Look ahead in OGSA-DAI
EPCC, University of Edinburgh
OGSA-DAI Training Workshop - April 2003
Release: P2R2
Talk Outline
4Discuss future changes for OGSA-DAI:
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2
Impact of GT3-alpha 4
Interface Changes
GDSR changes
Conclusions
OGSA-DAI Training Workshop, Release: P2R2
GT3 and OGSA-DAI
4 Globus GT3 releases up to GT3-alpha 3
– Based on draft 4 of the Grid Services Specification
– OGSA-DAI R2 is GT3-alpha 3 compliant
4 Globus GT3-alpha 4
– Compliant with OGSI Specification v1.0 (in 60-day review period)
– Due out in April (soon)
4 Globus GT3-beta
– Due out at end of May.
4 OGSA-DAI Release 2.5
– Due out at end May.
– Should be GT3-alpha 4/GT3-Beta compliant.
4 There may be another OGSA-DAI interim release
– Bug fixes & GT3-alpha 4 compliant
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Interfaces Changes
4 Now have (OGSI) normative WSDL and XSD
– Before used Globus (gsdl) defined xsd and wsdl
4 Some deficiencies in WSDL 1.1
– Lack of interface (portType) inheritance
• replaces the idea of service types
– Inability to describe additional information elements on a port type
• Need an open content model for service data elements
4 GWSDL bridges gap from WSDL 1.1 -> 1.2
– WSDL 1.2 currently is a W3C working draft
– OGSI will use WSDL 1.2 when this spec comes out
4 Tooling takes GWSDL-> WSDL
– Creates a WSLD 1.1 portType with all operations of extended interface
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GWSDL port types
4 Schema definition for a GWSDL portType
…
targetNamespace=http://www.gridforum.org/namespaces/2003/0
3/gridWSDLExtensions
xmlns:gwsdl=http://www.gridforum.org/namespaces/2003/03/gr
idWSDLExtensions
…
<element name="portType" type="gwsdl:portTypeType"/>
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GWSDL port Types
4Where
<complexType name="portTypeType">
<complexContent>
<extension base="wsdl:portTypeType">
<sequence>
<any namespace="##other"
minOccurs="0" maxOccurs="unbounded"/>
</sequence>
<attribute name=”extends” use=”optional”>
<simpleType>
<list itemType=”QName”/>
</simpleType>
</attribute>
<anyAttribute namespace="##other"/>
</extension>
</complexContent>
</complexType>
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Example GWSDL port type
4 Grid Data Service portType could now look like:
<wsdl:types> …</wsdl:types>
<wsdl:message …> … </wsdl:message>
<gwsdl:portType name=“GridDataService” extends=“ogsi:GridService”>
<wsdl:operation name="perform">
<wsdl:input message=“gds:PerformInputMessage"/>
<wsdl:output message=“gds:PerformOutputMessage"/>
…
</wsdl:operation>
<!-- service data can go here using gwsdl (see later) -->
</gwsdl:portType>
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Rules of inheritance
4WSDL 1.1 allows operation name overloading
– Allow multiple operations with the same name but with
• different number of arguments or
• different argument types
4WSDL 1.2 should be used to interpret GWSDL
– Current draft of WSDL 1.2 does not allow operation
overloading
• If two operations have the same QName when extending a
portType then the operations MUST be equivalent
4This has implications on the derivation chain of
portTypes and naming of portType operations
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Service Data
4GWSDL Service Data Definition
<gwsdl:portType name="NCName">*
<wsdl:documentation .... />?
<wsdl:operation name="NCName">*
…
<sd:serviceData name="NCName" … />*
…
<sd:staticServiceDataValues>?
<!-- used to initialise service data -->
<some element>*
</sd:staticServiceDataValues>
…
</gwsdl:portType>
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Example Service Data
<gwsdl:portType name=“GridDataService” extends=“ogsi:GridService”>
<wsdl:operation name="perform">
…
<sd:serviceData name=“DataResources"
type=“gdsf:DataResourceType”
minOccurs="1"
maxOccurs="unbounded"
mutability="mutable">
<wsdl:documentation>
A combination of a scheme, a location and a path…
</wsdl:documentation>
</sd:serviceData>
…
<sd:staticServiceDataValues>
<-- can initialise static service data here if required -->
</sd:staticServiceDataValues>
…
</wsdl:operation>
…
</gwsdl:portType>
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OGSA-DAI Implications
4Change OGSA-DAI WSDL to use GWSDL
4Define additional (aggregate) portTypes:
– GDS portType
• Extends GridService, GridDataTransport
– GDSF portType
• Extends GridService, Factory and NotificationSource
– GDSR portType
• Extends GridService, NotificationSource, ServiceGroup*.
4These aggregate portType names may
change.
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GDSR Changes
4Registration portType deprecated
4Replaced by:
– ServiceGroup
– ServiceGroupRegistration
– ServiceGroupEntry
4GDSR
– Will have to be re-worked to follow new portTypes
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Conclusions
4 Described some of the issues that will have an
immediate impact on OGSA-DAI
– OGSI/GT3-alpha 4 compatibility
• Introduction of GWSDL
– Refactoring of portTypes
– The way Service Data Elements are declared
• More changes may be required to work with GT3-alpha 4
– GT3-alpha 4 due out very soon
4 Next scheduled OGSA-DAI release
– Due at the end of May
– Will be GT3-alpha 4 or GT3-beta compatible
• Depends on the time lines
– There may be an interim OGSA-DAI release to offer
• GT3-alpha 4 compatibility
• Bug fixes
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