Download SC11 Poster GRelC

G. Aloisio - S. Fiore
The GRelC Project: architecture, history and a use
case in the environmental domain
The Climate-G testbed is an interdisciplinary effort involving partners from several institutions and joining expertise in the field of climate change and computational science.
Its main goal is to allow scientists carrying out geographical and cross-institutional data discovery, access, analysis, visualization and sharing of climate data.
The Climate-G partners involved into the testbed are: the Centro Euro-Mediterraneo
per i Cambiamenti Climatici (CMCC, Italy), the Institut Pierre-Simon Laplace
(IPSL/CNRS, France), the Fraunhofer Institut für Algorithmen und
Wissenschaftliches Rechnen (SCAI, Germany), the National Center for Atmospheric
Research (NCAR, USA) and Rensselaer Polytechnic Institute (RPI, USA), the
University of Reading (Reading, UK), the University of Cantabria (UC, Spain) and
the University of Salento (UniSalento, Italy).
The Climate-G Portal is the access point to the entire testbed infrastructure. It represents the scientific
gateway of the testbed and it is intended for scientists and researchers that easily and transparently
want to manage the available climate change experiments and datasets.
Basically, all of the activities related to the testbed infrastructure must be carried out exploiting high
level web interfaces available through the Climate-G Portal.
This means that all of the involved actors in the scene (system/portal administrators, scientists, guest
users, data and metadata providers, etc.) have to perform most/all of their activities through the portal.
Fig.4 shows the central role of the portal in the Climate-G infrastructure.
The GRelC DAIS is a general purpose data grid service for database access, query
and management.
This service acts as a standard front-end for database access on the grid. It provides
both basic and advanced primitives to transparently access, query, manage and
interact with different data sources, concealing the back-end heterogeneity, Globus
GSI and VOMS, security details, connection and other low level issues. It currently (i)
exploits the Web-Services paradigm (WS-I based), (ii) it is compatible with Globus
and gLite grid middleware/environments and (iii) it provides grid-enabled query
mechanisms leveraging compression, chunking, pre-fetching and streaming to
enhance performance on a wide area network/grid environment.
Moreover, it supports both global (by means of VOMS) and local (on the GRelC DAS
side) authorization levels, increasing flexibility, manageability and scalability in role
and policy management. The main goal of this data grid service is to efficiently,
securely and transparently manage databases on the grid, across virtual
organizations, with regard to modern grid standards and specifications (OGSA and
WSRF compliant) as well as existing middleware such as Globus, gLite, etc.
The GRelC project started in 2001 as a research effort at the University of Salento with a Ph.D. thesis.
The initial goal was both simple and ambitious: to provide a set of data grid services to transparently,
securely and efficiently manage relational databases in a grid environment. Until 2004, the GRelC
releases exploited a client-server architecture, a proprietary communication protocol and the Grid
Security Infrastructure. In 2006 the GRelC service was completely re-engineered to address
interoperability through a WS-based approach. Instead of moving towards OGSI (which seemed to be
too heavy), the GRelC service was implemented as a web service WS-I compliant and GSI enabled,
that is a very light implementation. The gLite-based release (2007) was a crucial step to meet the
EGEE community, their use cases and needs. This community provided new important requirements,
particulary in the Earth Science context (EGEE NA4). That release was also available for training and
dissemination purposes through the GILDA t-infrastructure.
From 2008, the GRelC software has been included into the Italian grid release (gLite-based) and
distributed into the Worker nodes and User Interfaces components across the Italian country. This way,
several performance tests based on the gLite middleware were also carried out to stress the system
and prove its stability. In the same year, GRelC was included into the EGEE RESPECT Program due to
its compatibility with the gLite middleware and its added value with regard to new database-oriented
functionalities that were not available in the gLite release at that time.
From 2009 to 2010 new GRelC releases (server and portal) addressing stability, management and
monitoring were made available to the user community. In 2011, the GRelC team will face new
challenges. The most relevant one will be related to the EGI Database of Databases (a global registry
hosting the list of DB resources available in the EGI context). The registry will complement the EGI
Application Database allowing scientists to know more about existing DBs, their location, main
purpose, available data, etc. This will help the co-operation and interaction among research groups,
promoting a more effective publishing and sharing of grid-enabled data sources.