GridNet Funding Report
Open Grid Forum 22
25-28th February 2008
Cambridge, MA, USA
Mr Elias Theocharopoulos,
NeSC,
The University of Edinburgh.
elias@nesc.ac.uk
This report summarises my attendance at OGF22 in Cambridge and its relevance to current
OGSA-DAI, NeSC, OMII-UK and UK e-Science activities.
Meetings Attended
Monday 25th
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Opening Session
SAGA Java Language binding
OGSA AuthZ
Workflow Management RG
OGSA-Data Architecture Future Directions
Tuesday 26th
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OGC-OGF Collaboration Workshop
Infrastructure Management – eBay
SAGA the Simple API for Grid Applications
SAGA + DAIS: next steps
Wednesday 27th
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The Encyclopedia of Life: A Web page for every species
Porting Applications with Globus Gridway
Thursday 28th
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Data Management Workshop
Relevance
My principal role at OGF22 was to present the work I am doing on an implementation of
WS-DAI and more precisely of DAIX using our product, OGSA-DAI. Therefore I
participated in the DAIS working group session by giving a presentation about the
implementation status and issues raised. Providing the status of this effort is important for the
next steps of the DAIS working group and was highly appreciated by the authors of this
specification, highlighting possible errata. As a result of my contributions, discussion will be
initiated in order to get certain parts of the WSDAI/DAIX documents clarified.
The following seemed to be the main points to be discussed in the near future are:
 Consider JDBC constraints in order to get full or intermediate tuples back as well as
getting number of rows back.
 Consider clarifying errors in DAIX in more precise way, i.e. give more
info to the client.
 Consider rephrasing parts that sounded ambiguous to the implementers.
The benefits of my attendance at the event included meeting with the authors of the WS-DAI
specification, and others (Isao Kojima and Said Mirza from AIST, Japan and Oscar Corcho
and Miguel Esteban from UPM, Spain) from the DAIS WG who are working on new
realisations for RDF to exchange ideas and experiences of implementing the WS-DAI family
of standards. I will continue to be involved in the ongoing discussion to resolve issues and
inconsistencies raised by my implementation.
I discussed with Miguel about a) Investigating whether our DAIX implementation can
support some advanced XQueries and b) his concerns about the response of the Factory
operations and more precisely the fact they seem to be inconsistent with the Core spec.
I spoke to Mike Jones from Manchester about his work on the SARoNGS project which
effectively is a gateway to use Shibboleth authentication in order to grant authentication from
NGS.
I attended the majority of the OGC-OGF Collision workshop. The aim of the workshop is to
bring the OGC and OGF communities together. This involves:
a) Enriching OGC's WPS with distributed grid mechanisms; and b) Provide workflow
functionality in order to get the data from WPS and the relevant services (WMS,WFS,WCS).
There hasn’t been any major progress towards this but it seems that BPEL is the most
accessible approach on first instance. There was also some discussion about adopting SAGA
as an API to build geo-spatial applications on top.
There is a need for some level of authentication especially when demographic data get
involved, because of its sensitive nature. The consensus was that an external authentication
mechanism/service should take care of the authentication, e.g. Shibboleth. There was a talk
from Muenster on the WPS-G(rid) implementation which is based on North 52 project. In
this case they use WAS (Web Authentication Service) for user authentication (by checking
the SAML credential) and WSS (Web Security Service) as a layer to prevent access to the
Web Service. They also emphasised that they care mostly about getting their work done
efficiently rather than focusing on standards.
My general impression was that there are a number of interesting efforts in the area of
GeoSpatial services for both workflow and security directions. It seems though that bringing
them under the umbrella of a common standard may not be a straight-forward process.
I attended the Workflow Management research group which was personally interesting. The
topic discussed was how different workflows that apply in grid environments could possibly
be unified or the one to use the other in an efficient and interoperable way. The different
types of interoperability were mentioned at the beginning which are: a) direct, b) message
passing, c) bridging, d) use of shared data stores and then the challenge of interoperability
between workflows was presented which can be summarised by the following points:
Requirement: embed existing workflow that run in a different environment
Challenge: Define workflows in an abstract way.
Benefit: Reuse
How to achieve it: -Define workflow at abstract level
-Allow workflow engines to be sub-forked as a sub-process.
Interesting questions raised were: a) whether to embed locally or in a distributed sense, b)
Native engine enactment of shared workflows (embedding) or shared abstract (meta)
description, c) How to approach abstract meta-language, semantics: either global solution, or
small things on a project to project mapping basis, d) Is it worth attempting a classification of
workflow requirements? and e) How to deal with the increasing complexity due to the
changes of the technology to update the versions of workflow engines.
The OGSA-DAI/Taverna endeavour in OMII-UK may be worth contributing as an example
of interoperability to this group. I have passed this on the contact details of the people who
implemented this work to the group chairs.
From a personal point of view, I improved my presentation skills and was exposed to work in
other groups, in particular the workflow management and SAGA groups which will be of use
to my future work.