OGSA F2F 17: March 14-16 2007, Belmont, CA
Attendees: A Stephen McGough
Main groups of focus: JSDL, Information Model, Interoperation, Security, QoS,
Workflow
At this OGSA f2f meeting we held a JSDL session to discuss further the ideas of JSDL
2.0 discussed at the last OGF meeting. The ideas of pre and post conditions in a JSDL
document were discussed along with capabilities and requirements that a job would have
in terms of enabling matching with resources. Concern was raised over pre and post
conditions being a back-door route to allowing workflows. This session was also to
determine how JSDL 2.0 would be specified, and its relationship to other groups in OGF.
We were able to contribute extensively to this session as it not only involves one of the
groups that we are most active within, but also, allows us to feed in requirements from
the UK community. It was decided that the group should proceed on two tracks. The first
being to develop extensions to JSDL 1.0 which can be used now, the second being to
draft up a JSDL 2.0 specification skeleton to allow development of some of these ideas.
The Information model has changed somewhat since the last session at OGF19. The
GLUE schema has been brought into the OGF standards body and as such there is much
interest to work with this. The GLUE and BES specifications have been taken as a
starting point for work in developing the Information model and this was presented as the
starting point for the model. There was some concern over starting from GLUE though as
it is used in many Grid instances for some time now this is as good a point to start from
as any. As this relates mostly to computational (BES) jobs at the moment this was useful
to take part in as we were able to feed the requirements from GridSAM into this work.
There is now much discussion within OGSA and OGF in general on the issues of
interoperability. During this f2f meeting the areas in which interoperability through
standards can be achieved were discussed and a list of projects which would be able to
take part in interoperation tests was constructed. This enabled us to propose GridSAM
and other UK based projects for these interoperation tests.
One of the main areas which has still to achieve any significant standardisation within the
Grid community is that of Security. There are many groups working in this area though at
this time there is little in the way of standards and interoperation. This was bourn out
from the recent HPC profile interoperations performed at SC06. The proposal here is to
define a simple security specification where complex issues such as delegation and
authentication are not addressed. In general to leave out all the controversial issues which
are preventing standardisation. This is good as far as our work on GridSAM is concerned
as our security model is simple – in the same way as proposed for this work. As the
GridSAM security model is that of the main OMII container this is useful for the whole
of OMII and we were able to help scope out what this work should be.
In a follow-up to the QoS BoF held at the last OGF we were involved with running a QoS
session at this f2f meeting. In terms of what the group were doing it seems as though
SLA is more appropriate than QoS. The feeling was that if we have continuous
parameters this would lead to too much choice at this stage and be too complex to deal
with. The idea of the photo processing lab style options (1 hour, 1 day, 1 week) or the
MacDonald’s menu style approach would be easier to deal with at present. Though
constraints (such as price) need to be placed on these as otherwise everyone will ask for
the “best” option all of the time. Although this does not fit directly in with what we have
been doing within the GRIDCC project does have much more traction for standardisation
and as such we were able to contribute to this work.
In continuation of our workflow efforts from the previous OGF we discussed the use of
workflow languages such as BPEL. There was concern within the group about BPEL on
issues such as workflows being unchangeable once deployed and workflows not being
first class entities. We were able to describe work that we had done through the GRIDCC
project to alleviate the unchangeable nature of BPEL documents through changing
endpoints dynamically. The general feeling was that OGSA should focus on ensuring that
the architecture is easy to use for workflows and that we can’t at this stage rule out the
need to write our own workflow language until we have gathered information on existing
workflow languages and the use of these. This was something we were able to contribute
to through our work on GRIDCC and through using GridSAM as part of a workflow
system.