实时道路数据

实时道路数据可提供所选路线的最新路况和事件动态，支持动态监控和快速响应。此数据与 BigQuery 中定期收集的数据不同，适用于需要及时信息的场景。

这些数据会持续流式传输，包括：行程时长（表示路线上的行驶时间）和速度读取间隔（表示路段密度）。

如需访问实时道路数据，您的合同必须包含实时运营软件包。

创建 Cloud Pub/Sub 订阅

将项目设置为接收实时数据后，系统会为您的项目提供一个专用的 Google Cloud Pub/Sub 主题。您可以在此 Pub/Sub 主题中找到所有已创建路线的实时数据。

以下代码示例展示了主题网址的格式。

projects/maps-platform-roads-management/topics/rmi-roadsinformation-PROJECT_NUMBER

您必须订阅提供给您的 Pub/Sub 主题，才能接收实时数据消息。如需简要了解如何订阅 Cloud Pub/Sub 主题并从中接收消息，请参阅订阅主题。

实时路况数据消息架构

每条实时数据消息都包含以下数据：

• 道路详情，例如 travel_duration 和 speed_reading_intervals。
• 路线标识符，例如 selected_route_id 和 display_name。

每条消息都按照以下 Protobuf 格式发布。

syntax = "proto3";

// Contains the road information like travel duration and speed reading
// intervals for a selected route.
message RoadsInformation {
  message TravelDuration {
    // The duration of travel through the route based on current road conditions.
    float duration_in_seconds = 1;
    // The duration of travel through the route without taking road conditions into consideration.
    float static_duration_in_seconds = 2;
  }
  message Timestamp {
    // Represents seconds of UTC time since Unix epoch
    // 1970-01-01T00:00:00Z. Must be from 0001-01-01T00:00:00Z to
    // 9999-12-31T23:59:59Z inclusive.
    int64 seconds = 1;

    // Non-negative fractions of a second at nanosecond resolution. Negative
    // second values with fractions must still have non-negative nanos values
    // that count forward in time. Must be from 0 to 999,999,999
    // inclusive.
    int32 nanos = 2;
  }
  // Represents the latitude and longitude of a coordinate
  // within speed reading interval.
  message LatLng {
    float latitude = 1;
    float longitude = 2;
  }
  message SpeedReadingInterval {
    // The coordinates on the polyline for the speed reading interval
    repeated LatLng interval_coordinates = 1;

    // Describes the categorized current speed of road conditions. Possible values are:
    // - "NORMAL": Road is flowing smoothly, no slowdown is detected.
    // - "SLOW": Slowdown detected, but no congestion formed.
    // - "TRAFFIC_JAM": Congestion detected.
    string speed = 2;
  }
  // Id for selected_route.
  string selected_route_id = 1;
  // User provided name for the route.
  string display_name = 2;
  // Intervals representing the road density across the route.
  repeated SpeedReadingInterval speed_reading_intervals = 3;
  // Travel time information.
  TravelDuration travel_duration = 4;
  // The time the road data was collected.
  Timestamp retrieval_time = 5;
  // Contains a geojson polyline representing the optimal route determined based
  // on user's input waypoints.
  string route_geometry = 6;
}

使用 Pub/Sub 将路线数据流式传输到 BigQuery

您可以配置 Pub/Sub 订阅，以将道路数据直接流式传输到 BigQuery 表中。这样一来，系统便可实现强大的数据存储功能，并对所提供的路线信息进行强大的分析。在设置此类订阅之前，您需要在 BigQuery 项目中创建合适的数据集和表，以便将数据写入其中。

如需详细了解如何创建写入 BigQuery 的 Pub/Sub 订阅，请参阅将数据流式传输到 BigQuery。

BigQuery 表架构

发布到您的 Pub/Sub 主题的消息（也可以写入您的 BigQuery 表）符合以下架构。创建目标 BigQuery 表时，您应使用此架构，以确保兼容性。

  {
    "mode": "NULLABLE",
    "name": "selected_route_id",
    "type": "STRING",
    "description": "Id for selected_route."
  },
  {
    "mode": "NULLABLE",
    "name": "display_name",
    "type": "STRING",
    "description": "User provided name for the route."
  },
  {
    "fields": [
      {
        "mode": "NULLABLE",
        "name": "speed",
        "type": "STRING",
        "description": "Describes the categorized current speed of traffic. Possible values are: \"NORMAL\": Traffic is flowing smoothly, no slowdown is detected.  \"SLOW\": Slowdown detected, but no traffic jam formed. \"TRAFFIC_JAM\": Traffic jam detected."
      },
      {
        "fields": [
          {
            "mode": "NULLABLE",
            "name": "latitude",
            "type": "NUMERIC"
          },
          {
            "mode": "NULLABLE",
            "name": "longitude",
            "type": "NUMERIC"
          }
        ],
        "mode": "REPEATED",
        "name": "interval_coordinates",
        "type": "RECORD",
        "description": "The geometry for this interval"
      }
    ],
    "mode": "REPEATED",
    "name": "speed_reading_intervals",
    "type": "RECORD",
    "description": "Intervals representing the traffic density across the route."
  },
  {
    "fields": [
      {
        "mode": "NULLABLE",
        "name": "duration_in_seconds",
        "type": "FLOAT",
        "description": "The duration of travel through the route based on current traffic conditions."
      },
      {
        "mode": "NULLABLE",
        "name": "static_duration_in_seconds",
        "type": "FLOAT",
        "description": "The duration of travel through the route without taking traffic conditions into consideration."
      }
    ],
    "mode": "NULLABLE",
    "name": "travel_duration",
    "type": "RECORD",
    "description": "Travel time information."
  },
  {
    "fields": [
      {
        "mode": "NULLABLE",
        "name": "seconds",
        "type": "INTEGER",
        "description": "Represents seconds of UTC time since Unix epoch 1970-01-01T00:00:00Z. Must be from 0001-01-01T00:00:00Z to 9999-12-31T23:59:59Z inclusive."
      },
      {
        "mode": "NULLABLE",
        "name": "nanos",
        "type": "INTEGER",
        "description": "Non-negative fractions of a second at nanosecond resolution. Negative second values with fractions must still have non-negative nanos values that count forward in time. Must be from 0 to 999,999,999 inclusive."
      }
    ],
    "mode": "NULLABLE",
    "name": "retrieval_time",
    "type": "RECORD",
    "description": "The time the traffic data was collected."
  },
  {
    "mode": "NULLABLE",
    "name": "route_geometry",
    "type": "STRING",
    "description": "Contains a geojson polyline representing the optimal route determined based on user's input waypoints"
  }