Illegal Characters in XML Content

Although Doradus allows text fields to use all Unicode characters, XML does not allow element content to contain certain characters. The only characters allowed within XML content are in the following:

#x9 | #xA | #xD | [#x20-#xD7FF] | [#xE000-#xFFFD] | [#x10000-#x10FFFF]

In an output message, when Doradus creates an XML element whose content would contain any characters outside of this set, it base64-encodes the entire element value and adds the attribute encoding="base64" to the element. For example, suppose a field value contains the Unicode value “ABC\u0000”. The 4th character, hex 0x00, is not valid in XML, hence the field value would be returned as follows:

<field name="foo" encoding="base64">QUJDAA==</field>

Similarly, in an input XML message, element content that contains invalid XML characters must be base64-encoded, and the application must add the encoding="base64" attribute to the corresponding element.