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Agreement Service for Resource Reservation and Allocation: Overview

Tiziana Ferrari, Elisabetta Ronchieri GRAAP WG, GGF14. Agreement Service for Resource Reservation and Allocation: Overview. The EGEE proejct. EGEE:

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Agreement Service for Resource Reservation and Allocation: Overview

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  1. Tiziana Ferrari, Elisabetta Ronchieri GRAAP WG, GGF14 Agreement Service forResource Reservation and Allocation:Overview

  2. The EGEE proejct • EGEE: • project funded by the European Union aiming at the realization of a production-quality wide-area Grid infrastructure for the support of a large number of scientific applications • gLite is the set of core Grid services developed within the project: • Data management services • Job scheduling and service discovery (Workload Management System) • Information services • Security services • Accounting • Monitoring • and others... • overall service architecture available at [ARCH]

  3. Requirements • Requirements: support of resource allocation and reservation. In order of priority: • Storage space reservation for guaranteed storage of: • large amounts of replicated data • Output files produced by distributed analysis jobs • Computing for the timely execution of high-priority jobs • Network bandwidth for guaranteed data throughput on shared paths • Agreement Service (AS): • A new gLite service • Based on WS-Agreement (see following slides) • supports agreement offer signalling for establishment of resource allocation Service Level Agreements

  4. Initiators • Our Agreement Initiators: • Users • Workload Management System (WMS): • Used as Agreement Service proxy in case of clients that are interested in the properties of the resource to be reserved, but not in its location • WMS is instrumented to discover: • the resources satisfying the client’s reservation requirements • the interfaces of the service providers associated to the resources discovered in step 1 • The Agreement Services that support the interfaces identified in step 2 • Performes resubmission of the agreement offer in case of failure • Supports logging and bookkeeping of the entire agreement signalling process • Data Management • To perform reservation of storage space before triggering a file transfer

  5. Architecture Agreement Initiators Agreement Offer Reservation request Reservation and Allocation Service Providers (RASPs) Computing farm Storage system Network infrastructure

  6. Agreement Service implementation 1/2 • Implementation work started in Dec 2004 (WS-Agreement reference draft: the one which went to public comment) • Agreement services use the WS-Agreement XML schema definitions, however: • We decided not to go for WSRF (due to lack of implementation experience), for this reason we currently do not comply to the current draft • A database (WMS Logging and Bookkeeping component) is used for mangement of state information • We currently have a single WS service (the so-called Agreement Service) exposing the following operations: • createAgreement(), agreementKill(), agreementUpdate() • getAgreementProperties(), getAgreementStatus() • getTemplates() • We plan to redesign the Agreement Service when the WS-Agreement draft will be finalized

  7. Agreement Service implementation 2/2 • Agreement Service for space reservation currently under development: • In C++ • Based on gSoap 2.7.1 • Corresponding storage space service provider interface: SRM v. 2.1 (Grid Resource Management WG, GGF) [SRM] • Correspondance between AS operations and SRM service provider operations: • createAgreement()  srmReserveSpace(), srmPrepareToPut/srmPrepareToGet • agreementKill()  srmReleaseSpace() • agreementUpdate()  srmUpdateSpace(), srmChangeFileStorageType() • getAgreementStatus()  srmGetSpaceMetaData()

  8. Comments: use of xs:choice • xs:choice in XML Schema definitions not correctly handled by gSoap 2.7.1 (corresponding class not correctly generated, i.e. no presence of arrays) • xs:choice replaced through the use of xs:sequence and minOccurs=0 Our version: From standard: <xs:complexType name="TermCompositorType"> <xs:sequence> <xs:element name="ExactlyOne" type="wsag:TermCompositorType" minOccurs="0" maxOccurs="unbounded"/> <xs:element name="OneOrMore" type="wsag:TermCompositorType" minOccurs="0" maxOccurs="unbounded"/> <xs:element name="All" type="wsag:TermCompositorType" minOccurs="0" maxOccurs="unbounded"/> <xs:element ref="wsag:ServiceDescriptionTerm" minOccurs="0" maxOccurs="unbounded"/> <xs:element ref="wsag:GuaranteeTerm" minOccurs="0" maxOccurs="unbounded"/> </xs:sequence> </xs:complexType> <xs:complexType name="TermCompositorType"> <xs:sequence> <xs:choice maxOccurs="unbounded"> <xs:element name="ExactlyOne" type="wsag:TermCompositorType"/> <xs:element name="OneOrMore" type="wsag:TermCompositorType"/> <xs:element name="All" type="wsag:TermCompositorType"/> <xs:element ref="wsag:ServiceDescriptionTerm" minOccurs="0"/> <xs:element ref="wsag:GuaranteeTerm" minOccurs="0"/> </xs:choice> </xs:sequence> </xs:complexType>

  9. Guarantee state monitoring • Guarantee state information: provided by the agreement service? • this information typically changes frequently over time and it is a function of private accounting information collected at the service provider level • Collection of guarantee status information from a general-purpose service such as the Agreement service, is extremely complex as information providers can choose different mechanisms and formats • Two approaches: • GRAAP: Guarantee state information currently provided by the Agreement service • Our preferred option: Guarantee state information directly notified by the service provider to the parties involved in the agreement

  10. Other comments • Service Description Terms vs Guarantee Terms: • It is sometimes difficult to decide if an attribute should belong to the SDT section or rather to the guarantees section. Eg. Lifetime of a reservation: is it an SDT or a guarantee term? • Handling of the recursive structure of Terms quite complex, especially for the implementation of the logic needed to support the “exactly one” and “one or more” compositors • gSoap parsing error on: xs:group <xs:complexType name="OfferItemType"> <xs:sequence> <xs:element ref="wsag:Location"/> <xs:group ref="xs:simpleRestrictionModel" minOccurs="0"/> <!--//AA REMOVE COMMENTS --> </xs:sequence> <xs:attribute name="name" type="xs:string"/> </xs:complexType>

  11. References • [ARCH] EGEE Middleware Architecture (https://edms.cern.ch/document/476451) • [AS] gLite Allocation and Reservation Architecture http://edms.cern.ch/document/508055 (v. 2.1) • [SRM] http://sdm.lbl.gov/gsm/ • Prototype code available from the gLite CVS repository: • http://jra1mw.cvs.cern.ch:8180/cgi-bin/jra1mw.cgi/ • See the org.glite.allocation sub-system

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