Summary and Conclusions

We have seen how Web caching can be used as an effective means to reduce the traffic load on the World Wide Web. We have discussed various architectures for web caches. Next, we discussed the issues that go into maintaining the cache, such as cacheability, replacement algorithms, and coherence checks. However one should understand that different solutions are suitable for different environments, and that usually no one solution is best for all types of environments. Also, it is difficult to measure the usefulness of a specific solution as different sites have different usage patterns such that no fixed technique will be satisfactory for everybody.

There are also other interesting areas related to web caching such as document prefetching. On low-cost networks it may be a good idea not to wait until the expiration time to refresh a page. Moreover, pages that have not been requested might be cached, if there is strong confidence that they will eventually be requested. Such actions define a pre-fetching cache. There have been several heuristic models proposed to support prefetching : for example, to get the images embedded in a document, or to figure out some correlations between which URLs the users are more likely to request following the current one.

To summarize we can say that web caching is certainly an effective technique which results in significant bandwidth saving, server load balancing, latency reduction and higher content availability.