Simple CBOR Filter Application Service

This simple-cbor-filter Application Service demonstrates end to end CBOR integration. It depends on the device-simple example device service from Device SDK Go to generate CBOR encode events.

This simple-cbor-filter Application Service uses two application functions:

• Built in Filter by Value Descriptor function to filter just for the Image values.
• Custom Process Images function which re-encodes the binary value as an Image and prints stats about the image to the console.

The end result from this application service is that it shows that the Application Functions SDK is un-marshaling CBOR encode events sent from the device-simple device service. These event can be processed by functions similar to JSON encoded events. The only difference is the CBOR encode events have the BinaryValue field set, while the JSON encoded events have the Value field set.

Follow these steps to run the end to end CBOR demonstration

1. Start EdgeX Mongo

   • clone developer-scripts repo
   • cd compose-files folder
   • run "docker-compose up mongo"
     • This uses the default compose file to start the EdgeX Mongo service which exposes it's port to apps running on localhost

2. Run EdgeX cores services

   • Clone edgex-go repo
   • Checkout the edinburgh branch
   • run "make build"
   • run "make run"
     • This starts all the required EdgeX services

3. Run simple-cbor-filter example

   • Clone app-functions-sdk-go repo
   • Checkout the edinburgh branch
   • run "make build"
   • cd to examples/simple-cbor-filter folder
   • run "./simple-cbor-filter"

4. Run device-simple device service

   • Clone https://github.com/edgexfoundry/device-sdk-go repo

   • Checkout the edinburgh branch

   • run "make build"

   • cd to example/cmd/device-simple folder

   • run "./device-simple"

     This sample device service will send a png (light bulb on) or jpeg (light bulb off) image every 30 seconds. The image it sends depends on the value of its switch resource, which is off (false) by default.

5. Now data will be flowing due to auto-events configured in device-simple.

   • In the terminal that you ran simple-cbor-filter you will see the messages like this:

     Received Image from Device: Simple-Device01, ReadingName: Image, Image Type: jpeg, Image Size: (1000,1307), Color in middle: {0 128 128}
     

     Note that the image received is a jpeg since the switch resource in device-simple is set to off (false)

   • The switch resource can be queried and changed using commands sent via PostMan by doing the following:

     1. Start PostMan

     2. Load the postman collection from the simple-cbor-filter example

        Device Simple Switch commands.postman_collection.json

     3. This collection contains 3 commands

        • Get Switch status
        • Turn Switch on
        • Turn Switch off

     4. Run Turn Switch on

   • Now see how the simple-cbor-filter output has changed

     Received Image from Device: Simple-Device01, ReadingName: Image, Image Type: png, Image Size: (1000,1307), Color in middle: {255 246 0 255}