src/trellis/proto/content_id.proto

// Copyright 2020 The Feed Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//      http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

syntax = "proto2";

package feedwire;

option optimize_for=LITE_RUNTIME;

// An identifier for a piece of content served by Now or delivered to the Now
// client(s).
// See [INTERNAL LINK] for the design of this feature.
// ContentId comprises a unique key for all content. The client will never have
// more than one piece of content with the same ContentID.
message ContentId {
  optional string content_domain = 1;

  // The type of content this represents. Generally, this is somewhat redundant,
  // as this ContentId proto will be embedded within a particular parent proto
  // that implies its type. It is repeated here for the purpose of making
  // ContentId fully self-contained, able to completely specify a piece of
  // content's ID without additional context.
  // Since Type is one of the components of content's uniqueness, it is safe
  // and reasonable for two related pieces of content with different types
  // (e.g. a card and its attached notification) to share the same id and
  // content_domain, and to differ only in their type.  However, Type is **not**
  // included when determing if two ContentIds are equivalent.
  enum Type {
    // Undefined type - DO NOT USE
    TYPE_UNDEFINED = 0;
    CARD = 1;
    CLUSTER = 3;
    // A feature, which is the indivisible unit of Feed content.
    FEATURE = 4;
    // A ContentId used only for identifying nodes in a tree structure.
    TREE_STRUCTURE = 7;
    // A ContentId for a collection.
    COLLECTION = 8;
    // A ContentId for a token, e.g. a NextPage token.
    TOKEN = 9;

    reserved 2, 5, 6;
  }
  // The type of content this represents
  optional Type type = 2;

  optional fixed64 id = 3;
}