Revision [1062]
This is an old revision of Serialization made by DavidLee on 2009-11-27 05:31:55.
Serialization
Commands that produce XML and output to text format require Serialization. Serialization is controlled via Serialization Options
These options are global to the shell, and can also be specified on a per-command basis for most commands.
Examples
It is not always obvious when parsing or serialization occurs, for example depending on the participants in a pipeline and the xpipe setting, there may or may not be serialization and parsing in a pipeline.
Example: The xcat command will serialize to text then xml2csv will parse text to XML
xcat *.xml | xml2csv
Example: This uses an internal event oriented StAX pipeline and does NOT serialize or parse text XML
set +xpipe xcat *.xml | xml2csv
Also depending on what technology individual commands use they may be outputing as 'pure XML' or as text.
Even with xpipe set, the external "cat" command requires text input so the xml is serialized and the xpipe is ignored.
set +xpipe xcat *.xml | cat
How redirection is specified may also affect if XML is serialized or parsed.
For example, the following will serialize to text
xslt -f stylesheet.xsl -i input.xml > file.xml
But this command will NOT serialize to text, but rather construct an XML variable which was never serialized.
It is the TinyTree representation which saxon produces directly from the xslt without a copy or serialization.
xslt -f stylesheet.xsl -i input.xml >{VAR}Similary the following may not ever produce or parse a text format depending on the implementation of "command".
var=$<(command)
Bare Attributes
Bare attribute values cannot be serialized. They can be placed into a variable and used as arguments to commands,
but they cannot be serialized or output through an output port (even using the >{var} notation.
To create a bare attribute you can use <[ ]> syntax and use any xquery expression which produces an attribute node.
This value value can be assigned to a variable or passed as an argument to a command that accepts attributes (such as xed
When any attempt is made to serialize an attribute it is converted to a string (the value part of the attribute).
Example
a=<[ <foo a="b" /> ]> echo <[ $a/@a ]>
Result
b
