adding new fields to messages for external app executions

Signed-off-by: Neil South <[email protected]>

src/Messaging/Common/ExportRequestType.cs

@@ -0,0 +1,9 @@
+
+namespace Monai.Deploy.Messaging.Common
+{
+    public enum ExportRequestType
+    {
+        None = 0,
+        ExternalProcessing
+    }
+}

src/Messaging/Events/ExportRequestEvent.cs

@@ -15,6 +15,7 @@
  */
 
 using System.ComponentModel.DataAnnotations;
+using Monai.Deploy.Messaging.Common;
 using Newtonsoft.Json;
 
 namespace Monai.Deploy.Messaging.Events
@@ -76,12 +77,13 @@ public class ExportRequestEvent : EventBase
         public List<string> ErrorMessages { get; private set; }
 
         /// <summary>
-        /// A list of data output plug-in type names to be executed by the export services.
-        /// Each string must be a fully-qualified type name.
-        /// E.g. <code>MyCompnay.MyProject.MyNamepsace.MyPlugin, MyCompnay.MyProject.MyNamepsace</code> where
-        /// <code>MyCompnay.MyProject.MyNamepsace</code> is the name of the assembly (DLL).
+        /// Gets or set the ExportRequest type.
+        /// For standard exports this will be ExportRequestType.None
+        /// but for exports to external apps this will be ExportRequestType.ExternalProcessing
         /// </summary>
-        public List<string> PluginAssemblies { get; private set; }
+        [JsonProperty(PropertyName = "export_request")]
+        [Required]
+        public ExportRequestType ExportRequest { get; set; } = default!;
 
         public ExportRequestEvent()
         {