Alex, Thank you very much and sorry my expressions in poor English. I almost clear "chain" now however I have a bit more questions. My thoughts "not only processing ICAP...." is as bellow. ICAP chain has only ability to connect to next service, or before go to next service, squid or previous service can control whether connect to next service or not (bypass). icap_service_1 ---> icap_service_2 --> and more. (only sequential process.) Or icap_service_1 ---> icap_service_3 --> .. (icap_service_1 can chose the next service.) Does that work for you? Thanks a lot, Seiji Kobayashi -----Original Message----- From: Alex Rousskov [mailto:rousskov@xxxxxxxxxxxxxxxxxxxxxxx] Sent: Wednesday, February 20, 2008 3:38 PM To: S.KOBAYASHI Cc: 'Squid Users' Subject: Re: What is the ICAP chain exactly? On Wed, 2008-02-20 at 12:43 +0900, S.KOBAYASHI wrote: > I'v read some documents but I don't understand yet about ICAP chain how to > work and how to setup in the squid.cof. > I wonder if the squid can control sequence of connecting to some ICAP > service. > It's not only processing ICAP services in a row, but also controls sequence > of ICAP services. > Do my thoughts make sense? Or Is it possible? For a given HTTP message, Squid 3.0 can select zero or one ICAP service. Future Squid versions will probably be able to select a list of ICAP services for a given HTTP message. The services would then be applied one after another, in a chain- or pipe-like manner, where the output of the previous service becomes the input of the next one. Developers are looking for those who need that kind of functionality. Sorry, I do not know what you mean by "not only processing ICAP services in a row, but also controls sequence of ICAP services". An example might help. Thank you, Alex. P.S. Squid2 with some ICAP patches can support ICAP service chaining, but poorly.