The HyperText Transfer Protocol (HTTP) is an application-level protocol for distributed, collaborative, hypermedia information systems. It is a generic, stateless protocol that can be used for many tasks (e.g., name servers and distributed object management systems) beyond its use for hypertext through extension of its request methods, error codes, and headers. An important feature of HTTP is the typing and negotiation of data representation, which allows systems to be built independently of the data being transferred.
HTTP/1.0 is described in RFC 1945. HTTP/1.1 is the latest version of the specification, and as of this writing HTTP/1.1 is covered in RFC 2616.
Only a small subset of HTTP response codes usually is used when writing mod_perl applications, but sometimes you need to know others as well. We will list the codes here. Their names are fairly self-explanatory, but you can find extended explanations in the appropriate RFC (see section 9 in RFC 1945 and section 10 in RFC 2616). You can always find the latest links to these RFCs at the World Wide Web Consortium’s site, http://www.w3.org/Protocols/.
While HTTP/1.1 is widely supported, HTTP/1.0 still remains the mainstream standard. Therefore, we will supply a summary for each version, including the corresponding Apache constants.
In mod_perl, these constants can be accessed via the
Apache::Constants package (e.g., to access the
HTTP_OK constant, use
Apache::Constants::HTTP_OK). See the
Apache::Constants manpage for more information.
Successful 2xx: 200 HTTP_OK 201 HTTP_CREATED 202 HTTP_ACCEPTED 204 HTTP_NO_CONTENT Redirection 3xx: 300 HTTP_MOVED_PERMANENTLY 301 HTTP_MOVED_TEMPORARILY 302 HTTP_SEE_OTHER 304 HTTP_NOT_MODIFIED Client Error 4xx: 400 HTTP_BAD_REQUEST 401 HTTP_UNAUTHORIZED 403 HTTP_FORBIDDEN 404 HTTP_NOT_FOUND Server Error 5xx: 500 HTTP_INTERNAL_SERVER_ERROR 501 HTTP_NOT_IMPLEMENTED 502 HTTP_BAD_GATEWAY 503 HTTP_SERVICE_UNAVAILABLE
Informational 1xx: 100 HTTP_CONTINUE 101 HTTP_SWITCHING_PROTOCOLS Successful 2xx: 200 HTTP_OK 201 HTTP_CREATED 202 HTTP_ACCEPTED 203 HTTP_NON_AUTHORITATIVE 204 HTTP_NO_CONTENT 205 HTTP_RESET_CONTENT 206 HTTP_PARTIAL_CONTENT Redirection 3xx: 300 HTTP_MULTIPLE_CHOICES 301 HTTP_MOVED_PERMANENTLY 302 HTTP_MOVED_TEMPORARILY 303 HTTP_SEE_OTHER 304 HTTP_NOT_MODIFIED 305 HTTP_USE_PROXY 306 307 HTTP_TEMPORARY_REDIRECT Client Error 4xx: 400 HTTP_BAD_REQUEST 401 HTTP_UNAUTHORIZED 402 HTTP_PAYMENT_REQUIRED 403 HTTP_FORBIDDEN 404 HTTP_NOT_FOUND 405 HTTP_METHOD_NOT_ALLOWED 406 HTTP_NOT_ACCEPTABLE 407 HTTP_PROXY_AUTHENTICATION_REQUIRED 408 HTTP_REQUEST_TIMEOUT 409 HTTP_CONFLICT 410 HTTP_GONE 411 HTTP_LENGTH REQUIRED 412 HTTP_PRECONDITION_FAILED 413 HTTP_REQUEST_ENTITY_TOO_LARGE 414 HTTP_REQUEST_URI_TOO_LARGE 415 HTTP_UNSUPPORTED_MEDIA_TYPE 416 HTTP_RANGE_NOT_SATISFIABLE 417 HTTP_EXPECTATION_FAILED Server Error 5xx: 500 HTTP_INTERNAL_SERVER_ERROR 501 HTTP_NOT IMPLEMENTED 502 HTTP_BAD_GATEWAY 503 HTTP_SERVICE_UNAVAILABLE 504 HTTP_GATEWAY_TIME_OUT 505 HTTP_VERSION_NOT_SUPPORTED
All the information related to web protocols can be found at the World Wide Web Consortium’s site, http://www.w3.org/Protocols/.
There are many mirrors of the RFCs all around the world. One of the good starting points is http://www.rfc-editor.org/.
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