Selenium Grid 3 versus Selenium Grid 4 – Devstringx

Back to Blog
Selenium Grid 3 Vs 4 Banner

Selenium Grid 3 versus Selenium Grid 4 – Devstringx

How Does Selenium Grid Work?

We can distribute the tests in parallel across a variety of browsers, operating systems, and machines thanks to Selenium Grid, a Selenium suite component, which greatly reduces the amount of time it takes to run the tests.

The two seemingly opposing demands for app testing—increasing test coverage and cutting down on test time—can pursue Selenium Grid.

Why Should a Person Think About Utilizing Selenium Grid?

Businesses are implementing agile strategies to communicate with their users frequently & quickly. To accomplish this, they must guarantee that the program functions flawlessly on all platforms, devices, and browsers.

In order to support these rapid releases, test automation plays a critical role in giving immediate feedback on quality.

However, with the rise in automated testing, it is difficult to get prompt and accurate input.

Using the Selenium Grid, we can run the automated tests in parallel to get around the speed and scaling issues across browsers.

We’ll look at the following points in this post from the Selenium 4 series:

  • Selenium Grid uses to run tests simultaneously on several platforms and browsers.
  • Challenges and restrictions of using the Selenium Grid 3 & Selenium Grid 4 Differences
  • Utilizing Applitools Ultrafast Test Cloud improved scaling and reduced flakiness.

How Exactly Does the Selenium Grid Operate?

Hub and node are the two main Grid building blocks. A hub and node configuration uses on the Selenium server.

The hub is given a test to run along with instructions on which “platform” (Windows, Linux, etc.) and “browser” (Chrome, IE, Firefox, Safari, etc.) the test should be run on. By configuring the capabilities and delivering them to the driver function Object() { [native code] }, this data is sent to the Grid.

The hub then chooses one available node with the specified browser-platform combination from the list of nodes registered under it, starts the Selenium instructions, and passes them to the chosen node. The browser and test case are run on the node.

Selenium Grid 3 Vs Selenium Grid 4 Go Head-to-Head

The sole elements of Selenium Grid 3 are the hub and nodes. Using Selenium Grid 3, a grid can only configure as a Hub-Node arrangement.

A hub configuration for the grid is possible, with one or more nodes registered to it. You can set up the hub and the nodes on the same machine or different machines. Each machine needs to have the selenium-standalone jar downloaded so that it may function as both a node with its own set of commands and a hub in the cluster.

Recommended to Read- Handle Shadow DOM In Selenium 4

Selenium Grid 3 can be seen as depicted in the diagram below:-

selenium architecture

With Selenium 4, the Grid has been completely redesigned from scratch to accommodate fully distributed testing. It also has substantial docker support.

Direct architecture of selenium

Diagram from Showing the Selenium 4 Architecture

The following Grid 4 components, support distributed testing and scaling of test execution, in addition to the hub and node:

Load balancing is done by the router, which keeps track of all incoming requests.

  • Distributor: Pays attention to new session requests and forwards them to the appropriate node based on its capabilities.

a key-value data store called a “session map” that keeps track of the details of the session that is now running

  • Event Bus: Serves as a conduit for communication between the Session Map, Node, and Distributor.

All four of the aforementioned elements combine into the hub.

Selenium Grid 4 Can be Configured In a Variety of Ways
  • Standalone: A single device that is both a hub and a node
  • Node and Hub: a single hub and numerous nodes registered to it on various devices
  • Distributed: Run each Selenium Grid component separately in a different process.
  • Docker: Docker uses to run the Selenium Grid and to create new instances.

Recommended to Read- Process Java Script Executor In Selenium Queryselector

Usage Restrictions for Selenium Grid

Although executing the tests in parallel on the Selenium Grid enables us to cover cross-browser/platform testing and reduce test execution time, it may also present some issues, such as:

  1. Costs associated with purchasing and maintaining infrastructure
  2. The requirement for a special machine setup
  3. Brittle tests caused by changes in infrastructure and rerunning the same tests on different browsers
  4. Scaling restrictions dependent on the machine’s underlying resources

Hub Selenium Grid

Furthermore, there are more effective ways to test the visual rendering across all environments while checking the functionality once to avoid the fuzziness involved with running the test ten times, and the approach of running each test across different browsers and devices still takes considerable execution time and may not be an efficient approach given that the functionality rarely changes between browsers adhering to the W3C protocol.

Each language has its own distinct bindings, and these bindings are part of the Selenium Client & WebDriver architecture. The same instructions can be written for one language and another because of bindings. For instance, the Java programming language contains a set of commands that have been created for C#, Python, JavaScript, and Ruby.

In order to operate the Browser Drivers and Web Browsers, WebDriver makes use of each Web browser’s built-in automation capability. A Browser Driver like ChromeDriver is responsible for controlling the Chrome browser.

The drivers have changed in Selenium 4. While RemoteWebDriver is ChromiumDriver’s parent, ChromeDriver and EdgeDriver extend it.


  • What is a selenium Grid?

Selenium Grid simplifies parallel tests running on multiple machines. It acts as an efficient intermediary, routing JSON commands from a central hub to registered nodes across the grid – ensuring that all desired tests conduct far more quickly and reliably than ever before!

  • Is selenium Grid a tool?

With Selenium Grid, testing suddenly becomes a breeze. We can easily execute scripts on multiple machines at once to speed up the feedback process and ensure accuracy across browsers and platforms. This efficient tool simplifies our workflow and takes away the need for waiting around between test cycles!

  • How many nodes does a selenium grid have?

With Selenium Grid, you can achieve remarkable levels of parallelism with virtually no limits! Unleash the power to run multiple driver.exe’s and browser windows simultaneously – up to 200 nodes at a time! Create an automated testing system like never before seen – because your imagination is the only limitation.

  • Why is a selenium grid used?

The Selenium Grid is an incredible testing tool that enables us to effortlessly run our tests across multiple machines, browsers, and operating systems. Making it a valuable member of the extensive Selenium Suite specialized in performing simultaneous tests on diverse platforms.

  • What is a testing grid?

Accelerated testing is made possible with grid-based automated UI testing. This allows you to run tests simultaneously across multiple machines, operating systems, and browsers – a time-efficient solution that eliminates the need for long wait times during individual test cycles.

  • What is Selenium 3?

Selenium 3 has been retired in favor of the latest version, Selenium 4. It boasts an upgrade to W3C WebDriver compliance for a more efficient and reliable web automation experience.

  • What is Selenium 4?

Selenium 4 just release an entirely revamped suite of tools and documents, covering the Web Driver, Grid, and IDE. This new version boasts improved browser support allowing any vendor to easily connect with Selenium IDE. Furthermore, these features will ensure a smoother user experience for everyone!

  • What are the selenium RC grid and WebDriver?

Selenium RC employs the power of its unique Remote-Control Server to communicate with any given browser, making testing web-based applications incredibly easy and efficient. WebDriver provides a simpler yet more powerful solution compared to Selenium RC as it talks directly with browsers in multiple programming languages, resulting in an even briefer API for complete control over your tests.


Related Post

Share this post

Back to Blog