Python Selenium Architecture

Source: Dev.to

High Level Selenium Architecture

Selenium is a tool to automate web‑based and mobile‑based applications.
For web‑based applications Selenium includes built‑in drivers to communicate with browsers. For mobile applications, Selenium requires an additional source called Appium.

Components

1. Language Binding
   This is where automation code is written. Selenium supports languages such as Java, Python, C#, etc. The binding converts code into WebDriver commands and acts as an interface between user code and Selenium.

2. Browser Drivers
   The middle layer that connects the code to the browser. Examples: ChromeDriver, EdgeDriver, SafariDriver, …

3. Browsers
   The final execution happens here. Examples: Chrome, Edge, Safari, …

Internal Selenium Architecture

WebDriver Class

The main entry point in Selenium.

from selenium import webdriver

driver = webdriver.Chrome()

It initializes the browser session and sends commands to the Remote WebDriver.

Remote WebDriver

The core component of Selenium. It receives commands from the WebDriver class, converts them to JSON, and forwards the requests to the appropriate browser driver.

Browser Engine

Handles actual rendering, interprets commands, and interacts with the DOM.

Browser Drivers

Bridge Selenium and the browser, executing the instructions within the browser.

Significance of Python Virtual Environment

A Python virtual environment allows developers to manage project dependencies independently. This is especially useful when working on multiple projects with different library requirements—for example, using Selenium 4 in one project and Selenium 3 in another.