Stian,
Many thanks for this informative answer.
Regards,
Ketan
On Fri, Oct 1, 2010 at 11:42 AM, Stian Soiland-Reyes <
[email protected]> wrote:
> On Mon, Sep 20, 2010 at 07:29, Ketan Maheshwari
> <[email protected]> wrote:
> > A question to the language developers of Taverna:
> > Is there a way to verify that the semantics are preserved for a given
> > workflow when translated from scufl to t2flow/scufl2 syntax?
>
> There's not a programmatic way to detect non-preservation at the
> moment, but if you check out
>
> http://www.mygrid.org.uk/dev/wiki/display/developer/Differences+between+Taverna+1+and+Taverna+2+workflows
> it will describe which cases do not map 1:1.
>
> In Scufl2 we'll try to do scufl-parsing directly (instead of using
> legacy T1 libraries as of the moment), which should make it easier to
> give warnings when translating a workflow which can't map 1:1 to
> Scufl2.
>
>
> As a thumb rule, here are the biggest changes:
>
> * Merged links to a port have a predictable, defined order in T2. In
> T1 it was the first finished upstream execution that got first into
> the merge.
>
> * Iteration strategies are always explicit. Taverna 1 did a kind of
> auto-generated cross product determined by the order of the
> connections of the ports. Taverna 2 translation now honours this, and
> generates an explicit iteration strategy that matches Taverna 1.
>
> * Note that T1 had a bug in iteration strategies where if you open a
> workflow, save it, and then open it again, the order of the ports
> could be flipped upside down, iterating outermost port first instead
> of innermost port. We've made the T2 translator read in the such
> strategies upside-down so that when doing load->run in both Taverna 1
> and Taverna 2, it will give the same results.
>
> * Coordination links could be used for branching Taverna 1, as
> Taverna 1 allowed several links to the same input port without having
> a merge. Only the "first" value received would be passed on. This was
> used with coordination links to hack a form of branching, by making
> one branch of the workflow never execute. In Taverna 2 all branches
> execute, but might be producing/forwarding errors.
>
> * On implicit iterations in Taverna 2, the next processors will start
> executing the first outputs of previous processors, even if the
> upstream processors are still iterating over the link. To avoid this
> and finish the full iteration in each processor, add RunAfter-links
> parallel to each data link. (We could make this an option to SCULFL2
> translation)
>
> * Errors in an individual iteration will not fail the whole iteration,
> just that particular iteration. An error document is inserted inplace
> of the service outputs. This also means that coordination links will
> be triggered even when there's an error in T2, as the iteration will
> still finish normally.
>
>
> --
> Stian Soiland-Reyes, myGrid team
> School of Computer Science
> The University of Manchester
>
>
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