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Mastering Internet of Things

You're reading from   Mastering Internet of Things Design and create your own IoT applications using Raspberry Pi 3

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Product type Paperback
Published in Mar 2018
Publisher Packt
ISBN-13 9781788397483
Length 410 pages
Edition 1st Edition
Concepts
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Author (1):
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Peter Waher Peter Waher
Author Profile Icon Peter Waher
Peter Waher
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Toc

Table of Contents (18) Chapters Close

Preface 1. Preparing Our First Raspberry Pi Project 2. Creating a Sensor to Measure Ambient Light FREE CHAPTER 3. Creating an Actuator for Controlling Illumination 4. Publishing Information Using MQTT 5. Publishing Data Using HTTP 6. Creating Web Pages for Your Devices 7. Communicating More Efficiently Using CoAP 8. Interoperability 9. Social Interaction with Your Devices Using XMPP 10. The Controller 11. Product Life Cycle 12. Concentrators and Bridges 13. Using an Internet of Things Service Platform 14. IoT Harmonization 15. Security for the Internet of Things 16. Privacy 17. Other Books You May Enjoy

Adding dynamic asynchronous resources

The actuator project (ActuatorHttp in the GitHub repository) also needs a /Momentary resource that returns the current state of the output in XML or JSON. The implementation is similar to that of the sensor, so it's straightforward to do. But we also need a way to control the output. We do that by adding a /Set resource. Since we will call asynchronous methods, we take this opportunity to add this resource as an asynchronous POST resource. This means we must explicitly handle errors and exceptions, as well as explicitly sending the response when it is ready:

this.httpServer.Register("/Set", null, async (req, resp) => 
{ 
   try 
   { 
         // Process resource here 
 
         resp.SendResponse();    // Sends response. 
   } 
   catch (Exception ex) 
   { 
         resp.SendResponse(ex);  // Sends error response....
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