web filtering with ICAP

Some time ago i had evaluated possibility of ICAP-server implementation in our Web filtering product. It's good idea to split into the communication & filtering parts, but there are some things, that does not allow to effectively implement ICAP-based solutions:

• ICAP-client must be smart enougth to make some content filtering tasks before forwarding to ICAP-server, file type detection, for example
• Sometimes, during filtering, filtering engine must have more information, that does not provided by ICAP-client
• To provide URL-filtering service, connection to ICAP-server is overhead

Thus, usage of ICAP is possible only in environment, where content-filtering is not primary task, and where is good infrastructure of ICAP-enabled clients - Cisco Cache Engine, for example