OGSA-DAI
An Overview
OGSA-DAI on OMII 2.0
OMII The Open Middleware Infrastructure Institute
NeSC, Edinburgh, 14 September 2005
Amy Krause
EPCC
a.krause@epcc.ed.ac.uk
Goals for this presentation
• Overview of OGSA-DAI
• How to install, configure and use OGSA-DAI WSI
1.0 on OMII 2.0
14 March 2005
http://www.ogsadai.org.uk/
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Goals for OGSA-DAI
• Aim to deliver application mechanisms that:
– Meet the data requirements of Grid applications
– Functionality, performance and reliability
– Reduce development cost of data centric Grid applications
– Provide consistent interfaces to data resources
– Acceptable and supportable by database providers
– Trustable, imposed demand is acceptable, etc.
– Provide a standard framework that satisfies standard
requirements
• A base for developing higher-level services
–
–
–
–
Data federation
Distributed query processing
Data mining
Data visualisation
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Terminology - Data
• Data Resource
– Any object that can source/sink data
– Example: relational databases, a file system
• Data Service
– Common interface to a data resource
– Exposes capabilities of the data resource
– SQL Queries, XPath Queries
– May provide additional capabilities
– Data transformations, 3rd party data delivery
• OGSA-DAI
– Open Grid Services Architecture Data Access and Integration
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http://www.ogsadai.org.uk/
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OGSA-DAI in a Nutshell
• All you need to know about OGSADAI in a handy pocket sized book!
• Updated for Version 6.0
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http://www.ogsadai.org.uk/
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High Level Design
Client
Client Toolkit API
Client
OGSA-DAI Data Services
WS-RF
WS-RF
OGSI
WS-I
OGSI
WS-I
SOAP over HTTP
WS-RF
Server
Presentation
WS-I
Business
Logic
DAI Core
Relational
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OGSI
XML
http://www.ogsadai.org.uk/
File
Data
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OGSA-DAI Services
• OGSA-DAI uses data services to represent and provide
access to a number of data resources
Data Service
accesses
Data
Resource
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Data
Resource
http://www.ogsadai.org.uk/
Data
Resource
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Heterogeneity
Data
Service
Xindice
MySQL
Oracle
DB2
• Data source abstraction behind data service
– plug in data resources for different data source technologies
– does not mandate any particular query language or data
format
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Multiple Service Interfaces
• WS-I:
– WSDL, SOAP, WS-I 1.0.
– Axis 1.2, OMII 1.0 or OMII 2.0
• WS-RF:
– WS-Addressing, WS-RF.
– Globus Toolkit 4.
• OGSI (deprecated in R7):
– OGSI 1.0.
– Globus Toolkit 3.
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Supported Data Resources
Relational
XML
MySQL

Xindice
DB2

eXist
Oracle

PostgreSQL

SQLServer

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Other

Files

?
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Activities
• An Activity dictates an action to be performed, e.g.
– Query a data resource
– Transform data
– Deliver results
• Engine processes a sequence of activities
• Subset of activities available to a Data Resource
– Specified in configuration files
• Data can flow between activities
SQL
Query
Statement
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WebRowSet
xml data
XSLT
Transform
http://www.ogsadai.org.uk/
HTML
data
Delivery
ToURL
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OGSA-DAI Deck of Activities
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Client Toolkit
• Why? Nobody wants to write XML!
• A programming API which makes writing
applications easier
– Now: Java
– Next: Perl, C, C#?
// Create a query
SQLQuery query = new SQLQuery(SQLQueryString);
ActivityRequest request = new ActivityRequest();
request.addActivity(query);
// Perform the query
Response response = gds.perform(request);
// Display the result
ResultSet rs = query.getResultSet();
displayResultSet(rs, 1);
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Interaction Examples
Container
Data
Service
Client
List Resources
Data Resource3
Data Resource2
Data Resource1
Data Resource
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Interaction Examples
Data Resource1
Data Resource2
Data Resource3
Container
Data
Service
Client
List Resources
Data Resource3
Data Resource2
Data Resource1
Data Resource
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Interaction Examples
To: Data Resource1
<query>
Select name from …
</query>
Client
Query
Container
Data
Service
Data Resource3
Data Resource2
Data Resource1
Data Resource
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http://www.ogsadai.org.uk/
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Interaction Examples
Container
Query
Client
<webRowSet>
<data>
<row> …
</data>
</webRowSet>
Data
Service
Data Resource3
Data Resource2
Data Resource1
Data Resource
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http://www.ogsadai.org.uk/
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Interaction Examples
Container
Query +
Delivery
Client
Data
Service
Data Resource3
Data Resource2
Data Resource1
Data Resource
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http://www.ogsadai.org.uk/
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Interaction Examples
Container
Query
Client
Data
Service
Data Resource3
Data Resource2
<webRowSet>
<data>
<row> …
</data>
</webRowSet>
Data Resource1
Data Resource
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http://www.ogsadai.org.uk/
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Why OGSA-DAI?
• Why use OGSA-DAI over JDBC?
– Can embed additional functionality at the service end
– Transformations, compressions
– Third party delivery
– The extensible activity framework
– Avoiding unnecessary data movement
– Common interface to heterogeneous data resources
– Relational, XML databases, and files
– Usefulness of the Registry for service discovery
– Dynamic service binding process
– Provision of good meta-data is necessary
– Language independence at the client end
– Do not need to use Java
– Platform independence
– Do not have to worry about connection technology, drivers, etc
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Current release: OGSA-DAI WS-I 1.0
• Based on Apache Axis, also works with OMII 2.0
•
middleware distribution
– An OGSA-DAI “Data Service” combining metadata,
configuration and perform document capabilities
– Access to service metadata provided by a partial
implementation of the WS-ResourceProperties
specification.
– Example clients for testing and coding reference.
– Client Toolkit
Caveats/Issues:
– No security support
– Interfaces will be extended for R7
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http://www.ogsadai.org.uk/
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OGSA-DAI Project Webpage
• http://www.ogsadai.org.uk
Background
News & Events
Software Releases
Documentation
On-line Tutorials
Support
Training Courses
Links
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http://www.ogsadai.org.uk/
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FAQ, Support, Mailing List
•
Frequently Asked Questions
– http://www.ogsadai.org.uk/support/faq.php
– Updated as common problems become clear
• Support for OGSA-DAI releases
– http://www.ogsadai.org.uk/support
– support@ogsadai.org.uk
– Use to report problems
•
Discussion list
– users@ogsadai.org.uk
– http://www.ogsadai.org.uk/support/list.php
– General discussion of OGSA-DAI, data and the Grid
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http://www.ogsadai.org.uk/
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