Is XML the Answer?
Extensible Markup Language (XML) is being widely touted as an answer to the complexities of integration. Unfortunately, like so many of the exaggerated claims that vested interests make about technologies associated with the Internet, XML is merely a very useful incremental step in simplifying the process of accomplishing integration. What makes XML powerful is its ability to universalize protocol formats. For example, the myriad of variations that define message-based protocols can generally distilled into XML, resulting in only one message communication vehicle. This does represent significant technical progress. In the XML document, the data, its description/definition, and some rules for parsing and representation can all be included. (It is important to note that schema representation in XML has been under discussion, and not all features, including schemas, are firm.)
Figure: XML Processing Flow
What has historically made integration tricky and difficult, however—interpreting and mapping the data properly between two systems—remains one of the primary disciplines of technical integration. It is possible over time that standards for semantics and lexical mapping will emerge that help automate the process, but until then, logical mapping of data between two systems will require a significant amount of human intervention.
In the case of HL7, under which an XML variation has already been demonstrated, the use of XML can help resolve many of the issues related to the lower-level protocols that had to be addressed. Integration can focus on interpretation and mapping of actual data content. While the analysis tasks remain almost identical and will continue to consume as much project time as in the past, overall time and effort to integrate two systems should diminish somewhat thanks to the more comprehensive messaging model that XML offers.
Additional information about XML is available on the web through XML.ORG and the World Wide Web Consortium.