Selenium WebDriver Architecture and Core Concepts

Posted on Oct 20, 2025 in Software Engineering

Selenium WebDriver Core Components

  • Selenium IDE: A record-and-playback tool for automating browsers.
  • Selenium WebDriver: The core tool for automating web applications.
  • Selenium Grid: Allows running tests on multiple machines simultaneously.

Understanding the WebDriver Hierarchy

Java Interfaces and the WebDriver Structure

In Java, an Interface acts as a blueprint containing abstract methods, default methods, and static variables.

  • WebDriver Interface: Initially designed as a core Java interface.
  • WebDriver Class Implementations: Concrete classes implement the WebDriver interface.

Browser-Specific Driver Implementations

  • Each browser requires a dedicated driver (e.g., ChromeDriver, FirefoxDriver, EdgeDriver).
  • WebDriver methods are tailored to work specifically with these different browsers.

The RemoteWebDriver Class

  • RemoteWebDriver: This is the main class that implements the WebDriver interface and facilitates communication with remote browsers.
  • Browser-Specific Drivers: Classes like ChromeDriver extend RemoteWebDriver to support specific browser interactions.

Understanding the WebDriver Class Hierarchy

The hierarchy flows as follows:

SearchContext Interface → WebDriver Interface → RemoteWebDriver Class → Browser-Specific Drivers (e.g., ChromeDriver, FirefoxDriver).

Note that WebDriver extends the SearchContext interface, confirming that WebDriver is not the root interface in the hierarchy.

WebDriver as an Application Programming Interface (API)

API Definition and Function

  • API Definition: An Application Programming Interface acts as an intermediary between the client program (e.g., Java test script) and the browser.
  • API Request-Response Model:
    • A user interaction is initiated by the client program.
    • A request is sent to the browser driver (the server).
    • The server processes the request and returns a response via the API.

Detailed API Request-Response Flow

  1. Request Initiation: A request is sent from the user or client program (e.g., clicking a button).
  2. Processing: The request is handled by the API, which interacts with the browser driver and potentially the database.
  3. Response Delivery: A response is sent back to the user, reflecting the result (e.g., an updated web page state).

Setting Up the Selenium Environment

Manual vs. Maven Setup

  • Manual Setup: Requires downloading JAR files from the Selenium website and manually adding them to your project. This necessitates manual updates for version changes.
  • Maven Setup: This is the easier and recommended approach, managing dependencies automatically through the pom.xml file and handling version updates smoothly.

Maven Project Configuration (pom.xml)

  • The pom.xml is the configuration file where project dependencies, including Selenium WebDriver, are declared.
  • Maven handles dependency management, significantly smoothing project setup and updates.

Writing Selenium Automation Scripts

Basic Automation Script Steps

A typical automation script follows these steps:

  • Launch the browser (e.g., using ChromeDriver).
  • Open the target URL (using get()).
  • Validate the page title (using getTitle()).
  • Close the browser session (using quit()).

Strategies for Locating Web Elements

  • Locator Strategies: Methods used to identify elements, including By.id(), By.name(), By.xpath(), and By.cssSelector().
  • Actions: Common interactions performed on located elements, such as clicking (click()) or sending text (sendKeys()).

How WebDriver Methods Interact with the Browser

WebDriver methods facilitate interaction with the browser, such as get(), findElement(), click(), and sendKeys().

These methods are implemented differently based on the specific browser driver being used.

Essential WebDriver Methods Reference

  • get(): Opens a specified URL.
  • getTitle(): Returns the title of the current page.
  • findElement(By locator): Finds a single web element using the provided locator strategy.
  • sendKeys(): Sends a key sequence to a web element (typically input fields).
  • click(): Clicks a web element.
  • quit(): Closes all browser windows and ends the WebDriver session.