Example of creating data schemae using Google's protocol buffers and Facebook's GraphQL Schema Language

directories_model.graphql

# this defines a new field type
scalar HTML

# this defines a new object type
type Institution {
  # the ! denotes a required field
  name: String!
  location: String
}

type Person {
  full_name: String!
  # [] denote a list, as opposed to a single value
  institutions: [Institution]
  biography: HTML
  job_title: String
  photo_url: String
}

type Project {
  title: String!
  description: HTML
  institutions: [Institution]
}

type Scheme {
  title: String!
}

union GrantHolder = [Person] | Project

type Grantee {
  holder: GrantHolder!
  scheme: Scheme!
  award_amount: Float
  year_awarded: Int
}

# this defines our actual public schema, e.g. the types we can use from it
schema {
  grantee: Grantee
  grant_holder: GrantHolder
  person: Person
  scheme: Scheme
  institution: Institution
  project: Project
  html: HTML
}

directories_model.proto

syntax = "proto3";

message HTML {
  string content = 1;
}

message Institution {
  string name = 1;
  string location = 2;
}

message Person {
  string full_name = 1;
  repeated Institution institutions = 2;
  HTML biography = 3;
  string job_title = 4;
  string photo_url = 5;
}

message Project {
  string title = 1;
  string description = 2;
  repeated Institution institutions = 3;
}

message Scheme {
  string title = 1;
}

message Grantee {
  oneof holder {
    Person person = 1;
    Project project = 2;
  }

  Scheme scheme = 3;
  uint32 award_amount = 4;
  uint32 year_awarded = 5;
}

Should Institution (and others) have a required field in the protobuf definitions?

@ephemer - This is proto3 version, which no longer has required or optional qualifiers on the field declarations.