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Appendix C. HTTP Status Codes

HTTP status codes are grouped as shown in Table C-1.

Table C-1. HTTP Status Code Groupings

Code Range

Response Meaning

100-199

Informational

200-299

Client request successful

300-399

Client request redirected, further action necessary

400-499

Client request incomplete

500-599

Server error

Table C-2 lists the HTTP status code constants defined by the HttpServletResponse interface and used as parameters to its setStatus() and sendError() methods. The version number in the last column refers to the HTTP protocol version that first defined the status code. The Servlet API 2.0 added constants for HTTP Version 1.1 status codes. Note that HTTP 1.1 status codes require an HTTP 1.1-compliant browser.

For more information on HTTP, see Web Client Programming by Clinton Wong (O'Reilly). The proposed HTTP/1.1 specification is available in RFC 2068 at http://www.ietf.org/rfc/rfc2068.txt.

Table C-2. HTTP Status Code Constants

Constant

Code

Default Message

Meaning

HTTP Version

SC_CONTINUE

100

Continue

The server has received the initial part of the request, and the client can continue with the remainder of its request.

1.1

SC_SWITCHING_PROTOCOLS

101

Switching Protocols

The server is willing to comply with the client's request to switch protocols to the one specified in the request's Upgrade header. This might include switching to a newer HTTP version.

1.1

SC_OK

200

OK

The client's request was successful and the server's response contains the requested data. This is the default status code.

1.0

SC_CREATED

201

Created

A resource has been created on the server, presumably in response to a client request. The response body should include the URL(s) where the new resource can be found, with the most specific URL set in the Location header. If the resource cannot be created immediately, an SC_ACCEPTED status code should be returned instead.

1.0

SC_ACCEPTED

202

Accepted

The request has been accepted for processing but has not yet completed. The server should describe the current status of the request in the response body. The server is under no obligation to act on or complete the request.

1.0

SC_NON_AUTHORITATIVE_INFORMATION

203

Non-Authoritative Information

The HTTP response headers came from a local or third-party source, rather than the original server. Normal servlets have no reason to use this status code.

1.1

SC_NO_CONTENT

204

No Content

The request succeeded but there was no new response body to return. Browsers receiving this code should retain their current document view. This is a useful code for a servlet to use when it accepts data from a form but wants the browser view to stay at the form, as it avoids the "Document contains no data" error message.

1.0

SC_RESET_CONTENT

205

Reset Content

The request succeeded and the browser should reset (reload) the current document view. This is a useful code for a servlet to use when it accepts data from a form and wants the form redisplayed in a fresh state.

1.1

SC_PARTIAL_CONTENT

206

Partial Content

The server has completed a partial GET request and returned the portion of the document specified in the client's Range header.

1.1

SC_MULTIPLE_CHOICES

300

Multiple Choices

The requested URL refers to more than one resource. For example, the URL may refer to a document translated into many languages. The response body should explain the client's options in a format appropriate for the response content type. The server can suggest a choice with the Location header.

1.1

SC_MOVED_PERMANENTLY

301

Moved Permanently

The requested resource has permanently moved to a new location and future references should use the new URL in their requests. The new location is given by the Location header. Most browsers automatically access the new location.

1.0

SC_MOVED_TEMPORARILY

302

Moved Temporarily

The requested resource has temporarily moved to another location, but future references should still use the original URL to access the resource. The new location is given by the Location header. Most browsers automatically access the new location.

1.0

SC_SEE_OTHER

303

See Other

The requested resource processed the request but the client should get its response by performing a GET on the URL specified in the Location header. This code is useful for a servlet that wants to receive POST data then redirect the client to another resource for the response.

1.1

SC_NOT_MODIFIED

304

Not Modified

The requested document has not changed since the date specified in the request's If-Modified-Since header. Normal servlets should not need to use this status code. They implement getLastModified() instead.

1.0

SC_USE_PROXY

305

Use Proxy

The requested resource must be accessed via the proxy given in the Location header.

1.1

SC_BAD_REQUEST

400

Bad Request

The server could not understand the request, probably due to a syntax error.

1.0

SC_UNAUTHORIZED

401

Unauthorized

The request lacked proper authorization. Used in conjunction with the WWW-Authenticate and Authorization headers.

1.0

SC_PAYMENT_REQUIRED

402

Payment Required

Reserved for future use. Proposals exist to use this code in conjunction with a Charge-To header, but this has not been standardized as of press time.

1.1

SC_FORBIDDEN

403

Forbidden

The request was understood, but the server is not willing to fulfill it. The server can explain the reason for its unwillingness in the response body.

1.0

SC_NOT_FOUND

404

Not Found

The requested resource was not found or is not available.

1.0

SC_METHOD_NOT_ALLOWED

405

Method Not Allowed

The method used by the client is not supported by this URL. The methods that are supported must be listed in the response's Allow header.

1.1

SC_NOT_ACCEPTABLE

406

Not Acceptable

The requested resource exists, but not in a format acceptable to the client (as indicated by the Accept header(s) in the request).

1.1

SC_PROXY_AUTHENTICATION_REQUIRED

407

Proxy Authentication Required

The proxy server needs authorization before it can proceed. Used with the Proxy-Authenticate header. Normal servlets should not need to use this status code.

1.1

SC_REQUEST_TIMEOUT

408

Request Timeout

The client did not completely finish its request within the time that the server was willing to listen.

1.1

SC_CONFLICT

409

Conflict

The request could not be completed because it conflicted with another request or the server's configuration. This code is most likely to occur with HTTP PUT requests, where the file being put is under revision control and the new version conflicts with some previous changes. The server can send a description of the conflict in the response body.

1.0

SC_GONE

410

Gone

The resource is no longer available at this server, and no alternate address is known. This code should be used only when the resource has been permanently removed. Normal servlets have no reason to use this status code.

1.1

SC_LENGTH_REQUIRED

411

Length Required

The server will not accept the request without a Content-Length header.

1.1

SC_PRECONDITION_FAILED

412

Precondition Failed

A precondition specified by one or more If... headers in the request evaluated to false.

1.1

SC_REQUEST_ENTITY_TOO_LARGE

413

Request Entity Too Large

The server will not process the request because the request content is too large. If this limitation is temporary, the server can include a Retry-After header.

1.1

SC_REQUEST_URI_TOO_LONG

414

Request-URI Too Long

The server will not process the request because the request URI is longer than the server is willing to interpret. This can occur when a client has accidentally converted a POST request into a GET request. Normal servlets have no reason to use this status code.

1.1

SC_UNSUPPORTED_MEDIA_TYPE

415

Unsupported Media Type

The server will not process the request because the request body is in a format unsupported by the requested resource.

1.1

SC_INTERNAL_SERVER_ERROR

500

Internal Server Error

An unexpected error occurred inside the server that prevented it from fulfilling the request.

1.0

SC_NOT_IMPLEMENTED

501

Not Implemented

The server does not support the functionality needed to fulfill the request.

1.0

SC_BAD_GATEWAY

502

Bad Gateway

A server acting as a gateway or proxy did not receive a valid response from an upstream server.

1.0

SC_SERVICE_UNAVAILABLE

503

Service Unavailable

The service (server) is temporarily unavailable but should be restored in the future. If the server knows when it will be available again, a Retry-After header may also be supplied.

1.0

SC_GATEWAY_TIMEOUT

504

Gateway Timeout

A server acting as a gateway or proxy did not receive a valid response from an upstream server during the time it was prepared to wait.

1.1

SC_HTTP_VERSION_NOT_SUPPORTED

505

HTTP Version Not Supported

The server does not support the version of the HTTP protocol used in the request. The response body should specify the protocols supported by the server. Normal servlets should not need to use this status code.

1.1



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