The Java language and platform have been considered by many as natural candidate for creating grid systems. The platform-independent runtime environment, safe and high-level language and its built-in support for networking and security are very valuable features. Despite its potential and the many proof-of-concept systems developed, the grid community is turning to web services technology as its implementation base. In this paper, we show that Java, by joining forces with Jini Technology can provide a very appealing technology base for highly dynamic grid systems. The key properties of Java and Jini technology are examined with reference to their role in grids. Then, the JGrid Jini-based serviceoriented grid system is overviewed describing its key concepts, services and how it extends Jini to address some of the unique requirements of grid systems.