针对实时出价的 Chrome Topics 实验

作为 Privacy Sandbox 的一部分，Chrome 提出了实验性 Topics API。Topics API 为网页上的第三方调用方（包括广告技术提供商）提供网页访问者当前可能感兴趣的粗略广告主题。这些主题可以补充当前网页的上下文信息，并且有助于支持针对用户兴趣投放广告。

Topics API 实验可供实时出价合作伙伴在出价请求中使用。填写申请表单，加入 Topics API 实验。如需了解详情，请与您的客户经理联系。

出价请求表示法

Google Authorized Buyers 协议

主题在 BidRequest 消息的 topics 字段中表示。此字段在该协议的公开 Beta 版中提供。

定义如下：

  // Experimental field; subject to change.
  // A coarse-grained topic that a website visitor might currently be interested
  // in based on recent browsing activity. See
  // https://developer.chrome.com/docs/privacy-sandbox/topics/ and/or
  // https://privacysandbox.com/intl/en_us/proposals/topics/ for more
  // information about the Topics API. Reach out to your account manager to
  // participate in the Topics API experiment.
  message Topic {
    // The value of a topic ID. A numerical identifier corresponding to a
    // coarse-grained advertising topic. See
    // https://github.com/patcg-individual-drafts/topics/blob/main/taxonomy_v1.md
    // for a list of topics in the initial taxonomy.
    optional int32 id = 1;
    // The version of the advertising taxonomy which defines the semantic
    // meaning of each topic ID for the topics, for example "v1".
    optional string taxonomy_version = 2;
    // The version of the classifier used by the browser to map hostnames to
    // topic IDs in the taxonomy.
    optional string classifier_version = 3;
  }

  // The list of topics that a website visitor might currently be interested in
  // inferred by the browser based on recent browsing activity. See
  // https://developer.chrome.com/docs/privacy-sandbox/topics/ and/or
  // https://privacysandbox.com/intl/en_us/proposals/topics/ for more
  // information about Topics API.
  repeated Topic topics = 74;

OpenRTB 协议

主题在 OpenRTB BidRequest.user.data 消息中表示为段。

字段	类型	说明
Data.ext.segtax	Integer	集中注册的分类的 ID。对于主题，这是广告分类的一个版本，定义了每个主题 ID 的语义含义。600 用于 Chrome 的 Topics 初始分类。
Data.ext.segclass	字符串	等同于 classifier_version。
Data.segment.id	字符串	相当于转换为字符串的 id。

Data.ext 是 BidRequest.user.data 消息的扩展。此扩展程序可在该协议的公开 Beta 版中使用。

定义如下：

// Ad Exchange extensions for the Data object.
message DataExt {
  // The ID for a taxonomy that is registered centrally. Used to define the
  // namespace and semantic meaning of the segment IDs. See
  // https://github.com/InteractiveAdvertisingBureau/openrtb/blob/master/extensions/community_extensions/segtax.md#enumeration-of-taxonomies
  // for the enumeration of the taxonomies that this value can take. Currently
  // only Chrome Topics API taxonomy (segtax=600) is supported.
  optional int32 segtax = 1;

  // The version of the classifier which produced the segment IDs within the
  // taxonomy. For example, in the case of Chrome Topics API (segtax=600), this
  // is the version of the classifier used by the browser to map hostnames to
  // topics in the taxonomy.
  optional string segclass = 2;
}

示例

以下示例展示了 Google Authorized Buyers 和 OpenRTB 协议如何表示 Chrome Topics API 返回的主题。

Chrome Topics API 响应，由 document.browsingTopics() 返回：

[
  {
    "modelVersion": "classifier_v1",
    "taxonomyVersion": "taxonomy_v1",
    "topic": 3
  },
  {
    "modelVersion": "classifier_v1",
    "taxonomyVersion": "taxonomy_v1",
    "topic": 44
  },
  {
    "modelVersion": "classifier_v1",
    "taxonomyVersion": "taxonomy_v1",
    "topic": 59
  }
]

Google Authorized Buyers 协议 BidRequest：

topics {
  id: 3
  taxonomy_version: "taxonomy_v1"
  classifier_version: "classifier_v1"
}
topics {
  id: 44
  taxonomy_version: "taxonomy_v1"
  classifier_version: "classifier_v1"
}
topics {
  id: 59
  taxonomy_version: "taxonomy_v1"
  classifier_version: "classifier_v1"
}

OpenRTB BidRequest：

{
  "user": {
    "data": [
      {
        "ext": {
          "segtax": 600,
          "segclass": "classifier_v1"
        },
        "segment": [
          { "id": "3" },
          { "id": "44" },
          { "id": "59" }
        ]
      }
    ]
  }
}

在上述示例中，taxonomy_version 表示使用了 semantic_v1 映射。根据分类，这些主题 ID 对应于以下主题：

主题 ID	主题值
3	/艺术与娱乐/漫画
44	/艺术与娱乐/歌剧
59	/汽车与交通工具/经典车

可用性

出价请求中是否包含主题会受现有隐私保护和控制机制的约束。例如，如果用户选择停用个性化广告或非个性化广告广告资源，则无法使用主题。