Speaker
Dr
Birger Koblitz
(CERN-IT)
Description
We present the ARDA Metadata Grid Application (AMGA) which is part of
the gLite middleware. AMGA provides a lightweight service to manage, store
and retrieve simple relational data on the grid, termed metadata.
In this presentation we will first give an overview of AMGA's design,
functionality, implementation and security features. AMGA was designed
in close collaborations with the different EGEE user communities and
combines high performance, which was very important to the high energy
physics community, with fine-grained access restrictions required in
particular by the BioMedical community. These access restrictions also
make full use of the EGEE VOMS services and are based on grid
certificates. To show to what extent the users' requirements have been
met, we will present performance measurements as well as show
uses-cases for the security features.
Several applications are currently using AMGA to store their
metadata. Among them are the MDM (Medical Data Manager) application
implemented by the BioMedical community, the GANGA physics analysis
tool from the Atlas and LHCb experimens and a Digital Library from the
generic applications.
The MDM application uses AMGA to store relational information on
medical images stored on the grid plus information on patients and
doctors in several tables. User applications can retrieve images baded
no their metadata for further processing. Access restrictions are of
the highest importance to the MDM application because the stored data
is highly confidential. MDM therefore makes use of the fine-grained
access restrictions of AMGA.
The GANGA application uses AMGA to store the status information of
jobs running on the grid which can be controlled by GANGA. AMGA's
simple relational database features are mainly used to ensure
consistency when several GANGA clients of the same user are accessing
the stored information remotely.
Finally, the Digital Library project makes similar use of AMGA as the
MDM application but provides many different schemas to store not only
images but information on texts, movies or music. Another difference
is that there is only a central librarian updating the library while
for MDM updates are triggered by the many image acquisition systems
themselves.
This presenation will also discuss future developments of AMGA, in
particular its features to replicate or federate metadata. They will
mainly allow users to make use of a better scaling behaviour but could
also allow better security by using federation to physically seperate
metadata. The replication features will be compared to current
proprietary solutions.
AMGA provides a very lightweight metadata service
as well as basic database access functionality on the Grid.
After a brief overview of AMGA's design, functionality, implementation
and security features we will show performance comparisons of AMGA with
direct database access as well as other Grid catalogue services. Finally
the replication features of AMGA are presented and a comparison done
with proprietary database replication solutions.
Author
Dr
Birger Koblitz
(CERN-IT)
Co-author
Mr
Nuno Santos
(CERN-IT)
