  Grid computing is a distributed computing paradigm which aims to aggregate
several heterogeneous and distributed resources, belonging to different and
independent organizations, in a dynamic, transparent and coordinated way. Since
its introduction, Grid computing has been successfully applied to solve several
scientific challenging applications. Despite of the consolidation of many of
its aspects, there are some issues that are still open. One of them is the
transparency: in many real Grid systems, users still need to be aware of Grid
computing, either for adapting their applications to this paradigm or for
wrapping them in a suitable software framework. In this paper we present the
ShareGrid Portal, a Web portal and a portal framework, built on top of the
ShareGrid project infrastructure. Its intent is both to ease the execution of
user applications in a Grid system and to allow developers to flexibly add new
portal functionalities. In this work, we compare it with other well-known Grid
portals and we show its user interface and its architecture. Finally we discuss
user experiences and future extensions.
