Add draft API

Author: glucaci

src/WorkflowCore/Interface/Persistence/ITransaction.cs

@@ -0,0 +1,10 @@
+namespace WorkflowCore.Interface
+{
+    public interface ITransaction
+    {
+        /// <summary>
+        /// The transaction session specific for each storage provider.
+        /// </summary>
+        object Session { get; }
+    }
+}

src/WorkflowCore/Interface/Persistence/IWorkflowRepository.cs

@@ -7,7 +7,7 @@ namespace WorkflowCore.Interface
 {
     public interface IWorkflowRepository
     {
-        Task<string> CreateNewWorkflow(WorkflowInstance workflow);
+        Task<string> CreateNewWorkflow(WorkflowInstance workflow, ITransaction transaction = null);
 
         Task PersistWorkflow(WorkflowInstance workflow);
 

src/WorkflowCore/Services/WorkflowController.cs

@@ -53,7 +53,7 @@ public Task<string> StartWorkflow<TData>(string workflowId, TData data = null, s
             return StartWorkflow(workflowId, null, data, reference);
         }
 
-        public async Task<string> StartWorkflow<TData>(string workflowId, int? version, TData data = null, string reference=null)
+        public async Task<string> StartWorkflow<TData>(string workflowId, int? version, TData data = null, string reference=null, ITransaction transaction = null)
             where TData : class, new()
         {
 
@@ -91,7 +91,7 @@ public async Task<string> StartWorkflow<TData>(string workflowId, int? version,
                 await middlewareRunner.RunPreMiddleware(wf, def);
             }
 
-            string id = await _persistenceStore.CreateNewWorkflow(wf);
+            string id = await _persistenceStore.CreateNewWorkflow(wf, transaction);
             await _queueProvider.QueueWork(id, QueueType.Workflow);
             await _queueProvider.QueueWork(id, QueueType.Index);
             await _eventHub.PublishNotification(new WorkflowStarted

src/providers/WorkflowCore.Persistence.MongoDB/Services/MongoPersistenceProvider.cs

@@ -122,9 +122,17 @@ static void CreateIndexes(MongoPersistenceProvider instance)
 
         private IMongoCollection<ExecutionError> ExecutionErrors => _database.GetCollection<ExecutionError>("wfc.execution_errors");
 
-        public async Task<string> CreateNewWorkflow(WorkflowInstance workflow)
+        public async Task<string> CreateNewWorkflow(WorkflowInstance workflow, ITransaction transaction = null)
         {
-            await WorkflowInstances.InsertOneAsync(workflow);
+            if (transaction?.Session is IClientSessionHandle clientSessionHandle)
+            {
+                await WorkflowInstances.InsertOneAsync(clientSessionHandle, workflow);
+            }
+            else
+            {
+                await WorkflowInstances.InsertOneAsync(workflow);
+            }
+
             return workflow.Id;
         }
 

src/providers/WorkflowCore.Persistence.MongoDB/Services/MongoTransaction.cs

@@ -0,0 +1,15 @@
+using MongoDB.Driver;
+using WorkflowCore.Interface;
+
+namespace WorkflowCore.Persistence.MongoDB.Services
+{
+    public class MongoTransaction : ITransaction
+    {
+        public MongoTransaction(IClientSessionHandle session)
+        {
+            Session = session;
+        }
+
+        public object Session { get; }
+    }
+}