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Information Services for Dynamically Assembled Semantic Grids. Mehmet S. Aktas, Geoffrey C. Fox, Marlon Pierce Community Grids Laboratory, INDIANA UNIVERSITY. www.opengrids.org. The First International Conference on Semantics, Knowledge and Grid – SKG 2005 , Beijing, China.

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Information services for dynamically assembled semantic grids

Information Services for Dynamically Assembled Semantic Grids

Mehmet S. Aktas, Geoffrey C. Fox, Marlon Pierce

Community Grids Laboratory, INDIANA UNIVERSITY

www.opengrids.org

The First International Conference on Semantics, Knowledge and Grid – SKG 2005, Beijing, China


Context as service metadata
Context as Service Metadata Grids

  • Context is metadata associated to both services and their activities

  • Context can be

    • independent of any interaction

      • slowly varying, quasi-static context

    • generated as result of interaction

      • dynamic context

        • Example: information associated to an activity or session

  • Gaggles: Collection of Services that

    • are set of actively collaborating managed services for a particular common goal

    • generate events as result of interactions

    • are very small part of the whole Grid

SKG-05, Beijing


Motivating scenario pattern informatics pi in a grid environment
Motivating Scenario: Pattern Informatics (PI) in a Grid Environment

  • PI in a Grid environment:

    • Hotspot forecasts are made using publicly available seismic records.

      • Southern California Earthquake Data Center

      • Advanced National Seismic System (ANSS) catalogs

    • Code location is unimportant, can be a service through remote execution

    • Results need to be visualized, stored, shared, modified

    • Grid/Web Services can provide these capabilities

SKG-05, Beijing


Information services for dynamically assembled semantic grids

WFS Environment

  • Support for slowly varying, quasi-static metadata

    • How do we support both prescriptive and descriptive metadata?

    • How do we enforce up-to-date information in registries?

  • Support for dynamic session related metadata

    • How do we manage dynamic workflows?

    • How do we enable correlation of service activities?

2

3

WMS

1

http://..../..../..txt

WMS Client

5,6,7

4

Data Filter

HP Search

PI Code

Data Filter

http://..../..../tmp.xml

Information Requirements in PI GIS Grid

PI GIS GRID

SKG-05, Beijing


Context information services motivations
Context Information Services Motivations Environment

  • Need to provide information describing services independent of their interactions.

    • generic anddomain specificcharacteristics of services

  • Need to manage all information associated with services for;

    • correlating activities of widely distributed services

    • enabling uniform query capabilities to both conversation-based or monolog context information

      • “Give me list of services satisfying C:{a,b,c..} QoS requirements and participating S:{x,y,z..} sessions”

    • management of events especially in multimedia collaboration

    • providing information to enable

      • session failure recovery capabilities

SKG-05, Beijing


Problem statement
Problem Statement Environment

What is a novel process of building

Information Services for both dynamic,

session related and slowly varying, static

context of widely distributed services

in Gaggles?

SKG-05, Beijing


What is ws context
What is WS-Context? Environment

  • Repository of Context Information

  • Allows for

    • Sharing Context info: metadata related to a particular transaction in multiple Web Service interactions

    • Sharing data: data in multiple Web service interactions

  • Nicely put, its a Distributed Variation of Shared Memory

  • Context Information dependent on the type of activity

    • Identify a transaction coordinator

    • Recovery information in event of a failure

    • Sharing info between participants (Security tokens, certificates, transaction IDs…)

SKG-05, Beijing


Architectural design requirements
Architectural Design Requirements Environment

  • Uniformity

    • need consistent interface to both static and dynamic context

  • Interoperability

    • need to leverage existing WS standards (UDDI, WS-Context) for service discovery and communication

  • Persistence

    • need to provide high availability of information

  • Dynamism

    • need to handle metadata based on changing user demands

  • Performance

    • need to support dynamic changes with min. delay

SKG-05, Beijing


Information services for dynamically assembled semantic grids

Extended Environment

UDDI Registry

Service

WSDL

The Architecture of Context Information Service

JDBC

Querying

and

Expeditor

Publishing

WSDL

WSDL

WSDL

Client

Client

Client

HTTP

WSDL

Database

Access

NB

Node

Storage

Sequencer

WSDL

HTTP(S)

SKG-05, Beijing


F ault t olerant h igh p erformance i nformation s ervices fthpis
F Environmentault Tolerant High Performance Information Services (FTHPIS)

  • Performance, compatibility, uniform interface

    • caching

      • Expeditor Module using Tuple Spaces paradigm

    • web service based programming interface, UDDI & WS-Context

      • Querying and Publishing Modules

  • From single point of failure to distributed system: fault tolerance

    • dynamic replication

      • Access Module

      • Storage Module

    • multi-publisher multicasting messaging

      • NaradaBrokering (www.naradabrokering.org)

SKG-05, Beijing


Information services for dynamically assembled semantic grids

Extended Environment

UDDI Registry

Service

WSDL

Distributed Dynamic Context Management

WSDL

Database

JDBC

Access

NB

Node

Storage

Querying

and

Expeditor

Sequencer

Publishing

WSDL

WSDL

Client

Computer Boundaries

Gaggle Boundaries

A

HTTP(S)

C

HTTP(S)

B

NB plays role is for fast and

reliable multi-publisher, multicast

messaging among peer IS Services

SKG-05, Beijing


Information services for dynamically assembled semantic grids

0 Environment

Extended UDDI

WFS

<context xsd:type="ContextType"timeout=“100">

<context-service>http://.../HPSearch</ context-service>

<parent-context>http://../abcdef:012345<parent-context/>

<content> shared data for HPSearch activity </content>

<activity-list mustUnderstand="true" mustPropagate="true">

<service>http://.../DataFilter1</service>

<service>http://.../PICode</service>

<service>http://.../DataFilter2</service>

</activity-list>

</context>

<context xsd:type="ContextType"timeout=“100">

<context-id>http://../abcdef:012345<context-id/>

<context-service>http://.../HPSearch</ context-service>

<content>http://danube.ucs.indiana.edu:8080\x.xml</content>

</context>

<context xsd:type="ContextType"timeout=“100">

<context-service>http://.../HPSearch</ context-service>

<content> HPSearch associated additional data generated during execution of workflow. </content>

</context>

<context xsd:type="ContextType"timeout=“100">

<context-service>http://.../HPSearch</ context-service>

<parent-context>http://../abcdef:012345<parent-context/>

<content> profile information related WMS </content>

</context>

<context xsd:type="ContextType"timeout=“100">

<context-service>http://.../WMS</ context-service>

<activity-list mustUnderstand="true" mustPropagate="true">

<service>http://.../WMS</service>

<service>http://.../HPSearch</service>

</activity-list>

</context>

2

3

4

WMS

1

http://..../..../..txt

WMS Client

7,8,9

6

Data Filter

HP Search

PI Code

5,11

10

Data Filter

http://..../..../x.gml

Context Information Service

The Pattern Informatics GIS-SOA based workflow application

session

service associated

shared state

user profile

activity

<?xml version="1.0" encoding="UTF-8"?>

<soap:Envelope xmlns:soap="http://www.w3...">

<soap:Header encodingStyle=“URL" mustUnderstand="true">

<context xmlns=“ctxt schema“ timeout="100">

<context-id>http..</context-id>

<context-service> http.. </context-service>

<context-manager> http.. </context-service>

<activity-list

mustUnderstand="true" mustPropagate="true">

<p-service>http://../WMS</p-service>

<p-service>http://../HPSearch</p-service>

</activity-list>

</context>

</soap:Header>

SOAP header

for Context

5,6: WMS starts a session, invokes HPSearch to run workflow script for PI Code with a session id

7,8,9: HPSearch runs the workflow script and generates output file in GML format (& PDF Format) as result

10: HPSearch writes the URI of the of the output file into Context

11: WMS polls the information from Context Service

12: WMS retrieves the generated output file by workflow script and generates a map

SKG-05, Beijing


System status i
System Status - I Environment

  • Extended UDDI Metadata Service

    • OGC (Open Geographic Information Systems (GIS) Consortium) specific service registry, up-to-date registry entries, metadata oriented query capabilities and XPATH query capabilities..

    • Status: 100 % completed. www.opengrids.org/extendeduddi

    • Application domains: PI GIS Grid (UC at Davis), IEISS GIS Grid (LANL)

  • WS-Context Complaint Metadata Services

    • WS-Context compatibility, support for shared dynamic context

    • Status: 100 % completed. www.opengrids.org/wscontext

    • Application domains: PI GIS Grid (UC at Davis), IEISS GIS Grid

SKG-05, Beijing


System status ii
System Status - II Environment

  • Unified UDDI & WS-Context Metadata Services

    • Both WS-Context and UDDI compatibility, uniform programming interface to dynamic & static metadata, caching (high performance), support for session-failure recovery capabilities

    • www.opengrids.org/wscontext

    • Application domains: PI GIS Grid (UC at Davis), IEISS GIS Grid, Global MMCS project

SKG-05, Beijing


Conclusions future work
Conclusions & Future Work Environment

  • There may be following gaps in Semantic/Traditional Grid Information Services.

    • needfor management of widely distributed, shared session-related dynamic metadata

    • need for enabling session failure recovery

    • need for uniform search interface to both interaction independent and conversation-based context

  • We introduce a novel architecture addressing these gaps by taking into account;

    • efficient metadata access and storage, decentralized fault tolerant storage capability, uniform interface to context, minimum response latency

  • We plan on investigating research issues related with fault tolerance and consistency as future work. We also want to evaluate the system as whole through extensive performance tests.

SKG-05, Beijing


Location of information and software for dependent grid projects
Location of information and software for dependent Grid Projects

  • htpp://www.naradabrokering.org provides Web service (and JMS) compliant distributed publish-subscribe messaging (software overlay network)

  • http://www.crisisgrid.org is an OGC (open geospatial consortium) Geographical Information System (GIS) compliant GIS and Sensor Grid.

  • http://www.opengrids.org has WS-Context, Extended UDDI etc.

SKG-05, Beijing