A lot of small fixes.

src/Squidex.Domain.Apps.Entities.MongoDb/Apps/MongoAppRepository.cs

@@ -13,6 +13,7 @@ using System.Threading.Tasks;
 using MongoDB.Driver;
 using Squidex.Domain.Apps.Entities.Apps.Repositories;
 using Squidex.Domain.Apps.Entities.Apps.State;
+using Squidex.Infrastructure;
 using Squidex.Infrastructure.MongoDb;
 using Squidex.Infrastructure.States;
 
@@ -74,15 +75,13 @@ namespace Squidex.Domain.Apps.Entities.MongoDb.Apps
                 return (existing.State, existing.Version);
             }
 
-            return (null, -1);
+            return (null, EtagVersion.NotFound);
         }
 
         public async Task WriteAsync(string key, AppState value, long oldVersion, long newVersion)
         {
             try
             {
-                value.Version = newVersion;
-
                 await Collection.UpdateOneAsync(x => x.Id == key && x.Version == oldVersion,
                     Update
                         .Set(x => x.UserIds, value.Contributors.Keys.ToArray())

src/Squidex.Domain.Apps.Entities.MongoDb/Assets/MongoAssetRepository.cs

@@ -15,6 +15,7 @@ using MongoDB.Driver;
 using Squidex.Domain.Apps.Entities.Assets;
 using Squidex.Domain.Apps.Entities.Assets.Repositories;
 using Squidex.Domain.Apps.Entities.Assets.State;
+using Squidex.Infrastructure;
 using Squidex.Infrastructure.MongoDb;
 using Squidex.Infrastructure.States;
 
@@ -53,7 +54,7 @@ namespace Squidex.Domain.Apps.Entities.MongoDb.Assets
                 return (existing.State, existing.Version);
             }
 
-            return (null, -1);
+            return (null, EtagVersion.NotFound);
         }
 
         public async Task<IReadOnlyList<IAssetEntity>> QueryAsync(Guid appId, HashSet<string> mimeTypes = null, HashSet<Guid> ids = null, string query = null, int take = 10, int skip = 0)
@@ -116,8 +117,6 @@ namespace Squidex.Domain.Apps.Entities.MongoDb.Assets
         {
             try
             {
-                value.Version = newVersion;
-
                 await Collection.UpdateOneAsync(x => x.Id == key && x.Version == oldVersion,
                     Update
                         .Set(x => x.State, value)

src/Squidex.Domain.Apps.Entities.MongoDb/Contents/MongoContentRepository.cs

@@ -89,8 +89,6 @@ namespace Squidex.Domain.Apps.Entities.MongoDb.Contents
 
             try
             {
-                value.Version = newVersion;
-
                 await Collection.InsertOneAsync(document);
             }
             catch (MongoWriteException ex)
@@ -126,7 +124,7 @@ namespace Squidex.Domain.Apps.Entities.MongoDb.Contents
                 return (SimpleMapper.Map(existing, new ContentState()), existing.Version);
             }
 
-            return (null, -1);
+            return (null, EtagVersion.NotFound);
         }
 
         public async Task<IReadOnlyList<IContentEntity>> QueryAsync(IAppEntity app, ISchemaEntity schema, Status[] status, ODataUriParser odataQuery)

src/Squidex.Domain.Apps.Entities.MongoDb/Rules/MongoRuleRepository.cs

@@ -13,6 +13,7 @@ using System.Threading.Tasks;
 using MongoDB.Driver;
 using Squidex.Domain.Apps.Entities.Rules.Repositories;
 using Squidex.Domain.Apps.Entities.Rules.State;
+using Squidex.Infrastructure;
 using Squidex.Infrastructure.MongoDb;
 using Squidex.Infrastructure.States;
 
@@ -47,7 +48,7 @@ namespace Squidex.Domain.Apps.Entities.MongoDb.Rules
                 return (existing.State, existing.Version);
             }
 
-            return (null, -1);
+            return (null, EtagVersion.NotFound);
         }
 
         public async Task<IReadOnlyList<Guid>> QueryRuleIdsAsync(Guid appId)
@@ -63,8 +64,6 @@ namespace Squidex.Domain.Apps.Entities.MongoDb.Rules
         {
             try
             {
-                value.Version = newVersion;
-
                 await Collection.UpdateOneAsync(x => x.Id == key && x.Version == oldVersion,
                     Update
                         .Set(x => x.State, value)

src/Squidex.Domain.Apps.Entities.MongoDb/Schemas/MongoSchemaRepository.cs

@@ -13,6 +13,7 @@ using System.Threading.Tasks;
 using MongoDB.Driver;
 using Squidex.Domain.Apps.Entities.Schemas.Repositories;
 using Squidex.Domain.Apps.Entities.Schemas.State;
+using Squidex.Infrastructure;
 using Squidex.Infrastructure.MongoDb;
 using Squidex.Infrastructure.States;
 
@@ -47,7 +48,7 @@ namespace Squidex.Domain.Apps.Entities.MongoDb.Schemas
                 return (existing.State, existing.Version);
             }
 
-            return (null, -1);
+            return (null, EtagVersion.NotFound);
         }
 
         public async Task<Guid> FindSchemaIdAsync(Guid appId, string name)
@@ -62,7 +63,7 @@ namespace Squidex.Domain.Apps.Entities.MongoDb.Schemas
         public async Task<IReadOnlyList<Guid>> QuerySchemaIdsAsync(Guid appId)
         {
             var schemaEntities =
-                await Collection.Find(x => x.State.AppId == appId).Only(x => x.Id)
+                await Collection.Find(x => x.AppId == appId).Only(x => x.Id)
                     .ToListAsync();
 
             return schemaEntities.Select(x => Guid.Parse(x["_id"].AsString)).ToList();
@@ -72,8 +73,6 @@ namespace Squidex.Domain.Apps.Entities.MongoDb.Schemas
         {
             try
             {
-                value.Version = newVersion;
-
                 await Collection.UpdateOneAsync(x => x.Id == key && x.Version == oldVersion,
                     Update
                         .Set(x => x.State, value)

src/Squidex.Domain.Apps.Entities/Apps/AppCommandMiddleware.cs

@@ -60,7 +60,7 @@ namespace Squidex.Domain.Apps.Entities.Apps
 
         protected Task On(AssignContributor command, CommandContext context)
         {
-            return handler.handler.UpdateSyncedAsync<AppDomainObject>(context, async a =>
+            return handler.UpdateSyncedAsync<AppDomainObject>(context, async a =>
             {
                 await GuardAppContributors.CanAssign(a.State.Contributors, command, userResolver, appPlansProvider.GetPlan(a.State.Plan?.PlanId));
 
@@ -70,7 +70,7 @@ namespace Squidex.Domain.Apps.Entities.Apps
 
         protected Task On(RemoveContributor command, CommandContext context)
         {
-            return handler.handler.UpdateSyncedAsync<AppDomainObject>(context, a =>
+            return handler.UpdateSyncedAsync<AppDomainObject>(context, a =>
             {
                 GuardAppContributors.CanRemove(a.State.Contributors, command);
 
@@ -80,7 +80,7 @@ namespace Squidex.Domain.Apps.Entities.Apps
 
         protected Task On(AttachClient command, CommandContext context)
         {
-            return handler.handler.UpdateSyncedAsync<AppDomainObject>(context, a =>
+            return handler.UpdateSyncedAsync<AppDomainObject>(context, a =>
             {
                 GuardAppClients.CanAttach(a.State.Clients, command);
 
@@ -90,7 +90,7 @@ namespace Squidex.Domain.Apps.Entities.Apps
 
         protected Task On(UpdateClient command, CommandContext context)
         {
-            return handler.handler.UpdateSyncedAsync<AppDomainObject>(context, a =>
+            return handler.UpdateSyncedAsync<AppDomainObject>(context, a =>
             {
                 GuardAppClients.CanUpdate(a.State.Clients, command);
 
@@ -100,7 +100,7 @@ namespace Squidex.Domain.Apps.Entities.Apps
 
         protected Task On(RevokeClient command, CommandContext context)
         {
-            return handler.handler.UpdateSyncedAsync<AppDomainObject>(context, a =>
+            return handler.UpdateSyncedAsync<AppDomainObject>(context, a =>
             {
                 GuardAppClients.CanRevoke(a.State.Clients, command);
 
@@ -110,7 +110,7 @@ namespace Squidex.Domain.Apps.Entities.Apps
 
         protected Task On(AddLanguage command, CommandContext context)
         {
-            return handler.handler.UpdateSyncedAsync<AppDomainObject>(context, a =>
+            return handler.UpdateSyncedAsync<AppDomainObject>(context, a =>
             {
                 GuardAppLanguages.CanAdd(a.State.LanguagesConfig, command);
 
@@ -120,7 +120,7 @@ namespace Squidex.Domain.Apps.Entities.Apps
 
         protected Task On(RemoveLanguage command, CommandContext context)
         {
-            return handler.handler.UpdateSyncedAsync<AppDomainObject>(context, a =>
+            return handler.UpdateSyncedAsync<AppDomainObject>(context, a =>
             {
                 GuardAppLanguages.CanRemove(a.State.LanguagesConfig, command);
 
@@ -130,7 +130,7 @@ namespace Squidex.Domain.Apps.Entities.Apps
 
         protected Task On(UpdateLanguage command, CommandContext context)
         {
-            return handler.handler.UpdateSyncedAsync<AppDomainObject>(context, a =>
+            return handler.UpdateSyncedAsync<AppDomainObject>(context, a =>
             {
                 GuardAppLanguages.CanUpdate(a.State.LanguagesConfig, command);
 
@@ -140,7 +140,7 @@ namespace Squidex.Domain.Apps.Entities.Apps
 
         protected Task On(ChangePlan command, CommandContext context)
         {
-            return handler.handler.UpdateSyncedAsync<AppDomainObject>(context, async a =>
+            return handler.UpdateSyncedAsync<AppDomainObject>(context, async a =>
             {
                 GuardApp.CanChangePlan(command, a.State.Plan, appPlansProvider);
 

src/Squidex.Domain.Apps.Entities/Assets/AssetCommandMiddleware.cs

@@ -67,7 +67,7 @@ namespace Squidex.Domain.Apps.Entities.Assets
 
             try
             {
-                var asset = await handler.handler.UpdateSyncedAsync<AssetDomainObject>(context, async a =>
+                var asset = await handler.UpdateSyncedAsync<AssetDomainObject>(context, async a =>
                 {
                     GuardAsset.CanUpdate(command);
 
@@ -88,7 +88,7 @@ namespace Squidex.Domain.Apps.Entities.Assets
 
         protected Task On(RenameAsset command, CommandContext context)
         {
-            return handler.handler.UpdateSyncedAsync<AssetDomainObject>(context, a =>
+            return handler.UpdateSyncedAsync<AssetDomainObject>(context, a =>
             {
                 GuardAsset.CanRename(command, a.State.FileName);
 
@@ -98,7 +98,7 @@ namespace Squidex.Domain.Apps.Entities.Assets
 
         protected Task On(DeleteAsset command, CommandContext context)
         {
-            return handler.handler.UpdateSyncedAsync<AssetDomainObject>(context, a =>
+            return handler.UpdateSyncedAsync<AssetDomainObject>(context, a =>
             {
                 GuardAsset.CanDelete(command);
 

src/Squidex.Domain.Apps.Entities/Contents/ContentQueryService.cs

@@ -61,7 +61,7 @@ namespace Squidex.Domain.Apps.Entities.Contents
             var schema = await FindSchemaAsync(app, schemaIdOrName);
 
             var content =
-                version > 0 ?
+                version > EtagVersion.Empty ?
                 await contentRepository.FindContentAsync(app, schema, id, version) :
                 await contentRepository.FindContentAsync(app, schema, id);
 

src/Squidex.Domain.Apps.Entities/Contents/IContentQueryService.cs

@@ -12,6 +12,7 @@ using System.Security.Claims;
 using System.Threading.Tasks;
 using Squidex.Domain.Apps.Entities.Apps;
 using Squidex.Domain.Apps.Entities.Schemas;
+using Squidex.Infrastructure;
 
 namespace Squidex.Domain.Apps.Entities.Contents
 {
@@ -21,7 +22,7 @@ namespace Squidex.Domain.Apps.Entities.Contents
 
         Task<(ISchemaEntity Schema, long Total, IReadOnlyList<IContentEntity> Items)> QueryWithCountAsync(IAppEntity app, string schemaIdOrName, ClaimsPrincipal user, bool archived, string query);
 
-        Task<(ISchemaEntity Schema, IContentEntity Content)> FindContentAsync(IAppEntity app, string schemaIdOrName, ClaimsPrincipal user, Guid id, long version = -1);
+        Task<(ISchemaEntity Schema, IContentEntity Content)> FindContentAsync(IAppEntity app, string schemaIdOrName, ClaimsPrincipal user, Guid id, long version = EtagVersion.Any);
 
         Task<ISchemaEntity> FindSchemaAsync(IAppEntity app, string schemaIdOrName);
     }

src/Squidex.Domain.Apps.Entities/DomainObjectState.cs

@@ -10,10 +10,12 @@ using System;
 using Newtonsoft.Json;
 using NodaTime;
 using Squidex.Infrastructure;
+using Squidex.Infrastructure.Commands;
 
 namespace Squidex.Domain.Apps.Entities
 {
     public abstract class DomainObjectState<T> : Cloneable<T>,
+        IDomainState,
         IEntity,
         IEntityWithCreatedBy,
         IEntityWithLastModifiedBy,

src/Squidex.Domain.Apps.Entities/EntityMapper.cs

@@ -23,6 +23,7 @@ namespace Squidex.Domain.Apps.Entities
             SetCreatedBy(entity, @event);
             SetLastModified(entity, headers);
             SetLastModifiedBy(entity, @event);
+            SetVersion(entity, headers);
 
             updater?.Invoke(entity);
 
@@ -31,12 +32,20 @@ namespace Squidex.Domain.Apps.Entities
 
         private static void SetId(IEntity entity, EnvelopeHeaders headers)
         {
-            if (entity is IUpdateableEntity updateable)
+            if (entity is IUpdateableEntity updateable && updateable.Id == Guid.Empty)
             {
                 updateable.Id = headers.AggregateId();
             }
         }
 
+        private static void SetVersion(IEntity entity, EnvelopeHeaders headers)
+        {
+            if (entity is IUpdateableEntityWithVersion updateable)
+            {
+                updateable.Version = headers.EventStreamNumber();
+            }
+        }
+
         private static void SetCreated(IEntity entity, EnvelopeHeaders headers)
         {
             if (entity is IUpdateableEntity updateable && updateable.Created == default(Instant))

src/Squidex.Infrastructure/EventSourcing/ExpectedVersion.cs → src/Squidex.Domain.Apps.Entities/IUpdateableEntityWithVersion.cs

@@ -1,17 +1,15 @@
 // ==========================================================================
-//  ExpectedVersion.cs
+//  IUpdateableEntityWithVersion.cs
 //  Squidex Headless CMS
 // ==========================================================================
 //  Copyright (c) Squidex Group
 //  All rights reserved.
 // ==========================================================================
 
-namespace Squidex.Infrastructure.EventSourcing
+namespace Squidex.Domain.Apps.Entities
 {
-    public static class ExpectedVersion
+    public interface IUpdateableEntityWithVersion
     {
-        public const int Any = -2;
-
-        public const int Empty = -1;
+        long Version { get; set; }
     }
 }

src/Squidex.Domain.Apps.Entities/Rules/RuleCommandMiddleware.cs

@@ -43,7 +43,7 @@ namespace Squidex.Domain.Apps.Entities.Rules
 
         protected Task On(UpdateRule command, CommandContext context)
         {
-            return handler.handler.UpdateSyncedAsync<RuleDomainObject>(context, async c =>
+            return handler.UpdateSyncedAsync<RuleDomainObject>(context, async c =>
             {
                 await GuardRule.CanUpdate(command, appProvider);
 
@@ -53,7 +53,7 @@ namespace Squidex.Domain.Apps.Entities.Rules
 
         protected Task On(EnableRule command, CommandContext context)
         {
-            return handler.handler.UpdateSyncedAsync<RuleDomainObject>(context, r =>
+            return handler.UpdateSyncedAsync<RuleDomainObject>(context, r =>
             {
                 GuardRule.CanEnable(command, r.State.RuleDef);
 
@@ -63,7 +63,7 @@ namespace Squidex.Domain.Apps.Entities.Rules
 
         protected Task On(DisableRule command, CommandContext context)
         {
-            return handler.handler.UpdateSyncedAsync<RuleDomainObject>(context, r =>
+            return handler.UpdateSyncedAsync<RuleDomainObject>(context, r =>
             {
                 GuardRule.CanDisable(command, r.State.RuleDef);
 
@@ -73,7 +73,7 @@ namespace Squidex.Domain.Apps.Entities.Rules
 
         protected Task On(DeleteRule command, CommandContext context)
         {
-            return handler.handler.UpdateSyncedAsync<RuleDomainObject>(context, c =>
+            return handler.UpdateSyncedAsync<RuleDomainObject>(context, c =>
             {
                 GuardRule.CanDelete(command);
 

src/Squidex.Domain.Apps.Entities/Schemas/SchemaCommandMiddleware.cs

@@ -47,7 +47,7 @@ namespace Squidex.Domain.Apps.Entities.State.SchemaDefs
 
         protected Task On(AddField command, CommandContext context)
         {
-            return handler.handler.UpdateSyncedAsync<SchemaDomainObject>(context, s =>
+            return handler.UpdateSyncedAsync<SchemaDomainObject>(context, s =>
             {
                 GuardSchemaField.CanAdd(s.State.SchemaDef, command);
 
@@ -59,7 +59,7 @@ namespace Squidex.Domain.Apps.Entities.State.SchemaDefs
 
         protected Task On(DeleteField command, CommandContext context)
         {
-            return handler.handler.UpdateSyncedAsync<SchemaDomainObject>(context, s =>
+            return handler.UpdateSyncedAsync<SchemaDomainObject>(context, s =>
             {
                 GuardSchemaField.CanDelete(s.State.SchemaDef, command);
 
@@ -69,7 +69,7 @@ namespace Squidex.Domain.Apps.Entities.State.SchemaDefs
 
         protected Task On(LockField command, CommandContext context)
         {
-            return handler.handler.UpdateSyncedAsync<SchemaDomainObject>(context, s =>
+            return handler.UpdateSyncedAsync<SchemaDomainObject>(context, s =>
             {
                 GuardSchemaField.CanLock(s.State.SchemaDef, command);
 
@@ -79,7 +79,7 @@ namespace Squidex.Domain.Apps.Entities.State.SchemaDefs
 
         protected Task On(HideField command, CommandContext context)
         {
-            return handler.handler.UpdateSyncedAsync<SchemaDomainObject>(context, s =>
+            return handler.UpdateSyncedAsync<SchemaDomainObject>(context, s =>
             {
                 GuardSchemaField.CanHide(s.State.SchemaDef, command);
 
@@ -89,7 +89,7 @@ namespace Squidex.Domain.Apps.Entities.State.SchemaDefs
 
         protected Task On(ShowField command, CommandContext context)
         {
-            return handler.handler.UpdateSyncedAsync<SchemaDomainObject>(context, s =>
+            return handler.UpdateSyncedAsync<SchemaDomainObject>(context, s =>
             {
                 GuardSchemaField.CanShow(s.State.SchemaDef, command);
 
@@ -99,7 +99,7 @@ namespace Squidex.Domain.Apps.Entities.State.SchemaDefs
 
         protected Task On(DisableField command, CommandContext context)
         {
-            return handler.handler.UpdateSyncedAsync<SchemaDomainObject>(context, s =>
+            return handler.UpdateSyncedAsync<SchemaDomainObject>(context, s =>
             {
                 GuardSchemaField.CanDisable(s.State.SchemaDef, command);
 
@@ -109,7 +109,7 @@ namespace Squidex.Domain.Apps.Entities.State.SchemaDefs
 
         protected Task On(EnableField command, CommandContext context)
         {
-            return handler.handler.UpdateSyncedAsync<SchemaDomainObject>(context, s =>
+            return handler.UpdateSyncedAsync<SchemaDomainObject>(context, s =>
             {
                 GuardSchemaField.CanEnable(s.State.SchemaDef, command);
 
@@ -119,7 +119,7 @@ namespace Squidex.Domain.Apps.Entities.State.SchemaDefs
 
         protected Task On(UpdateField command, CommandContext context)
         {
-            return handler.handler.UpdateSyncedAsync<SchemaDomainObject>(context, s =>
+            return handler.UpdateSyncedAsync<SchemaDomainObject>(context, s =>
             {
                 GuardSchemaField.CanUpdate(s.State.SchemaDef, command);
 
@@ -129,7 +129,7 @@ namespace Squidex.Domain.Apps.Entities.State.SchemaDefs
 
         protected Task On(ReorderFields command, CommandContext context)
         {
-            return handler.handler.UpdateSyncedAsync<SchemaDomainObject>(context, s =>
+            return handler.UpdateSyncedAsync<SchemaDomainObject>(context, s =>
             {
                 GuardSchema.CanReorder(s.State.SchemaDef, command);
 
@@ -139,7 +139,7 @@ namespace Squidex.Domain.Apps.Entities.State.SchemaDefs
 
         protected Task On(UpdateSchema command, CommandContext context)
         {
-            return handler.handler.UpdateSyncedAsync<SchemaDomainObject>(context, s =>
+            return handler.UpdateSyncedAsync<SchemaDomainObject>(context, s =>
             {
                 GuardSchema.CanUpdate(s.State.SchemaDef, command);
 
@@ -149,7 +149,7 @@ namespace Squidex.Domain.Apps.Entities.State.SchemaDefs
 
         protected Task On(PublishSchema command, CommandContext context)
         {
-            return handler.handler.UpdateSyncedAsync<SchemaDomainObject>(context, s =>
+            return handler.UpdateSyncedAsync<SchemaDomainObject>(context, s =>
             {
                 GuardSchema.CanPublish(s.State.SchemaDef, command);
 
@@ -159,7 +159,7 @@ namespace Squidex.Domain.Apps.Entities.State.SchemaDefs
 
         protected Task On(UnpublishSchema command, CommandContext context)
         {
-            return handler.handler.UpdateSyncedAsync<SchemaDomainObject>(context, s =>
+            return handler.UpdateSyncedAsync<SchemaDomainObject>(context, s =>
             {
                 GuardSchema.CanUnpublish(s.State.SchemaDef, command);
 
@@ -169,7 +169,7 @@ namespace Squidex.Domain.Apps.Entities.State.SchemaDefs
 
         protected Task On(ConfigureScripts command, CommandContext context)
         {
-            return handler.handler.UpdateSyncedAsync<SchemaDomainObject>(context, s =>
+            return handler.UpdateSyncedAsync<SchemaDomainObject>(context, s =>
             {
                 GuardSchema.CanConfigureScripts(s.State.SchemaDef, command);
 
@@ -179,7 +179,7 @@ namespace Squidex.Domain.Apps.Entities.State.SchemaDefs
 
         protected Task On(DeleteSchema command, CommandContext context)
         {
-            return handler.handler.UpdateSyncedAsync<SchemaDomainObject>(context, s =>
+            return handler.UpdateSyncedAsync<SchemaDomainObject>(context, s =>
             {
                 GuardSchema.CanDelete(s.State.SchemaDef, command);
 

src/Squidex.Domain.Apps.Entities/SquidexCommand.cs

@@ -15,6 +15,6 @@ namespace Squidex.Domain.Apps.Entities
     {
         public RefToken Actor { get; set; }
 
-        public long? ExpectedVersion { get; set; }
+        public long ExpectedVersion { get; set; }
     }
 }

src/Squidex.Infrastructure.GetEventStore/EventSourcing/Events/GetEventStore.cs

@@ -89,7 +89,7 @@ namespace Squidex.Infrastructure.EventSourcing
 
         public Task AppendEventsAsync(Guid commitId, string streamName, ICollection<EventData> events)
         {
-            return AppendEventsInternalAsync(streamName, ExpectedVersion.Any, events);
+            return AppendEventsInternalAsync(streamName, EtagVersion.Any, events);
         }
 
         public Task AppendEventsAsync(Guid commitId, string streamName, long expectedVersion, ICollection<EventData> events)

src/Squidex.Infrastructure.MongoDb/EventSourcing/MongoEventStore.cs

@@ -129,12 +129,12 @@ namespace Squidex.Infrastructure.EventSourcing
 
         public Task AppendEventsAsync(Guid commitId, string streamName, ICollection<EventData> events)
         {
-            return AppendEventsInternalAsync(commitId, streamName, ExpectedVersion.Any, events);
+            return AppendEventsInternalAsync(commitId, streamName, EtagVersion.Any, events);
         }
 
         public Task AppendEventsAsync(Guid commitId, string streamName, long expectedVersion, ICollection<EventData> events)
         {
-            Guard.GreaterEquals(expectedVersion, -1, nameof(expectedVersion));
+            Guard.GreaterEquals(expectedVersion, EtagVersion.Any, nameof(expectedVersion));
 
             return AppendEventsInternalAsync(commitId, streamName, expectedVersion, events);
         }
@@ -151,7 +151,7 @@ namespace Squidex.Infrastructure.EventSourcing
 
             var currentVersion = await GetEventStreamOffset(streamName);
 
-            if (expectedVersion != ExpectedVersion.Any && expectedVersion != currentVersion)
+            if (expectedVersion != EtagVersion.Any && expectedVersion != currentVersion)
             {
                 throw new WrongEventVersionException(currentVersion, expectedVersion);
             }
@@ -174,7 +174,7 @@ namespace Squidex.Infrastructure.EventSourcing
                     {
                         currentVersion = await GetEventStreamOffset(streamName);
 
-                        if (expectedVersion != ExpectedVersion.Any)
+                        if (expectedVersion != EtagVersion.Any)
                         {
                             throw new WrongEventVersionException(currentVersion, expectedVersion);
                         }
@@ -210,7 +210,7 @@ namespace Squidex.Infrastructure.EventSourcing
                 return document[nameof(MongoEventCommit.EventStreamOffset)].ToInt64() + document[nameof(MongoEventCommit.EventsCount)].ToInt64();
             }
 
-            return -1;
+            return EtagVersion.Empty;
         }
 
         private static FilterDefinition<MongoEventCommit> CreateFilter(string streamFilter, StreamPosition streamPosition)

src/Squidex.Infrastructure.MongoDb/States/MongoSnapshotStore.cs

@@ -41,7 +41,7 @@ namespace Squidex.Infrastructure.States
                 return (existing.Doc, existing.Version);
             }
 
-            return (default(T), -1);
+            return (default(T), EtagVersion.NotFound);
         }
 
         public async Task WriteAsync(string key, T value, long oldVersion, long newVersion)

src/Squidex.Infrastructure/Commands/AggregateHandler.cs

@@ -65,10 +65,15 @@ namespace Squidex.Infrastructure.Commands
         {
             Guard.NotNull(context, nameof(context));
 
-            var domainObjectCommand = GetCommand(context);
-            var domainObjectId = domainObjectCommand.AggregateId;
+            var domainCommand = GetCommand(context);
+            var domainObjectId = domainCommand.AggregateId;
             var domainObject = await stateFactory.CreateAsync<T>(domainObjectId.ToString());
 
+            if (domainCommand.ExpectedVersion != EtagVersion.Any && domainCommand.ExpectedVersion != domainObject.Version)
+            {
+                throw new DomainObjectVersionException(domainObjectId.ToString(), typeof(T), domainObject.Version, domainCommand.ExpectedVersion);
+            }
+
             await handler(domainObject);
 
             await domainObject.WriteAsync(log);
@@ -92,13 +97,18 @@ namespace Squidex.Infrastructure.Commands
         {
             Guard.NotNull(context, nameof(context));
 
-            var domainObjectCommand = GetCommand(context);
-            var domainObjectId = domainObjectCommand.AggregateId;
+            var domainCommand = GetCommand(context);
+            var domainObjectId = domainCommand.AggregateId;
 
             using (await lockPool.LockAsync(Tuple.Create(typeof(T), domainObjectId)))
             {
                 var domainObject = await stateFactory.GetSingleAsync<T>(domainObjectId.ToString());
 
+                if (domainCommand.ExpectedVersion != EtagVersion.Any && domainCommand.ExpectedVersion != domainObject.Version)
+                {
+                    throw new DomainObjectVersionException(domainObjectId.ToString(), typeof(T), domainObject.Version, domainCommand.ExpectedVersion);
+                }
+
                 await handler(domainObject);
 
                 await domainObject.WriteAsync(log);

src/Squidex.Infrastructure/Commands/DomainObjectBase.cs

@@ -15,16 +15,16 @@ using Squidex.Infrastructure.States;
 
 namespace Squidex.Infrastructure.Commands
 {
-    public abstract class DomainObjectBase<TBase, TState> : IDomainObject where TState : new()
+    public abstract class DomainObjectBase<TBase, TState> : IDomainObject where TState : IDomainState, new()
     {
         private readonly List<Envelope<IEvent>> uncomittedEvents = new List<Envelope<IEvent>>();
         private Guid id;
-        private TState state = new TState();
+        private TState state;
         private IPersistence<TState> persistence;
 
         public long Version
         {
-            get { return persistence?.Version ?? -1; }
+            get { return state.Version; }
         }
 
         public TState State
@@ -32,6 +32,12 @@ namespace Squidex.Infrastructure.Commands
             get { return state; }
         }
 
+        protected DomainObjectBase()
+        {
+            state = new TState();
+            state.Version = EtagVersion.Empty;
+        }
+
         public IReadOnlyList<Envelope<IEvent>> GetUncomittedEvents()
         {
             return uncomittedEvents;
@@ -78,19 +84,26 @@ namespace Squidex.Infrastructure.Commands
 
         public async Task WriteAsync(ISemanticLog log)
         {
-            await persistence.WriteSnapshotAsync(state);
+            var events = uncomittedEvents;
 
-            try
-            {
-                await persistence.WriteEventsAsync(uncomittedEvents.ToArray());
-            }
-            catch (Exception ex)
-            {
-                log.LogFatal(ex, w => w.WriteProperty("action", "writeEvents"));
-            }
-            finally
+            if (events.Count > 0)
             {
-                uncomittedEvents.Clear();
+                state.Version += events.Count;
+
+                await persistence.WriteSnapshotAsync(state);
+
+                try
+                {
+                    await persistence.WriteEventsAsync(uncomittedEvents.ToArray());
+                }
+                catch (Exception ex)
+                {
+                    log.LogFatal(ex, w => w.WriteProperty("action", "writeEvents"));
+                }
+                finally
+                {
+                    uncomittedEvents.Clear();
+                }
             }
         }
     }

src/Squidex.Infrastructure/Commands/ICommand.cs

@@ -10,6 +10,6 @@ namespace Squidex.Infrastructure.Commands
 {
     public interface ICommand
     {
-        long? ExpectedVersion { get; set; }
+        long ExpectedVersion { get; set; }
     }
 }

src/Squidex.Infrastructure/Commands/IDomainState.cs

@@ -0,0 +1,15 @@
+// ==========================================================================
+//  IDomainState.cs
+//  Squidex Headless CMS
+// ==========================================================================
+//  Copyright (c) Squidex Group
+//  All rights reserved.
+// ==========================================================================
+
+namespace Squidex.Infrastructure.Commands
+{
+    public interface IDomainState
+    {
+        long Version { get; set; }
+    }
+}

src/Squidex.Infrastructure/EtagVersion.cs

@@ -0,0 +1,19 @@
+// ==========================================================================
+//  EtagVersion.cs
+//  Squidex Headless CMS
+// ==========================================================================
+//  Copyright (c) Squidex Group
+//  All rights reserved.
+// ==========================================================================
+
+namespace Squidex.Infrastructure
+{
+    public static class EtagVersion
+    {
+        public const long Any = -2;
+
+        public const long Empty = -1;
+
+        public const long NotFound = long.MinValue;
+    }
+}

src/Squidex.Infrastructure/EventSourcing/CommonHeaders.cs

@@ -20,6 +20,8 @@ namespace Squidex.Infrastructure.EventSourcing
 
         public static readonly string EventStreamNumber = "EventStreamNumber";
 
+        public static readonly string SnapshotVersion = "SnapshotVersion";
+
         public static readonly string Timestamp = "Timestamp";
 
         public static readonly string Actor = "Actor";

src/Squidex.Infrastructure/EventSourcing/EnvelopeExtensions.cs

@@ -26,9 +26,21 @@ namespace Squidex.Infrastructure.EventSourcing
             return envelope;
         }
 
+        public static long SnapshotVersion(this EnvelopeHeaders headers)
+        {
+            return headers[CommonHeaders.SnapshotVersion].ToInt64(CultureInfo.InvariantCulture);
+        }
+
+        public static Envelope<T> SetSnapshotVersion<T>(this Envelope<T> envelope, long value) where T : class
+        {
+            envelope.Headers.Set(CommonHeaders.SnapshotVersion, value);
+
+            return envelope;
+        }
+
         public static long EventStreamNumber(this EnvelopeHeaders headers)
         {
-            return headers[CommonHeaders.EventStreamNumber].ToInt32(CultureInfo.InvariantCulture);
+            return headers[CommonHeaders.EventStreamNumber].ToInt64(CultureInfo.InvariantCulture);
         }
 
         public static Envelope<T> SetEventStreamNumber<T>(this Envelope<T> envelope, long value) where T : class

src/Squidex.Infrastructure/States/IPersistence.cs

@@ -20,6 +20,6 @@ namespace Squidex.Infrastructure.States
 
         Task WriteSnapshotAsync(TState state);
 
-        Task ReadAsync(long expectedVersion = ExpectedVersion.Any);
+        Task ReadAsync(long expectedVersion = EtagVersion.Any);
     }
 }

src/Squidex.Infrastructure/States/Persistence.cs

@@ -12,6 +12,8 @@ using System.Linq;
 using System.Threading.Tasks;
 using Squidex.Infrastructure.EventSourcing;
 
+#pragma warning disable RECS0012 // 'if' statement can be re-written as 'switch' statement
+
 namespace Squidex.Infrastructure.States
 {
     internal sealed class Persistence<TOwner, TState> : IPersistence<TState>
@@ -25,8 +27,8 @@ namespace Squidex.Infrastructure.States
         private readonly Action invalidate;
         private readonly Func<TState, Task> applyState;
         private readonly Func<Envelope<IEvent>, Task> applyEvent;
-        private long versionSnapshot = -1;
-        private long versionEvents = -1;
+        private long versionSnapshot = EtagVersion.Empty;
+        private long versionEvents = EtagVersion.Empty;
         private long version;
 
         public long Version
@@ -55,19 +57,19 @@ namespace Squidex.Infrastructure.States
             this.streamNameResolver = streamNameResolver;
         }
 
-        public async Task ReadAsync(long expectedVersion = ExpectedVersion.Any)
+        public async Task ReadAsync(long expectedVersion = EtagVersion.Any)
         {
-            versionSnapshot = -1;
-            versionEvents = -1;
+            versionSnapshot = EtagVersion.Empty;
+            versionEvents = EtagVersion.Empty;
 
             await ReadSnapshotAsync();
             await ReadEventsAsync();
 
             UpdateVersion();
 
-            if (expectedVersion != ExpectedVersion.Any && expectedVersion != version)
+            if (expectedVersion != EtagVersion.Any && expectedVersion != version)
             {
-                if (version == ExpectedVersion.Empty)
+                if (version == EtagVersion.Empty)
                 {
                     throw new DomainObjectNotFoundException(ownerKey, typeof(TOwner));
                 }
@@ -84,6 +86,11 @@ namespace Squidex.Infrastructure.States
             {
                 var (state, position) = await snapshotStore.ReadAsync(ownerKey);
 
+                if (position < EtagVersion.Empty)
+                {
+                    position = EtagVersion.Empty;
+                }
+
                 versionSnapshot = position;
                 versionEvents = position;
 
@@ -150,7 +157,7 @@ namespace Squidex.Infrastructure.States
 
             if (eventArray.Length > 0)
             {
-                var expectedVersion = UseEventSourcing() ? version : ExpectedVersion.Any;
+                var expectedVersion = UseEventSourcing() ? version : EtagVersion.Any;
 
                 var commitId = Guid.NewGuid();
 
@@ -159,7 +166,7 @@ namespace Squidex.Infrastructure.States
 
                 try
                 {
-                    await eventStore.AppendEventsAsync(commitId, GetStreamName(), Version, eventData);
+                    await eventStore.AppendEventsAsync(commitId, GetStreamName(), expectedVersion, eventData);
                 }
                 catch (WrongEventVersionException ex)
                 {

src/Squidex/Areas/Api/Controllers/Apps/AppClientsController.cs

@@ -12,6 +12,7 @@ using Microsoft.AspNetCore.Mvc;
 using Microsoft.Extensions.Primitives;
 using NSwag.Annotations;
 using Squidex.Areas.Api.Controllers.Apps.Models;
+using Squidex.Domain.Apps.Core.Apps;
 using Squidex.Domain.Apps.Entities.Apps.Commands;
 using Squidex.Infrastructure.Commands;
 using Squidex.Infrastructure.Reflection;
@@ -81,7 +82,7 @@ namespace Squidex.Areas.Api.Controllers.Apps
 
             await CommandBus.PublishAsync(command);
 
-            var response = SimpleMapper.Map(command, new ClientDto { Name = command.Id });
+            var response = SimpleMapper.Map(command, new ClientDto { Name = command.Id, Permission = AppClientPermission.Editor });
 
             return CreatedAtAction(nameof(GetClients), new { app }, response);
         }

src/Squidex/Pipeline/CommandMiddlewares/ETagCommandMiddleware.cs

@@ -11,6 +11,7 @@ using System.Globalization;
 using System.Threading.Tasks;
 using Microsoft.AspNetCore.Http;
 using Microsoft.Extensions.Primitives;
+using Squidex.Infrastructure;
 using Squidex.Infrastructure.Commands;
 
 namespace Squidex.Pipeline.CommandMiddlewares
@@ -33,6 +34,10 @@ namespace Squidex.Pipeline.CommandMiddlewares
             {
                 context.Command.ExpectedVersion = expectedVersion;
             }
+            else
+            {
+                context.Command.ExpectedVersion = EtagVersion.Any;
+            }
 
             await next();
 

tests/Squidex.Domain.Apps.Entities.Tests/Contents/GraphQLTests.cs

@@ -483,7 +483,7 @@ namespace Squidex.Domain.Apps.Entities.Contents
 
             var refContents = new List<IContentEntity> { contentRef };
 
-            A.CallTo(() => contentQuery.FindContentAsync(app, schema.Id.ToString(), user, contentId, -1))
+            A.CallTo(() => contentQuery.FindContentAsync(app, schema.Id.ToString(), user, contentId, EtagVersion.Any))
                 .Returns((schema, content));
 
             A.CallTo(() => contentQuery.QueryWithCountAsync(app, schema.Id.ToString(), user, false, A<HashSet<Guid>>.That.Matches(x => x.Contains(contentRefId))))
@@ -543,7 +543,7 @@ namespace Squidex.Domain.Apps.Entities.Contents
 
             var refAssets = new List<IAssetEntity> { assetRef };
 
-            A.CallTo(() => contentQuery.FindContentAsync(app, schema.Id.ToString(), user, contentId, -1))
+            A.CallTo(() => contentQuery.FindContentAsync(app, schema.Id.ToString(), user, contentId, EtagVersion.Any))
                 .Returns((schema, content));
 
             A.CallTo(() => assetRepository.QueryAsync(app.Id, null, A<HashSet<Guid>>.That.Matches(x => x.Contains(assetRefId)), null, int.MaxValue, 0))
@@ -602,7 +602,7 @@ namespace Squidex.Domain.Apps.Entities.Contents
                   }}
                 }}";
 
-            A.CallTo(() => contentQuery.FindContentAsync(app, schema.Id.ToString(), user, contentId, -1))
+            A.CallTo(() => contentQuery.FindContentAsync(app, schema.Id.ToString(), user, contentId, EtagVersion.Any))
                 .Returns((schema, content));
 
             var result = await sut.QueryAsync(app, user, new GraphQLQuery { Query = query });

tests/Squidex.Infrastructure.Tests/Commands/AggregateHandlerTests.cs

@@ -10,11 +10,11 @@ using System;
 using System.Collections.Generic;
 using System.Threading.Tasks;
 using FakeItEasy;
-using Squidex.Infrastructure.Commands.TestHelpers;
 using Squidex.Infrastructure.EventSourcing;
 using Squidex.Infrastructure.Log;
 using Squidex.Infrastructure.States;
 using Squidex.Infrastructure.Tasks;
+using Squidex.Infrastructure.TestHelpers;
 using Xunit;
 
 namespace Squidex.Infrastructure.Commands
@@ -29,17 +29,16 @@ namespace Squidex.Infrastructure.Commands
         private readonly Envelope<IEvent> event1 = new Envelope<IEvent>(new MyEvent());
         private readonly Envelope<IEvent> event2 = new Envelope<IEvent>(new MyEvent());
         private readonly CommandContext context;
+        private readonly CommandContext invalidContext = new CommandContext(A.Dummy<ICommand>());
         private readonly Guid domainObjectId = Guid.NewGuid();
+        private readonly MyCommand command;
         private readonly MyDomainObject domainObject = new MyDomainObject();
         private readonly AggregateHandler sut;
 
-        public sealed class MyEvent : IEvent
-        {
-        }
-
         public AggregateHandlerTests()
         {
-            context = new CommandContext(new MyCommand { AggregateId = domainObjectId });
+            command = new MyCommand { AggregateId = domainObjectId };
+            context = new CommandContext(command);
 
             A.CallTo(() => store.WithSnapshots<MyDomainObject, object>(domainObjectId.ToString(), A<Func<object, Task>>.Ignored))
                 .Returns(persistence);
@@ -58,13 +57,29 @@ namespace Squidex.Infrastructure.Commands
         [Fact]
         public Task Create_with_task_should_throw_exception_if_not_aggregate_command()
         {
-            return Assert.ThrowsAnyAsync<ArgumentException>(() => sut.CreateAsync<MyDomainObject>(new CommandContext(A.Dummy<ICommand>()), x => TaskHelper.False));
+            return Assert.ThrowsAnyAsync<ArgumentException>(() => sut.CreateAsync<MyDomainObject>(invalidContext, x => TaskHelper.False));
         }
 
         [Fact]
         public Task Create_synced_with_task_should_throw_exception_if_not_aggregate_command()
         {
-            return Assert.ThrowsAnyAsync<ArgumentException>(() => sut.CreateSyncedAsync<MyDomainObject>(new CommandContext(A.Dummy<ICommand>()), x => TaskHelper.False));
+            return Assert.ThrowsAnyAsync<ArgumentException>(() => sut.CreateSyncedAsync<MyDomainObject>(invalidContext, x => TaskHelper.False));
+        }
+
+        [Fact]
+        public Task Create_with_task_should_should_throw_exception_if_version_is_wrong()
+        {
+            command.ExpectedVersion = 2;
+
+            return Assert.ThrowsAnyAsync<DomainObjectVersionException>(() => sut.CreateAsync<MyDomainObject>(context, x => TaskHelper.False));
+        }
+
+        [Fact]
+        public Task Create_synced_with_task_should_should_throw_exception_if_version_is_wrong()
+        {
+            command.ExpectedVersion = 2;
+
+            return Assert.ThrowsAnyAsync<DomainObjectVersionException>(() => sut.CreateSyncedAsync<MyDomainObject>(context, x => TaskHelper.False));
         }
 
         [Fact]
@@ -150,13 +165,29 @@ namespace Squidex.Infrastructure.Commands
         [Fact]
         public Task Update_with_task_should_throw_exception_if_not_aggregate_command()
         {
-            return Assert.ThrowsAnyAsync<ArgumentException>(() => sut.UpdateAsync<MyDomainObject>(new CommandContext(A.Dummy<ICommand>()), x => TaskHelper.False));
+            return Assert.ThrowsAnyAsync<ArgumentException>(() => sut.UpdateAsync<MyDomainObject>(invalidContext, x => TaskHelper.False));
         }
 
         [Fact]
         public Task Update_synced_with_task_should_throw_exception_if_not_aggregate_command()
         {
-            return Assert.ThrowsAnyAsync<ArgumentException>(() => sut.UpdateSyncedAsync<MyDomainObject>(new CommandContext(A.Dummy<ICommand>()), x => TaskHelper.False));
+            return Assert.ThrowsAnyAsync<ArgumentException>(() => sut.UpdateSyncedAsync<MyDomainObject>(invalidContext, x => TaskHelper.False));
+        }
+
+        [Fact]
+        public Task Update_with_task_should_should_throw_exception_if_version_is_wrong()
+        {
+            command.ExpectedVersion = 2;
+
+            return Assert.ThrowsAnyAsync<DomainObjectVersionException>(() => sut.UpdateAsync<MyDomainObject>(context, x => TaskHelper.False));
+        }
+
+        [Fact]
+        public Task Update_synced_with_task_should_should_throw_exception_if_version_is_wrong()
+        {
+            command.ExpectedVersion = 2;
+
+            return Assert.ThrowsAnyAsync<DomainObjectVersionException>(() => sut.UpdateSyncedAsync<MyDomainObject>(context, x => TaskHelper.False));
         }
 
         [Fact]

tests/Squidex.Infrastructure.Tests/Commands/CommandContextTests.cs

@@ -7,7 +7,7 @@
 // ==========================================================================
 
 using System;
-using Squidex.Infrastructure.Commands.TestHelpers;
+using Squidex.Infrastructure.TestHelpers;
 using Xunit;
 
 namespace Squidex.Infrastructure.Commands

tests/Squidex.Infrastructure.Tests/Commands/DomainObjectBaseTests.cs

@@ -11,10 +11,10 @@ using System.Collections.Generic;
 using System.Linq;
 using System.Threading.Tasks;
 using FakeItEasy;
-using Squidex.Infrastructure.Commands.TestHelpers;
 using Squidex.Infrastructure.EventSourcing;
 using Squidex.Infrastructure.Log;
 using Squidex.Infrastructure.States;
+using Squidex.Infrastructure.TestHelpers;
 using Xunit;
 
 namespace Squidex.Infrastructure.Commands
@@ -35,7 +35,7 @@ namespace Squidex.Infrastructure.Commands
         [Fact]
         public void Should_instantiate()
         {
-            Assert.Equal(-1, sut.Version);
+            Assert.Equal(EtagVersion.NotFound, sut.Version);
         }
 
         [Fact]
@@ -47,7 +47,7 @@ namespace Squidex.Infrastructure.Commands
             sut.RaiseEvent(event1);
             sut.RaiseEvent(event2);
 
-            Assert.Equal(-1, sut.Version);
+            Assert.Equal(EtagVersion.NotFound, sut.Version);
             Assert.Equal(new IEvent[] { event1, event2 }, sut.GetUncomittedEvents().Select(x => x.Payload).ToArray());
 
             sut.ClearUncommittedEvents();
@@ -71,7 +71,7 @@ namespace Squidex.Infrastructure.Commands
             sut.RaiseEvent(event1);
             sut.RaiseEvent(event2);
 
-            var newState = "STATE";
+            var newState = new MyDomainState();
 
             sut.UpdateState(newState);
 
@@ -104,7 +104,7 @@ namespace Squidex.Infrastructure.Commands
             sut.RaiseEvent(event1);
             sut.RaiseEvent(event2);
 
-            var newState = "STATE";
+            var newState = new MyDomainState();
 
             sut.UpdateState(newState);
 

tests/Squidex.Infrastructure.Tests/Commands/EnrichWithTimestampCommandMiddlewareTests.cs

@@ -9,7 +9,7 @@
 using System.Threading.Tasks;
 using FakeItEasy;
 using NodaTime;
-using Squidex.Infrastructure.Commands.TestHelpers;
+using Squidex.Infrastructure.TestHelpers;
 using Xunit;
 
 namespace Squidex.Infrastructure.Commands

tests/Squidex.Infrastructure.Tests/EventSourcing/CompoundEventConsumerTests.cs

@@ -9,6 +9,7 @@
 using System.Threading.Tasks;
 using FakeItEasy;
 using Squidex.Infrastructure.Tasks;
+using Squidex.Infrastructure.TestHelpers;
 using Xunit;
 
 namespace Squidex.Infrastructure.EventSourcing
@@ -18,10 +19,6 @@ namespace Squidex.Infrastructure.EventSourcing
         private readonly IEventConsumer consumer1 = A.Fake<IEventConsumer>();
         private readonly IEventConsumer consumer2 = A.Fake<IEventConsumer>();
 
-        private sealed class MyEvent : IEvent
-        {
-        }
-
         [Fact]
         public void Should_return_given_name()
         {

tests/Squidex.Infrastructure.Tests/EventSourcing/EnvelopeExtensionsTests.cs

@@ -81,7 +81,18 @@ namespace Squidex.Infrastructure.EventSourcing
             sut.SetEventStreamNumber(eventStreamNumber);
 
             Assert.Equal(eventStreamNumber, sut.Headers.EventStreamNumber());
-            Assert.Equal(eventStreamNumber, sut.Headers["EventStreamNumber"].ToInt32(culture));
+            Assert.Equal(eventStreamNumber, sut.Headers["EventStreamNumber"].ToInt64(culture));
+        }
+
+        [Fact]
+        public void Should_set_and_get_snapshot_version()
+        {
+            const int snapshotVersion = 123;
+
+            sut.SetSnapshotVersion(snapshotVersion);
+
+            Assert.Equal(snapshotVersion, sut.Headers.SnapshotVersion());
+            Assert.Equal(snapshotVersion, sut.Headers["SnapshotVersion"].ToInt64(culture));
         }
     }
 }

tests/Squidex.Infrastructure.Tests/EventSourcing/EventDataFormatterTests.cs

@@ -11,17 +11,13 @@ using System.Linq;
 using Newtonsoft.Json;
 using NodaTime;
 using Squidex.Infrastructure.Json;
+using Squidex.Infrastructure.TestHelpers;
 using Xunit;
 
 namespace Squidex.Infrastructure.EventSourcing
 {
     public class EventDataFormatterTests
     {
-        public sealed class MyEvent : IEvent
-        {
-            public string MyProperty { get; set; }
-        }
-
         public sealed class MyOldEvent : IEvent, IMigratedEvent
         {
             public string MyProperty { get; set; }

tests/Squidex.Infrastructure.Tests/EventSourcing/Grains/EventConsumerGrainTests.cs

@@ -12,16 +12,13 @@ using FakeItEasy;
 using FluentAssertions;
 using Squidex.Infrastructure.Log;
 using Squidex.Infrastructure.States;
+using Squidex.Infrastructure.TestHelpers;
 using Xunit;
 
 namespace Squidex.Infrastructure.EventSourcing.Grains
 {
     public class EventConsumerGrainTests
     {
-        public sealed class MyEvent : IEvent
-        {
-        }
-
         public sealed class MyEventConsumerGrain : EventConsumerGrain
         {
             public MyEventConsumerGrain(IEventStore eventStore, IEventDataFormatter eventDataFormatter, ISemanticLog log)
@@ -67,7 +64,7 @@ namespace Squidex.Infrastructure.EventSourcing.Grains
             A.CallTo(() => eventConsumer.Name)
                 .Returns(consumerName);
 
-            A.CallTo(() => persistence.ReadAsync(ExpectedVersion.Any))
+            A.CallTo(() => persistence.ReadAsync(EtagVersion.Any))
                 .Invokes(new Action<long>(s => apply(state)));
 
             A.CallTo(() => persistence.WriteSnapshotAsync(A<EventConsumerState>.Ignored))

tests/Squidex.Infrastructure.Tests/PropertiesBagTests.cs

@@ -86,7 +86,7 @@ namespace Squidex.Infrastructure
             Assert.True(bag.Contains("NewKey"));
 
             Assert.Equal(1, bag.Count);
-            Assert.Equal(123, bag["NewKey"].ToInt32(c));
+            Assert.Equal(123, bag["NewKey"].ToInt64(c));
 
             Assert.False(bag.Contains("OldKey"));
         }
@@ -174,7 +174,7 @@ namespace Squidex.Infrastructure
         {
             bag.Set("Key", "abc");
 
-            Assert.Throws<InvalidCastException>(() => bag["Key"].ToInt32(CultureInfo.InvariantCulture));
+            Assert.Throws<InvalidCastException>(() => bag["Key"].ToInt64(CultureInfo.InvariantCulture));
         }
 
         [Fact]
@@ -214,7 +214,7 @@ namespace Squidex.Infrastructure
         {
             bag.Set("Key", long.MaxValue);
 
-            Assert.Throws<InvalidCastException>(() => bag["Key"].ToInt32(c));
+            Assert.Throws<InvalidCastException>(() => bag["Key"].ToInt64(c));
         }
 
         [Fact]
@@ -347,7 +347,7 @@ namespace Squidex.Infrastructure
 
         private void AssertNumber()
         {
-            AssertInt32(123);
+            AssertInt64(123);
             AssertInt64(123);
             AssertSingle(123);
             AssertDouble(123);
@@ -420,10 +420,10 @@ namespace Squidex.Infrastructure
             Assert.Equal(expected, (long?)dynamicBag.Key);
         }
 
-        private void AssertInt32(int expected)
+        private void AssertInt64(int expected)
         {
-            Assert.Equal(expected, bag["Key"].ToInt32(c));
-            Assert.Equal(expected, bag["Key"].ToNullableInt32(c));
+            Assert.Equal(expected, bag["Key"].ToInt64(c));
+            Assert.Equal(expected, bag["Key"].ToNullableInt64(c));
 
             Assert.Equal(expected, (int)dynamicBag.Key);
             Assert.Equal(expected, (int?)dynamicBag.Key);

tests/Squidex.Infrastructure.Tests/States/StateEventSourcingTests.cs

@@ -15,16 +15,13 @@ using Microsoft.Extensions.Caching.Memory;
 using Microsoft.Extensions.Options;
 using Squidex.Infrastructure.EventSourcing;
 using Squidex.Infrastructure.Tasks;
+using Squidex.Infrastructure.TestHelpers;
 using Xunit;
 
 namespace Squidex.Infrastructure.States
 {
     public class StateEventSourcingTests
     {
-        public sealed class MyEvent : IEvent
-        {
-        }
-
         private class MyStatefulObject : IStatefulObject
         {
             private readonly List<IEvent> appliedEvents = new List<IEvent>();
@@ -115,7 +112,7 @@ namespace Squidex.Infrastructure.States
         [Fact]
         public async Task Should_read_events_from_snapshot()
         {
-            statefulObjectWithSnapShot.ExpectedVersion = ExpectedVersion.Any;
+            statefulObjectWithSnapShot.ExpectedVersion = EtagVersion.Any;
 
             A.CallTo(() => snapshotStore.ReadAsync(key))
                 .Returns((2, 2L));
@@ -131,7 +128,7 @@ namespace Squidex.Infrastructure.States
         [Fact]
         public async Task Should_throw_exception_if_events_are_older_than_snapshot()
         {
-            statefulObjectWithSnapShot.ExpectedVersion = ExpectedVersion.Any;
+            statefulObjectWithSnapShot.ExpectedVersion = EtagVersion.Any;
 
             A.CallTo(() => snapshotStore.ReadAsync(key))
                 .Returns((2, 2L));
@@ -144,7 +141,7 @@ namespace Squidex.Infrastructure.States
         [Fact]
         public async Task Should_throw_exception_if_events_have_gaps_to_snapshot()
         {
-            statefulObjectWithSnapShot.ExpectedVersion = ExpectedVersion.Any;
+            statefulObjectWithSnapShot.ExpectedVersion = EtagVersion.Any;
 
             A.CallTo(() => snapshotStore.ReadAsync(key))
                 .Returns((2, 2L));
@@ -177,7 +174,7 @@ namespace Squidex.Infrastructure.States
         [Fact]
         public async Task Should_not_throw_exception_if_noting_expected()
         {
-            statefulObject.ExpectedVersion = ExpectedVersion.Any;
+            statefulObject.ExpectedVersion = EtagVersion.Any;
 
             SetupEventStore(0);
 
@@ -187,7 +184,7 @@ namespace Squidex.Infrastructure.States
         [Fact]
         public async Task Should_provide_state_from_services_and_add_to_cache()
         {
-            statefulObject.ExpectedVersion = ExpectedVersion.Any;
+            statefulObject.ExpectedVersion = EtagVersion.Any;
 
             SetupEventStore(0);
 
@@ -200,7 +197,7 @@ namespace Squidex.Infrastructure.States
         [Fact]
         public async Task Should_serve_next_request_from_cache()
         {
-            statefulObject.ExpectedVersion = ExpectedVersion.Any;
+            statefulObject.ExpectedVersion = EtagVersion.Any;
 
             SetupEventStore(0);
 
@@ -218,7 +215,7 @@ namespace Squidex.Infrastructure.States
         [Fact]
         public async Task Should_write_to_store_with_previous_position()
         {
-            statefulObject.ExpectedVersion = ExpectedVersion.Any;
+            statefulObject.ExpectedVersion = EtagVersion.Any;
 
             InvalidateMessage message = null;
 
@@ -248,7 +245,7 @@ namespace Squidex.Infrastructure.States
         [Fact]
         public async Task Should_wrap_exception_when_writing_to_store_with_previous_position()
         {
-            statefulObject.ExpectedVersion = ExpectedVersion.Any;
+            statefulObject.ExpectedVersion = EtagVersion.Any;
 
             SetupEventStore(3);
 
@@ -263,7 +260,7 @@ namespace Squidex.Infrastructure.States
         [Fact]
         public async Task Should_remove_from_cache_when_invalidation_message_received()
         {
-            statefulObject.ExpectedVersion = ExpectedVersion.Any;
+            statefulObject.ExpectedVersion = EtagVersion.Any;
 
             var actualObject = await sut.GetSingleAsync<MyStatefulObject>(key);
 
@@ -275,7 +272,7 @@ namespace Squidex.Infrastructure.States
         [Fact]
         public async Task Should_return_same_instance_for_parallel_requests()
         {
-            statefulObject.ExpectedVersion = ExpectedVersion.Any;
+            statefulObject.ExpectedVersion = EtagVersion.Any;
 
             A.CallTo(() => snapshotStore.ReadAsync(key))
                 .ReturnsLazily(() => Task.Delay(1).ContinueWith(x => ((object)1, 1L)));

tests/Squidex.Infrastructure.Tests/States/StateSnapshotTests.cs

@@ -100,7 +100,7 @@ namespace Squidex.Infrastructure.States
             statefulObject.ExpectedVersion = 0;
 
             A.CallTo(() => snapshotStore.ReadAsync(key))
-                .Returns((0, -1));
+                .Returns((0, EtagVersion.Empty));
 
             await Assert.ThrowsAsync<DomainObjectNotFoundException>(() => sut.GetSingleAsync<MyStatefulObject>(key));
         }
@@ -119,10 +119,10 @@ namespace Squidex.Infrastructure.States
         [Fact]
         public async Task Should_not_throw_exception_if_noting_expected()
         {
-            statefulObject.ExpectedVersion = ExpectedVersion.Any;
+            statefulObject.ExpectedVersion = EtagVersion.Any;
 
             A.CallTo(() => snapshotStore.ReadAsync(key))
-                .Returns((0, -1));
+                .Returns((0, EtagVersion.Empty));
 
             await sut.GetSingleAsync<MyStatefulObject>(key);
         }
@@ -130,7 +130,7 @@ namespace Squidex.Infrastructure.States
         [Fact]
         public async Task Should_provide_state_from_services_and_add_to_cache()
         {
-            statefulObject.ExpectedVersion = ExpectedVersion.Any;
+            statefulObject.ExpectedVersion = EtagVersion.Any;
 
             var actualObject = await sut.GetSingleAsync<MyStatefulObject>(key);
 
@@ -141,7 +141,7 @@ namespace Squidex.Infrastructure.States
         [Fact]
         public async Task Should_serve_next_request_from_cache()
         {
-            statefulObject.ExpectedVersion = ExpectedVersion.Any;
+            statefulObject.ExpectedVersion = EtagVersion.Any;
 
             var actualObject1 = await sut.GetSingleAsync<MyStatefulObject>(key);
 
@@ -157,7 +157,7 @@ namespace Squidex.Infrastructure.States
         [Fact]
         public async Task Should_not_serve_next_request_from_cache_when_detached()
         {
-            statefulObject.ExpectedVersion = ExpectedVersion.Any;
+            statefulObject.ExpectedVersion = EtagVersion.Any;
 
             var actualObject1 = await sut.CreateAsync<MyStatefulObject>(key);
 
@@ -173,7 +173,7 @@ namespace Squidex.Infrastructure.States
         [Fact]
         public async Task Should_write_to_store_with_previous_version()
         {
-            statefulObject.ExpectedVersion = ExpectedVersion.Any;
+            statefulObject.ExpectedVersion = EtagVersion.Any;
 
             InvalidateMessage message = null;
 
@@ -204,7 +204,7 @@ namespace Squidex.Infrastructure.States
         [Fact]
         public async Task Should_wrap_exception_when_writing_to_store_with_previous_version()
         {
-            statefulObject.ExpectedVersion = ExpectedVersion.Any;
+            statefulObject.ExpectedVersion = EtagVersion.Any;
 
             A.CallTo(() => snapshotStore.ReadAsync(key))
                 .Returns((123, 13));
@@ -220,7 +220,7 @@ namespace Squidex.Infrastructure.States
         [Fact]
         public async Task Should_remove_from_cache_when_invalidation_message_received()
         {
-            statefulObject.ExpectedVersion = ExpectedVersion.Any;
+            statefulObject.ExpectedVersion = EtagVersion.Any;
 
             var actualObject = await sut.GetSingleAsync<MyStatefulObject>(key);
 
@@ -232,7 +232,7 @@ namespace Squidex.Infrastructure.States
         [Fact]
         public async Task Should_return_same_instance_for_parallel_requests()
         {
-            statefulObject.ExpectedVersion = ExpectedVersion.Any;
+            statefulObject.ExpectedVersion = EtagVersion.Any;
 
             A.CallTo(() => snapshotStore.ReadAsync(key))
                 .ReturnsLazily(() => Task.Delay(1).ContinueWith(x => (1, 1L)));

tests/Squidex.Infrastructure.Tests/Commands/TestHelpers/MyCommand.cs → tests/Squidex.Infrastructure.Tests/TestHelpers/MyCommand.cs

@@ -8,14 +8,15 @@
 
 using System;
 using NodaTime;
+using Squidex.Infrastructure.Commands;
 
-namespace Squidex.Infrastructure.Commands.TestHelpers
+namespace Squidex.Infrastructure.TestHelpers
 {
     internal sealed class MyCommand : IAggregateCommand, ITimestampCommand
     {
         public Guid AggregateId { get; set; }
 
-        public long? ExpectedVersion { get; set; }
+        public long ExpectedVersion { get; set; }
 
         public Instant Timestamp { get; set; }
     }

tests/Squidex.Infrastructure.Tests/Commands/TestHelpers/MyDomainObject.cs → tests/Squidex.Infrastructure.Tests/TestHelpers/MyDomainObject.cs

@@ -6,11 +6,11 @@
 //  All rights reserved.
 // ==========================================================================
 
-using Squidex.Infrastructure.EventSourcing;
+using Squidex.Infrastructure.Commands;
 
-namespace Squidex.Infrastructure.Commands.TestHelpers
+namespace Squidex.Infrastructure.TestHelpers
 {
-    internal sealed class MyDomainObject : DomainObjectBase<MyDomainObject, object>
+    internal sealed class MyDomainObject : DomainObjectBase<MyDomainObject, MyDomainState>
     {
     }
 }

tests/Squidex.Infrastructure.Tests/TestHelpers/MyDomainState.cs

@@ -0,0 +1,17 @@
+// ==========================================================================
+//  MyDomainState.cs
+//  Squidex Headless CMS
+// ==========================================================================
+//  Copyright (c) Squidex Group
+//  All rights reserved.
+// ==========================================================================
+
+using Squidex.Infrastructure.Commands;
+
+namespace Squidex.Infrastructure.TestHelpers
+{
+    public class MyDomainState : IDomainState
+    {
+        public long Version { get; set; }
+    }
+}

tests/Squidex.Infrastructure.Tests/Commands/TestHelpers/MyEvent.cs → tests/Squidex.Infrastructure.Tests/TestHelpers/MyEvent.cs

@@ -8,9 +8,10 @@
 
 using Squidex.Infrastructure.EventSourcing;
 
-namespace Squidex.Infrastructure.Commands.TestHelpers
+namespace Squidex.Infrastructure.TestHelpers
 {
     internal sealed class MyEvent : IEvent
     {
+        public string MyProperty { get; set; }
     }
 }