A custom function is defined at engineering time for implementing actions to be executed in case of a disconnection event in which a client is unable to communicate with a server. At engineering time, code specifying the action to be implemented by the custom function is written into a function file that is stored on the web-server. Subsequently at run time, a browser running on a client requests a certain page to be displayed from the web-server. On occasion of a client-server disconnection; the communication component notifies a certain displayed page about the disconnection; and the custom function is executed with certain page being displayed.