Selenium Grid Hub and Node

Selenium Grid uses a hub-node concept. Hub is a machine where you only run tests against it, but the execution will be done by different machines called nodes.


Selenium Grid Hub:

  • The hub is the central point where QA Engineers load tests into.
  • There should be only one hub in a grid.
  • The hub is launched only on a single machine.
  • On the machine containing the hub, the tests will run, and you will see the browser information on the node.

Selenium Grid Node:

  • Nodes are Selenium instances that will execute the tests loaded on the hub.
  • There can be one or more nodes in a grid.
  • Nodes can be launched on multiple machines with different browsers and Operating system. Nodes can be the same computer.
  • The machines running the nodes need not be the same platform as that of the hub.