title: Supporting of GUID Type in grpc service Net core 3.0
body: <p>Net Core 3.0 is come out. Now there is a possibility to create and host a grpc service on ASP.NET Core. </p>
  
  <p>We start a creation of grpc service with description of a contract of that service in <a href="https://docs.microsoft.com/en-us/aspnet/core/grpc/?view=aspnetcore-3.0#c-tooling-support-for-proto-files" rel="nofollow noreferrer">proto files</a>.</p>
  
  <p>But I don't know how to describe a message with GUID field type.
  It is a not built-in type, it is just a struct. But that type is widely used everywhere. May be say, it is used as a built-in type in the webservices.</p>
  
  <p>The GUID struct is used in other kinds of .NET services like WCF, ASP.NET(Core) Web API without any additional actions. </p>
  
  <p>As for the proto3 language, it has not a Well-Known GUID type. All Well-Known types are <a href="https://developers.google.com/protocol-buffers/docs/reference/csharp/namespace/google/protobuf/well-known-types" rel="nofollow noreferrer">here</a>.</p>
  
  <p>Therefore I have a question, how to describe GUID type in the proto file in ASP NET Core 3.0? Are should we create an additional message? Or may be is there a proto file with description of GUID type which can be just imported?</p>
  
  <p>I didn't find any useful information. I also didn't find a proto file contained UUID message <a href="https://github.com/protocolbuffers/protobuf/tree/master/src/google/protobuf" rel="nofollow noreferrer">here</a>.</p>