7.2.2 Length ...........................................43
   8 Connections.............................................43
    8.1 Persistent Connections ..............................43
     8.1.1 Purpose ..........................................43
     8.1.2 Overall Operation ................................44
     8.1.3 Proxy Servers ....................................45
     8.1.4 Practical Considerations .........................45
    8.2 Message Transmission Requirements ...................46
   9 Method Definitions......................................48
    9.1 Safe and Idempotent Methods .........................48




 
RFC 2068                        HTTP/1.1                    January 1997


     9.1.1 Safe Methods .....................................48
     9.1.2 Idempotent Methods ...............................49
    9.2 OPTIONS .............................................49
    9.3 GET .................................................50
    9.4 HEAD ................................................50
    9.5 POST ................................................51
    9.6 PUT .................................................52
    9.7 DELETE ..............................................53
    9.8 TRACE ...............................................53
   10 Status Code Definitions................................53
    10.1 Informational 1xx ..................................54
     10.1.1 100 Continue ....................................54
     10.1.2 101 Switching Protocols .........................54
    10.2 Successful 2xx .....................................54
     10.2.1 200 OK ..........................................54
     10.2.2 201 Created .....................................55
     10.2.3 202 Accepted ....................................55
     10.2.4 203 Non-Authoritative Information ...............55
     10.2.5 204 No Content ..................................55
     10.2.6 205 Reset Content ...............................56
     10.2.7 206 Partial Content .............................56
    10.3 Redirection 3xx ....................................56
     10.3.1 300 Multiple Choices ............................57
     10.3.2 301 Moved Permanently ...........................57
     10.3.3 302 Moved Temporarily ...........................58
     10.3.4 303 See Other ...................................58
     10.3.5 304 Not Modified ................................58
     10.3.6 305 Use Proxy ...................................59
    10.4 Client Error 4xx ...................................59
     10.4.1 400 Bad Request .................................60
     10.4.2 401 Unauthorized ................................60
     10.4.3 402 Payment Required ............................60
     10.4.4 403 Forbidden ...................................60
     10.4.5 404 Not Found ...................................60
     10.4.6 405 Method Not Allowed ..........................61
     10.4.7 406 Not Acceptable ..............................61
     10.4.8 407 Proxy Authentication Required ...............61
     10.4.9 408 Request Timeout .............................62
     10.4.10 409 Conflict ...................................62
     10.4.11 410 Gone .......................................62
     10.4.12 411 Length Required ............................63
     10.4.13 412 Precondition Failed ........................63
     10.4.14 413 Request Entity Too Large ...................63
     10.4.15 414 Request-URI Too Long .......................63
     10.4.16 415 Unsupported Media Type .....................63
    10.5 Server Error 5xx ...................................64
     10.5.1 500 Internal Server Error .......................64
     10.5.2 501 Not Implemented .............................64




 
RFC 2068                        HTTP/1.1                    January 1997


     10.5.3 502 Bad Gateway .................................64
     10.5.4 503 Service Unavailable .........................64
     10.5.5 504 Gateway Timeout .............................64
     10.5.6 505 HTTP Version Not Supported ..................65
   11 Access Authentication..................................65
    11.1 Basic Authentication Scheme ........................66
    11.2 Digest Authentication Scheme .......................67
   12 Content Negotiation....................................67
    12.1 Server-driven Negotiation ..........................68
    12.2 Agent-driven Negotiation ...........................69
    12.3 Transparent Negotiation ............................70
   13 Caching in HTTP........................................70
     13.1.1 Cache Correctness ...............................72
     13.1.2 Warnings ........................................73
     13.1.3 Cache-control Mechanisms ........................74
     13.1.4 Explicit User Agent Warnings ....................74
     13.1.5 Exceptions to the Rules and Warnings ............75
     13.1.6 Client-controlled Behavior ......................75
    13.2 Expiration Model ...................................75
     13.2.1 Server-Specified Expiration .....................75
     13.2.2 Heuristic Expiration ............................76
     13.2.3 Age Calculations ................................77
     13.2.4 Expiration Calculations .........................79
     13.2.5 Disambiguating Expiration Values ................80
     13.2.6 Disambiguating Multiple Responses ...............80
    13.3 Validation Model ...................................81