About Partial Page Rendering

Partial page rendering (PPR) functionality in ADF UIX provides the ability the re-render (refresh) a limited portion of a page without redrawing the entire page and without writing any custom JavaScript code.

UIX uses hidden inline frames (iframes) to implement its PPR functionality. Iframes act as the communication channel between the browser and the web application, thus UIX can send partial page events and re-render partial page contents in the background without discarding the contents of the current page.

PPR is currently supported on the following browsers:

Internet Explorer 5.5 and above (Windows)
Mozilla 1.0/Netscape 7.0

On all other platforms, UIX automatically uses full page rendering.

Not all UIX components support PPR. The PPR enabled components in this release are:

hGrid - Uses PPR for every event.
hideShow and hideShowHeader - Uses PPR to optimize the hide and show actions.
lovInput - Uses PPR to implement validation and update of a field using a list of predefined values.
processing - The processing element and its indexed children are periodically refreshed automatically in PPR mode.
subTabLayout - Uses PPR to update its contents when switching between tabs.
table - Uses PPR for these actions:
- table navigation (scrolling between record sets)
- column sorting
- adding a new row
- updating the total value
- detail disclosure (row-leve hide/show)

When the user interacts with a PPR enabled component on an intial page, UIX provided JavaScript event handlers force a navigation in a hidden ifram. The browser sends a partial page event request to the application for the updated contents. This event is similar to any full page event request, which is a goto event and a value event parameter. The partial page event also sends other event parameters that identify the type of rendering mode and the set of partial target nodes to re-draw.

When the application receives the partial page event request, it determines the set of partial targets to render and generates the contents for refresh, but only the contents generated by the partial targets are sent back to the iframe in the browser.

When the browser receives the partial page response, the new contents for each partial target are copied from the hidden iframe into the main browser window, thus replacing the existing contents for each partial target.

Prerequisites for PPR

The following conditions must be met for PPR to work properly:

The ID must be set on the PPR enabled component that fires the partial page event.
The IDs of the partial target components that should be refreshed must also be set.
The <body> element must be present on the page. UIX automatically adds this element to a UIX XML page. For UIX JSP developers, you must explicitly use <uix:body>.
You must explicitly identify the scripts that generate content by calling document.write() or document.writeln() . By default the generatesContent attribute of the <script> element is set to false, i.e., the script does not generate content. Make sure you set the generatesContent attribute to true for any scripts that call document.write() or document.writeln(). For example:
```
	
...
<script generatesContent="true">
  document.write("Hello there");
</script>
...        
```

Note: By default PPR is enabled regardless of the acessibility mode. To turn PPR off, add the following configuration parameter in the uix-config.xml file:


...
<default-configuration>
  <disable-partial-rendering>true</disable-partial-rendering>
</default-configuration>
...

PPR Attributes

Use the following attributes on a PPR enabled component:

partialRenderMode - Specifies whether PPR is enabled. Available values are none, self, multiple. By default PPR is disabled. Set this attribute to self to specify that the component itself should be updated using PPR. Set the value to multiple to specify that multiple partial targets should be updated or re-rendered, then specify the list of partial targets in the partialTargets attribute.
partialTargets - Specifies the set of partial targets for re-rendering. By default the ID of the component that fires the partial page event is automatically included in this list.

Screen readers

Screen readers do not re-read the full page in a partial page request. PPR causes the screen reader to read the page starting from the component that fired the partial action. Hence, you should place the partial targets after the component that fires the partial request; otherwise the screen reader would not read the updated partial targets.