Post on 31-Mar-2015
TU/e
/AIS GroupTechnische UniversiteitEindhovenUniversity of Technology
Modeling Grid Workflows withColored Petri Nets
Carmen Bratosin, Wil van der Aalst, and Natalia Sidorova
October 22-24, 2007 Aarhus, Denmark
CPN'07 2
TU/e
/AIS GroupTechnische UniversiteitEindhovenUniversity of Technology
What is a Grid? A world wide distributed infrastructure
composed by heterogeneous resources linked by common standards.
Status1. Grid technologies available: Globus,
Condor, OGSA-DAI , Taverna etc.2. Workflows for organizing the job flow
October 22-24, 2007 Aarhus, Denmark
CPN'07 3
TU/e
/AIS GroupTechnische UniversiteitEindhovenUniversity of Technology
Grid architecture
Resource allocation
User processes
Middleware
Resources layer
User request
s
Resource informati
on
Resource ids
Job descriptions
October 22-24, 2007 Aarhus, Denmark
CPN'07 4
TU/e
/AIS GroupTechnische UniversiteitEindhovenUniversity of Technology
Resources
colset Props = list Prop;colset ResID = string;colset Res = product ResID * Props * Props;
- Computing or Storage Elements- Characterized by a set of properties: e.g. CPU etc.
October 22-24, 2007 Aarhus, Denmark
CPN'07 5
TU/e
/AIS GroupTechnische UniversiteitEindhovenUniversity of Technology
Grid Workflow
• Two different types of elements:
• Jobs running
• Control elements
October 22-24, 2007 Aarhus, Denmark
CPN'07 6
TU/e
/AIS GroupTechnische UniversiteitEindhovenUniversity of Technology
Grid jobs
Requirements: minimal set of properties that a resource should fulfill
Running job: characterized by process instance id and the allocated resource id
October 22-24, 2007 Aarhus, Denmark
CPN'07 7
TU/e
/AIS GroupTechnische UniversiteitEindhovenUniversity of Technology
Middleware
fun en((rid,free,busy),req) = m_leq(req,free);fun take((rid,free,busy),req) = (rid,m_min(free,req),m_add(busy,req));fun return((rid,free,busy),req) = (rid,m_add(free,req),m_min(busy,req));
October 22-24, 2007 Aarhus, Denmark
CPN'07 8
TU/e
/AIS GroupTechnische UniversiteitEindhovenUniversity of Technology
Patterns: multiple allocation
October 22-24, 2007 Aarhus, Denmark
CPN'07 9
TU/e
/AIS GroupTechnische UniversiteitEindhovenUniversity of Technology
Patterns: multiple allocation
October 22-24, 2007 Aarhus, Denmark
CPN'07 10
TU/e
/AIS GroupTechnische UniversiteitEindhovenUniversity of Technology
Process mining example
start endprepare log analyze log select algorithm
heuristic miner
check conformance
return results
alpha miner
genetic miner
...+ -
start set parameters
partition log for 10 fold checking
1
+
check results
10
2
...
run algorithm
-
endreturn results
October 22-24, 2007 Aarhus, Denmark
CPN'07 11
TU/e
/AIS GroupTechnische UniversiteitEindhovenUniversity of Technology
October 22-24, 2007 Aarhus, Denmark
CPN'07 12
TU/e
/AIS GroupTechnische UniversiteitEindhovenUniversity of Technology
October 22-24, 2007 Aarhus, Denmark
CPN'07 13
TU/e
/AIS GroupTechnische UniversiteitEindhovenUniversity of Technology
Verification of grid workflows
Two steps process:1.Structural verification without
resource constraints2.Structural verification with resource
constraints
October 22-24, 2007 Aarhus, Denmark
CPN'07 14
TU/e
/AIS GroupTechnische UniversiteitEindhovenUniversity of Technology
Verification of grid workflows: Step 1 (“infinite” resources)
• Wanted property: soundness
• Two additional conditions:
1. the marking of the requirements places remains the same for all the reachable markings and
2. the resource pool place marking in the final state has the same value as in the initial state.
Home Properties-----------------------
Home Markings [28]
Liveness Properties-----------------------
Dead Markings [28] Dead Transition Instances None Live Transition Instances None
October 22-24, 2007 Aarhus, Denmark
CPN'07 15
TU/e
/AIS GroupTechnische UniversiteitEindhovenUniversity of Technology
Verification of grid workflows: Step 1
• Wanted property: soundness
• Two additional conditions:
1. the marking of the requirements places remains the same for all the reachable markings and
2. the resource pool place marking in the final state has the same value as in the initial state.
Home Properties-----------------------
Home Markings [28]
Liveness Properties-----------------------
Dead Markings [28] Dead Transition Instances None Live Transition Instances None
October 22-24, 2007 Aarhus, Denmark
CPN'07 16
TU/e
/AIS GroupTechnische UniversiteitEindhovenUniversity of Technology
Verification of grid workflows: Step 2 limited amount of resources
• Wanted property: no deadlocks
• Analysis of a grid model with multiple instances and a limited set of resources
Home Properties
-----------------------
Home Markings
None
Liveness Properties
-----------------------
Dead Markings
[420,456,952]
October 22-24, 2007 Aarhus, Denmark
CPN'07 17
TU/e
/AIS GroupTechnische UniversiteitEindhovenUniversity of Technology
Correcting process mining workflow
Identified problem: multiple resources are claimed without being released
Solution: Claiming/releasing more resources
October 22-24, 2007 Aarhus, Denmark
CPN'07 18
TU/e
/AIS GroupTechnische UniversiteitEindhovenUniversity of Technology
October 22-24, 2007 Aarhus, Denmark
CPN'07 19
TU/e
/AIS GroupTechnische UniversiteitEindhovenUniversity of Technology
October 22-24, 2007 Aarhus, Denmark
CPN'07 20
TU/e
/AIS GroupTechnische UniversiteitEindhovenUniversity of Technology
Conclusions• A structural method to design grid workflows
• CPN Tools helped in finding model problems
Future work
• Extend the model with time
• Extend model such that resources can become unreliable
• Analysis of different allocation policies base d on resource history