Forms and Event-driven Processing

In this section:

Forms are the visual interface to a WebFOCUS Maintain application, giving it a dynamic and attractive face while enabling you to make the application flexible and to place its power at the fingertips of the application end users.

WebFOCUS Maintain supports a full set of controls, such as list boxes, buttons, and ActiveX components, by which end users can manipulate data and drive the application. You can design forms that enable end users to:

You develop these forms and the associated logic using the Form Editor. This is a sample form:

Form example image

Forms are event-driven, and enable:

For an introduction to using forms and developing event-driven applications, see How to Use Forms, Designing Event-driven Applications, and Creating Event-driven Applications. Forms, and the Form Editor used to design and create them, are described in greater detail in Developing and Using Forms in the Developing WebFOCUS Maintain Applications manual.

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How to Use Forms

Forms are deployment-independent. You design a form to meet the needs of your application. WebFOCUS Maintain automatically implements the form as a webpage. This enables you to focus on logic, and leave implementation details to WebFOCUS Maintain.

Forms have standard form features, including:

Forms are displayed one at a time in one web browser session.

You can transfer control from one form to another, from a form to another Maintain procedure or to a WebFOCUS procedure, and from a form to any Internet resource, such as an email client, a webpage, or an FTP server.

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Designing a Form

Forms offer a diverse set of ways by which an application end user can select options, invoke procedures, display and edit fields, and get helpful information. For example, if you want the user to select an option or procedure, you can use any of the following controls:

If you want to display or edit data, you can use these controls:

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Designing Event-driven Applications

The flow of control in conventional processing is mostly pre-determined, that is, the programmer determines the few paths that the user will be able to take through the procedure.

To make your application user interface more responsive to the user, WebFOCUS Maintain offers event-driven processing. Each time that an event occurs, it invokes, or triggers, the assigned event handler. In WebFOCUS Maintain, the event is something the application end user does in a form, and the event handler is a function or a URL. For example, you might create a button that, when clicked by a user, triggers an event handler that reads a data source and displays the data in the form.

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Creating Event-driven Applications

Developing a procedure by writing out sequential lines of source code may be sufficient for conventional linear processing, but event-driven processing demands event-driven development. Developing an application in this way lets you build much of the application logic around the user interface. In effect, you develop the application as you develop the interface in the Form Editor. For example, you could start by creating a form, creating a control, and then coding an event handler for one of the control events. WebFOCUS Maintain also provides you with a number of automated tools for developing applications. For example, you can use the Language Wizard to generate source code for various operations such as retrieving and updating data.