type HeaderField = record { text; text; };

type HttpRequest = record {
  method: text;
  url: text;
  headers: vec HeaderField;
  body: blob;
  certificate_version: opt nat16;
};

type HttpUpdateRequest = record {
  method: text;
  url: text;
  headers: vec HeaderField;
  body: blob;
};

type HttpResponse = record {
  status_code: nat16;
  headers: vec HeaderField;
  body: blob;
  upgrade : opt bool;
  streaming_strategy: opt StreamingStrategy;
};

// Each canister that uses the streaming feature gets to choose their concrete
// type; the HTTP Gateway will treat it as an opaque value that is only fed to
// the callback method

type StreamingToken = record {
  // application-specific type
};

type StreamingCallbackHttpResponse = record {
  body: blob;
  token: opt StreamingToken;
};

type StreamingStrategy = variant {
  Callback: record {
    callback: func (StreamingToken) -> (opt StreamingCallbackHttpResponse) query;
    token: StreamingToken;
  };
};

service : {
  http_request: (request: HttpRequest) -> (HttpResponse) query;
  http_request_update: (request: HttpUpdateRequest) -> (HttpResponse);
}