- 1) Introduction
- 2) Notational Conventions and Generic Grammar
- 3) Protocol Parameters
- 4) HTTP Message
- 5) Request
- 6) Response
- 7) Entity
- 8) Connections
- 9) Method Definitions
- 10) Status Code Definitions
- 1) Informational 1xx
- 2) Successful 2xx
- 3) Redirection 3xx
- 4) Client Error 4xx
- 1) 400 Bad Request
- 2) 401 Unauthorized
- 3) 402 Payment Required
- 4) 403 Forbidden
- 5) 404 Not Found
- 6) 405 Method Not Allowed
- 7) 406 Not Acceptable
- 8) 407 Proxy Authentication Required
- 9) 408 Request Timeout
- 10) 409 Conflict
- 11) 410 Gone
- 12) 411 Length Required
- 13) 412 Precondition Failed
- 14) 413 Request Entity Too Large
- 15) 414 Request-URI Too Long
- 16) 415 Unsupported Media Type
- 17) 416 Requested Range Not Satisfiable
- 18) 417 Expectation Failed
- 5) Server Error 5xx
- 11) Access Authentication
- 12) Content Negotiation
- 13) Caching in HTTP
- 1) ..
- 2) Expiration Model
- 3) Validation Model
- 4) Response Cacheability
- 5) Constructing Responses From Caches
- 6) Caching Negotiated Responses
- 7) Shared and Non-Shared Caches
- 8) Errors or Incomplete Response Cache Behavior
- 9) Side Effects of GET and HEAD
- 10) Invalidation After Updates or Deletions
- 11) Write-Through Mandatory
- 12) Cache Replacement
- 13) History Lists
- 14) Header Field Definitions
- 1) Accept
- 2) Accept-Charset
- 3) Accept-Encoding
- 4) Accept-Language
- 5) Accept-Ranges
- 6) Age
- 7) Allow
- 8) Authorization
- 9) Cache-Control
- 10) Connection
- 11) Content-Encoding
- 12) Content-Language
- 13) Content-Length
- 14) Content-Location
- 15) Content-MD5
- 16) Content-Range
- 17) Content-Type
- 18) Date
- 19) ETag
- 20) Expect
- 21) Expires
- 22) From
- 23) Host
- 24) If-Match
- 25) If-Modified-Since
- 26) If-None-Match
- 27) If-Range
- 28) If-Unmodified-Since
- 29) Last-Modified
- 30) Location
- 31) Max-Forwards
- 32) Pragma
- 33) Proxy-Authenticate
- 34) Proxy-Authorization
- 35) Range
- 36) Referer
- 37) Retry-After
- 38) Server
- 39) TE
- 40) Trailer
- 41) Transfer-Encoding
- 42) Upgrade
- 43) User-Agent
- 44) Vary
- 45) Via
- 46) Warning
- 47) WWW-Authenticate
- 15) Security Considerations
- 16) Acknowledgments
- 17) References
- 18) Authors' Addresses
- 19) Appendices
- 20) Index
- 21) Full Copyright Statement
- 22) Acknowledgement
13.5.4 Combining Byte Ranges
A response might transfer only a subrange of the bytes of an entity- body, either because the request included one or more Range specifications, or because a connection was broken prematurely. After several such transfers, a cache might have received several ranges of the same entity-body.
If a cache has a stored non-empty set of subranges for an entity, and an incoming response transfers another subrange, the cache MAY combine the new subrange with the existing set if both the following conditions are met:
- Both the incoming response and the cache entry have a cache validator.
- The two cache validators match using the strong comparison function (see Section 13.3.3).
If either requirement is not met, the cache MUST use only the most recent partial response (based on the Date values transmitted with every response, and using the incoming response if these values are equal or missing), and MUST discard the other partial information.