Understanding the Difference Between Protocol and JSON Wire Protocol

Understanding the Difference Between Protocol and JSON Wire Protocol

5 April 2024 Stephan Petzl Leave a comment Tech-Help

Introduction to Protocols

Protocols are the foundation of data exchange over networks. They define a set of rules that must be adhered to for the successful transmission and reception of data. For instance, when a browser communicates with a server, it must create an HTTP request following the HTTP protocol specifications. The server, in turn, processes this request and responds per the same specifications, ensuring a standardized communication process.

Defining JSON Wire Protocol

JSON Wire Protocol, on the other hand, is a specific protocol that was utilized for client-server communication within the context of web automation. It was a RESTful web service that used JSON over HTTP to communicate between a client and a server. This protocol was designed to map automation commands, like clicking or typing, into Selenium or Appium commands, which would then be sent as HTTP requests and receive HTTP responses.

The Role of JSON in Communication

JSON (JavaScript Object Notation) is a lightweight data interchange format that is easy for humans to read and write and easy for machines to parse and generate. It is a text format that is completely language-independent but uses conventions familiar to programmers of the C-family of languages. JSON has become a widely accepted standard for data exchange due to its simplicity and ease of use.

Example of a JSON Object:

  "Student": {
    "FirstName": "John",
    "LastName": "Doe",
    "IdNumber": "12345",
    "City": "New York",
    "EmailID": "john.doe@example.com"

Benefits of Using JSON Wire Protocol

  • Enables writing tests in any programming language.
  • Allows tests to be run on cloud services or local Selenium Grid setups.
  • Supports the creation of different browser-specific drivers using the same standards.

The Transition to the WebDriver W3C Standard

The JSON Wire Protocol has now been superseded by the WebDriver W3C Living Document, which is the new standard for web automation. The WebDriver protocol is organized into commands, with each HTTP request representing a single command that results in a single HTTP response. The communication process is defined by a series of actions that the remote end (an HTTP server) takes upon receiving a command from the client.


The evolution from JSON Wire Protocol to the WebDriver W3C standard marks a significant advancement in web automation protocols. Understanding these protocols and their application is crucial for developers and testers who aim to leverage automation tools like Selenium effectively.

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