Wednesday, July 13, 2011

HTTP Status Code

Following is a list of all the available HTTP 1.1 status codes, along with their associated message and interpretation. You should be cautious in using the status codes that are available only in HTTP 1.1, since many browsers still only support HTTP 1.0. If you do use status codes specific to HTTP 1.1, in most cases you want to either explicitly check the HTTP version of the request (via the getProtocol method of the HttpServletRequest) or reserve it for situations when no HTTP 1.0 status code would be particularly meaningful to the client anyhow.

Status Code Associated Message Meaning
100 Continue Continue with partial request. (New in HTTP 1.1)
101 Switching Protocols Server will comply with Upgrade header and
change to different protocol. (New in HTTP 1.1)
200 OK Everything's fine; document follows for GET and
POST requests. This is the default for servlets; if you
don't use setStatus, you'll get this.
201 Created Server created a document; the Location header
indicates its URL.
202 Accepted Request is being acted upon, but processing is not
203 Non-Authoritative Information Document is being returned normally, but some of the
response headers might be incorrect since a document copy is being
used. (New in HTTP 1.1)
204 No Content No new document; browser should continue to display previous
document. This is a useful if the user periodically reloads a page
and you can determine that the previous page is already up to date.
However, this does not work for pages that are automatically
reloaded via the Refresh response header or the equivalent <META
HTTP-EQUIV="Refresh" ...>
header, since returning this status
code stops future reloading. JavaScript-based automatic reloading
could still work in such a case, though.
205 Reset Content No new document, but browser should reset document view.
Used to force browser to clear CGI form fields. (New in HTTP 1.1)
206 Partial Content Client sent a partial request with a Range
header, and server has fulfilled it. (New in HTTP 1.1)
300 Multiple Choices Document requested can be found several places; they'll be
listed in the returned document. If server has a preferred choice,
it should be listed in the Location response header.
301 Moved Permanently Requested document is elsewhere, and the URL for it is given
in the Location response header. Browsers should
automatically follow the link to the new URL.
302 Found Similar to 301, except that the new URL should be
interpreted as a temporary replacement, not a permanent one. Note:
the message was "Moved Temporarily" in HTTP 1.0, and the constant in
HttpServletResponse is SC_MOVED_TEMPORARILY,
not SC_FOUND.Very useful header, since browsers
automatically follow the link to the new URL. This status code is
so useful that there is a special method for it, sendRedirect.

Using response. sendRedirect(url) has a couple of
advantages over doing response. setStatus
and response.
setHeader("Location", url)
. First, it is easier. Second, with sendRedirect,
the servlet automatically builds a page containing the link (to show
to older browsers that don't automatically follow redirects).
can handle relative URLs, automatically translating them to
absolute ones.

Note that this status code is sometimes used interchangeably with
301. For example, if you erroneously ask for
(missing the trailing slash), some servers will send 301 and others
will send 302.

Technically, browsers are only supposed to automatically follow the redirection if the original request was GET.

See the 307 header for details.

303 See Other Like 301/302, except that if the original request was POST,
the redirected document (given in the Location header)
should be retrieved via GET. (New in HTTP 1.1)
304 Not Modified Client has a cached document and performed a conditional
request (usually by supplying an If-Modified-Since
header indicating that it only wants documents newer than a
specified date). Server wants to tell client that the old, cached
document should still be used.
305 Use Proxy Requested document should be retrieved via proxy listed in Location
header. (New in HTTP 1.1)
307 Temporary Redirect This is identical to 302 ("Found" or "Temporarily Moved").
It was added to HTTP 1.1 since many browsers erroneously followed
the redirection on a 302 response even if the original message was a
POST, even though it really ought to have followed the
redirection of a POST request only on a 303 response.
This response is intended to be unambigously clear: follow
redirected GET and POST requests in
the case of 303 responses, only follow the redirection for GET

requests in the case of 307 responses. Note: for some reason there
is no constant in HttpServletResponse corresponding to
this status code. (New in HTTP 1.1)
400 Bad Request Bad syntax in the request.
401 Unauthorized Client tried to access password-protected page without
proper authorization. Response should include a WWW-Authenticate
header that the browser would use to pop up a username/password
dialog box, which then comes back via the Authorization
403 Forbidden Resource is not available, regardless of authorization.
Often the result of bad file or directory permissions on the server.
404 Not Found No resource could be found at that address. This is the
standard "no such page" response. This is such a common and
useful response that there is a special method for it in HttpServletResponse:
The advantage of sendError
over setStatus is that, with sendError,
the server automatically generates an error page showing the error
405 Method Not Allowed The request method (GET, POST, HEAD,
DELETE, PUT, TRACE, etc.) was
not allowed for this particular resource. (New in HTTP 1.1)
406 Not Acceptable Resource indicated generates a MIME type incompatible with
that specified by the client via its Accept header.
(New in HTTP 1.1)
407 Proxy Authentication Required Similar to 401, but proxy server must return a Proxy-Authenticate
header. (New in HTTP 1.1)
408 Request Timeout The client took too long to send the request. (New in HTTP
409 Conflict Usually associated with PUT requests; used for
situations such as trying to upload an incorrect version of a file.
(New in HTTP 1.1)
410 Gone Document is gone; no forwarding address known. Differs from
404 in that the document is is known to be permanently gone in this
case, not just unavailable for unknown reasons as with 404. (New in
HTTP 1.1)
411 Length Required Server cannot process request unless client sends a Content-Length
header. (New in HTTP 1.1)
412 Precondition Failed Some precondition specified in the request headers was
false. (New in HTTP 1.1)
413 Request Entity Too Large The requested document is bigger than the server wants to
handle now. If the server thinks it can handle it later, it should
include a Retry-After header. (New in HTTP 1.1)
414 Request URI Too Long The URI is too long. (New in HTTP 1.1)
415 Unsupported Media Type Request is in an unknown format. (New in HTTP 1.1)
416 Requested Range Not Satisfiable Client included an unsatisfiable Range header
in request. (New in HTTP 1.1)
417 Expectation Failed Value in the Expect request header could not be
met. (New in HTTP 1.1)
500 Internal Server Error Generic "server is confused" message. It is often the result
of CGI programs or (heaven forbid!) servlets that crash or return
improperly formatted headers.
501 Not Implemented Server doesn't support functionality to fulfill request.
Used, for example, when client issues command like PUT
that server doesn't support.
502 Bad Gateway Used by servers that act as proxies or gateways; indicates
that initial server got a bad response from the remote server.
503 Service Unavailable Server cannot respond due to maintenance or overloading. For
example, a servlet might return this header if some thread or
database connection pool is currently full. Server can supply a Retry-After
504 Gateway Timeout Used by servers that act as proxies or gateways; indicates
that initial server didn't get a response from the remote server in
time. (New in HTTP 1.1)
505 HTTP Version Not Supported Server doesn't support version of HTTP indicated in request
line. (New in HTTP 1.1)