Lecture 7: Internet Applications #3.3: HTTP/1.1

Proxy Caches

A proxy server is an HTTP server which fetches Web objects (pages, images, etc) on behalf of its clients. Proxies normally cache all "cacheable" reponses, so that if an entity is stored locally, it is returned instead of sending a request to the originating server. Such shared caches can significantly reduce an organisation's "download volume", as well as give significant performance improvements to the end-user.

Requests to a proxy server are always specified as full URLs, so the first line of a typical GET request now looks like:

GET http://www.latrobe.edu.au/index.html HTTP/1.1
Host: www.latrobe.edu.au
....other request headers...<newline><newline>

Whilst proxy servers (and caches) were described in HTTP/1.0, the rules as to how caching should be controlled were unspecified. Note that in HTTP/1.1, the Host: request header is always required.

Lecture 7: Internet Applications #3.3: HTTP/1.1

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