diff --git a/core/src/abstractions/persistence-provider.ts b/core/src/abstractions/persistence-provider.ts
index 35b3fde..71faac4 100644
--- a/core/src/abstractions/persistence-provider.ts
+++ b/core/src/abstractions/persistence-provider.ts
@@ -8,7 +8,7 @@ export interface IPersistenceProvider {
     getRunnableInstances(): Promise<Array<string>>;
 
     createEventSubscription(subscription: EventSubscription): Promise<void>;
-    getSubscriptions(eventName: string, eventKey: string, asOf: Date): Promise<Array<EventSubscription>>;
+    getSubscriptions(eventName: string, eventKey: string, asOf?: Date): Promise<Array<EventSubscription>>;
     terminateSubscription(id: string): Promise<void>;
 
     createEvent(event: Event): Promise<string>;    
diff --git a/core/src/abstractions/workflow-host.ts b/core/src/abstractions/workflow-host.ts
index 84c0653..1a7df45 100644
--- a/core/src/abstractions/workflow-host.ts
+++ b/core/src/abstractions/workflow-host.ts
@@ -6,7 +6,7 @@ export interface IWorkflowHost {
     stop();
     startWorkflow(id: string, version: number, data: any): Promise<string>;    
     registerWorkflow<TData>(workflow: new () => WorkflowBase<TData>);
-    publishEvent(eventName: string, eventKey: string, eventData: any, eventTime: Date): Promise<void>;
+    publishEvent(eventName: string, eventKey: string, eventData: any, eventTime?: Date): Promise<void>;
     suspendWorkflow(id: string): Promise<boolean>;
     resumeWorkflow(id: string): Promise<boolean>;
     terminateWorkflow(id: string): Promise<boolean>;
diff --git a/core/src/models/event.ts b/core/src/models/event.ts
index 864bf04..5ba24ec 100644
--- a/core/src/models/event.ts
+++ b/core/src/models/event.ts
@@ -3,6 +3,6 @@ export class Event {
     public eventName: string;
     public eventKey: string;
     public eventData: any;
-    public eventTime: Date;
+    public eventTime?: Date;
     public isProcessed: boolean;
 }
\ No newline at end of file
diff --git a/core/src/services/event-queue-worker.ts b/core/src/services/event-queue-worker.ts
index ea3dd6e..8daa529 100644
--- a/core/src/services/event-queue-worker.ts
+++ b/core/src/services/event-queue-worker.ts
@@ -57,7 +57,7 @@ export class EventQueueWorker implements IBackgroundWorker {
             if (gotLock) {
                 try {
                     let evt = await self.persistence.getEvent(eventId);
-                    if (evt.eventTime <= new Date())
+                    if (evt.eventTime === undefined || evt.eventTime <= new Date())
                     {
                         let subs = await self.persistence.getSubscriptions(evt.eventName, evt.eventKey, evt.eventTime);
                         let success = true;
diff --git a/core/src/services/memory-persistence-provider.ts b/core/src/services/memory-persistence-provider.ts
index 988eb84..0f6cc4c 100644
--- a/core/src/services/memory-persistence-provider.ts
+++ b/core/src/services/memory-persistence-provider.ts
@@ -40,8 +40,8 @@ export class MemoryPersistenceProvider implements IPersistenceProvider {
         wfes_subscriptions.push(subscription);
     }
 
-    public async getSubscriptions(eventName: string, eventKey: string, asOf: Date): Promise<Array<EventSubscription>> {        
-        return wfes_subscriptions.filter(x => x.eventName == eventName && x.eventKey == eventKey && x.subscribeAsOf <= asOf);
+    public async getSubscriptions(eventName: string, eventKey: string, asOf?: Date): Promise<Array<EventSubscription>> {        
+        return wfes_subscriptions.filter(x => x.eventName == eventName && x.eventKey == eventKey && (asOf ? x.subscribeAsOf <= asOf : true));
     }
 
     public async terminateSubscription(id: string): Promise<void> {
diff --git a/core/src/services/workflow-host.ts b/core/src/services/workflow-host.ts
index dff2fea..1347433 100644
--- a/core/src/services/workflow-host.ts
+++ b/core/src/services/workflow-host.ts
@@ -75,7 +75,7 @@ export class WorkflowHost implements IWorkflowHost {
         this.registry.registerWorkflow<TData>(new workflow());
     }
 
-    public async publishEvent(eventName: string, eventKey: string, eventData: any, eventTime: Date): Promise<void> {
+    public async publishEvent(eventName: string, eventKey: string, eventData: any, eventTime?: Date): Promise<void> {
         //todo: check host status        
 
         this.logger.info("Publishing event %s %s", eventName, eventKey);
diff --git a/providers/workflow-es-mongodb/src/mongodb-provider.ts b/providers/workflow-es-mongodb/src/mongodb-provider.ts
index 00dce32..62f3828 100644
--- a/providers/workflow-es-mongodb/src/mongodb-provider.ts
+++ b/providers/workflow-es-mongodb/src/mongodb-provider.ts
@@ -98,10 +98,11 @@ export class MongoDBPersistence implements IPersistenceProvider {
         return deferred;
     }
 
-    public async getSubscriptions(eventName: string, eventKey: string, asOf: Date): Promise<Array<EventSubscription>> {        
+    public async getSubscriptions(eventName: string, eventKey: string, asOf?: Date): Promise<Array<EventSubscription>> {        
         var self = this;
         var deferred = new Promise<Array<EventSubscription>>((resolve, reject) => {
-            self.subscriptionCollection.find({ eventName: eventName, eventKey: eventKey, subscribeAsOf: { $lt: asOf } })
+            if (asOf === undefined) {
+                self.subscriptionCollection.find({ eventName: eventName, eventKey: eventKey })
                 .toArray((err, data) => {
                     if (err)
                         reject(err);
@@ -109,6 +110,16 @@ export class MongoDBPersistence implements IPersistenceProvider {
                         item.id = item["_id"].toString();
                     resolve(data);
                 });
+            } else {
+                self.subscriptionCollection.find({ eventName: eventName, eventKey: eventKey, subscribeAsOf: { $lt: asOf } })
+                .toArray((err, data) => {
+                    if (err)
+                        reject(err);
+                    for (let item of data)
+                        item.id = item["_id"].toString();
+                    resolve(data);
+                });
+            }
         });
         return deferred;
     }
diff --git a/providers/workflow-es-mysql/src/mysql-provider.ts b/providers/workflow-es-mysql/src/mysql-provider.ts
index 6422585..c4f76ef 100644
--- a/providers/workflow-es-mysql/src/mysql-provider.ts
+++ b/providers/workflow-es-mysql/src/mysql-provider.ts
@@ -102,11 +102,17 @@ export class MySqlPersistence implements IPersistenceProvider {
     });
     return deferred;
   }
-  public async getSubscriptions(eventName: string, eventKey: string, asOf: Date): Promise<Array<EventSubscription>> {
+  public async getSubscriptions(eventName: string, eventKey: string, asOf?: Date): Promise<Array<EventSubscription>> {
     var deferred = new Promise<Array<EventSubscription>>(
       async (resolve, reject) => {
           try {
-              var instances = await subscriptionCollection.findAll({
+              var instances = asOf === undefined ? await subscriptionCollection.findAll({
+                  where: {
+                      eventName: eventName,
+                      eventKey: eventKey
+                  },
+                  include: [Workflow]
+              }) : await subscriptionCollection.findAll({
                   where: {
                       eventName: eventName,
                       eventKey: eventKey,