The XML/EDI application described in this paper was developed as part of an EU XML/EDI pilot project. This aimed to determine how the XML family of standards can be used to develop the next generation of EDI applications in two sectors - transport, described here, and healthcare. The application shows how XSLT stylesheets can be used to drive a forms interface which is device-independent, and which has multiple-language capabilities. It also highlights areas where the XML family of standards was insufficiently developed to cope with the requirements of a forms-based messaging system.

The core of the application comprises two modules which use XSLT stylesheets to generate the interface resulting messages. The 'Generate Form' module outputs a form in the mark-up appropriate for the user's device (e.g. HTML or WML), and in the language selected by the user. It takes as input a form specification, and resource files containing form labels and context references for data items. The 'Validate' module validates user-entered values against a constraints file, returns error messages in the user's language, and populates an XML message from the data entered into the form by the user. Both modules use generic and extensible data structures developed during the course of the project, and are entirely independent of the application domain (in this case, transport). They also make use of XSLT stylesheets which generate secondary XSLT stylesheets, reducing maintenance and facilitating re-use by separating domain-specific data from application code.

Two additional modules, driven by a browser ActiveX, are used to provide elements which XML-based standards were unable to deliver. These modules are 'Process Control', which generates the interface used to drive processing actions, and 'User Input' which saves values entered in then HTML form by the user to file.

A key feature of the application is its ability to produce output in the format appropriate to the user at the point in time at which it is needed. The demonstration will show a message being generated for a WAP-enabled handheld device, with a capability for the user to input a response to the message.

The project consortium made a number of recommendations to the European Commission and to W3C on where XML standards should be further developed to fill gaps in the current and projected standards coverage.