[glue-wg] WLCG Information System - GLUE

[Etienne URBAH]

Flavia,


Information Services
--------------------
I just finished reading your presentation 'WLCG Information Officer' at 
http://indico.cern.ch/getFile.py/access?contribId=2&sessionId=0&resId=0&materialId=slides&confId=83604

Inside the EGDI project http://edgi-project.eu/ integrating Service 
Grids (such as WLCG) and Desktop Grids (such as SZDG or IberCivis), I am 
working on standardization.

In particular, I consider that an IS (Information System) permitting 
providers to publish information and clients to discover information is 
the mandatory foundation for any distributed data processing 
infrastructure (Grid).

Moreover, standardized interface about data model and protocol for 
information providers and client queries is mandatory for interoperation 
between grids such as EGI, OSG, Desktop Grids, ...

Therefore, I am member of the OGF GLUE Working Group 
http://forge.gridforum.org/sf/projects/glue-wg


Other involved parties
----------------------
For interoperation, I suggest you to add following stakeholders to your 
list of 'Other involved parties' :
-  OGF GLUE,
-  the EC-funded DCI projects (EDGI, EGI-Inspire, EMI, IGE, StatusLab, 
Venus-C),
-  University of Chicago/ANL  http://forge.ogf.org/sf/go/doc16100
-  Naregi-Renkei, which is currently using CIM.


WLCG Information Service
------------------------
The current WLCG Information Service is the BDII based on the GLUE 1.3 
schema and bootstrapped with the GOCDB https://goc.gridops.org/ and the 
CIC https://cic.gridops.org/

Thank you very much for having gathered the opinion of the 4 LCH 
experiments.  Although it is a pity that the 4 LCH experiments do not 
really trust the WLCG Information Service yet, it is very important that 
IS designers, developers and integrators know this distrust, in order to 
search for the real reasons, and to carefully fix all issues.


Below are some issues which I know, and proposals for solutions :

-  Accuracy of published information (in particular storage capacity) :
    The solution is to take into account 'information provider code' as 
real software, which must be designed using the best practices of 
software engineering, must have an installation manual, and must be 
deployed on all sites using the best practices of grid operation.
    When an adequate 'information provider' exists and has an adequate 
installation manual, sites publishing inaccurate information should be 
blamed.

-  Relevance and lifetime of published information :
    Among the various items of information published inside the BDII, 
users need to know which items they can trust and for how long.
    This is clearly a requirement for a document (or wiki page) 
containing a table describing the most relevant items and their probable 
lifetime.
    Moreover, it is probably the role of the WLCG Information Officer 
(yourself) to write down and publish this table.

-  Rigid implementation of GLUE 1.3 (unless it has already been fixed) :
    As far as I know, inside a single 'Grid Site' modeled by 'GlueSite' 
and 'GlueCluster', it would be useful to model each set of machines 
having same physical characteristics as a separate 'GlueSubCluster', but 
this is difficult to achieve because installation software does NOT 
support this completely yet.
    The solution would be to improve the installation software.

-  Query language :
    I am an experienced programmer in various languages, but I assess 
that building LDAP queries to extract useful information is difficult.
    A (perhaps restricted) SQL interface would be much easier to use, 
and there are many software developers and even users who already have a 
little experience with SQL.

-  Bad terminology by GLUE 1.3 :
    A 'Job Queue' is modeled by a 'GlueCE', and a 'Grid CE' is modeled 
by a 'GlueSubCluster'.
    Which user would be happy with that ?
    The solution is GLUE 2.0, where a 'Job Queue' is modeled by a 
'ComputingEndpoint', and a 'Grid CE' is modeled by a 'ComputingResource'.


Do not hesitate to provide answers or ask for precisions.

Best regards.

-----------------------------------------------------
Etienne URBAH         LAL, Univ Paris-Sud, IN2P3/CNRS
                       Bat 200   91898 ORSAY    France
Tel: +33 1 64 46 84 87      Skype: etienne.urbah
Mob: +33 6 22 30 53 27      mailto:urbah at lal.in2p3.fr
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