QCDml Tutorial

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QCDml Tutorial

• How to mark up your configurations

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Contents

• FAQs on using XML schema
• Defining QCDml
• Namespaces and validation
• Example XML IDs
• Ensemble and config
• Ensemble actions, algorithms and management
  metadata
• Config what goes where
• Babble about BinX
• Metadata catalogue demo

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FAQs about XML schema

• What is XML schema?
• Collection of rules for XML documents
• An XML schema is itself an XML document
• Why do we need an XML schema?
• Computers can read and understand XML IDs
• ltlengthgt16lt/lengthgt
• Meaning of length is context dependent
• Do I need to learn XML schema
• No. Schema makes it easier to produce XML

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QCDml1.0

• Metadata split into two schemata
• Ensemble XML ltmarkovChain/gt
• Config XML ltgaugeConfiguration/gt
• N.B. use lowerCamelConvention
• ILDG website for XML schema files
• http//www.lqcd.org/ildg
• Go to Metadata and follow links
• Version 1.0 online and ready to use

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Namespaces

• Example XML ID for UKQCD data

• XML Namespace defined by W3.org as
• A collection of names identified by a URI
  reference

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First namespace

• URI defines namespace for QCDml

• This is the default namespace
• All elements of QCDml belong to this namespace

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Second namespace

• Namespace of XML schema itself

• Prefix ltxsigt for elements of XML schema
• XML ID is valid against WC3 XML schema

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SchemaLocation

• The namespace of the schema

• The file which contains the schema
• URI namespace can be URL of the schema instance
  not compulsory

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Logical filename

• Unique URI for a file in a namespace

• Uniquely identifies this ensemble in ILDG
  namespace

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Validation

• Verify XML ID is valid against a schema
• Schema aware applications can use XML ID
• Can write XML in vi,emacs etc
• CMM uses XMLSpy for schema and ID manipulation
• built in validator, create XML ID from schema
• http//www.w3.org/XML/Schema
• Many different tools

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QCDml Ensemble ltaction/gt
UML representation of schema
Split into quark and gluon sections
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Ensemble XML - actions

• Inheritance tree - check for your action in schema

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Which elements?

• Schema defines required elements
• UKQCD NP clover

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UKQCD Ensemble example
Glossary not computer readable How cSW was
determined References etc
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NumberOfFlavours
Number of degenerate flavours for which these
coupling values apply
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MILC 21 staggered Ensemble
ltcouplings/gt is array valued Non-degenerate
flavours shown with different couplings Mass
0.02 Mass 0.05
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Management

• Metadata created when Ensemble registered with
  ILDG
• Yet to be created middleware will do this

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Algorithm

• Algorithmic metadata split between ensemble and
  algorithm
• Most metadata is unconstrained parameter ltname/gt
  ltvalue/gt pairs
• Relevant information can be found
• Glossary document for references etc
• Hierarchical structure for algorithms is
• difficult to create
• difficult to make extenisble

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Algorithm Example
Glossary for detailed information
Unconstrained parameter ltname/gt ltvalue/gt pairs
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Config XML
Machine and code details In principle these could
be different for configurations in the same
ensemble
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Config Management
Checksum for config binary Zeroeth ltrevision/gt is
generate data, as this occurs before submission
to ILDG
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Precision
Precision (double or float) in which the
calculation was done
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markovStep
Logical File name of the ensemble in the ILDG
namespace
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dataLFN
Logical File name of the configuration in the
ILDG namespace
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The markov chain
Where the configuration is in the trajectory of
markov chain
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avePlaquette
Very useful metadata, can be used to check data
transformations are correct
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Config UKQCD example
Application codes can write this info either as
QCDml Or tool can convert the IO to QCDml
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BinX

• XML markup for binary data
• Library for manipulating marked up data
• Production codes do not use BinX library
• But easy to mark up data format in BinX style
• ILDG middleware can use BinX for data
  manipulations
• http//www.edikt.org/binx
• BinX under discussion by Middleware Metadata WG
  for file format.

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Gauge config BinX
Small Written once per ensemble write code on top
of BinX library Change array order 2x3 ?
3x3 average plaquette ILDG BinX based gauge
config manipulator?
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Correlator data
Compact. No standard shape to correlators BinX
will read in any shape
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Array stripper
BinX BJs Xpath reader Code reads this
XML Produces single slice array in text/XML From
any size/shape array Schema for correlator
channels ILDG middleware extract channel from any
correlator