Middleware independent I nformation Service Harry Enke, - - PowerPoint PPT Presentation

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Middleware independent I nformation Service Harry Enke, - - PowerPoint PPT Presentation

Feb 17, 2024 342 likes •603 views

Middleware independent I nformation Service Harry Enke, Astrophysical Institute Potsdam AstroGrid-D Stellaris, an interoperable Information Service 1 H. Enke, ISGC 2008 Outline 1. Why middleware independent components? 2. Stellaris as

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1 Stellaris, an interoperable Information Service

  • H. Enke, ISGC 2008

Middleware independent I nformation Service Harry Enke, Astrophysical Institute Potsdam AstroGrid-D

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2 Stellaris, an interoperable Information Service

  • H. Enke, ISGC 2008

Outline

  • 1. Why middleware independent components?
  • 2. Stellaris as middleware independent information

service

Intro RDF + SPARQL Components

  • 3. UseCases / Examples

Job information Resource information Integration of Resources into the Grid (Robotic Telescopes)

  • 4. Summary

Thanks to M. Hoegqvist, I. Nickelt and the AstroGrid-D team

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3 Stellaris, an interoperable Information Service

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Why middleware independent components?

Many users and Virtual Organisations are using more than one middleware. Communities have to broker agreements with providers using different middleware. Information from different middleware components may not be consistent. Interfacing with non grid-components may be necessary.

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4 Stellaris, an interoperable Information Service

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Why middleware independent components?

Both user and VOs want

  • information on available resources or

brokering facilities for storage and compute requirements

  • information about charges (fees)
  • information about their jobs

(runtime and accounting)

  • access and store metadata for their data sets

in a middleware-independent form.

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5 Stellaris, an interoperable Information Service

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Metadata Requirements

Metadata Requirements for a Community Grid Resource metadata Activity State Application metadata Scientific metadata

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6 Stellaris, an interoperable Information Service

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Requirements for a CG information service

AstroGrid-D‘s requirements for Stellaris

  • A uniform interface compatible with existing tools, based
  • n standards
  • support for flexible and extensible metadata schemes,
  • integration of the following metadata types:

Resource metadata Activity State Application metadata Scientific metadata

  • authentication and authorization for access control.
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7 Stellaris, an interoperable Information Service

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The Stellaris I nformation Service

Stellaris is a database application

  • Data is represented in RDF format
  • Data is uploaded and retrieved via web based

protocols (http(s), soap)

  • SPARQL is a query language for data extraction

(SPARQL Protocol and RDF Query Language is a recursive acronym)

  • Fine grained access control is possible through

grid security mechanisms

  • Persistent storage on disk by RDBMS
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8 Stellaris, an interoperable Information Service

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Stellaris: RDF example

A simple RDF tuple (graph) subject predicate

  • bject
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9 Stellaris, an interoperable Information Service

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Stellaris: RDF I ntroduction

RDF is a recommendation of W3C. Numerous tools and interfaces available from the semantic web community. Stellaris uses RDF/XML syntax.

A general XSLT from XML to RDF is available. Stellaris does translation on the fly.

The RDF data model makes statements about resources. A statement is divided into the

  • resource (subject) itself, a
  • predicate describes an unidirectional relation to an
  • object

This (subject, predicate, object)-tuple is often called a RDF triple.

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10 Stellaris, an interoperable Information Service

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Stellaris: RDF I ntroduction

Subject and predicate are URI (Uniform Resource Identifiers), while the object can be literal (a value) or an URI. RDF-URI are globally unique identifiers. Combining multiple RDF-Statements generates RDF-Graphs

  • r contexts.

Contexts are organized as tree-like structures within Stellaris. Besides from RDF/XML syntax the Notation 3 (N3) format is supported as well.

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11 Stellaris, an interoperable Information Service

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RDF vs XML

  • XML is a document format

A XML document can be interpreted in many different ways

  • RDF is an information model

RDF can be represented in an XML format A RDF document has only one interpretation, independent of the representation

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12 Stellaris, an interoperable Information Service

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Stellaris: Vocabulary / Schema

  • RDF is semi-structured data, which allows for

easy changes of vocabulary without changing the stored data

  • Vocabulary used with Stellaris:

Well known XML schemata Dublin Core, GLUE Additional: custom vocabulary defined by community, VO, application

  • r user

RTML: Robotic Telescope Markup Language

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13 Stellaris, an interoperable Information Service

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Stellaris: SPARQL example

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14 Stellaris, an interoperable Information Service

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Stellaris: SPARQL query

Create an object (referencing various schema)

@prefix file: <http://www.gac-grid.de/schema/files#> . @prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> . @prefix rtml: <http://www.rtml.org/v3.1a#> <http://storage.gac-grid.de/test/eaglenebula.fits> rdf:type <file:DataObject>; file:owner "Telescope user"; file:location <http://telescopes.aip.de/pictures/eaglenebula.fits>; file:filesize "259342"; rtml:Telescope <rtml://de.aip.Robotel/STELLA> .

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15 Stellaris, an interoperable Information Service

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Stellaris: SPARQL query

Do a query: (return location, owner and telescope of the file referenced by URI)

PREFIX file: <http://www.gac-grid.de/schema/files#> . PREFIX rtml: <http://www.rtml.org/v3.1a#> . SELECT ?location ?owner ?telescope FROM <http://telescopes.aip.de/context/robotic_telescopes> FROM NAMED <http://stellaris.astrogrid.net/context/files> WHERE { <http://storage.gac-grid.org/test/eaglenebula.fits> file:location ?location; file:owner ?owner; rtml:telescope ?telescope . }

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Stellaris: I nternals

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17 Stellaris, an interoperable Information Service

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Stellaris: I nterface

Request-Handler: Security: Handles authentication and authorization (ACL, VOMRS, X509) Context Management: internal interface for commands: create / retrieve / update / delete query

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18 Stellaris, an interoperable Information Service

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Stellaris: I nterface

Request-Handler: Synchronized View: handles concurrency issues Event View: passes request to storage management

  • r query engine
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19 Stellaris, an interoperable Information Service

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Resource I nformation with Stellaris

Globus-MDS information is uploaded to Stellaris after a XML to RDF transformation (GLUE). A visual map displays current status data of resources SPARQL queries deliver information to the command line or applications

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20 Stellaris, an interoperable Information Service

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UseCases: Grid Job Monitoring I

submission host execution host Information service

job submission

GUI

SPARQL query browser job status Upload job status (RDF)

Globus EPR

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21 Stellaris, an interoperable Information Service

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UseCases: Grid Job Monitoring I I

submission host execution host information service

job submission

GUI

SPARQL query browser

Globus Audit Usage Record

upload Usage Record (RDF)

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22 Stellaris, an interoperable Information Service

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Grid Job Monitoring GUI Timeline

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UseCases: Robotic Telescopes in Grid

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24 Stellaris, an interoperable Information Service

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Robotic Telescopes in Grid

Integration of robotic telescopes into the grid is an example of interoperability with other components Basic middleware: Globus for job submission, staging, job control security,VO management Robotic Telescope Components: Controller host with interface for RTML requests Heterogeneous Telescopes Network Component: RTML Interaction of components through Stellaris

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25 Stellaris, an interoperable Information Service

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Summary

Interoperability for user and VOs requires an information service for middleware independent

(Resource metadata, Activity State information, Application metadata Scientific metadata)

Stellaris with the RDF data model and SPARQL query language is a good candidate for the task. An information service such as Stellaris is needed for keeping the user or VO in the focus of the efforts to build an efficient eScience infrastructure