Using XML as the Foundation for a Network Resource Description Language Peter A. Dinda

2 Motivation Network Resource Interface for external tools –A standard, text-based representation for network data –Integrating our own tools such as RPS –Integrating other tools such as NWS –Enhancing existing text-based interfaces –Potentially proposing a Grid standard Network data is structured data

3 XML in a Nutshell #1 Standard for presenting structured information via tag-based markup –Like HTML, except user gets to define the tags and their grammar “DTD” or “Schema” (can be part of doc) –Unlike HTML, “well-formed” XML is always a tree, so it’s easy to parse Tags can be anything but must nest –Unlike HTML, no styles or links are defined They are DTDs! XSL, Xlink, Xpointer, blah blah Self-defining text-based structured data format

4 XML in a Nutshell #2 “Well-formed” XML –It can be produced by the XML grammar “Valid” XML –Well-formed and the document can be produced by your grammar (ie, the DTD) Free XML parsers usually don’t “validate” –Probably not much of an issue for resource data

5 XML Tools Free parsers available for C, Java, Perl, Python Lots of commercial stuff –Microsoft (IE4, IE5, XML Notepad, lots of others) Most parsers/tools don’t support the DOM interface and so are not interchangeable

6 DTD/Schema Standardization XSL (styles), Xlink/Xpointer (links),... DTDs being developed for very specific kinds of information –News stories We could propose DTDs to the Grid Forum so that tools could exchange information

7 Proof of Concept Wrote XML serialization for RPS’s LoadMeasurement objects Used Expat, a free (non-validating) XML parser written in C

8 An XML Serialized LoadMeasurement <!DOCTYPE HostLoadList [ ]> pyramid.cmcl.cs.cmu.edu DTD - the grammar for the HostLoadList document that follows Document - the serialized LoadMeasurement object

9 Effort/Efficiency