Caching

Caching tries to explore the high level of redundancy in the data transfer over the Internet. A cache stores local copies of files that have been accessed recently and are likely to be accessed again, so that next time they are requested they are served locally instead of from the remote server. Although there may be many ways caching can be actually implemented, from this definition we can predict what would generally be the advantages and disadvantages of this technique.

Advantages

The following are some important benefits of caching:

• Caching reduces bandwidth consumption; this leads to less traffic in the network, and, of course, less congestion.
• Lower latencies, because some documents are served from cache, and because of the reduction in the network traffic.
• Lower load on the remote servers.
• Robustness against server failures.
• Lower telecommunication costs (relevant in some countries).
• As a side-effect, the Web usage patterns can be analyzed.
• It is transparent to the user.
• Logs can be maintained as to what is being accessed.
• Certain types of documents can be blocked at the proxy cache itself.

Drawbacks

There are few problems one needs to consider when one uses Web caching:

• The main problem is that the data stored locally may be stale, due to lack of proper updating.
• The primary remote server may not get the correct number of hits to their pages.