About Page Rendering Controls

Regions

A region is a area on a page that serves as a container for content. Each page can have any number of regions. The content of a region is determined by the region source. For example, a region may contain a report based on a SQL query you define, or it may contain static HTML.

You control the appearance of a region through a specific region template. You can use regions to group page controls (such as items or buttons). You can also create simple regions that do not generate additional HTML, or create elaborate regions that frame content within HTML tables or images.

Buttons

As you design your application, you can use buttons to direct users to a specific page or URL, or submit a page. When you submit a page, the Application Express engine posts or process information. A button can be implemented as an HTML button, an image, or by using a template. Buttons can be placed in predefined region template positions or among items in a form.

Items

Items are HTML form elements such as text fields, select lists, and check boxes with an associated session state. Item attributes affect the display and behavior of items on a page. For example, these attributes can impact where a label displays, how large an item will be, and whether or not the item will display next to, or below the previous item.

There are two categories of items: page items and application items. Page items are placed on a page and have associated user interface properties, such as Display As, Label, and Label Template. Application items are not associated with a page and therefore have no user interface properties. An application item can be used as a global variable.

Computations

Computations are units of logic used to assign session state to items. You can use computations to assign a value to an identified item when a page is submitted or displayed.

Processes

Processes are logic controls used to execute data manipulation language (DML) or PL/SQL. For example, you can use a process to populate session state at the time a page is rendered, to execute some type of logic (for example, using PL/SQL), or to make a call to the rendering engine. Typically a process performs an action. A process may be hand coded PL/SQL, or the invocation of a predefined process.