The transaction engineering activity extends transaction design to technical implementation. The underlying technology may vary widely depending upon enterprise technology standards and the functionality of the Web site. Some of the more common Web technologies include HTML, XML/XSL, XHTML, WAP/ WML, and ASP. The SLKD Auto Rental example relies upon HTML for presentation of Web page content, and HTML forms for the capture of data from the browser. The example also uses eXtensible Markup Language (XML) as the technology for describing transaction content that is exchanged between Web architecture layers.

Although XML is a fairly recent technology, ^[1] it is a subset of the well-established Standard Generalized Markup Language (SGML) technology. ^[2] XML is a self-describing extensible metadata language. XML can be used to describe the content of a document, file, message, or, as in the case of the SLKD Auto Rental example, a transaction. XML allows the architect to define custom transactions in order to meet specific requirements. Another advantage of XML is that it is platform agnostic. That is, XML can be exchanged with and processed on any platform that accepts ASCII text and supports an XML parser. In addition, when XML transactions are architected to allow for highly variable and diverse content, they exhibit extensive support for transactions that contain globally diverse data. ^[3]