我目前有一个esp8266使用找到的示例代码here向Azure发送消息。下面的代码是我尝试使用java库调用arduino上的direct方法。我创建了一个与simplesample_mqtt.c
中定义的模型具有相同属性的对象。然后我调用MethodResult.invoke(deviceId, methodName, responseTimeout, connectTimeout, device);
并传入设备对象,deviceId和我想要调用的方法但是我得到了超时异常。
BackEndApplication.java
package com.microsoft.docs.iothub.samples;
import java.io.IOException;
import java.util.concurrent.TimeUnit;
import com.microsoft.azure.sdk.iot.service.devicetwin.DeviceMethod;
import com.microsoft.azure.sdk.iot.service.devicetwin.MethodResult;
import com.microsoft.azure.sdk.iot.service.exceptions.IotHubException;
public class BackEndApplication {
// Connection string for your IoT Hub
// az iot hub show-connection-string --hub-name {your iot hub name}
public static final String iotHubConnectionString = "HostName=Something.azure-devices.net;SharedAccessKeyName=Owner;SharedAccessKey=jdjdjdjdjdjdjdjdjdjd";
// Device to call direct method on.
public static final String deviceId = "DeviceIdUsedByArduino";
// Name of direct method and payload.
public static final String methodName = "TurnFanOn";
public static final Long responseTimeout = TimeUnit.SECONDS.toSeconds(30);
public static final Long connectTimeout = TimeUnit.SECONDS.toSeconds(5);
public static void main(String[] args) {
try {
System.out.println("Calling direct method...");
ContosoAnemometer device = new ContosoAnemometer();
device.DeviceId = deviceId;
device.WindSpeed = 1;
device.Temperature = 1;
device.Humidity = 1;
// Create a DeviceMethod instance to call a direct method.
DeviceMethod methodClient = DeviceMethod.createFromConnectionString(iotHubConnectionString);
// Call the direct method.
MethodResult result = methodClient.invoke(deviceId, methodName, responseTimeout, connectTimeout, device);
if (result == null) {
throw new IOException("Direct method invoke returns null");
}
// Show the acknowledgement from the device.
System.out.println("Status: " + result.getStatus());
System.out.println("Response: " + result.getPayload());
} catch (IotHubException e) {
System.out.println("IotHubException calling direct method:");
System.out.println(e.getMessage());
} catch (IOException e) {
System.out.println("IOException calling direct method:");
System.out.println(e.getMessage());
}
System.out.println("Done!");
}
}
iot_configs.h
#define IOT_CONFIG_CONNECTION_STRING "HostName=Something.azure-devices.net;DeviceId=DeviceIdUsedByArduino;SharedAccessKey=somthing="
对Arduino的回应
Connected to wifi
Fetching NTP epoch time failed! Waiting 2 seconds to retry.
Fetched NTP epoch time is: 1527899856
IoT Hub SDK for C, version 1.1.29
IoTHubClient accepted the message for delivery
Message Id: 0 Received.
Result Call Back Called! Result is: IOTHUB_CLIENT_CONFIRMATION_OK
异常抛出
Calling direct method...
IotHubException calling direct method:
IoT Hub not found! {"errorCode":404103,"trackingId":"09128374091283749028h-G:5-TimeStamp:06/02/2018 00:39:09","message":"Timed out waiting for device to subscribe.","timestampUtc":"2018-06-02T00:39:09.7655165Z"}
Done!
答案 0 :(得分:0)
请参阅此sample,了解如何运行简单设备方法。 在此示例中,它使用 IoTHubClient_LL_SetDeviceMethodCallback 来设置回调到后端的直接方法。你提到的样本只是为了行动。
<强> [更新]:强>
实际上,Azure-iot-sdk-c序列化程序中的WITH_METHOD和WITH_ACTION之间存在差异。可以通过后端的云到设备消息调用ACTION,而需要在DeviceMethodCallback中处理METHOD。
直接方法是同步的,在超时期后成功或失败(默认值:30秒,可设置为3600秒)。作为该方法的结果,设备可以返回一些消息体,但是该方法不需要这样做。对方法调用的排序或任何并发语义无法保证。直接方法遵循请求 - 响应模式,适用于需要立即确认其结果的通信。
如果要使用METHOD而不是ACTION,则需要使用WITH_METHOD宏在模型中声明函数,并且需要通过 IoTHubClient_LL_SetDeviceMethodCallback 实现设备方法回调处理。