ILDG Middleware Working Group

1
ILDG Middleware Working Group

• Progress Report Metadata Catalogues

2
ILDG Middleware Working Group

• Architectural recap
• Metadata catalogue service
• Stores QCDml documents in back end
• Query for configurations/ensembles matching
  particular metadata
• Retrieve LFNs/ensemble URIs
• Retrieve metadata
• Obtain information
• Replica location service (RLS)
• Allows copies of datasets (configurations) to be
  located
• Provides information allowing download of
  datasets
• (Optional) SRM service
• Allows query-retrieve style access to ILDG data

3
ILDG Middleware Working Group

• Focussed mostly on metadata catalogue web service
• Standardisation
• Implementation
• Some work towards RLS
• Provisional task list (work in progress)

4
ILDG Middleware Working Group

• Metadata catalogue service standardisation
• WSDL interface definition refined
• Based on prototype developed by Tsukuba
• Enhanced in light of implementation
• Behavioural specification
• Return values, status codes, errors etc
• Test suite developed
• Defines tests that a service must pass to be
  ILDG compatible
• Perl-based implementation courtesy of LATFOR

5
Metadata Catalogue Service Definition

• Simple interface
• public interface MDCInterface
• public QueryResults doEnsembleURIQuery(
• String queryFormat, String queryString, int
  startIndex,
• int maxResults)
• public QueryResults doConfigurationLFNQuery(
• String queryFormat, String queryString, int
  startIndex,
• int maxResults)
• public MetadataResult getEnsembleMetadata(String
  ensembleURI)
• public MetadataResult getConfigurationMetadata(
• String configurationLFN)
• public MDCinfo getMDCinfo()

6
ILDG Middleware Working Group

• Metadata catalogue service implementations
• Carried out in parallel with interface
  standardisation
• Implementations exist at the following sites
• UKQCD
• LATFOR
• USQCD
• Tsukuba
• Most sites at version 1.0 (stable)

7
ILDG Middleware Working Group

• Metadata catalogue client implementations
• USQCD (prototype)
• Query an individual service
• http//www.usqcd.org/mdc-web-client
• LATFOR (prototype)
• Query across all services
• http//www-zeuthen.desy.de/ape-cgi-bin/ildg-mdc.cg
  i
• UKQCD graphical browser
• Work in progress
• Will include a graphical query builder to assist
  query construction

8
Towards a Replica Location Service

• Initial brainstorming of tasks has occurred
• Have identified design issues in the following
  areas
• Authentication
• Catalogue information
• Storage elements
• etc
• VOMS
• With view to access control
• File catalogue
• File transfer
• Will support these activities with upcoming
  telephone conferences and possibly face to face
  meetings
• Yet to be agreed work in progress
• Hope to identify a schedule soon