Caching Shared DCA State

  Because DCAs are applications that run simultaneously on multiple client machines, we must address the issue of where the shared state will be located. We propose that long-term state be stored on a DCA server, with caches local to each client. Caches work well in other distributed environments, e.g., distributed file systems [7, 17] and distributed shared memory systems [12]. We believe that DCAs will see the same benefits.

Caches improve response times for accessing data, and reduce resource requirements. Accessing a local in-memory copy of data is always faster and cheaper than going to disk or access over a network connection. Network connections can also block waiting for a server's response, slowing access time even more. In addition to improving performance, caches containing a subset of shared state can operate with less memory, which may be a limited resource in the cases of Personal Digital Assistants and Network Computers. Also, being able to access data locally saves bandwidth by reducing the number of messages sent by a client application over the network.