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Appendix B. Changes from Previous RFCs

This appendix summarizes the major changes in RFC 9110 compared to previous related RFCs. RFC 9110 consolidates and updates the core semantics of HTTP/1.1, replacing the RFC 7230-7235 series of specifications.

B.1. Changes from RFC 2818​

RFC 2818 defined the use of HTTPS. Major changes include:

  • Integration of HTTPS definition into the HTTP semantics specification
  • Updated requirements and recommendations for certificate validation
  • Enhanced guidance for secure connections

B.2. Changes from RFC 7230​

RFC 7230 defined HTTP/1.1 message syntax and routing. Major changes include:

  • Separation of message abstraction from HTTP/1.1-specific syntax
  • Reorganization of field syntax and semantics descriptions
  • Updated requirements for connection management and proxy behavior
  • Clarification of message forwarding and transformation rules

B.3. Changes from RFC 7231​

RFC 7231 defined HTTP/1.1 semantics and content. Major changes include:

  • Improved description of method semantics
  • Enhanced definition and usage guidance for status codes
  • Updated content negotiation mechanisms
  • Refined semantics of representation metadata
  • Improved security and privacy considerations

B.4. Changes from RFC 7232​

RFC 7232 defined HTTP/1.1 conditional requests. Major changes include:

  • Clarification of validator generation and comparison rules
  • Improved conditional request processing semantics
  • Updated guidance for ETag and Last-Modified usage
  • Enhanced description of precondition evaluation

B.5. Changes from RFC 7233​

RFC 7233 defined HTTP/1.1 range requests. Major changes include:

  • Improved syntax and semantics of range requests
  • Updated multipart range response handling
  • Enhanced caching guidance for partial content
  • Clarification of range unit extensibility

B.6. Changes from RFC 7235​

RFC 7235 defined the HTTP/1.1 authentication framework. Major changes include:

  • Improved definition and registration of authentication schemes
  • Enhanced syntax for challenges and credentials
  • Updated concept of protection spaces
  • Improved security considerations related to authentication

B.7. Changes from RFC 7538​

RFC 7538 defined the 308 (Permanent Redirect) status code. Major changes include:

  • Integration of 308 status code into the core status code set
  • Consistent description with other redirect status codes
  • Updated deployment considerations and best practices

B.8. Changes from RFC 7615​

RFC 7615 defined HTTP authentication scheme registration. Major changes include:

  • Updated registration procedures for authentication schemes
  • Integration into unified IANA Considerations section
  • Improved guidance for new authentication schemes

B.9. Changes from RFC 7694​

RFC 7694 defined HTTP client-initiated content coding. Major changes include:

  • Integration of content coding related concepts
  • Updated Accept-Encoding semantics
  • Improved content coding negotiation mechanism

Overall Changes​

RFC 9110, as a unified specification for HTTP semantics, includes major improvements:

  1. Structural Reorganization - Separation of HTTP semantics from version-specific (HTTP/1.1) syntax
  2. Terminology Unification - Standardization of terminology usage across the HTTP specification family
  3. Semantic Clarification - Resolution of many long-standing ambiguities and implementation differences
  4. Enhanced Security - Updated security and privacy related considerations and recommendations
  5. Improved Extensibility - Clearer extension points and registration guidance
  6. Version Independence - Semantic definitions applicable to all HTTP versions (HTTP/1.1, HTTP/2, HTTP/3, etc.)

Note: For detailed change lists and technical details, please refer to Appendix B of RFC 9110.

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