XML (version 1.6-2)

catalogResolve: Look up an element via the XML catalog mechanism

Description

XML parsers use a catalog to map generic system and public addresses to actual local files or potentially different remote files. We can use a catalog to map a reference such as http://www.omegahat.org/XSL/ to a particular directory on our local machine and then not have to modify any of the documents if we move the local files to another directory, e.g. install a new version in an alternate directory. This function provides a mechanism to query the catalog to resolve a URI, PUBLIC or SYSTEM identifier.

Usage

catalogResolve(id, type = "uri", debug = FALSE)

Arguments

id

the name of the (generic) element to be resolved

type

a string, specifying whether the lookup is for a uri, system or public element

debug

logical value indicating whether to turn on debugging output written to the console (TRUE) or not (FALSE).

Value

• A character vector. If the element was resolved, the single element is the resolved value. Otherwise, the character vector will contain no elements.

concept

XML

References

http://www.xmlsoft.org http://www.sagehill.net/docbookxsl/Catalogs.html provides a short, succinct tutorial on catalogs.

See Also

xmlTreeParse

Examples

Sys.putenv("XML_CATALOG_FILES" = system.file("exampleData", "catalog.xml", package = "XML"))

catalogResolve("-//OASIS//DTD DocBook XML V4.4//EN", "public")

catalogResolve("http://www.omegahat.org/XSL/foo.xsl")

catalogResolve("http://www.omegahat.org/XSL/article.xsl", "uri")
catalogResolve("http://www.omegahat.org/XSL/math.xsl", "uri")


  # This one does not resolve anything, returning an empty value.
catalogResolve("http://www.oasis-open.org/docbook/xml/4.1.2/foo.xsl", "uri")