We periodically have to stop the handlers and, from an administrative standpoint, we need to arrange the elements in the space at some point in time. Taking out and putting back in fires notifications which we have setup to do other things. On fault tolerance, JavaSpaces makes use of Jini's transaction so that one or more operations over one or more spaces can be wrapped into an atomic unit. Either they all happen or not. In this way you can keep the internal state of your entries consistent even in the presence of paritial failure.
Load balancing is an excellent point.
Yes, SteveP, exactly. Each tool does its job, and the sum of the parts is powerful. We're coming to the end of the hour, but there are still some good questions on the queue. Yeah, sure, sounds great. While I can see the need for the admin to monitor a space, seems the overhead would be costly.