Adding DelayResponse configuration method to SlackEndpointConfiguration

SlackNet.AspNetCore/SlackEndpointConfiguration.cs

@@ -71,10 +71,22 @@ public SlackEndpointConfiguration UseSocketMode(bool useSocketMode = true, Socke
         return this;
     }
 
+    /// <summary>
+    /// Delay responding to Slack until after handlers have completed.
+    /// May be required in environments that pause or shut down after a request has been completed.
+    /// </summary>
+    [Obsolete(Warning.Experimental)]
+    public SlackEndpointConfiguration DelayResponse(bool delay = true)
+    {
+        DelayedResponse = delay;
+        return this;
+    }
+
     public string RoutePrefix { get; private set; } = "slack";
     public string VerificationToken { get; private set; }
     public string SigningSecret { get; private set; }
     public bool VerifyEventUrl { get; private set; } = true;
     public bool SocketMode { get; private set; }
+    public bool DelayedResponse { get; private set; }
     public SocketModeConnectionOptions SocketModeConnectionOptions { get; set; }
 }

SlackNet.AspNetCore/SlackRequestMiddleware.cs

@@ -34,18 +34,31 @@ public async Task Invoke(HttpContext context)
             await _next(context).ConfigureAwait(false);
     }
 
-    private static async Task Respond(HttpResponse httpResponse, SlackResult slackResult)
+    private async Task Respond(HttpResponse httpResponse, SlackResult slackResult)
     {
-        httpResponse.StatusCode = (int)slackResult.Status;
+        try
+        {
+            if (_configuration.DelayedResponse)
+            {
+                foreach (var callback in slackResult.RequestCompletedCallbacks)
+                    await callback().ConfigureAwait(false);
+            }
+            else
+            {
+                // Note: HttpResponse's completed callbacks are called in FILO order
+                foreach (var callback in slackResult.RequestCompletedCallbacks.Reverse())
+                    httpResponse.OnCompleted(callback);
+            }
+        }
+        finally
+        {
+            httpResponse.StatusCode = (int)slackResult.Status;
 
-        // Note: HttpResponse's completed callbacks are called in FILO order
-        foreach (var callback in slackResult.RequestCompletedCallbacks.Reverse())
-            httpResponse.OnCompleted(callback);
+            if (slackResult.ContentType != null)
+                httpResponse.ContentType = slackResult.ContentType;
 
-        if (slackResult.ContentType != null)
-            httpResponse.ContentType = slackResult.ContentType;
-
-        if (slackResult.Body != null)
-            await httpResponse.WriteAsync(slackResult.Body).ConfigureAwait(false);
+            if (slackResult.Body != null)
+                await httpResponse.WriteAsync(slackResult.Body).ConfigureAwait(false);
+        }
     }
 }

SlackNet.AspNetCore/Warning.cs

@@ -0,0 +1,6 @@
+namespace SlackNet.AspNetCore;
+
+static class Warning
+{
+    public const string Experimental = "This API is experimental, and likely to change in the future.";
+}