the snarl service: standards-based naming for accessing resources in an lfc
DESCRIPTION
The SNARL Service: Standards-based Naming for Accessing Resources in an LFC. Karolina Sarnowska CERN Openlab Summer Program 2008. Outline. Introduction and Background SNARL Development Conclusion. Interoperability, Grid Standards, and SNARL. Introduction & background. - PowerPoint PPT PresentationTRANSCRIPT
Karolina SarnowskaCERN Openlab Summer Program 2008
Introduction and Background
SNARL Development
Conclusion
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Interoperability, Grid Standards, and SNARL
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Community of users, developers, and vendors
Leading global standardization effort
Efforts strive to accelerate grid adoption
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Need means of accessing resources
What’s in a name? human-readable refers to specific resource
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Describes standard way of mapping names to grid endpoints
RNS 1.0 Operations: Add List Remove Query Update
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Handles: Convey information needed to address Web service endpoint
<Address> <Reference Parameters> <Metadata>
<Security Context>
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SRM srmLs srmMkdir srmPrepareToPut srmRm srmMv
RNS add list remove query update
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Catalog of data files on storage elements
Each logical file entry can correspond to multiple physical files (replicas)
Provides mapping between logical file names and storage URLs
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Standards-based Naming for Accessing Resources in an LFC
RNS implementation for LFCs
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SNARLService
(1) RNS Requests
(3) RNS Resonses
LFC/grid /atlas /alice /cms /dteamGrid
Client (2) LFC API Calls
SESE
SE
Creating an RNS compliant web service with Axis2/C
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1. Setup web services framework with Axis2/C
2. Create RNS compliant service with WSDL2C
3. Implement RNS operations with LFC API calls
4. Create clients for (interoperability) testing
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Web services engine implemented in C
Handles SOAP message processing
Built-in support includes: WS-Addressing WS-Policy WS-SecurityPolicy
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1. Specify RNS compliant web service in WSDL
2. Use WSDL2C tool to generate web service skeleton in C
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Need to map RNS operation to LFC API calls Add List Remove Query Update
Naming dilemma: should replicas appear in namespace?
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SNARLService
(1) RNS List
(3) EPR
LFC•lfn: /grid/foo
GridClient
(2) LFC API Calls
SE•fooReplicaA
SE•fooReplicaB
If new logical file name: lfc_creatg
If new replica: lfc_addreplica(name specified by storage URL)
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REQUEST: specify name of new entry
<soap:Envelopexmlns:soap=‘http://www.w3.org/2003/soap-envelope’xmlns:wsa=‘http://www.w3.org/2005/03/addressing’><soap:Header> <wsa:Action> http://schemas.ggf.org/rns/2006/03/rns/add </wsa:Action></soap:Header>
<soap:Body> <rns:add xmlns:rns=‘http://schemas.ggf.org/rns/2006/05/rns’>
<rns:entry_name> /grid/foo </rns:entry_name> </rns:add>
</soap:Body></soap:Envelope>
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RESPONSE: EPR of newly created entry <soap:Envelope
xmlns:soap=‘http://www.w3.org/2003/soap-envelope’xmlns:wsa=‘http://www.w3.org/2005/03/addressing’><soap:Header> <wsa:Action> http://schemas.ggf.org/rns/2006/03/rns/add Response </wsa:Action></soap:Header>
<soap:Body> <rns:addResponse xmlns:rns=‘http://schemas.ggf.org/rns/2006/05/rns’>
<rns:entry_reference> <wsa:Address> http://pcitgd02.cern.ch:9090/axis2/services/snarl
</wsa:/Address> <wsa:ReferenceParameters> /grid/foo </wsa:ReferenceParameters> </rns:entry_reference>
</rns:addResponse> </soap:Body></soap:Envelope>
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Genesis IIGenesis II
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(3) RNS Resonse
LFC/grid /atlas /alice /cms /dteam
GridClient
(2) LFC API Calls
SESE
SE
(1) RNS Request
SNARLService
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Add security contextUpdate for RNS 2.0Add ByteIO implementation for data accessExplore use as interface between LFC and
other tools
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Implementation of RNS specification for existing grid system is possible
Interoperability using RNS specification is achievable
RNS operations are very basic
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Akos FrohnerErwin LaureDM TeamAndrew GrimshawMark Morgan
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1. "Open Grid Forum," http://www.ogf.org.2. M. Pereira, O. Tatebe, L. Luan, and T. Anderson, "Resource
Namespace Service Specification," https://forge.gridforum.org/sf/docman/do/downloadDocument/projects.gfswg/docman.root.working_drafts/doc8272/5, World Wide Web Consortium, 2006.
3. M. M. Morgan and A. S. Grimshaw, "Genesis II – Standards Based Grid Computing," Seventh IEEE International Symposium on Cluster Computing and the Grid, 2007.
4. “Apache Axis2/C,” http://ws.apache.org/axis2c
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