Documentation Update: Use MessagePack Hub Protocol in SignalR for ASP.NET Core | Microsoft Learn

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Page: Use MessagePack Hub Protocol in SignalR for ASP.NET Core | Microsoft Learn
Source File: https://github.com/dotnet/AspNetCore.Docs/blob/live/aspnetcore/signalr/messagepackhubprotocol.md

Summary

Clarify that CustomResolver in the server configuration snippet is a user-defined MessagePack-CSharp resolver (not a built-in type) and provide a runnable, minimal configuration using built-in resolvers (for example, StandardResolver/ContractlessStandardResolver) plus a concrete example of how to supply a custom resolver implementation.

Suggested Fixes

Instructions for Copilot: Copilot should only fix suggestions with a checkmark and do not make any updates for unchecked suggestions.

• In “Configure MessagePack on the server”, update the customization code snippet that currently uses new CustomResolver() to either (a) replace it with a built-in resolver example, or (b) explicitly label it as user-defined and include the required using statements and package note so the snippet is runnable. For example, replace the resolver line with a built-in resolver and show full snippet:

  using MessagePack;
  using MessagePack.Resolvers;
  
  services.AddSignalR()
      .AddMessagePackProtocol(options =>
      {
          options.SerializerOptions = MessagePackSerializerOptions.Standard
              .WithResolver(ContractlessStandardResolver.Instance) // or StandardResolver.Instance
              .WithSecurity(MessagePackSecurity.UntrustedData);
      });

  Also add 1–2 sentences immediately before the snippet clarifying that resolvers come from MessagePack-CSharp and that CustomResolver is not provided by ASP.NET Core/SignalR.

• If you want to keep the CustomResolver example, add a short, concrete subsection directly under the server customization paragraph (for example, “Example: creating a custom resolver”) that defines what it is and provides a minimal implementation (or a link to an official MessagePack-CSharp resolver example). Include a small code block that compiles, such as a composite resolver setup:

  using MessagePack;
  using MessagePack.Resolvers;
  
  // Example custom resolver composition
  var resolver = CompositeResolver.Create(
      // add any custom formatters/resolvers first
      StandardResolver.Instance
  );
  
  services.AddSignalR().AddMessagePackProtocol(options =>
  {
      options.SerializerOptions = MessagePackSerializerOptions.Standard
          .WithResolver(resolver)
          .WithSecurity(MessagePackSecurity.UntrustedData);
  });

  Add a brief note stating: “A ‘resolver’ is a MessagePack-CSharp concept (an IFormatterResolver) that controls how types are serialized; you only need a custom resolver if you are customizing type handling beyond the built-in resolvers.”

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