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App Service Configurable

App-Service-Configurable is provided as an easy way to get started with processing data flowing through EdgeX. This service leverages the App Functions SDK and provides a way for developers to use configuration instead of having to compile standalone services to utilize built in functions in the SDK. For a full list of supported/built-in functions view the README located in the App Functions SDK repository.

Getting Started

To get started with the configurable app service, you'll want to start by determining which functions are required in your pipeline. Using a simple example. let's assume you wish to use the following functions from the SDK:

  1. FilterByDeviceName - to filter events for a specific device.
  2. TransformToXML - to transform the data to XML
  3. HTTPPost - to send the data to an HTTP endpoint that takes our XML data
  4. MarkAsPushed - to call Core Data API to mark the event as having been pushed

Once the functions have been identified, we'll go ahead and build out the configuration in the configuration.toml file under the [Writable.Pipeline] section:

  LogLevel = 'DEBUG'
    ExecutionOrder = "FilterByDeviceName,TransformToXML,HTTPPost,MarkAsPushed"
        FilterValues = "Random-Float-Device,Random-Integer-Device"
        url = ""
        mimeType = "" #OPTIONAL - default application/json

The first line of note is ExecutionOrder = "FilterByDeviceName,TransformToXML,HTTPPost,MarkAsPushed". This specifies the order in which to execute your functions. Each function specified here must also be placed in the [Writeable.Pipeline.Functions] section.

Next, each function and its required information is listed. Each function typically has associated Parameters that must be configured to properly execute the function as designated by [Writable.Pipeline.Functions.{FunctionName}.Parameters]. Knowing which parameters are required for each function, can be referenced by taking a look at the documentation located here. In a few cases, such as TransformToXML, TransformToJSON, or SetOutputData, there are no parameters required.

Note: By default, the configuration provided is set to use MessageBus as a trigger from CoreData. This means you must have EdgeX Running with devices sending data in order to trigger the pipeline. You can also change the trigger to be HTTP. For more on triggers, view the documentation here.

That's it! Now we can run/deploy this service and the functions pipeline will process the data with functions we've defined.

Deploying Multiple Instances

What if I want to deploy multiple pipelines using this service?

It not uncommon to have different sets of function pipelines that need to be deployed. This is where --profiles comes in handy. You can create different "profile" folders inside the /res directory with different configurations. This is typically used in other EdgeX services for having a separate configuration for Docker based deployments and native deployments. Since the pipeline is specified in the configuration.toml file, we can use this as a way to run the app-service-configurable application with different profiles by specifying the "--profile=http-export" and "--confdir=/res" as command line options when deploying. If running with Registry enabled, the service key used will be AppService-[profile name], e.g AppService-http-export when using --profile option or just AppService if not using the --profile option.

Input Data Not An EdgeX Event

What if my input data isn't an EdgeX Event ?

The default TargetType for data flowing into the functions pipeline is an EdgeX event. There are cases when this incoming data might not be an EdgeX event. In these cases the Pipeline can be configured using UseTargetTypeOfByteArray=true to set the TargetType to be a byte array, i.e. byte[]. The first function in the pipeline must then be one that can handle the byte[]data. The compression, encryption and export functions are examples of pipeline functions that will take input data that is byte[]. Here is an example of how to configure the functions pipeline to compress, encrypt and then export the byte[] data via HTTP.

  LogLevel = 'DEBUG'
    UseTargetTypeOfByteArray = true
    ExecutionOrder = "CompressWithGZIP, EncryptWithAES, HTTPPost"
        Key = "aquqweoruqwpeoruqwpoeruqwpoierupqoweiurpoqwiuerpqowieurqpowieurpoqiweuroipwqure"
        InitVector = "123456789012345678901234567890"
        url = ""

If along with this pipeline configuration, you also configured the Binding to be http trigger, you could then send any data to the app-service-configurable' s /api/v1/trigger endpoint and have it compressed, encrypted and sent to your configured URL above.


Environment Variable Overrides For Docker

App Service Configurable no longer has docker specific profiles. It now relies on environment variable overrides in the docker compose files for the docker specific differences. The following environment settings are required in the compose files when using App Service Configurable.

edgex_registry: consul://edgex-core-consul:8500
edgex_profile : [target profile]
edgex_service : http://[service name]:[port]
Service_Host : [service name]
Clients_CoreData_Host: edgex-core-data
Clients_Logging_Host : edgex-support-logging
Logging_EnableRemote: "true"
Database_Host : edgex-mongo
Database_Username : appservice
Database_Password : password

The following is an example docker compose entry for App Service Configurable:

    image: edgexfoundry/docker-app-service-configurable:1.1.0
      edgex_registry: consul://edgex-core-consul:8500
      edgex_service: http://edgex-app-service-configurable-rules:48096
      edgex_profile: rules-engine
      Service_Host: edgex-app-service-configurable-rules
      Clients_CoreData_Host: edgex-core-data
      Clients_Logging_Host : edgex-support-logging
      Logging_EnableRemote: "true"      
      MessageBus_SubscribeHost_Host: edgex-core-data
      - "48096:48096"
    container_name: edgex-app-service-configurable-rules
    hostname: edgex-app-service-configurable-rules
          - edgex-app-service-configurable-rules
      - data
      - command

Note: App Service Configurable is designed to be run multiple times each with different profiles. This is why in the above example the name edgex-app-service-configurable-rules is used for the instance running the rules-engine profile.

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