$client = new SoapClient("http://example.com/service.wsdl"); // Login to the SOAP server and obtain the session ID $sessionID = $client->login("username", "password"); // ...Do some API calls using the session ID // Log out of the SOAP server $client->logout($sessionID);In this example, we create a new instance of the `SoapClient` class and connect to the SOAP server using the WSDL file located at `http://example.com/service.wsdl`. Then, we authenticate the user with a username and password provided to the `login` method and obtain a session ID. We can then perform some API calls using the session ID. Finally, when we're done using the SOAP server, we call the `logout` method and pass in the session ID to end the session. The SoapClient library is a built-in PHP library for working with SOAP web services.