> ## Documentation Index > Fetch the complete documentation index at: https://dragonwingdocs.qualcomm.com/llms.txt > Use this file to discover all available pages before exploring further. # 使用 QSH 客户端 API 开发应用程序 `SessionClient` 示例应用程序展示了如何使用 QSH 客户端 API 开发应用程序。默认情况下，此示例应用程序构建在设备上的 `/usr/bin` 目录中。有关完整的代码示例，请参阅 `/build-qcom-wayland/workspace/sources/sensinghub/sensing-hub/examples/SessionClient/SessionClient.cpp` 文件。 下图显示了流式传输加速度计传感器的调用流程以及 QSH 客户端 API 的使用方法。
图：流式传输指定传感器的调用流程

图：流式传输指定传感器的调用流程

在此示例中，客户端应用程序可以针对 SUID 查询、属性查询和流式传输活动使用不同的传感器会话。它也可以对所有活动使用同一个会话；但是，必须妥善处理同步。 客户端应用程序可以向 aDSP 发送各种请求，如下所示： 1. SUID 查询，检索指定传感器的 SUID： a. 通过使用新的 `sessionFactory()` 类调用 `getSession()` API 来创建 SUID 接口。请求 SUID 是任何用例中获取所请求数据类型 SUID 的第一个也是最重要的请求。 ``` /* Create a new ISession for UID discovery */ sessionFactory* factory = new sessionFactory(); if(nullptr == factory){ printf("failed to create factory instance"); return false; } ISession* suidSession = factory->getSession(); if(nullptr == suidSession){ printf("failed to create uid session"); return false; } ``` b. 通过调用 `open()` API 打开已创建的会话接口。 ``` /* Open the suidSession */ int ret = suidSession->open(); if(-1 == ret){ printf("failed to open ISession for uid query"); return false; } ``` c. 通过调用 `setCallBacks()` API 设置回调，并处理 SUID 活动的响应、事件或错误。 ``` /* Set callbacks for the session for 'uid' */ ret = suidSession->setCallBacks(uid, suidResp, nullptr, suidEvent); if(-1 == ret) printf("all callbacks are null, no need to register it"); ``` d. 通过调用 `sendRequest()` API，创建并发送针对指定数据类型 SUID 的 Pb 编码请求消息。 ``` /* * Create SUID request message * (Please refer sns_client.proto and sns_suid.proto for more details) * */ string pb_req_encoded = ""; sns_suid_req pb_suid_req; pb_suid_req.set_data_type(sensorName); pb_suid_req.set_register_updates(true); sns_client_request_msg pb_req_msg; pb_req_msg.set_msg_id(SNS_SUID_MSGID_SNS_SUID_REQ); string pb_req_msg_encoded; pb_req_msg.SerializeToString(&pb_req_msg_encoded); /* send proto encoded message to sensing-hub using the opened session */ unique_lock respLock(respMutex); ret = suidSession->sendRequest(uid, pb_req_msg_encoded); if(0 != ret){ printf("Error in sending uid discovery request"); return false; } ``` e. 在收到所请求数据类型的 SUID 事件后，通过调用 `close()` API 关闭会话并将其删除。 ``` /* Close and delete the session once SUIDs are received */ suidSession->close(); delete suidSession; delete factory; ``` 2. 属性请求，检索指定传感器的属性： a. 通过使用新的 `sessionFactory()` 类调用 `getSession()` 来创建属性接口会话。请求属性对于获取任何用例中所请求数据类型的能力非常重要。 ``` /* Create a new ISession for attribute query */ sessionFactory* factory = new sessionFactory(); if(nullptr == factory){ printf("failed to create factory instance"); return false; } ISession* attributeSession = factory->getSession(); if(nullptr == attributeSession){ printf("failed to create attribute session"); return false; } ``` b. 通过调用 `open()` API 打开已创建的会话接口。 ``` /* open the attributeSession session */ int ret = attributeSession->open(); if(-1 == ret){ printf("failed to open ISession for attribute query"); return false; ``` c. 通过调用 `setCallBacks()` 设置回调，并处理属性活动的响应、事件或错误。 ``` for (const suid& uid : suidList) { /* set callbacks for the session for 'uid' */ int ret = attributeSession->setCallBacks(uid, attributeResp, nullptr, attributeEvent); if(-1 == ret) printf("all callbacks are null, no need to register it"); ``` d. 通过调用 `sendRequest()` API，创建并发送针对指定数据类型属性的 Pb 编码配置请求。 ``` /* create pb-encoded config request message to be sent for attribute query */ sns_client_request_msg pb_req_msg; pb_req_msg.set_msg_id(SNS_STD_MSGID_SNS_STD_ATTR_REQ); pb_req_msg.mutable_request()->clear_payload(); pb_req_msg.mutable_suid()->set_suid_high(uid.high); /* send proto encoded message to sensing-hub using the opened session */ unique_lock respLock(respMutex); ret = attributeSession->sendRequest(uid, pb_req_msg_encoded); ``` e. 在收到所请求数据类型的属性事件后，通过调用 `close()` API 关闭会话。 ``` /* close and delete the session once all attributes are received */ attributeSession->close(); delete attributeSession; delete factory; ``` 3. 传感器流式传输，流式传输传感器并接收数据事件： a. 通过使用新的 `sessionFactory()` 类调用 `getSession()` 来创建用于流式传输传感器的接口会话。在这里，请求传感器数据是任何用例中所请求数据类型的最后阶段。 ``` ``sessionFactory()class. /* create a new ISession for streaming activity */ sessionFactory* factory = new sessionFactory(); if(nullptr == factory){ printf("failed to create factory instance"); return false; } ISession* streamingSession = factory->getSession(); if(nullptr == streamingSession){ printf("failed to create streaming session"); return false; } ``` b. 通过调用 `open()` API 打开已创建的会话接口。 ``` /* open the streamingSession session */ int ret = streamingSession->open(); if(-1 == ret){ printf("failed to open ISession for attribute query"); return false; ``` c. 通过调用 `setCallBacks()` 设置回调，并处理流式传输活动的响应、事件或错误。 ``` for (const suid& uid : suidList){ /* set callbacks for the session for 'uid' */ int ret = streamingSession->setCallBacks(uid, dataResp, dataError, dataEvent); if(-1 == ret) printf("all callbacks are null, no need to register it"); ``` d. 通过调用 `sendRequest()` API，创建并发送针对指定数据类型传感器流式传输的 Pb 编码配置请求，最终启用所请求的传感器。 ``` /* create pb-encoded config request message to be sent for streaming request */ string pb_req_encoded = ""; sns_std_sensor_config pb_stream_cfg; pb_stream_cfg.set_sample_rate(sampleRate); pb_stream_cfg.SerializeToString(&pb_req_encoded); sns_client_request_msg pb_req_msg; pb_req_msg.mutable_request()->mutable_batching()->set_batch_period(batchPeriod); pb_req_msg.set_msg_id(SNS_STD_SENSOR_MSGID_SNS_STD_SENSOR_CONFIG); /* send proto encoded message to sensing-hub using the opened session */ unique_lock respLock(respMutex); ret = streamingSession->sendRequest(uid, pb_req_msg_encoded); ``` e. 在事件回调中处理样本，并等待指定的测试持续时间。 ``` void handle_event_cb(const uint8_t *data, size_t size, uint64_t time_stamp){ if(true == deletion_started){ printf("\nEvent coming when deletion of qmi connection started"); return; } sns_client_event_msg pb_event_msg; /* Parse the pb encoded event */ pb_event_msg.ParseFromArray(data, size); /* Iterate over all events in the message */ for (int i = 0; i < pb_event_msg.events_size(); i++) { auto& pb_event = pb_event_msg.events(i); } ``` 4. 停止传感器流式传输客户端，通过发送禁用请求来停止流式传输： a. 调用 `sendRequest()` API。 ``` pb_req_msg.set_msg_id(SNS_CLIENT_MSGID_SNS_CLIENT_DISABLE_REQ); pb_req_msg.mutable_suid()->set_suid_high(uid.high); pb_req_msg.mutable_suid()->set_suid_low(uid.low); /* send disable request to sensing-hub */ int ret = streamingSession->sendRequest(uid, pb_req_msg_encoded); ``` b. 在收到所请求数据类型的流式传输事件后，通过调用 `close()` API 关闭会话。 ``` /* close and delete the streamingSession */ streamingSession->close(); delete streamingSession; delete factory; ``` 以下代码片段显示了 `SessionClient` 示例应用程序的输出。它以 10 Hz 的采样率和 2 秒的批处理周期启用加速度计传感器，持续 10 秒，并打印接收到的传感器事件。 ``` root@qcm6490:~# SessionClient Streaming configuration is as follows : Sensor name : accel Sample rate : 10 Hz Batch period : 2 sec Test duration : 10 sec SUID discovery response received. Received SUIDs for accel, number of SUIDs received = 1 SUID received - suid_low=6360260105974108950 suid_high=7037810611998542250 Sensor suid list created requesting attributes for - suid_low=6360260105974108950 suid_high=7037810611998542250 Attribute query response received. Attributes for - suid_low=6360260105974108950 suid_high=7037810611998542250 are: attribute count 0 and values are: attr_id: 16 sint: 0 attribute count 1 and values are: attr_id: 9 sint: 50sint: 240sint: 240 attribute count 2 and values are: attr_id: 12 std: LPM std: NORMAL std: HIGH_PERF attribute count 3 and values are: attr_id: 5 std: sns_accel.proto attribute count 4 and values are: attr_id: 0 std: icm4x6xx attribute count 5 and values are: attr_id: 1 std: TDK-Invensense attribute count 6 and values are: attr_id: 26 boolean 1 attribute count 7 and values are: attr_id: 17 boolean 0 attribute count 8 and values are: attr_id: 10 sint: 6 attribute count 9 and values are: attr_id: 15 sint: 16 attribute count 10 and values are: attr_id: 21 boolean 1 attribute count 11 and values are: attr_id: 22 sint: 3sint: 2sint: 1 attribute count 12 and values are: attr_id: 2 std: accel attribute count 13 and values are: attr_id: 4 sint: 82179 attribute count 14 and values are: attr_id: 13 boolean 1 attribute count 15 and values are: attr_id: 14 boolean 0 attribute count 16 and values are: attr_id: 18 sint: 0 attribute count 17 and values are: attr_id: 20 flt: 0.000000 flt: 0.000000 flt: 0.000000 flt: 0.000000 flt: 0.000000 flt: 0.000000flt: 0.000000 flt: 0.000000 flt: 0.000000 flt: 0.000000 flt: 0.000000 flt: 0.000000 attribute count 18 and values are: attr_id: 19 sint: 0 attribute count 19 and values are: attr_id: 11 attribute count 20 and values are: attr_id: 7 flt: 0.000019 flt: 0.000037 flt: 0.000075 flt: 0.000150 flt: 0.000299 attribute count 21 and values are: attr_id: 24 attribute count 22 and values are: attr_id: 23 flt: 0.000299 attribute count 23 and values are: attr_id: 6 flt: 12.500000 flt: 25.000000 flt: 50.000000 flt: 100.000000 flt: 200.000000 flt: 500.000000 attribute count 24 and values are: attr_id: 25 flt: 1000.000000 flt: 2000.000000 attribute count 25 and values are: attr_id: 8 sint: 80 attribute count 26 and values are: attr_id: 3 boolean 1 Attributes for all SUIDs received Streaming started sending request for - suid_low=6360260105974108950 suid_high=7037810611998542250 Data request response received. Received re-configuration event Cal event packet received Received Samples: [0.347159], [-0.181959], [9.450213], Received Samples: [0.102951], [-0.183156], [9.545981], Received Samples: [0.096965], [-0.189142], [9.550770], Received Samples: [0.092177], [-0.192733], [9.541193], Received Samples: [0.090980], [-0.183156], [9.555558], Received Samples: [0.093374], [-0.185551], [9.555558], Received Samples: [0.108936], [-0.184354], [9.541193], Received Samples: [0.098162], [-0.185551], [9.565135], Received Samples: [0.095768], [-0.185551], [9.550770], Received Samples: [0.100556], [-0.193930], [9.550770], Received Samples: [0.092177], [-0.186748], [9.550770], Received Samples: [0.094571], [-0.199916], [9.541193], Received Samples: [0.105345], [-0.199916], [9.550770], Received Samples: [0.098162], [-0.185551], [9.550770], ``` 有关常见问题的故障排查，请参阅"调试"。 有关更多信息，请参阅 [QSH 直接通道 API 工作流](https://docs.qualcomm.com/doc/80-80023-7A/topic/qsh_direct_channel_api_workflow.html)。