SignalR Client Features doc -> SignalR Clients overview doc (#18293)

Author: analogrelay

aspnetcore/signalr/client-features.md

@@ -1,5 +1,5 @@
 ---
-title: SignalR client features
+title: ASP.NET Core SignalR clients
 author: bradygaster
 description: Learn which features are supported by the various ASP.NET Core SignalR clients.
 ms.author: bradyg
@@ -8,25 +8,41 @@ ms.date: 11/12/2019
 no-loc: [Blazor, "Identity", "Let's Encrypt", Razor, SignalR]
 uid: signalr/client-features
 ---
-# ASP.NET Core SignalR client features
+# ASP.NET Core SignalR clients
+
+## Versioning, support, and compatibility
+
+The SignalR clients ship alongside the server components and are versioned to match. Any supported client can safely connect to any supported server, and any compatibility issues would be considered bugs to be fixed. SignalR clients are supported in the same support lifecycle as the rest of .NET Core. See [the .NET Core Support Policy](https://dotnet.microsoft.com/platform/support/policy/dotnet-core) for details.
+
+Many features require a compatible client **and** server. See below for a table showing the minimum versions for various features.
+
+The 1.x versions of SignalR map to the 2.1 and 2.2 .NET Core releases and have the same lifetime. For version 3.x and above, the SignalR version exactly matches the rest of .NET and has the same support lifecycle.
+
+| SignalR version | .NET Core version | Support level | End of support |
+| - | - | - | - |
+| 1.0.x | 2.1.x | Long Term Support | August 21, 2021 |
+| 1.1.x | 2.2.x | End Of Life | December 23, 2019 |
+| 3.x or higher | *same as SignalR version* | See the [the .NET Core Support Policy](https://dotnet.microsoft.com/platform/support/policy/dotnet-core) |
+
+**NOTE:** In ASP.NET Core 3.0, the JavaScript client *moved* to the `@microsoft/signalr` npm package.
 
 ## Feature distribution
 
 The table below shows the features and support for the clients that offer real-time support. For each feature, the *minimum* version supporting this feature is listed. If no version is listed, the feature isn't supported.
 
-| Feature | .NET | JavaScript | Java |
-| ---- | :-: | :-: | :-: |
-| Azure SignalR Service Support |1.0.0|1.0.0|1.0.0|
-| [Server-to-client Streaming](xref:signalr/streaming)          |1.0.0|1.0.0|1.0.0|
-| [Client-to-server Streaming](xref:signalr/streaming)          |3.0.0|3.0.0|3.0.0|
-| Automatic Reconnection ([.NET](/aspnet/core/signalr/dotnet-client?view=aspnetcore-3.0&tabs=visual-studio#handle-lost-connection), [JavaScript](/aspnet/core/signalr/javascript-client?view=aspnetcore-3.0#reconnect-clients))          |3.0.0|3.0.0|❌|
-| WebSockets Transport |1.0.0|1.0.0|1.0.0|
-| Server-Sent Events Transport |1.0.0|1.0.0|❌|
-| Long Polling Transport |1.0.0|1.0.0|3.0.0|
-| JSON Hub Protocol |1.0.0|1.0.0|1.0.0|
-| MessagePack Hub Protocol |1.0.0|1.0.0|❌|
-
-Support for automatic reconnect in the Java client is tracked in [our issue tracker](https://github.com/dotnet/AspNetCore/issues/8711).
+| Feature | Server | .NET client | JavaScript client | Java client |
+| ---- | :-: | :-: | :-: | :-: |
+| Azure SignalR Service Support |2.1.0|1.0.0|1.0.0|1.0.0|
+| [Server-to-client Streaming](xref:signalr/streaming)          |2.1.0|1.0.0|1.0.0|1.0.0|
+| [Client-to-server Streaming](xref:signalr/streaming)          |3.0.0|3.0.0|3.0.0|3.0.0|
+| Automatic Reconnection ([.NET](/aspnet/core/signalr/dotnet-client?view=aspnetcore-3.0&tabs=visual-studio#handle-lost-connection), [JavaScript](/aspnet/core/signalr/javascript-client?view=aspnetcore-3.0#reconnect-clients))          |3.0.0|3.0.0|3.0.0|❌|
+| WebSockets Transport |2.1.0|1.0.0|1.0.0|1.0.0|
+| Server-Sent Events Transport |2.1.0|1.0.0|1.0.0|❌|
+| Long Polling Transport |2.1.0|1.0.0|1.0.0|3.0.0|
+| JSON Hub Protocol |2.1.0|1.0.0|1.0.0|1.0.0|
+| MessagePack Hub Protocol |2.1.0|1.0.0|1.0.0|❌|
+
+Support for enabling additional client features is tracked in [our issue tracker](https://github.com/dotnet/AspNetCore/issues).
 
 ## Additional resources
 

aspnetcore/toc.yml

@@ -557,7 +557,7 @@
     - name: Clients
       displayName: signalr
       items:
-        - name: SignalR client features
+        - name: Overview
           uid: signalr/client-features
           displayName: signalr
         - name: .NET client
@@ -1286,4 +1286,4 @@
 - name: API reference
   href: /dotnet/api/?view=aspnetcore-2.2
 - name: Contribute
-  href: https://github.com/dotnet/AspNetCore.Docs/blob/master/CONTRIBUTING.md
+  href: https://github.com/dotnet/AspNetCore.Docs/blob/master/CONTRIBUTING.md