title: Can I compose gRPC proto definitions to multiple proto files?
body: <p>I have a gRPC API definition like this (from Akka docs example), but much longer (4000 lines just the <code>service</code> part).</p>
  
  <pre class="lang-proto prettyprint-override"><code>service GreeterService {
      rpc SayHello (HelloRequest) returns (HelloReply) {}
  
      rpc ItKeepsTalking (stream HelloRequest) returns (HelloReply) {}
  
      rpc ItKeepsReplying (HelloRequest) returns (stream HelloReply) {}
  
      rpc StreamHellos (stream HelloRequest) returns (stream HelloReply) {}
  }
  
  </code></pre>
  
  <p>However, the RPC list now grew too long and I want to "break it" into multiple files somehow, so the file is more readable. Something like this</p>
  
  <pre class="lang-proto prettyprint-override"><code>// file 1:
  service GreeterServicePartA {
      rpc SayHello (HelloRequest) returns (HelloReply) {}
  
      rpc ItKeepsTalking (stream HelloRequest) returns (HelloReply) {}
  }
  
  // file 2:
  service GreeterServicePartB {
      rpc ItKeepsReplying (HelloRequest) returns (stream HelloReply) {}
  
      rpc StreamHellos (stream HelloRequest) returns (stream HelloReply) {}
  }
  
  // main proto file:
  import "file1"
  import "file2"
  service GreeterService = GreeterServicePartA + GreeterServicePartB
  </code></pre>
  
  <p>Even just defining the RPCs separately in different files and then writing something like this would help me:</p>
  
  <pre class="lang-proto prettyprint-override"><code>service GreeterService {
      rpc SayHello = importedSayHello
  
      rpc ItKeepsTalking = importedKeepsTalking
  
      rpc ItKeepsReplying = importedKeepsReplying
  
      rpc StreamHellos = importedStreamHellos
  }
  </code></pre>
  
  <p>Is it possible to somehow "compose" services in gRPC proto definitions like that?</p>