As a standard format in messaging applications. This includes industry-standard protocols as well as more home-grown solutions.

As a standard format for data exchange between applications and users.

As a standard representation for external data storage. This may include traditional database records or it may include more complex content such as documentation.

Objects can automatically “project” themselves as XML documents. This includes projecting object properties as XML elements and attributes as well as supporting nested elements (represented as object collections, embedded objects, or object relationships). The projected XML can be served as standard files or as online content (such as in response to HTTP requests). The object projection can also used to automatically generate an XML DTD or Schema (the standard XML methods for defining the contents of an XML document).

XML documents can be automatically transformed into an equivalent object representation. You can use the resulting objects to perform business logic or for storage in the Caché object database. Incoming XML can be read from files, streams, or from incoming HTTP requests. Caché can validate any incoming XML using industry-standard XML DTD or Schema validation.

For special applications, you can customize Caché's XML support in a number of ways. This includes an easy way to create custom XML server code as well as the ability to create custom XML import mechanisms (using Caché's SAX interface).

Caché includes, within Studio, an XML Schema Wizard that automatically generates class definitions from XML schemas. For more information, refer to the section on XML Schemas.

The Caché SAX parser—a builit-in SAX XML validating parser using the standard Xerces library. SAX is a parsing engine that provides complete XML validation and document parsing. Caché SAX communicates with a Caché process using a high-performance, in-process call-in mechanism. Using Caché SAX you can process XML document using either Caché's built-in XML support (q.v.) or by providing your own custom SAX interface classes within Caché.

The Caché XML library—a set of Caché classes for working with XML. These classes include %XML.Adaptor, which gives any class the ability to automatically project (serialize) its object instances to XML and vice versa; %XML.Reader which provides the ability to read XML documents and automatically convert them into object instances; and %XML.TextReader which provides a way to read generic XML documents without defining an object mapping.