Headers

HTTP Headers

If-Match: <etag_value>
If-Match: <etag_value>, <etag_value>, …

If-None-Match: "<etag_value>"
If-None-Match: "<etag_value>", "<etag_value>", …
If-None-Match: *

If-Modified-Since: <day-name>, <day> <month> <year> <hour>:<minute>:<second> GMT

If-Range: <day-name>, <day> <month> <year> <hour>:<minute>:<second> GMT
If-Range: <etag>

If-Unmodified-Since: <day-name>, <day> <month> <year> <hour>:<minute>:<second> GMT

Last-Modified: <day-name>, <day> <month> <year> <hour>:<minute>:<second> GMT

ETag: W/"<etag_value>"
ETag: "<etag_value>"

• Cache-Control, Content-Location, Date, ETag, Expires, Vary
• RFC 9110RFCRFC 9110IETF Request for Comments standard document.RFC
• developer.mozilla.org/en-US/docs/Web/HTTP/HeadersLinkdeveloper.mozilla.org/en-US/docs/Web/HTTP/HeadersCache-Control, Content-Location, Date, ETag, Expires, Vary · https://www.rfc-editor.org/rfc/rfc9110#field.etag · https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers笔记：Headers
• end-to-end header
  • 应该从客户端一路传到最终后端
  • User-Agent, Accept
• hop-by-hop header
  • 只对当前这一跳连接有效，代理不应该继续转发
  • Connection, Keep-Alive, Proxy-Authenticate, Proxy-Authorization, TE, Trailer, Transfer-Encoding, Upgrade
  • Connection 可以指定额外的 hop-by-hop header
    • Connection: X-Foo
    • 代理转发到后端前应该删除它

Idempotency-Key

• I-D draft-ietf-httpapi-idempotency-key-header-07IETF DraftI-D draft-ietf-httpapi-idempotency-key-header-07IETF Internet-Draft document.IETF · Internet-Draft
• 相同 Key 的原请求仍在执行 409 Conflict
• 相同 Key 但请求内容不同 422 Unprocessable Content
• adopted by
  • Stripe
  • Adyen
  • OpenAI
  • Integrated Finance
    • X-Idempotency-Status: processed|replayed
  • Worldpay
    • Idempotency-Status
• Alternative
  • PayPal - PayPal-Request-Id
  • AWS - ClientToken, ClientRequestToken
• Cache TTL
  • 普通内部 API、短暂网络重试 1-6h
  • 常规公共 API 24h
  • 支付、下单、不可逆操作 24-72h
  • Idempotency-Key → resource_id / operation_id