Dear Stian,

Here you can find the bet solution we thought:
http://myexperiment.elda.org/workflows/27/download?version=1

Any suggestion??

Thanks in advance

2011/9/12 Marta Villegas <[email protected]>

> Thank you for your help and for a very detailed and useful answer.
>
> In fact, I agree all a) b) c) options have problems...
>
> in fact option C is not very good solution for us either because it would
> pass the error to the following processor as you said.
>
> But it would be nice to have some beanshell option to detect elements with
> errors in a list. So the beanshell designer can decide what to do with that
> error: make the whole list fail, make an output list with correct values and
> error values, skip the errors, etc.
>
> Thanks for opening the new feature request.
>
>
> 2011/9/9 Stian Soiland-Reyes <[email protected]>
>
>> If the error is caused by the occasional failure, such as due to
>> network variations, etc, then you can improve this by setting the
>> Retry setting on services that call over the network:
>>
>>
>> http://www.mygrid.org.uk/dev/wiki/display/taverna/Advanced+workflow+configuration+video#Advancedworkflowconfigurationvideo-Retries
>>
>>
>> However, if the service for certain values always will fail, you would
>> need a "filter/replace error" shim. This is unfortunately not
>> currently easy to do with Beanshell script as Taverna by default
>> prevents execution on data with errors.
>>
>>
>> When we earlier talked to some users about what options they wanted
>> for error handling, we considered:
>> a) Removing errors from the list  (skipping them)
>> b) Replacing errors with a replacement input value, e.g.
>> "myStandardGene", empty string, etc.
>> c) Replacing calls on errors with a replacement output value, e.g. "--
>> ERROR HERE!!--"
>>
>> The consideration was not conclusive, but roughly each of these come
>> with issues:
>> a) Breaks the order of the list - result in position 5 might now come
>> from position 7 in incoming list (5 & 6 were errors) - which makes it
>> hard to use with later dot products
>>
>> b) Not sure which "fake input" would work well in many cases - and
>> could end up with "fake data" sneaking its way into the results
>>
>> c) "Error message" values could be passed on to the next service,
>> which don't know it's an error, and falls over with new errors or
>> strange outputs, but these are no longer linked back to original
>> error.
>>
>>
>> As engineers we thought that we could address c) by giving out the
>> replacement output as "An error with a replacement value". The service
>> which could fail would have an error handling configuration with "[x]
>> Substitute errors with __my_value______"
>>
>> Thus the default for downstream services would be to fail (as of now)
>> - but with a possible error handling configuration to "[x] Allow error
>> replacement values" which would run using the provided replacement
>> value.  We were not sure if the outputs of such processors should then
>> be normal values or "errors with replacement values".
>>
>> We did not proceed with implementing any of these options, as they
>> seemed to require a fair bit of effort and raised more open questions.
>>
>>
>>
>> Now - for your case I assume that as you are just concatenating
>> strings as the final step, you are not overly concerned with these
>> workflow implications for the general case, as you only want to deal
>> with or handling the errors that have occurred before giving a single
>> line-separated string back to the user.
>>
>> This is the kind of practical use case that we would have needed back
>> then - this is much simpler to implement, but would unfortunately
>> require writing a Taverna plugin or patch.
>>
>> I've registered this as a New Feature request:
>> http://www.mygrid.org.uk/dev/issues/browse/T2-1991
>> .. but I can't give any promises as to when it would be implemented.
>>
>>
>> The only workaround I can think of would be to use the "Failover"
>> mechanism - specifying an alternate service to the one that
>> occasionally fails. Unfortunately the Taverna 2 user interface does
>> not yet show this feature -
>> http://www.mygrid.org.uk/dev/issues/browse/T2-294 suggests creating
>> that processor in Taverna 1 and then use Copy and Paste. See
>>
>> http://www.mygrid.org.uk/usermanual1.7/workbench_windows.html#ame_alternate_processors
>> for Taverna 1 documentation.
>>
>>
>>
>> See attached where I have manually edited the .t2flow to add a string
>> constant as an alternate service to "Sometime fails". (Note that the
>> alternate service would need to provide values for all the service
>> outputs - and at the same list depth)
>>
>>
>>
>>
>> On Fri, Sep 9, 2011 at 10:03, Marta Villegas <[email protected]>
>> wrote:
>> > Hi,
>> >
>> > I'm using "merge string list to a string" component to concatenate a
>> list of
>> > outputs in most of our workflows. We do that because it's more user
>> friendly
>> > to copy that output with all results than coping each element of the
>> list.
>> > We work with lists with more than 500 elements.
>> >
>> > The problem comes when some elements have an error, then "merge string
>> list"
>> > is not able to create the concatenation and gives an error.
>> > Here I attach an example workflow that shows the problem...
>> >
>> > the exected result without errors would be a list like:
>> > String0
>> > String1
>> > String2
>> > String3
>> > ....
>> >
>> > with errors the result now is:
>> > [an error message]
>> >
>> > I would like to have:
>> > String0
>> > String1
>> > [error]
>> > String3
>> > ....
>> >
>> > Is there any way to do this?
>> >
>> > Thanks in advance.
>> >
>> >
>> > --
>> > Marta Villegas
>> > [email protected]
>> >
>> >
>> ------------------------------------------------------------------------------
>> > Why Cloud-Based Security and Archiving Make Sense
>> > Osterman Research conducted this study that outlines how and why cloud
>> > computing security and archiving is rapidly being adopted across the IT
>> > space for its ease of implementation, lower cost, and increased
>> > reliability. Learn more.
>> http://www.accelacomm.com/jaw/sfnl/114/51425301/
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>> >
>> >
>>
>>
>>
>> --
>> Stian Soiland-Reyes, myGrid team
>> School of Computer Science
>> The University of Manchester
>>
>>
>> ------------------------------------------------------------------------------
>> Why Cloud-Based Security and Archiving Make Sense
>> Osterman Research conducted this study that outlines how and why cloud
>> computing security and archiving is rapidly being adopted across the IT
>> space for its ease of implementation, lower cost, and increased
>> reliability. Learn more. http://www.accelacomm.com/jaw/sfnl/114/51425301/
>> _______________________________________________
>> taverna-users mailing list
>> [email protected]
>> [email protected]
>> Web site: http://www.taverna.org.uk
>> Mailing lists: http://www.taverna.org.uk/about/contact-us/
>>
>>
>
>
> --
> Marta Villegas
> [email protected]
>



-- 
Marta Villegas
[email protected]
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