Setting HTTP Status Codes
When a Web server responds to a request from a browser or other Web client,
the response typically consists of a status line, some response headers,
a blank line, and the document. Here is a minimal example:
HTTP/1.1 200 OK
Content-Type: text/plain
Hello World
The status line consists of the HTTP version,
an integer that is interpreted as a status code, and a very short message
corresponding to the status code. In most cases, all of the headers are optional
except for Content-Type, which specifies the MIME type of the document that
follows. Although most responses contain a document, some don't. For
example, responses to HEAD requests should never include a document, and there
are a variety of status codes that essentially indicate failure, and either don't
include a document or only include a short "error message document".
Servlets can perform a variety of tasks by manipulating the status line
and the response headers. For example, they can forward the user to other sites;
indicate that the attached document is an image, Adobe Acrobat file, or (most commonly)
HTML file; tell the user that a password is required to access
the document; and so forth. This section will discuss the various different
status codes and what can be accomplished with them, while
the following section
will discuss the response headers.
NEXT
This tutorial is now available as a book: Core Servlets and JavaServer Pages by Marty Hall, published by Sun Microsystems Press.
Read all about it at CoreServlets.com
Server-Side Web Applications using Java Servlets versions 2.1/2.2 and JavaServer Pages (JSP) version 1.0: A Tutorial
© 1999-2000 Marty Hall.
All source code freely available for unrestricted use.
Created for work in the Research and Technology Development Center of the Johns Hopkins University Applied Physics Lab, for courses in the Johns Hopkins Part-Time MS Program in Computer Science, and for various industry seminars and on-site Java short courses.
Please note that this is a first draft of the tutorial, so please send corrections, comments, and suggestions to me at hall@apl.jhu.edu.
Reprinted with permission from the author. Click here to visit the original version
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