Sun Java System Web Server 7.0 Update 2 NSAPI Developer's Guide

Responses

The server’s response includes the following:

HTTP Protocol Version, Status Code, and Reason Phrase

The server sends back a status code, which is a three-digit numeric code. The five categories of status codes are:

100-199 code indicate a provisional response.
200-299 code indicate a successful transaction.
300-399 code indicate the requested resource should be retrieved from a different location.
400-499 code indicate an error was caused by the browser.
500-599 code indicate a serious error occurred in the server.

The following table lists some common status codes.

Table A–1 Common HTTP Status Codes


Status Code	Meaning
`200`	The Request has succeeded for the method used (`GET`, `POST`, `HEAD`).
`201`	The request has resulted in the creation of a new resource reference by the returned URI.
`206`	The server has sent a response to byte range requests.
`302`	Found. Redirection to a new URL. The original URL has moved. This result is not an error. Most browsers will get the new page.
`304`	Use a local copy. If a browser already has a page in its cache, and the page is requested again, some browsers such as Netscape Navigator relay to the web server the “last-modified” timestamp on the browser’s cached copy. If the copy on the server is not newer than the browser’s copy, the server returns a 304 code instead of returning the page, reducing unnecessary network traffic. This result is not an error.
`400`	Sent if the request is not a valid HTTP/1.0 or HTTP/1.1 request. For example HTTP/1.1 requires a host to be specified either in the `Host` header or as part of the URI on the request line.
`401`	Unauthorized. The user requested a document but did not provide a valid user name or password.
`403`	Forbidden. Access to this URL is forbidden.
`404`	Not found. The document requested is not on the server. This code can also be sent if the server is configured to protect the document for unauthorized personnel.
`408`	If the client starts a request but does not complete it within the keep-alive timeout configured in the server, then this response will be sent and the connection closed. The request can be repeated with another open connection.
`411`	The client submitted a `POST` request with chunked encoding, which is of variable length. However, the resource or application on the server requires a fixed length - a `Content-Length` header to be present. This code tells the client to resubmit its request with `Content-Length`.
`413`	Some applications, for example, certain NSAPI plug-ins cannot handle very large amounts of data, so returns this error code.
`414`	The URI is longer than the maximum the web server is willing to serve.
`416`	Data was requested outside the range of a file.
`500`	A server-related error occurred. The server administrator must check the error log in the server.
`503`	Sent if the quality of service mechanism was enabled and bandwidth or connection limits were attained. The server then serves requests with that code.

Response Headers

The response headers contain information about the server and the response data. This section lists some common response headers.

Server: Name and version of the web server
Date: Current date in Greenwich Mean Time
Last-Modified: Date when the document was last modified
Expires: Date when the document expires
content-length: Length of the data that follows (in bytes)
content-type: MIME type of the data that follows
WWW-Authenticate: Used during authentication and includes information that tells the browser software what information is necessary for authentication such as user name and password

Response Data

The server sends a blank line after the last header. It then sends the response data such as an image or an HTML page.