Introducing XML Extensions

XML Extensions for Enterprise Developer allows Enterprise Developer applications to interoperate freely and easily with other applications that use the Extensible Markup Language (XML) standard. To accomplish this, XML Extensions leverages the similarities between the COBOL data model and the XML data model in order to turn COBOL into an "XML engine." Of primary importance to this goal is the ability to import and export XML documents to and from standard COBOL data structures.

Note: A COBOL data structure, as used in this document, is a COBOL data item. In general, it is a group data item, but in some cases, it may be a single elementary data item. The Enterprise Developer compiler XMLGEN directive generates an XML-format symbol table into a file called a model file. The XML-format symbol table provides a map between the COBOL data structure specified in an XML Extensions statement and the XML representation of the COBOL data structure. This map can be used to move data in either direction at runtime. Extensible Stylesheet Language Transformations (XSLT) of the XML data representation can be used to match XML element names to COBOL data-names in cases where the names differ.

By allowing standard COBOL data structures to be imported from and exported to XML documents, XML Extensions enables the direct processing and manipulation of XML-based electronic documents by the COBOL application programmer. Furthermore, XML Extensions does this without requiring the application programmer to become thoroughly familiar with the numerous XML-related specifications and the time-consuming process required to emit and consume well-formed XML.

Specifically, an XML document may be imported into a COBOL data structure under COBOL program control using a single, simple COBOL statement, and, similarly, the content of a COBOL data structure may be used to generate an XML document with equal simplicity. XML Extensions' approach handles both simple and extremely complex structures with ease. Individual data elements are automatically converted as needed between their COBOL internal data types and the external coding used by XML. Not only can the transition to and from XML take place when this happens, but powerful transforms, which are coded using XSLT, can be applied at the same time. This powerful mechanism gives XML Extensions the capabilities needed to be useful in a wide range of e-commerce and Web applications.

In order to add this powerful document-handling capability to a COBOL application, the programmer need only describe the information to be received or transmitted to the external components as COBOL data definitions. In many cases, this description will simply be the already-existing data area defined in the COBOL application.