title: gRPC / Protobuf interface versioning
body: <p>Let's say we use gRCP/Protobuf to connect many application.
  Those application are developped and released at their own team, with their own speed. Over time there will be different version of the the same app (e.g. desktop apps install on user PCs) that use different version on defined interface.</p>
  
  <p>While Protobuf is meant to allow backward compatibility, <strong>is there a way to know what version of interface is running at different points?</strong></p>
  
  <p>The simplest implementation is to have interface version equal to app version.
  But as many languages are used, it is not trivial to implement app versioning in all of them.</p>
  
  <p>So how version interface and let server to know client version？
  I think server should be able to log</p>
  
  <blockquote>
    <p>DATETIME connection from AppName v.version [using interface v.version]</p>
  </blockquote>