Futures on computingAmsterdam 22 May 00DISCworld is a metacomputing system entirely written in Java. Because Java does not have a pointer mechanism of its own, the Australian researchers invented their DRAM's: DISCworld remote access mechanism, which are implemented as a Java class. DRAM objects can be data or jobs. A DRAM contains a unique ID, a description of the object content, information on the location and size and whether or not the DRAM may be moved across the network. The futures mechanism extends a DRAM to a DRAMF, adding another properity that gives the estimated time when the object will become available. This can be used by the system to prepare for arrivel, for instance by setting up the necessary services, and fetch additional data, and perform additional computations. DRAMF's can be sent between servers, and may also be used by clients in the composition of new procssing requests. Because only pointers to the acutal data are transferred, the future mechanism prevents unnesseray transfer of large amounts of data. Another advantage of DRAMF's is that, even when the server where the original data resides is down, or for some reason not reachable, a lot of processing stil can go on, manipulating the DRAMF. When the data come available again, they can be used. DRAM's can be connected to a graphical icon. Users can then manipulate the icon with the mouse in the usal way, for instance drop it onto an application to let it get executed. This way, complex environments with an easy to use user interface can be built.
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