Step 1: Start the hub
The Hub is the central point that will receive all the test request and distribute them the the right nodes.
Open a command prompt and navigate to the directory where you copied the selenium-server-standalone file. Type the following command:
java -jar selenium-server-standalone-2.14.0.jar -role hub
The hub will automatically start-up using port 4444 by default. To change the default port, you can add the optional parameter -port when you run the command. You can view the status of the hub by opening a browser window and navigating to: http://localhost:4444/grid/console
Step 2: Start the nodes
Regardless on whether you want to run a grid with new WebDriver functionality, or a grid with Selenium 1 RC functionality, or both at the same time, you use the same selenium-server-standalone jar file to start the nodes.
java -jar selenium-server-standalone-2.14.0.jar -role node -hub http://localhost:4444/grid/register
Note: The port defaults to 5555 if not specified whenever the "-role" option is provided and is not hub.
For backwards compatibility "wd" and "rc" roles are still a valid subset of the "node" role. But those roles limit the types of remote connections to their corresponding API, while "node" allows both RC and WebDriver remote connections.
( using java as an example ) Now that the grid is in-place, we need to access the grid from our test cases. For the Selenium 1 RC nodes, you can continue to use the DefaultSelenium object and pass in the hub information:
Selenium selenium = new DefaultSelenium(“localhost”, 4444, “*firefox”, “http://www.google.com”);
For WebDriver nodes, you will need to use the RemoteWebDriver and the DesiredCapabilities object to define which browser, version and platform. you wish to use. Create the target browser capabilities you want to run the tests against:
DesiredCapabilities capability = DesiredCapabilities.firefox();
Pass that into the RemoteWebDriver object:
WebDriver driver = new RemoteWebDriver(new URL("http://localhost:4444/wd/hub"), capability);
The hub will then assign the test to a matching node.
A node matches if all the requested capabilities are met. To request specific capabilities on the grid, specify them before passing it into the WebDriver object.
capability.setBrowserName();
capability.setPlatform();
capability.setVersion()
capability.setCapability(,);
Example: A node registered with the setting:
-browser browserName=firefox,version=3.6,platform=LINUX
will be a match for:capability.setBrowserName(“firefox” );
capability.setPlatform(“LINUX”);
capability.setVersion(“3.6”);
and would also be a match for
capability.setBrowserName(“firefox” );
capability.setVersion(“3.6”);
The capabilities that are not specified will be ignored. If you specify capabilities that do not exist on your grid (for example, your test specifies Firefox version 4.0, but have no Firefox 4 instance) then there will be no match and the test will fail to run.