The Mobile JSON Wire Protocol

174ae1c2a863b7daf240a86da84671bd?s=47 Jonathan Lipps
September 09, 2015

The Mobile JSON Wire Protocol

The JSON Wire Protocol (JSONWP) is the version of the WebDriver spec currently implemented by all the Selenium clients. It defines an HTTP API that models the basic objects of web automation---sessions, elements, etc. The JSON Wire Protocol is the magic that powers Selenium’s client/server architecture, enables services like Selenium Grid or Sauce Labs to work, and gives you the ability to write your test scripts in any language.

The JSONWP has served Selenium faithfully for a number of years, but the future of automated testing lies beyond the borders of the web browser. Mobile automation is an essential ingredient in any build, and tools like Appium or Selendroid have made it possible to run tests against mobile apps using the JSONWP. The JSONWP’s current incarnation isn’t enough to automate all the new behaviors that mobile apps support, however. Complex gestures, multiple device orientations, airplane mode, and the ability to use both native and web contexts, for example, are all essential to mobile automation.

For this reason the leaders of the Selenium project, in concert with other Selenium-based projects like Appium and Selendroid, met to discuss the future of the JSONWP. We’ve been working on its next version, called the "Mobile JSON Wire Protocol" (MJSONWP). Appium and Selendroid already implement much of the MJSONWP spec. In this talk I’ll dive into the specifics of the MJSONWP extensions, how they relate to the original JSONWP, and how the Selenium clients have begun to implement them.

Finally, I will talk about the future of the MJSONWP and how it’s related to the current and future versions of the WebDriver spec. I’ll share how you can get help with the creation of the MJSONWP, and discuss issues with the authors of the new spec before the API is set in stone. We need the help of everyone who’s involved in mobile automation to come up with the best and most future-proof version of the MJSONWP. Ultimately, your understanding of how Selenium works will be improved, and you’ll have a much better handle on how projects like Appium and Selenium work together to make sure you have the best automation methods available.


Jonathan Lipps

September 09, 2015