Introduction to XDIME and the XDIME aggregator

XDIME provides a device-independent authoring facility. Based on the capabilities of the output device, the XDIME aggregator selects and aggregates output in the form of pages, portlets, and URLs.

Background and summary

Although mobile devices support a small number of standards, there are differences between the standards and how they are implemented. These standards include the following:

HDML version 3.0
HTML version 3.2 and 4.0
i-mode HTML (cHTML)
MML (J-Phone Mobile Markup Language)
Palm WCA (Web Clipping Applications)
WML version 1.1 and 1.3
XHTML version 1.0 Mobile, Basic, Transitional, and Full
VDXML version 2.0
XHTML 1.1
HDML
Note: Mobile Portal Accelerator generates WML markup for HDML devices, but an OpenWave gateway must be used to convert the WML to HDML for HDML devices.

How the standards are implemented can differ, and many do not support style sheets. As a result, you would need profoundly different markup to get consistent results. Also, differences in device capabilities could mean that the same markup renders differently on different devices. How the markup is rendered can be unpredictable.

XML-based Device Independent Markup Extensions (XDIME) solves this problem by creating a true device-independent authoring facility. It gives authors a way to build powerful and robust applications without needing to know the capabilities of each device. XDIME also protects the application from underlying changes in devices. Using XDIME, Mobile Portal Accelerator lets authors write application markup once and render it on many different devices.

XDIME is an XML vocabulary that describes content. It references policies which define device specifics, such as layout, styling, and asset references. XDIME then provides tags that references these policies. Using conditional markup, device characteristics can be checked within the portal content.

XDIME is based on XHTML 1.0 Strict and early drafts of XForms. XDIME uses a CSS-style grammar for stylistic control.

The role of an aggregator in WebSphere® Portal is to collect information about the user's request, select related pages or portlets, and aggregate the output for display. The XDIME aggregator extends WebSphere Portal aggregation support to include XDIME.

When Mobile Portal Accelerator receives a request from a device, the XDIME aggregator uses the navigation tree created by the Manage Mobile Pages portlet to select and aggregate the output in XDIME. This output includes pages, portlets, and URLs. The standard portlet API (encompassing JSR 168 and 286) is supported. Note that the IBM portlet API is no longer recommended for use.

In the aggregation process, the capabilities of the receiving device are evaluated. Using extended properties, the content is then rendered in an appropriate format for the device. For example, the aggregator might check if the device supports images. The device capability properties are compared with the device repository to determine if the page, URL, or portlet should be displayed for the node. The aggregator also supports preload notices.

For more information about preload notices, refer to the topic Introduction to Manage Mobile Pages.

Differences between XDIME 1 and XDIME 2

XDIME 2 is a new version of XDIME that conforms to the following current or proposed W3C standards: XHTML 2.0, XForms 1.0, DISelect 1.0, and CSS 2.1.

The following features are supported in XDIME 2 but not in XDIME 1:

Flexible targeting for layouts, allowing complete restructuring of the page solely by changing the styles
Client Framework widgets to enhance user experience on higher-end devices
Simpler to control fragmentation and form fragmentation link text

The following features are supported in XDIME 1 but not in XDIME 2:

Inline metadata
Modifying layouts from within markup
Overlays: multiple cards in VML
Dissection control
Charts
Server side includes
Native markup
Montages
Client side form validation
Branding
Embedding policies within the page

XDIME portlets

A set of XDIME portlets is provided for out-of-the-box capability and as samples for demonstration purposes:

Mobile Welcome to WebSphere Portal portlet displays the WebSphere Portal logo, the Mobile Portal Accelerator product title, version number, build level, and license and copyright information.
Mobile Change Of Address portlet is a sample based on a standard change of address form used to input address information for a user. This portlet supports HTML and XDIME markup and references a Multi-Channel Server layout policy.
Mobile Reminder portlet lets users save and display short text messages on their portal page.
Mobile World Clock portlet enables users to view current local times around the world.
Media Access Proxy Sample portlet provide a way to check that the MAP is installed and operating correctly.
Mobile Struts sample portlet is an enhanced version of the MailReader Struts Portlet that is packaged with the standard Struts distribution.
Mobile XDIME JSR 168 sample portlet demonstrates capabilities of XDIME. It is written to the JSR 168 specification.
Mobile Welcome to WebSphere Portal portlet displays the WebSphere Portal logo on devices supporting logos, the Mobile Portal Accelerator product title, version number, build level, license, and copyright information.
Mobile Calendar sample portlet demonstrates how to use remote policies in a portlet.

Tip: If you want to install the sample portlets, such as the Mobile Calendar sample portlet, check the WAR files found in the wp_root/wp.mobile/wp.mobile.mwp/installableApps directory.