Manual:ApiMain.php

ApiMain is the main API class, used for both external and internal processing. When executed, it will create the requested formatter object, instantiate and execute an object associated with the needed action, and use formatter to print results. In case of an exception, an error message will be printed using the same formatter. To use the API from another application, run it using the faux>Special:MyLanguage/Manual:WebRequest.php|FauxRequest object, in which case any internal exceptions will not be handled but passed up to the caller. After successful execution, use  for the resulting data.

getResult
gets the ApiResult object associated with the current request.