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Differences Between Selenium Grid 3 and Grid 4

Differences Between Selenium Grid 3 and Grid 4

In this tutorial, you will learn about the differences between Selenium Grid 3 and Grid 4. Selenium Grid is a part of the Selenium Suite that allows you to run tests on different machines against different browsers in parallel. This helps in reducing the execution time of test suites and enables cross-browser testing.

Selenium Grid 3

Selenium Grid 3 uses a hub-and-node architecture. The Hub is the central point that receives test requests and distributes them to registered Nodes based on availability and capability. It relies on external tools like Selenium standalone server JARs to set up and manage the grid. Selenium Grid 3 has limitations in scalability, configuration complexity, and does not support modern web protocols like W3C WebDriver standard completely.

Selenium Grid 4

Selenium Grid 4 is a complete redesign of Grid 3 with modern architecture and advanced features. It follows a distributed, event-driven model and supports both standalone and distributed modes. Grid 4 supports the W3C WebDriver standard by default and comes with built-in observability, advanced logging, and Docker support. It includes additional services like the Router, Distributor, Session Map, and Node Manager for better scalability and load balancing.

Selenium Grid 3 vs Grid 4

Feature Selenium Grid 3 Selenium Grid 4
Architecture Hub and Node

  • Hub: The central server that receives test requests and routes them to available nodes.
  • Node: A remote machine that executes the tests based on the configuration.
 Distributed with multiple services.

  • Router: Routes requests to the Distributor or sessions.
  • Distributor: Assigns new sessions to available Nodes.
  • Session Map: Tracks active sessions and their mapping to Nodes.
  • Node: Machines where tests are executed.
  • Event Bus: Ensures communication among distributed components.
WebDriver Protocol Support Partial W3C support Full W3C WebDriver support
Setup Complexity Setup complexity of Grid 3 is manual and complex Grid 4 setup is simplified with built-in services
Docker Support Manual Docker configuration Native Docker support with Selenium Grid 4 images
Observability Limited logs and no built-in monitoring Built-in observability and better logging
Scalability Limited Highly scalable and cloud-ready
Communication Direct between Hub and Node Event-driven via Event Bus

Selenium Grid 4 architecture:

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