[ogsa-wg] Taverna workflows

[Stephen M Pickles]

Support for security in Taverna is, as Donal says, ongoing
work.

However, at least one group is using Taverna to invoke secured
services today. AstroGrid takes advantage of Taverna's plug-in
technology to retrieve the necessary credentials to invoke
a secured service from the "AstroGrid Runtime", a stateful
service local to the user's desktop. This works fine for
AstroGrid.

Stephen

> -----Original Message-----
> From: ogsa-wg-bounces at ogf.org 
> [mailto:ogsa-wg-bounces at ogf.org] On Behalf Of Donal K. Fellows
> Sent: 05 July 2007 10:00
> To: ogsa-wg
> Subject: [ogsa-wg] Taverna workflows
> 
> It's been an action on me to find out about Taverna. Since 
> the workflow
> session today was cancelled (national holidays? pah!) I'll report what
> I've learned so far here before I forget due to vacation. :-)
> 
> Taverna is a data-oriented workflow system (as opposed to
> control-oriented, though it also supports control links between
> processors) for automating tasks as seen from the client-side; it's
> intended to replace "human workflows" which involved cutting 
> and pasting
> chunks of text between web pages (previously a time-consuming and
> error-prone process). It's not designed to handle cases with complex
> recovery from failures, but is instead focussed on automated 
> handling of
> sets of data. It's GUI-oriented (though there is a command-line
> execution module) and as such it has got a number of features 
> to enable
> scaling of the complexity of workflows to 
> scientifically-useful levels:
> in particular, it has recursive decomposition and a way to mark
> processing nodes as "not interesting" and hence normally hidden. One
> limitation is that Taverna essentially assumes that the 
> processing nodes
> are free to use (both by the user *and* by anyone else) which has a
> consequence in terms of its (non-existent) security model[*]. 
> It's also
> not designed with dynamic instantiation of services in mind (there's a
> plugin for service discovery, but it's not integrated into 
> the workflow
> system itself, just the GUI design tool).
> 
> In short, if you're doing scientific workflows that use local 
> components
> and free static services available over the web, Taverna is very good.
> But it's got substantial weaknesses for domains where services are
> secured, costly or dynamic. Far more information than I've 
> mentioned is
> available online at
>     http://taverna.sourceforge.net/index.php?doc=docroot.html
> 
> I hope this is informative. :-)
> 
> Donal.
> [* I understand that there's work ongoing to add some kind of security
>     support, but I don't know how that's progressing. It's not in the
>     latest production release for sure. ]
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