ICAP is generally used to implement virus scanning and content filters in transparent HTTP proxy caches.
ICAP concentrates on leveraging edge-based devices (caching proxies) to help deliver value-added services.
[2] Don Gillies took over the project in the spring of 2000 and enhanced the protocol in three main ways: Gillies prototyped the first ICAP client and server for the NetCache series of internet caches in mid-2000 (known as ICAP 0.9 protocol) and produced training materials for vendors.
The client was written in C++ in the core of the NetCache server, and the demonstration ICAP Server was written in Perl and employed the Debian word-replacement filters to rewrite web pages, skipping over the HTML tags, and translating web pages into Swedish Chef or Jive in real time.
[3] With knowledge learned from the prototyping experience, Gillies revised the IETF draft standard to make RPCs using only chunked encoding, greatly simplifying the ICAP protocol.