Transcript Easter Pastel Eggs - exercise

Chapter 6
Generating the Server
Response: HTTP Status
Codes
Nguyen Thi Nhung
Contents
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Format of the HTTP response
Common HTTP 1.1 Status Codes
How to set status codes
What the status codes are good for
Some examples
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Introduction
HTTP Request:
“Get me the document called /index.html”
HTTP Response:
“Okay, here it is! It’s in HTML format”
Server
(w3c.org)
Client
HTTP Message
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HTTP Request format
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HTTP Response format
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HTTP Message Examples
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Status code classes
Overall range
Defined range
Category
100-199
100-101
Informational
200-299
200-206
Successful
300-399
300-307
Redirection
400-499
400-417
Client error
500-599
500-505
Server error
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100 - Continue
Request message
Expect
= "Expect" ":" 1#expectation
expectation = "100-continue" | expectation-extension
expectation-extension = token [ "=" ( token | quoted-string )
*expect-params ]
expect-params = ";" token [ "=" ( token | quoted-string ) ]
Server
Request message
Client
HTTP/1.1 100 Continue
Request message
POST / HTTP/1.1
…..
Server
Request message
Client
HTTP/1.1 200 OK
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200 – OK
• The request has succeeded.
• This status is default for servlet
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300 – 399 Redirected request to new location
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301 – Moved Permanently
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302 – Found
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404 – Not found
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500 – Internal Server Error
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Specifying Status Codes
• Code 200 is set automatically
• Use response.setStatus(int, String)
• Call setStatus() before returning any of the
content with PrintWriter
• Can use defined constant for readability
(SC_MOVED_TEMPORARILY,
SC_NOT_FOUND)
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sendRedirect() method
• A shortcut to set 302 code
• Direct the browser to connect to a new
location
• Generate 302 code and Location header
giving the URL of new document
• response.sendRedirect("http://www.google
.com");
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sendError() method
• A shortcut to set 400s code
• Used when no document is found on the
server
• Generate 400s code and a short message in
HTML format and send to client
• response.sendError(res.SC_NOT_FOUND,
”Sorry, the page cannot be found”);
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Examples
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WrongDestination.java
SearchEngines.java
SearchSpec.java
SearchUtilities.java
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THANK YOU!