Websydian v6.1 online documentationOnline documentation - Websydian v6.1

The Event Handler Main Function

The Event Handler function is one of the Websydian main functions.  An Event Handler function must be defined for each user event on an HTML page, and each defined Event Handler will - in the generated Document Template - result in an HTML form containing a push button and a number of form fields.  A Websydian application will typically contain many Event Handler functions.

Call of Event Handler

The Event Handler function is called (through the Dispatcher function) when the user triggers a web event on the HTML page.

When a user presses an Event Handler push button on an HTML page (generated by a Page Generator function), this will trigger a call to the Dispatcher function which in turn will route the call to the appropriate Event Handler function.  The Event Handler function will then receive and validate the input parameters (if any) from the calling HTML page.

Development of Event Handler functions involves determining the input parameter fields received by the Event Handler function.  These fields will either be hidden or appear in the HTML forms on the calling HTML page.  Development of Event Handlers also involves specifying any database update functionality that might be associated with the events.

An Event Handler function must always produce an HTML page as a response to the web user.  It does so by calling a Page Generator function, which will produce an HTML page as a response to the web user.

Therefore, It must be specified which Page Generator function should be called as response to the event.

More Information

The Structure diagram for the Event Handler and the Structure diagram for the Validation and Conversion enhancements show the Plex building blocks of Event Handler functions.