentdb)
+    .WithReference(postgresSnapshotsDb, "postgresSnapshotsDb")
+    .WaitFor(postgresSnapshotsDb)
+    .WithReference(sqlServerSnapshotsDb, "sqlServerSnapshotsDb")
+    .WaitFor(sqlServerSnapshotsDb)
+    .WithReference(mongodbSnapshotsDb, "mongoDbSnapshotsDb")
+    .WaitFor(mongodbSnapshotsDb)
+    .WithReference(redis, "redis")
+    .WaitFor(redis);
+
+builder
+    .Build()
+    .Run();

samples/banking/Banking.AppHost/Banking.AppHost.csproj

@@ -0,0 +1,23 @@
+<Project Sdk="Aspire.AppHost.Sdk/13.0.1">
+
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFramework>net10.0</TargetFramework>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
+    <UserSecretsId>3f5f156a-5139-482c-a37e-99163d5f39d7</UserSecretsId>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <PackageReference Include="Aspire.Hosting.MongoDB" />
+    <PackageReference Include="Aspire.Hosting.PostgreSQL" />
+    <PackageReference Include="Aspire.Hosting.Redis" />
+    <PackageReference Include="Aspire.Hosting.SqlServer" />
+    <PackageReference Include="CommunityToolkit.Aspire.Hosting.KurrentDB" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="..\Banking.Api\Banking.Api.csproj" />
+  </ItemGroup>
+
+</Project>

samples/banking/Banking.AppHost/appsettings.Development.json

@@ -0,0 +1,8 @@
+{
+  "Logging": {
+    "LogLevel": {
+      "Default": "Information",
+      "Microsoft.AspNetCore": "Warning"
+    }
+  }
+}

samples/banking/Banking.AppHost/appsettings.json

@@ -0,0 +1,9 @@
+{
+  "Logging": {
+    "LogLevel": {
+      "Default": "Information",
+      "Microsoft.AspNetCore": "Warning",
+      "Aspire.Hosting.Dcp": "Warning"
+    }
+  }
+}

samples/banking/Banking.Domain/Accounts/AccountEvents.cs

@@ -0,0 +1,16 @@
+using Eventuous;
+
+namespace Banking.Domain.Accounts;
+
+public static class AccountEvents {
+    public static class V1 {
+        [EventType("V1.Deposited")]
+        public record Deposited(decimal Amount);
+
+        [EventType("V1.Withdrawn")]
+        public record Withdrawn(decimal Amount);
+
+        [EventType("V1.Snapshot")]
+        public record Snapshot(decimal Balance);
+    }
+}

samples/banking/Banking.Domain/Accounts/AccountState.cs

@@ -0,0 +1,26 @@
+using Eventuous;
+
+namespace Banking.Domain.Accounts;
+
+[Snapshots(typeof(AccountEvents.V1.Snapshot), StorageStrategy = SnapshotStorageStrategy.SeparateStore)]
+public record AccountState : State<AccountState> {
+    public decimal Balance { get; init; }
+
+    public AccountState() {
+        On<AccountEvents.V1.Snapshot>(When);
+        On<AccountEvents.V1.Deposited>(When);
+        On<AccountEvents.V1.Withdrawn>(When);
+    }
+
+    private AccountState When(AccountState state, AccountEvents.V1.Snapshot e) => state with {
+        Balance = e.Balance
+    };
+
+    private AccountState When(AccountState state, AccountEvents.V1.Deposited e) => state with {
+        Balance = state.Balance + e.Amount
+    };
+
+    private AccountState When(AccountState state, AccountEvents.V1.Withdrawn e) => state with {
+        Balance = state.Balance - e.Amount
+    };
+}

samples/banking/Banking.Domain/Banking.Domain.csproj

@@ -0,0 +1,6 @@
+<Project Sdk="Microsoft.NET.Sdk">
+  <ItemGroup>
+    <ProjectReference Include="$(CoreRoot)\Eventuous.Domain\Eventuous.Domain.csproj"/>
+    <ProjectReference Include="$(CoreRoot)\Eventuous.Shared\Eventuous.Shared.csproj"/>
+  </ItemGroup>
+</Project>

samples/banking/README.md

@@ -0,0 +1,13 @@
+### Project description
+
+A small example demonstrating the use of snapshots stored as an event in the aggregate stream
+
+### How to use snapshots?
+
+First, declare the type of event that represents a snapshot of the current state. In this example, see AccountEvents.V1.Snapshot. This name is chosen just for the example; ideally, it should correspond to something from your domain, for example, the closing of a shift
+
+Once we have a declared snapshot type, we need to link it to the state. Note the declaration of the AccountState type - it has the Snapshots attribute applied to it, which is given a list of types that are snapshot events. This attribute helps the EventReader understand that it needs to read the stream in reverse order up to the first encountered snapshot, and not load events prior to the snapshot
+
+You also need to define the logic according to which the snapshot event will occur. Since a snapshot is a regular event, you can create it at any moment during command processing, based on the available data to make the decision. An example can be seen in AccountService - the ApplySnapshot method.
+
+Essentially, this is all you need to start using snapshots (it is assumed that a package with source generators has been added to the project).

src/Core/gen/Eventuous.Shared.Generators/Constants.cs

@@ -5,6 +5,9 @@ namespace Eventuous.Shared.Generators;
 
 internal static class Constants {
     public const string BaseNamespace      = "Eventuous";
+    public const string StateType          = "State";
     public const string EventTypeAttribute = "EventTypeAttribute";
     public const string EventTypeAttrFqcn  = $"{BaseNamespace}.{EventTypeAttribute}";
+    public const string SnapshotsAttribute  = "SnapshotsAttribute";
+    public const string SnapshotsAttrFqcn   = $"{BaseNamespace}.{SnapshotsAttribute}";
 }

src/Core/gen/Eventuous.Shared.Generators/Helpers.cs

@@ -0,0 +1,8 @@
+// Copyright (C) Eventuous HQ OÜ. All rights reserved
+// Licensed under the Apache License, Version 2.0.
+
+namespace Eventuous.Shared.Generators;
+
+internal static class Helpers {
+    public static string MakeGlobal(string typeName) => !typeName.StartsWith("global::") ? $"global::{typeName}" : typeName;
+}