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App Services Configuration

Overview

Before you can use the Application Service to export data you need to configure it for the endpoint you want to use.

The Application Service is configured using a TOML file which is passed to the service when it starts. The toml file contains a collection of functions to help process the data. These functions can specify what endpoint to send the data to, which data to process, how to transform the data and so on.

The functions will process the messages in the order you specify. This is known as a “Functions Pipeline”. The first function in the service is a trigger, this starts the processing. It could be something like a message landing in the watched message queue.

Edge Xpert supports all the functions provided by the EdgeX Foundry’s Configurable Application Service. The available functions are defined in the Application Service SDK.

Edge Xpert also expands the export capabilities by offering additional built-in functions you can specify in your functions pipeline. For more information see Application Service Built-in Functions

Application Services also support multiple pipelines to export device data to, or receive messages from, the Cloud. For further information on configuring multiple pipelines, see Multiple Pipelines Example

For general guidance about preparing the Application Service configuration please refer to the EdgeX Foundry documentation. The format of the configuration toml file should comply with the format defined here.

Edge Xpert provides example configuration files for all the supported application files. These are found in the /usr/share/edgexpert/examples/app-configurable directory.

You can install multiple Application Service containers, each with a different pipeline function for different purposes. For example, you could deploy one application service to export temperature data to the Azure IoT Hub for further processing and another to export humidity data to Kafka. The two Application Services run as independent docker containers based on the same Edge Xpert image.

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