A XmlChan is a specialised form of Channel which supports XML I/O operations. Writing an Object to an XmlChan (using AST_WRITE) will, if the Object is suitable, generate an XML description of that Object, and reading from an XmlChan will create a new Object from its XML description.

Normally, when you use an XmlChan, you should provide " source" and " sink" routines which connect it to an external data store by reading and writing the resulting XML text. These routines should perform any conversions needed between external character encodings and the internal ASCII encoding. If no such routines are supplied, a Channel will read from standard input and write to standard output.

Alternatively, an XmlChan can be told to read or write from specific text files using the SinkFile and SourceFile attributes, in which case no sink or source function need be supplied.

AST_XMLCHAN

The XmlChan class inherits from the Channel class.

In addition to those attributes common to all Channels, every XmlChan also has the following attributes:

• XmlFormat: System for formatting Objects as XML

• XmlLength: Controls output buffer length

• XmlPrefix: The namespace prefix to use when writing

The XmlChan class does not define any new routines beyond those which are applicable to all Mappings.