Merge pull request #95494 from vwxyzh/patch-5

update message size limitation.

Author: Jak-MS

articles/azure-signalr/signalr-concept-messages-and-connections.md

@@ -18,9 +18,21 @@ Azure SignalR Service supports the same formats as ASP.NET Core SignalR: [JSON](
 
 ## Message size
 
-Azure SignalR Service has no size limit for messages.
-
-Large messages are split into smaller messages that are no more than 2 KB each and transmitted separately. SDKs handle message splitting and assembling. No developer efforts are needed.
+The following limits apply for Azure SignalR Service messages:
+
+* Client messages:
+  * For long polling or server side events, the client cannot send messages larger than 1MB.
+  * There is no size limit for Websockets for service.
+  * App server can set a limit for client message size. Default is 32KB. For more information, see [Security considerations in ASP.NET Core SignalR](/aspnet/core/signalr/security?#buffer-management).
+  * For serverless, the message size is limited by upstream implementation, but under 1MB is recommended.
+* Server messages:
+  * There is no limit to server message size, but under 16MB is recommended.
+  * App server can set a limit for client message size. Default is 32KB. For more information, see [Security considerations in ASP.NET Core SignalR](/aspnet/core/signalr/security?#buffer-management).
+  * Serverless:
+    * Rest API: 1MB for message body, 16KB for headers.
+    * There is no limit for Websockets, [management SDK persistent mode](https://github.com/Azure/azure-signalr/blob/dev/docs/management-sdk-guide.md), but under 16MB is recommended.
+
+For Websockets clients, large messages are split into smaller messages that are no more than 2 KB each and transmitted separately. SDKs handle message splitting and assembling. No developer efforts are needed.
 
 Large messages do negatively affect messaging performance. Use smaller messages whenever possible, and test to determine the optimal message size for each use-case scenario.