The GlideSystem server-side API is not constructed using the
new keyword, but is available to all server-side scripts via the variable
gs. This API allows us to get various kinds of useful information about the system, the user's session, the current date/time, or other bits of useful info. It also allows you to interact with the user, by displaying informational or error messages.
addErrorMessage() and addInfoMessage()
addErrorMessage() method will display a red error message at the top of the user's browser window on the next page they load after the server-side script that calls this method runs. This same functionality can also be achieved from a client-script, using the
g_form API (