harmony 鸿蒙Service Overview

2022-08-09
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Service Overview

Introduction

The pan-sensor service subsystem provides a lightweight sensor service framework. You can call APIs offered by this framework to query the sensor list, enable or disable a sensor, and subscribe to or unsubscribe from sensor data. The following figure shows the architecture of the lightweight sensor framework.

Figure 1 Sensor service framework

Sensor API: provides APIs for performing basic operations on sensors, including querying the sensor list, subscribing to or unsubscribing from sensor data, and executing control commands. This module makes application development simpler.
Sensor Framework: manages sensor data subscription, creates and destroys data channels, and implements communication with the Sensor Service module.
Sensor Service: interacts with the HDF module to receive, parse, and distribute data, manages sensors on hardware and sensor data reporting, and controls sensor permissions.

Available APIs

Table 1 APIs of the sensor framework

API	Description	Parameter
int32_t GetAllSensors( SensorInfo *sensorIn fo, int32_t count)	Obtains information about all sensors in the system. Return value: Returns 0 if the information is obtained; returns a non-zero value otherwise.	sensorInfo (not NULL): information about all sensors in the system count (not NULL): total number of sensors in the system
int32_t SubscribeSensor (int32_t sensorTypeId, SensorUser *user)	Subscribes to sensor data. The system will report the obtained sensor data to the subscriber. Return value: Returns 0 if the subscription is successful; returns a non-zero value otherwise.	sensorTypeId: ID of a sensor type user (not NULL): sensor subscriber that requests sensor data. A subscriber can obtain data from only one sensor.
int32_t UnsubscribeSensor (int32_t sensorTypeId, SensorUser *user)	Unsubscribes from sensor data. The system will no longer report sensor data to the subscriber. Return value: Returns 0 if the sensor data reporting mode is successfully set; returns a non-zero value otherwise.	sensorTypeId: ID of a sensor type user (not NULL): sensor subscriber that requests sensor data. A subscriber can obtain data from only one sensor.
int32_t SetBatch(int32_t sensorTypeId, SensorUser *user, int64_t samplingInterval, int64_t reportInterval)	Sets the data sampling interval and data reporting interval for the specified sensor. Return value: Returns 0 if the sensor data reporting mode is successfully set; returns a non-zero value otherwise.	sensorTypeId: ID of a sensor type user (not NULL): sensor subscriber that requests sensor data. A subscriber can obtain data from only one sensor. samplingInterval: sensor data sampling interval, in nanoseconds reportInterval: sensor data reporting interval, in nanoseconds
int32_t ActivateSensor(int32_t sensorTypeId, SensorUser *user)	Enables the specified sensor that has been subscribed to. Return value: Returns 0 if the sensor data reporting mode is successfully set; returns a non-zero value otherwise.	sensorTypeId: ID of a sensor type user (not NULL): sensor subscriber that requests sensor data. A subscriber can obtain data from only one sensor.
int32_t DeactivateSensor(int32_t sensor TypeId, SensorUser *user)	Disables an enabled sensor. Return value: Returns 0 if the sensor data reporting mode is successfully set; returns a non-zero value otherwise.	sensorTypeId: ID of a sensor type user (not NULL): sensor subscriber that requests sensor data. A subscriber can obtain data from only one sensor.
int32_t SetMode(int32_t sensorTypeId, SensorUser *user, int32_t mode)	Sets the data reporting mode for the specified sensor. Return value: Returns 0 if the sensor data reporting mode is successfully set; returns a non-zero value otherwise.	sensorTypeId: ID of a sensor type user (not NULL): sensor subscriber that requests sensor data. A subscriber can obtain data from only one sensor. mode: data reporting mode of the sensor