[kepler-users] Workflow with instances dependency

Ilkay Altintas altintas at sdsc.edu
Tue Jun 12 17:28:25 PDT 2007


You can have a workflow the has the instances of web services for  
item K of your simulation under PN or SDF (given n below is known  
before scheduling) and has monitoring actors (check and get results  
if necessary) for the tasks in item K-1. So assuming that your Task 1  
through 4 depends also on each other and there are n items, one way  
to model it is:

Task1(K-1)    Check Task4 (K-1)
|                                             |
V                                            V
K-Assigner(0..K..n) -> Task1 (K) -> Task2 (K)-------------- -> Task3  
(K) -> Task4 (K)

K-Assigner will keep assigning the new items as the item before is  
processed. In this way, you can model it using web services as only  
web services for one item will be used at one time.

If you do this in PN, you might end up having thousands of web  
services at the same time for Task 1, but you can get around it by  
limiting it in the workflow by the K-Assigner actor.

There might be more efficient ways of doing the same thing by keeping  
two instances running at the same time using PN. Something like  
below, but the one below won't work.

K-Assigner(0..K..n) -> Task1 (K-1) -> Task2 (K-1) -> Task3 (K-1) ->  
Task4 (K-1)
|                                                            |
V                                                           V
                                   -> Task1 (K) -> Task2 (K)  
------------------------> Task3 (K) -> Task4 (K)

Hope you get the illustrations correctly...


On Jun 6, 2007, at 5:44 PM, Luis Assunção wrote:

> Hi
> In my current research I have to modulate a simulation where I have  
> thousands of input items and for each item I have the following  
> workflow.
> Task1 ->Task2->Task3->Task4
> But Task2 of item K depends of the completion of Task1 from item  
> K-1 and Task3 of item K depends of the completion of Task4 from  
> item K-1
> I am interested to use modeling based on Workflows and I am also  
> interested to support task execution as a Web Service.
> I am tried to modeling using Kepler with Web Service actor but I  
> think it isn’t suitable to describe an workflow with thousand of  
> instances (huge graphical boxes) and worst I don’t know the best  
> way to describe task execution with dependencies from previous  
> execution?
> Can someone advise me about what is the best pattern to this case?
> I appreciate in advance some advising.
> Many thanks
> Luis Assuncao
> Email: lass at isel.ipl.pt
> _______________________________________________
> Kepler-users mailing list
> Kepler-users at ecoinformatics.org
> http://mercury.nceas.ucsb.edu/ecoinformatics/mailman/listinfo/ 
> kepler-users

Lab Director, Scientific Workflow Automation Technologies (SWAT)
San Diego Supercomputer Center(SDSC), UCSD
9500 Gilman Drive, MC: 0505  La Jolla, CA  92093-0505
phone: (858) 822-5453                        fax: (858) 534-8303
web: http://users.sdsc.edu/~altintas

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