RFC 3507 (rfc3507) - Page 2 of 49

Internet Content Adaptation Protocol (ICAP)

RFC 3507                          ICAP                        April 2003


Table of Contents

   1.   Introduction............................................3
   2.   Terminology.............................................5
   3.   ICAP Overall Operation..................................8
        3.1   Request Modification..............................8
        3.2   Response Modification............................10
   4.   Protocol Semantics.....................................11
        4.1   General Operation................................11
        4.2   ICAP URIs........................................11
        4.3   ICAP Headers.....................................12
              4.3.1   Headers Common to Requests and
                      Responses................................12
              4.3.2   Request Headers..........................13
              4.3.3   Response Headers.........................14
              4.3.4   ICAP-Related Headers in HTTP
                      Messages.................................15
        4.4   ICAP Bodies: Encapsulation of HTTP
              Messages.........................................16
              4.4.1   Expected Encapsulated Sections...........16
              4.4.2   Encapsulated HTTP Headers................18
        4.5   Message Preview..................................18
        4.6   "204 No Content" Responses outside of
              Previews.........................................22
        4.7   ISTag Response Header............................22
        4.8   Request Modification Mode........................23
              4.8.1   Request..................................23
              4.8.2   Response.................................24
              4.8.3   Examples.................................24
        4.9   Response Modification Mode.......................27
              4.9.1   Request..................................27
              4.9.2   Response.................................27
              4.9.3   Examples.................................28
        4.10  OPTIONS Method...................................29
              4.10.1  OPTIONS request..........................29
              4.10.2  OPTIONS response.........................30
              4.10.3  OPTIONS examples.........................33
   5.   Caching................................................33
   6.   Implementation Notes...................................34
        6.1   Vectoring Points.................................34
        6.2   Application Level Errors.........................35
        6.3   Use of Chunked Transfer-Encoding.................37
        6.4   Distinct URIs for Distinct Services..............37
   7.   Security Considerations................................37
        7.1   Authentication...................................37
        7.2   Encryption.......................................38
        7.3   Service Validation...............................38
   8.   Motivations and Design Alternatives....................39



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