4WWW95: making WWW caching servers cooperate

authors:

• radhika maplani, university of california at berkeley
• jacob lorch, university of california at berkeley
• david berger, Enterprise Integration Technology

limitations on caching today:

• client caching: has a low hit rate
• single proxy cache: might become a bottle neck
• multiple proxy caches: they do not cooperate

the solution:

make multiple caching proxy servers work together:

• the implementation is based on CERN's httpd
• proxy servers use IP multicast to communicate with each other

how this basically works:

1. a browser sends a HTTP request to one of the proxy servers
2. if the proxy server has the document, it sends it back to the client and we are done
3. if the proxy server doesn't have the document in its cache, it sends a request for that document to the other proxy servers using IP multicast.
4. if any of the other proxy servers has the document, it sends it to the requesting proxy server which forwards the document to the client
5. if none of the proxy servers has the document, the request is passed to the server specified in the URL and the request is handled as usual

a possible extension would be a so called "proxy redirect": instead of transferring the document from one proxy server to another, the first proxy server could send a proxy redirect message back to the client, so the client could request the document directly from the proxy server which has the document in its cache. to implement such a mechanism, an extension to the HTTP standard would be necessary. such an extension is proposed and might become part of the HTTP V1.x standard.

back to 4WWW95 main document.