Sun Java System Web Server 6.1 SP7 NSAPI Programmer's Guide


The server’s response includes the following:

HTTP Protocol Version, Status Code, and Reason Phrase

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

Table 12–2 Common HTTP Status Codes

Status Code  



OK, request has succeeded for the method used (GET, POST, HEAD).


The request has resulted in the creation of a new resource reference by the returned URI. 


The server has sent a response to byte range requests. 


Found. Redirection to a new URL. The original URL has moved. This is not an error and most browsers will get the new page. 


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 is not an error. 


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.


Unauthorized. The user requested a document but didn’t provide a valid user name or password. 


Forbidden. Access to this URL is forbidden. 


Not found. The document requested isn’t on the server. This code can also be sent if the server has been told to protect the document by telling unauthorized people that it doesn’t exist. 


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. 


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.


Some applications (e.g., certain NSAPI plug-ins) cannot handle very large amounts of data, so they will return this code. 


The URI is longer than the maximum the web server is willing to serve. 


Data was requested outside the range of a file. 


Server error. A server-related error occurred. The server administrator should check the server’s error log to see what happened. 


Sent if the quality of service mechanism was enabled and bandwidth or connection limits were attained. The server will then serve requests with that code. See the "quality of service" section. 

Response Headers

The response headers contain information about the server and the response data.

The following table lists some common response headers.

Table 12–3 Common Response Headers

Response Header  



Name and version of the web server. 


Current date (in Greenwich Mean Time). 


Date when the document was last modified. 


Date when the document expires. 


Length of the data that follows (in bytes). 


MIME type of the following data. 


Used during authentication and includes information that tells the browser software what 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.