The snarl service standards based naming for accessing resources in an lfc
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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.

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

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The snarl service standards based naming for accessing resources in an lfc

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

Karolina Sarnowska

CERN Openlab Summer Program 2008


Outline

Outline

  • Introduction and Background

  • SNARL Development

  • Conclusion


Introduction background

Interoperability, Grid Standards, and SNARL

Introduction & background


The high level problem interoperability

The High-level Problem: Interoperability


Open grid forum

Open Grid Forum

  • Community of users, developers, and vendors

  • Leading global standardization effort

  • Efforts strive to accelerate grid adoption


The low level problem naming for resource access

The Low-level Problem: Naming for Resource Access

  • Need means of accessing resources

  • What’s in a name?

    • human-readable

    • refers to specific resource


Resource naming service rns

Resource Naming Service (RNS)

  • Describes standard way of mapping names to grid endpoints

  • RNS 1.0 Operations:

    • Add

    • List

    • Remove

    • Query

    • Update


Endpoint references eprs

Endpoint References (EPRs)

Handles: Convey information needed to address Web service endpoint

<Address>

<Reference Parameters>

<Metadata>

<Security Context>


Srm vs rns

SRM vs RNS

SRM

RNS

add

list

remove

query

update

  • srmLs

  • srmMkdir

  • srmPrepareToPut

  • srmRm

  • srmMv


Lfc the lcg file catalog

LFC: The LCG File Catalog

  • 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


My summer project snarl

My Summer Project: SNARL

  • Standards-based Naming for Accessing Resources in an LFC

  • RNS implementation for LFCs

LFC

/grid

/atlas

/alice

/cms

/dteam

(1) RNS Requests

SE

Grid

Client

SE

SNARL

Service

(2) LFC API

Calls

SE

(3) RNS Resonses


Snarl development

Creating an RNS compliant web service with Axis2/C

SNARL Development


Development process

Development Process

  • Setup web services framework with Axis2/C

  • Create RNS compliant service with WSDL2C

  • Implement RNS operations with LFC API calls

  • Create clients for (interoperability) testing


Apache axis2 c

Apache Axis2/C

  • Web services engine implemented in C

  • Handles SOAP message processing

  • Built-in support includes:

    • WS-Addressing

    • WS-Policy

    • WS-SecurityPolicy


Wsdl2c

WSDL2C

  • Specify RNS compliant web service in WSDL

  • Use WSDL2C tool to generate web service skeleton in C


Implementing rns operations

Implementing RNS Operations

  • Need to map RNS operation to LFC API calls

    • Add

    • List

    • Remove

    • Query

    • Update

  • Naming dilemma: should replicas appear in namespace?


Lfn vs replica

LFN vs. Replica

(1) RNS List

Grid

Client

SNARL

Service

(3) EPR

(2) LFC API Calls

  • SE

  • fooReplicaA

  • LFC

  • lfn: /grid/foo

  • SE

  • fooReplicaB


Translating rns add to lfc api

Translating RNS Add to LFC API

  • If new logical file name: lfc_creatg

  • If new replica: lfc_addreplica

    (name specified by storage URL)


Rns operations add

RNS Operations: Add

REQUEST: specify name of new 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 </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>


Rns operations add1

RNS Operations: Add

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>


Interoperability testing

Interoperability Testing

LFC

/grid

/atlas

/alice

/cms

/dteam

Genesis II

Grid

Client

(1) RNS Request

SE

(3) RNS

Resonse

SE

SNARL

Service

(2) LFC API

Calls

SE


Conclusions

Conclusions


Future directions

Future Directions

  • Add security context

  • Update for RNS 2.0

  • Add ByteIO implementation for data access

  • Explore use as interface between LFC and other tools


Summary

Summary

  • Implementation of RNS specification for existing grid system is possible

  • Interoperability using RNS specification is achievable

  • RNS operations are very basic


Thank y ou

Thank You!

  • Akos Frohner

  • Erwin Laure

  • DM Team

  • Andrew Grimshaw

  • Mark Morgan


Questions

"Open Grid Forum," http://www.ogf.org.

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.

M. M. Morgan and A. S. Grimshaw, "Genesis II – Standards Based Grid Computing," Seventh IEEE International Symposium on Cluster Computing and the Grid, 2007.

“Apache Axis2/C,” http://ws.apache.org/axis2c

Questions?


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