Support for serialization is defined in the as yet unreleased DOM3 specification and Xerces 2.x supports an initial implementation of this which should be considered experimental though unlikely to change substantially.
To serialize a DOM tree you will need to create a DOM Writer object using the registered LS Implementation, e.g.
OBJECT x = CREATE "dynamic", "dyndom"
REM get the DOM LS implementation
OBJECT impls = x.getDOMImplementation("LS")
OBJECT writer = impls.createDOMWriter()
The specification allows for multiple registered implementation objects.
Once you have a writer object you can specify the encoding to use with the read/write property Encoding$ (UTF-8 by default) and how new lines are to be handled with the newline$ read/write property (O/S specific default such as HEX(0A) on Unix or HEX(0D0A) on Windows). The feature mechananism allows some control over how the serialization is to be done. E.g. to enable a formatted output you could set this feature on
writer.setFeature("format-pretty-print", TRUE)
A list of the feature strings can be found here.
To generate a string containing the text of the document use the following:
OBJECT s = writer.writeToString(OBJECT root) REDIM z$ = s.text$
The MemBufOutput object holds the generated string and guarantees that it is tidied up when the object is NIULLed.
The object passed can be the document node or any node in the tree. The tree below the node is serialized. The WriterFilter object can be used to setup a callback function allowing the KCML program to filter the nodes included in the serialized output and to specify classes of nodes to be included.
This example processes the books.xml file and strips out the <author> tags when it serializes it to a string:
DIM z$, OBJECT x, OBJECT p, OBJECT impls, OBJECT writer, OBJECT filter, OBJECT s
DIM _FILTER_ACCEPT=1, _FILTER_REJECT=2, _FILTER_SKIP=3
OBJECT x = CREATE "dynamic", "dyndom"
REM parse the file
OBJECT p = x.CreateParser()
p.DoNamespaces = FALSE
p.parse("books.xml")
OBJECT root = p.Document.DocumentElement
REM create a writer object
OBJECT impls = x.getDOMImplementation("LS")
OBJECT writer = impls.createDOMWriter()
REM setup for serialization
writer.setFeature("format-pretty-print", TRUE)
writer.NewLine$ = HEX(0D0A)
REM add a filter to strip the <author> tags
OBJECT filter = p.Document.createWriterFilter()
filter.SetFilter(BYREF 'accept)
writer.SetFilter(OBJECT filter)
REM print to a string via a string object
OBJECT s = writer.writeToString(OBJECT root)
REDIM z$ = s.text$
END
DEFSUB 'accept(OBJECT node)
REM filter callback function
RETURN (node.NodeName$ == "author" ? _FILTER_REJECT : _FILTER_ACCEPT)
END SUB
An entire document, including the XML header and DOCTYPE, if applicable, can be serialized using the writeDocToString() method. Such documents can only be encoded as UTF-8 and the encoding property of the writer object is ignored.
For other XML DOM examples click here.