A Fragmented Approach by Tim Micheletto

It is a way of having multiple cache servers handling data to perform a sort of load balancing It is also referred to as a Cache Cluster

There are two main approaches for distributed cache servers The first method is copied cache servers, where all of the cache servers maintain the same data The second method is domain based method, where each cache server only caches for specific domains

The Cache servers only hold fragments of the whole data, and distribute portions of the cache to other cache servers Each fragment has an associated part and expiration Clients query multiple cache servers simultaneously for the data The clients gather what they can from the cache servers and then ask for the rest from the original server

I implemented a portion of my specification for the cache servers themselves in C# I created a simple network simulator that would drive the hosts and clients on my computer Each server was created in its own process, and maintained its own set cache which was initialized differently from each of the other servers The client would query each of the cache servers for a particular data set, and then query the servers a second time to see if the servers had updated their data If changes had occurred that meant the cache servers had updated themselves

I expected the cache servers to return that they didn’t have a particular data set I then expected the cache servers to go ahead and try to find that data for upcoming queries Finally I expected to find those missing data sets when querying the cache servers a second time

The servers did provide only the expected data sets to the client Upon the second query, I found that the servers had updated their caches

A more complete implementation would need to be done The test setup would need to simulate a much more realistic environment We would need to test the ability of the client to put all of the data together, and for it to be able to pull the missing pieces from the original server

The current protocol has a fair amount of overhead, and would need to be optimized for use in a MANET Due to the nature of the cache servers they would need to be fairly static within the MANET to be practical, and as such would only be usable in certain situations where there are many servers The cache servers would have to detect situations where the actual server is unable to send specific portions of data, otherwise issues where the client would be unable to put together the whole data set may occur