© 2005 Global Grid Forum The information contained herein is subject to change without notice Leading the pervasive adoption of grid computing for research and industry The DAIS-WG Specifications Norman Paton University of Manchester (DAIS-WG Co-Chair)

DAIS Specifications A consistent set of interfaces to access data resources. Partial virtualization/abstraction of the data resource: –Still need to know type of underlying data resource. –Data resource accessed using existing query language.

Specification Documents Web Services Data Access and Integration – The Core (WS- DAI) Specification, Version Web Services Data Access and Integration – The Relational Realisation (WS-DAIR) Specification, Version Web Services Data Access and Integration – The XML Realization Current status: –Recently completed Public Comment Period.

WS-DAI Specifications as Part of Data Profile WS-DAI WS-DAIRWS-DAIX Sets general pattern for realisations Possible Future Realisations Extensions for specific kinds of data resource Relational SQL XML XQuery/XPath

Interface types Uses a classification of interface types: –Originally postulated in the OGSA Data Services document. – Data description: –Provides properties that characterise the behaviour provided. Data access: –Provides access to data through a service interface. Data factory: –Provides service interface for the creation of derived data resources.

WS-DAI Specification Defines: –Some base messages/operations: Retrieve a property document. Destroy relationship between a data service and a data resource. Perform generic query. –Some base message exchange patterns for realisations to use. –Some resource-type-independent properties.

Data description Elements in a properties document, extended in realisations. Some may require explanation: –DatasetMap: allows different return types to be supported. –ConfigurationMap: configures data resources resulting from factory messages. DataResourceAbstractName ParentDataResource DataResourceManagement ConcurrentAccess DatasetMap ConfigurationMap LanguageMap DataResourceDescription Readable Writeable TransactionInitiation TransactionIsolation ChildSensitiveToParent ParentSensitiveToChild DataResourceAbstractName ParentDataResource DataResourceManagement ConcurrentAccess DatasetMap ConfigurationMap LanguageMap DataResourceDescription Readable Writeable TransactionInitiation TransactionIsolation ChildSensitiveToParent ParentSensitiveToChild WS-DAI

Data description – relational extensions DataResourceAbstractName ParentDataResource DataResourceManagement ConcurrentAccess DatasetMap ConfigurationMap LanguageMap DataResourceDescription Readable Writeable TransactionInitiation TransactionIsolation ChildSensitiveToParent ParentSensitiveToChild DataResourceAbstractName ParentDataResource DataResourceManagement ConcurrentAccess DatasetMap ConfigurationMap LanguageMap DataResourceDescription Readable Writeable TransactionInitiation TransactionIsolation ChildSensitiveToParent ParentSensitiveToChild WS-DAI CIMDescription SQLPropertyDocument SQLResponseItem SQLResponseItemSequenceNumber SQLResponseItemName NumberOfSQLRowSets NumberOfSQLUpdateCounts NumberOfSQLReturnValues NumberOfSQLOutputParameters NumberOfSQLCommunicationsAreas SQLResponseItem SQLResponseItemSequenceNumber SQLResponseItemName NumberOfSQLRowSets NumberOfSQLUpdateCounts NumberOfSQLReturnValues NumberOfSQLOutputParameters NumberOfSQLCommunicationsAreas SQLResponsePropertyDocument RowsetPropertyDocument RowSchema NumberOfRows RowSchema NumberOfRows

Direct Access Consumer SQLExecute ( SQLExecuteRequest ( DataResourceAbstractName, DatasetFormatURI, SQLExpression, SQLExpressionParameters)) SQLExecuteResponse ( SQLRowSet, SQLUpdateCount, SQLReturnValue, SQLOutputParameter, SQLCommunicationsArea) Database Data Service Relational Database RelationalDescription Readable, Writeable, etc Relational Schema, etc SQLAccess

Indirect Access Consumer SQLExecuteFactoryResponse ( Reference (SQLResponseAccess)) SQLRowsetFactory( SQLRowsetFactoryRequest( DataResourceAbstractName, portTypeQName, ConfigurationDocument, Count)) SQLRowSetSelectionFactoryResponse (Reference ( SQLRowSetAccess)) GetTuples ( GetTuplesRequest ( DataResourceAbstractName, StartPosition,Count)) GetTuplesResponse ( SQLResponse (SQLRowSet, SQLCommunicationsArea)) SQLExecuteFactory ( SQLExecuteFactoryRequest ( DataResourceAbstractName, PortTypeQName, ConfigurationDocument, SQLExpression)) Consumer WebRowSet RowSet Data Service SQLRowSetDescription ……, etc SQLRowSetAccess SQLResponse Data Service SQLResponseDescription ……, etc SQLResponseFactory SQLRowSet Relational Data Service SQLAccessDescription ……, etc SQLAccessFactory Relational Database

Potential Relevance to Virtual Observatories For existing data models: –Provide a design for standard interfaces to Relational and XML databases. Extensibility points: –Different data models and languages by extending WS- DAI in new specifications. –Different response formats, by advertising and selecting supported representations. –Different delivery mechanisms, by implementing data movement interfaces on response access services. Designed to be usable alone and to combine effectively with other standards. For specialised data models, WS-DAI provides a starting point for designs. Advantages: –Many fiddly design decisions are made for you. –Examples exist for use as templates. –Consistent with other realisations: Conforms to expectations. Quicker learning. Able to share implementation experiences and some code. Disadvantage: –Need to follow the WS-DAI view of the world.