XML and HTML

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Where to Use XML

XML is important to the business application developer because it offers a standard language and syntax suitable for intersystem data transfer. Every business system needs to interact with at least one other system in some fashion. The other system can be an external system of a business partner or an internal system (perhaps a data warehouse) that needs information from another internal system (for example, the production order entry system).

Until now, the standard technique used to transfer information between two business systems has been to write a set of interface programs. System one would create an interface file with the required information. Or, system one might write the information to interface tables in a database. The target system will read that information, validate it, and update the target system database. In rare cases, the source or target system will access the other system's database directly, but this approach requires simultaneous access to both systems and developers who understand both systems.

Interface systems often require serious planning and attention. Carefully predefined and documented interface format specifications are necessary so that each system's developers can understand what is required. The normal process flows in both systems need to be accounted for. Most important, the data transformation requirements are embedded in the interface system logic.

As business requirements and the systems that support these requirements change, interface system requirements may change as well. Implementing these changes requires careful coordination and integrated testing plans, even if only two systems are involved. When multiple target systems or their interfaces need to be adjusted for a single-source system, modifications to the existing integration process can become unmanageable. If multiple business partners' systems are involved, one can only hope that their interface specifications are adaptable and up to date and that the original developers are still available.

XML promises to improve this process significantly. As general purpose, self-describing data repositories, XML files are readily accessible by multiple systems. Intricate coordination and data mapping designs are not as crucial since the XML files describe themselves. Systems need only to create XML documents based on an agreeable DTD or to input data from an XML file based on their own requirements. Modifications to the source or the target system do not need to be so closely coordinated. Often, new data tags (information) in an XML document can be ignored by a processing system if that system has no need for the data. The new data will not, by itself, obscure the data required by the processing system.

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