Advantages to the Developer
Apart from the advantages of XForms already cited elsewhere, XForms brings the following advantages to the sphere of mobile applications:
- XForms was designed to support multiple modalities. Applications that work on mobile devices are also deployable in other ways too, thus much improving the return on your development investment.
- XForms does most of its work on the client-side, thus reducing the number and size of server calls. This is still an important consideration for mobile devices, which tend to have to operate on narrow and expensive bandwidth.
Building Mobile Applications
Whilst there is a Basic profile of XForms, the only known, commercial implementation also supports almost the entire XForms/XML Schema feature set.
Open Source Implementations
Xfolite
Xfolite is a light-weight XForms client for the J2ME platform. It was originally created at Nokia Research Center, and it includes a DOM and XPath 1.0 implementation as well as an XForms engine that implements the XForms 1.1 specification almost completely. XML Schemas and CSS are outside project scope, however. Xfolite is licensed under the LGPL license.
Commercial Implementations
PicoForms
PicoForms has an XForms implementation that runs on cell phones supporting MIDP 2.0 and CLDC 1.x. It also supports PDAs including Palm and Pocket PCs. PicoForms is also able to provide customers (and evaluators) with an online development space, that allows forms to be tested on a mobile phone/PDA emulator.
Picoforms runs as an plugin to Internet Explorer. The license is around $30 (US) per client (desktop).
To enable your forms to work with Picoforms just add the following line to your code:
<?import namespace="xf" implementation="#default#pxf"?>
Sample Applications for PicoForms
UK Pension Industry
This application uses a set of industry standard XML schema (produced by Origo Services) in the UK. XForms lends itself well to building applications over such schema, as the schema can be consumed directly by the application, often without modification.
The Scenario
The Schemas describe the data requirements for a financial adviser requesting information about the value of funds in a customer's personal pension policy. An adviser is likely to want to do this immediately prior to meeting with their client, probably in the client's own home. They want the information to be as up-to-date as possible.
The Application
The following screenshots give an idea of the application running on a mobile phone emulator. The application can be accessed in an emulator here.
To begin with the user must search for the details of the client they are interested in. This simulates communication with the adviser's own back-office system. This can be achieved either by entering a unique reference for the client, or the client's name.
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