XML Converter
The XML converter uses no integration object metadata. The rules for converting between XML documents and property sets are essentially the same as the XML Hierarchy Converter. This service, however, does not create an XML hierarchy property set, but instead the XML document’s root element becomes a Type top-level property set (for example, Service Method Arguments). The service is intended for importing and exporting hierarchical data (arguments, definitions, and so on) and for passing property set arguments to and from business services.
The following shows the translation of an XML document into a property set representation within Siebel XML, and back again.

External entity resolution (XXE) has been disabled by default for security reasons and XML conversion will fail if the xml input has unknown External entities. To allow the external entities (XXE), user need to add the user property DisableDefaultEntityResolution with value False to the previous business services.
When DisableDefaultEntityResolution = false, external entities (XXE) will be ALLOWED.
When DisableDefaultEntityResolution = true, external entities (XXE) will be NOT BE ALLOWED
When DisableDefaultEntityResolution user property is ABSENT, external entities (XXE) will be NOT BE ALLOWED
The following topics are also described here: