About Page Rendering

Page

Page attributes control specific characteristics of a page such as the page name, display attributes such as the page title and the associated page template, header text, and the selected authorization scheme to name just a few. You access page attributes from the Page Definition.

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 to enable users to submit a page. When you submit a page, the Application Express engine posts or processes 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 the item will display next to, or below the previous item.

There are two categories of items: page items and application items. Page-level items are placed on a page and have associated user interface properties, such as Display As, Label, and Label Template. Application-level 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.

Application-level computations assign a value to an item each time a page is rendered. A page-level computation assigns a value to an identified item when a page is displayed or submitted (rendered and processed).

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.

Dynamic Actions

Dynamic actions provide a way to define complex client-side behavior declaratively without the need for JavaScript. You can specify an action that is performed based on a defined set of conditions. You can also specify which elements are affected by the action as well as when and how they are affected.