As a software testing veteran with over 10+ years architecting test automation frameworks for top enterprises, I’ve seen firsthand Selenium WebDriver‘s incredible growth. Just as web and mobile apps have grown more advanced over the years, so too have the tools to test them.
In this comprehensive guide, we’ll explore the Selenium WebDriver architecture evolution:
- Selenium 3 limitations
- Upgraded Selenium 4 architecture
- Key benefits of the new architecture
- Criteria for considering an upgrade
- Importance of real device cloud testing
So whether you’re new to Selenium or an experienced user, read on!
My Background in Test Automation
Before we dive in, let me introduce myself. I’m a seasoned quality assurance architect with over a decade of experience designing end-to-end test automation frameworks.
I’ve led testing teams at top Fortune 500 companies in building sophisticated frameworks in Selenium, Appium, UFT, and other tools to test complex web, mobile and desktop applications.
Over my career, I’ve been hands-on in scripting thousands of test cases across over 3500+ unique real mobile devices and browsers.
I’ve witnessed firsthand Selenium WebDriver’s rise from a fledgling open source tool back in 2009 to an industry standard used by testing teams worldwide today.
Brief Selenium Evolution Timeline
Let’s rewind and look at some key milestones:
2004 – Jason Huggins creates JavaScript tool Selenium Core
2006 – Selenium 1 adds a server for cross-browser testing
2009 – Selenium WebDriver created for direct browser automation
2011 – Selenium RC and WebDriver combined into Selenium 2
2016 – Selenium 3 focuses on enhancements
2020 – Selenium 4 upgrades architecture for better performance
Today, Selenium accelerates test automation at over 1 million organizations! Its growth directly aligns with the web app explosion over the past decade.
Overview of Selenium WebDriver Capabilities
Before we dive into the architectures, let’s define Selenium WebDriver itself:
Selenium WebDriver is an open source automation library used by QA teams to streamline & automate front-end GUI testing. It simulates user interactions with web apps through simple scripts written in languages like Java, C#, Python, JavaScript etc.
Some key capabilities it delivers:
- Launching browsers and navigating to URLs
- Interacting with page elements like buttons, forms etc.
- Inputting data and submitting forms
- Asserting that expected page content or titles load
- Testing across browsers like Chrome, Firefox, Safari etc.
It provides native support for automating actions you’d manually perform in the browser.
Now let’s shift gears and compare the Selenium 3 and Selenium 4 architectures powering this popular test framework.
Selenium 3 Architecture
Selenium 3 introduced some neat capabilities, but had architectural limitations in terms of communication protocols and browser support. Let‘s break down what comprises the Selenium 3 architecture:
Client Driver Libraries
Selenium provides native language bindings for Java, C#, Python, JavaScript, Ruby and more. You use these libraries to write test automation scripts that drive browser testing.
JSON Wire Protocol
This protocol encodes requests/responses required for communication between client libraries and browser drivers.
Browser Drivers
These native programs (like ChromeDriver for Chrome) broker interactions between client script code and target browsers.
Browsers for Testing
The web browsers (Chrome, Firefox) where test scripts execute and simulate user navigation, form entry etc.
Here is a diagram showing how the components fit together:
[Diagram showing Selenium 3 component interaction flow]While this architecture got the job done, it had some downsides:
- Extra communication latency from JSON wire protocol translation
- Limited capabilities for instrumenting tests
- Flaky tests and browser compatibility issues
This set the stage for architectural upgrades in…
Selenium 4 Architecture
Selenium 4 resolves many shortcomings around browser instrumentation, communication overhead between components, and speed/reliability.
Here is how the updated Selenium 4 architecture fits together:
[Diagram showing Selenium 4 component interaction flow]As you can see, the legacy JSON Wire Protocol is replaced by the new W3C WebDriver specification that enables direct communication between client and browser driver.
This has several advantages:
Faster, More Reliable Tests
Removing middleware communication improves test stability and speed.
Better Browser Compatibility
Direct browser instrument improves Selenium version support across Chrome, Firefox, Edge etc.
W3C Web Standard Alignment
Closer alignment to W3C standards around browser automation.
Advanced Instrumentation
Opens options for advanced event logging, step profiling, network mocking etc.
As you can see, Selenium 4 establishes a solid foundation for the next generation of test scripting!
Comparison of Key Selenium 3 vs Selenium 4 Differences
Let‘s call out some other key differences between the two architectures:
| Feature | Selenium 3 | Selenium 4 |
| Communication Protocol | JSON Wire Protocol | W3C WebDriver Protocol |
Simplified Selenium Grid – Makes distributed testing easier to orchestrate across multiple machines.
Enhanced Selenium IDE – Now supports parallel test execution across execution nodes to reduce cycle time.
Relative Locators – Finds elements relative to other elements, leading to more robust page object locators.
Native Chrome DevTools Access – Allows instrumenting tests with advanced Chrome debugging capabilities.
As you can see, Selenium 4 delivers much needed upgrades!
When Should Teams Consider Upgrading from Selenium 3 to 4?
Here some key criteria to evaluate when considering a Selenium architecture upgrade:
1. Browser Support
If testing Safari or legacy IE, stick with Selenium 3 until official support is added.
2. Team Skill Level
The learning curve is low, but less technical teams may prefer avoiding short-term disruption.
3. Test Suite Maturity
Focus first on addressing existing flaky tests before tackling an upgrade.
4. Transition Approach
Run a pilot test suite in Selenium 4 as a canary, before gradually rolling it out to all tests.
As with any upgrade, pin down supported browsers and set realistic timelines around test suite migration.
Importance of Real Device Cloud Testing
Whichever Selenium version used, be sure to test against real devices! Simulators and emulators don’t adequately replicate the thousands of device and OS variations that exist.
A cloud-based real device testing platform gives on-demand access to diverse mobile devices hosted in global data centers. This provides the best way to deliver seamless, consistent UX across all platforms your customers use – iOS, Android, tablets, phones etc.
Conclusion – The Future is Bright for Selenium Users
In closing, Selenium WebDriver has truly evolved from humble beginnings as a niche open source tool to an industry standard test framework under the hood of automation suites worldwide.
And the new Selenium 4 architecture establishes a future-proof foundation able to better support the demands of modern web and mobile application testing.
While the Selenium project is backwards compatible for some time, teams should proactively budget upgrades where possible to benefit. As web apps grow more advanced, so too must the test tools scaling to meet demand.
Let me know if you have any other questions! I‘m happy to offer additional guidance to your team in considering if/when Selenium 4 may make sense. Thanks!
