Schematic Description of Grid Exceptions

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Schematic Description of Grid Exceptions
Arun Jagatheesan San Diego Supercomputer Center
(SDSC) High Energy Physics Group, University
of Florida
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Outline

• Why describe?
• How to describe?
• What to describe?

• Who / MIB (Men Involved Behind the scene)?
• RFS (Request for Suggestions)
• NOTE Still in learning phase

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Data Grid Management System (DGMS)

• Before we start, why we were interested Data,
  Knowledge Management in Grids
• Data Grid Management System as set of Services
• Credit (DGMS)
• Reagan Moore (SDSC) Knowledge Grids
• Jim Gray (Microsoft) VLDB Suggestions
• Arcot Rajasekar (SDSC) Data Grids
• You (TIA for your suggestions in workshop)

A question session will follow. Take Notes
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What Datagrid and DGMS

• Data Grid Logical view of collection of
  heterogeneous data spread across virtual
  organization(s) providing a transparent access
  irrespective of data location, storage media,
  storage format and data identifier (name)
• DGMS System to manage relationship between data
  and events associated with the data grid workflow
  to help in automated data and knowledge discovery

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Descriptions Required

• DGMS required Grid Data Flow distributed
  operations on the grid specified using XML
  documents
• Also required
• Description of Exceptions in inter-grid and intra
  grid environments
• Description of Handling Cases which might
  dynamically change

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Why descriptions?
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Whatz ahead for Grid

• Grid as it was meant to be.

Grid in a Cell??
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Exception Handling in Grid
Service Requestor
Store file1.xyz in data grid
Grid / Executor
Service Providers
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Exception Handling in Grid User
Service Requestor
Just send me an e-mail of failure
Grid / Executor
Service Providers
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Exception Handling in Grid - Provider
Service Requestor
Archival System Maintenance required for tape
robot or try after 1 working day
Grid / Executor
Service Providers
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Exception Handling in Grid System
Service Requestor
Mission Critical Grid Need to find another
Service Provider
Grid / Executor
Service Providers
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Exception Handling

• Grid User Specified
• Service Provider Specified
• Grid/System Specified

• 2 Questions
• How do we dynamically specify the different
  exception handling associated with the same
  exception
• Who does the real exception handling

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How to description?
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Customized Exception Handling

• Try (store file1.xyz in data grid) catch any
  exception and handle
• Using Arun_Out_of_Office_Handler (User)
• Using Vegas_HPSS_Handler (Service Provider)
• Using GriPhyN_Level1_Handler (System)

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Exception Name spaces

• xmlnscondor http//www.cs.wisc.edu/condor/exce
  ptions
• ltgdflexceptiongt
• ltfaultHandler nameArunFirstHandler"gt
• ltfault valuecondorFileNotFoundgt
• ltactiongt
• ltmail name"faultHandlerMail"gt
• ltTogtarun_at_sdsc.edult/Togt
• ltbodygtSum of all Fears - SOS Grid lt/bodygt
• lt/mailgt
• ltloggtFatal Error Mercury Risinglt/loggt lt/ac
  tiongt
• ltflowgtdielt/flowgt
• ltfaultgt
• lt/faultHandlergt
• lt/gdflexceptiongt

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What to describe?
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The Grid Scenario Again
Service Requestor
Do this on the grid as mentioned in this VDL
document
Grid / Executor
Service Providers
go.org
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The Grid Scenario Again
Service Requestor
Now where the the hell did the grid service
crash? If I now it, I could handle it
appropriately
Grid / Executor
Service Providers
gator.edu
go.org
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So what we need

• Need for Name spaces describing the taxonomies of
  error handling with respect to the Service
  Provider, Type of the error (generic/specific),
  the policies in the grid
• Need for description of what happened exactly.
  Just a message Some thing bad happended during
  the service invocation is not fine to recover
  from it.

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Sum up

• VDL/DAG Submission (For each operation on the
  grid)
• User App has its own customized error handler
  based on the name spaces/ categories of error
  types
• Service provider has its own error handler based
  on the name spaces/ categories of its own domain
  which is shared with the grid
• Grid (System) has its own error handler based on
  the grid policies and efficiency concerns
• All these error handlers could change
  dynamically.

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Advantages

• Structured Handling based on profiles
• Handled by the respective providers
• Profiles can be dynamically changed
• Suitable for inter-grid and intra-grid scenarios

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Disadvantages

• Xtra processing
• Definition and categorization of grid errors
  required
• New Mechanisms to parse and handle these
  exception documents (probably in XML) is required

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Summary

• Grid Exceptions involve The Service Requestor,
  Service Provider and the Grid Policy which change
  dynamically
• Generic Classification of Grid Errors which could
  be extended later is required
• Error types and error handling description based
  on service provider required to handle if more
  efficiently