Edgex的application开发SDK

SDK是围绕“函数管道”的思想构建的。函数管道是按指定顺序处理数据的各种函数的集合。函数管道由配置中的指定触发器执行。toml。管道中的第一个函数被触发管道的事件调用(例如events.Model)。管道中的每个连续调用都将调用前一个函数的返回结果。让我们看一个简单的示例，该示例创建一个管道来过滤特定的设备id，然后将数据转换为XML：

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package main



import (

    "fmt"

    "github.com/edgexfoundry/app-functions-sdk-go/appsdk"

    "github.com/edgexfoundry/app-functions-sdk-go/pkg/transforms"

    "os"

)



func main() {



    // 1) First thing to do is to create an instance of the EdgeX SDK, giving it a service key

    edgexSdk := &appsdk.AppFunctionsSDK{

        ServiceKey: "SimpleFilterXMLApp", // Key used by Registry (Aka Consul)

    }



    // 2) Next, we need to initialize the SDK

    if err := edgexSdk.Initialize(); err != nil {

        edgexSdk.LoggingClient.Error(fmt.Sprintf("SDK initialization failed: %v\n", err))

        os.Exit(-1)

    }



    // 3) Since our FilterByDeviceName Function requires the list of Device Names we would

    // like to search for, we'll go ahead and define that now.

    deviceNames := []string{"Random-Float-Device"}



    // 4) This is our pipeline configuration, the collection of functions to

    // execute every time an event is triggered.

    if err := edgexSdk.SetFunctionsPipeline(

            transforms.NewFilter(deviceNames).FilterByDeviceName, 

            transforms.NewConversion().TransformToXML,

        ); err != nil {

            edgexSdk.LoggingClient.Error(fmt.Sprintf("SDK SetPipeline failed: %v\n", err))

            os.Exit(-1)

        }



    // 5) shows how to access the application's specific configuration settings.

    appSettings := edgexSdk.ApplicationSettings()

    if appSettings != nil {

        appName, ok := appSettings["ApplicationName"]

        if ok {

            edgexSdk.LoggingClient.Info(fmt.Sprintf("%s now running...", appName))

        } else {

            edgexSdk.LoggingClient.Error("ApplicationName application setting not found")

            os.Exit(-1)

        }

    } else {

        edgexSdk.LoggingClient.Error("No application settings found")

        os.Exit(-1)

    }



    // 6) Lastly, we'll go ahead and tell the SDK to "start" and begin listening for events to trigger the pipeline.

    edgexSdk.MakeItRun()

}

上面的示例只是为了演示应用程序的结构。注意，最后一个函数的输出在这个应用程序的任何地方都不可用。您必须提供一个函数，以便使用前一个函数中的数据。让我们继续，并添加以下函数，将输出打印到控制台。

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func printXMLToConsole(edgexcontext *appcontext.Context, params ...interface{}) (bool,interface{}) {

  if len(params) < 1 { 

    // We didn't receive a result

    return false, errors.New("No Data Received")

  }

  println(params[0].(string))

  return true, nil

}

https://github.com/edgexfoundry/ ... pplication-services