REST web services are the next great frontier in Drupal development. As more and more devices come online, Drupal's role is changing fast. Producing an HTML page is now just one of many responsibilities that a web application must handle gracefully. Drupal must also serve as the backend to iPhone apps, Android Apps, Video game consoles, high-tech coffee makers, smart watches, smart thermostats, and just about any other internet capable device out there. Drupal is ready for this task—are you?
In this example-heavy talk, I'll give an overview of the different contributed modules and techniques for producing web services in Drupal, and highlight the use-case for each (spoiler alert: the Services module is king). I'll show a number of code samples for custom web services, and talk a bit about my real-world experience building web services for corporate clients. Finally, I'll argue that web services are a massive untapped business opportunity that Drupal shops need to start selling.
The Internet of Things has arrived, and Drupal's role in that brave new world is producing REST services.
#Update:
Here are the slides http://slides.com/mattkorostoff/build-the-internet-of-things/
Here is a video recording of this same talk from DrupalCamp Baltimore: http://mattkorostoff.com/article/building-rest-web-services-with-drupal-7