The SNARL Service: Standards-based Naming for Accessing Resources in an LFC

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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