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For 2021 - online Python 3 training - see ((here)).

Our plans were to retire in summer 2020 and see the world, but Coronavirus has lead us into a lot of lockdown programming in Python 3 and PHP 7.
We can now offer tailored online training - small groups, real tutors - works really well for groups of 4 to 14 delegates. Anywhere in the world; course language English.

Please ask about private 'maintenance' training for Python 2, Tcl, Perl, PHP, Lua, etc.
3 digit HTTP status codes - what are they, which are most common, which should be a concern?

We often talk during web related course / course modules about the status codes that are returned by servers - but I don't think I've ever written up a (near?) complete list. They are all three digit codes, and they're grouped by hundreds - so 200 series code are success, 400 codes are requests that can't be met, etc. Here's the list:

Informational - 100 series
Continue - 100
Switch Protocol - 101

Success - 200 series
OK - 200
Created - 201
Accepted - 202
NonAuthoritative Information - 203
No Content - 204
Reset Content - 205
Partial Content - 206

Redirection - 300 series
Multiple Choice - 300
Moved Permanently - 301
Found - 302
See Other - 303
Not Modified - 304
Use Proxy - 305
Temporary Redirect - 307

Client Error - 400 series
Bad Request - 400
Unauthorized - 401
Payment Required - 402
Forbidden - 403
Not Found - 404
Method Not Allowed - 405
Not Acceptable - 406
Proxy Authentication Required - 407
Request TimeOut - 408
Conflict - 409
Gone - 410
Length Required - 411
Precondition Failed - 412
Request Entity Too Large - 413
Request URI Too Long - 414
Unsupported Media Type - 415
Requested Range Not Satisfiable - 416
Expectation Failed - 417

Server Error - 500 series
Internal Server Error - 500
Not Implemented - 501
Bad Gateway - 502
Service Unavailable - 503
Gateway TimeOut - 504
Version Not Supported - 505

other extension / non standard / no longer used codes listed at the end of this article

So - which are the important codes? As a web site provider, you want to take a very careful look at the 500 series codes as they indicate something potentially wrong with your web server. Anything more that 0.5% in the 400 series would worry me too, as that indcates that you may have users being (mis)lead into asking for pages that don't exist, or knocking on locked doors.

How can we analyse the relative number of access codes? I've written a ruby program (source code [here]) to look through server log files - defaulting to 100 days of data, and here are my results starting 1st June 2011:

  wizard:sep11 graham$ ./ruby_100
  200 - 96.04% 10750468
  206 -  0.06% 7033
  226 -  0.00% 8
  250 -  0.01% 1015
  301 -  0.12% 13330
  302 -  0.07% 7554
  304 -  1.70% 190774
  400 -  0.01% 965
  403 -  0.60% 67093
  404 -  1.38% 154432
  405 -  0.00% 17
  408 -  0.01% 759
  416 -  0.00% 8
  500 -  0.01% 642
  111941 accesses per day
  4664.2 accesses per hour
  77.74 accesses per minute
  wizard:sep11 graham$


Studious readers will note that we have very many code 403 and 404 codes than I said were acceptable just up above. This is because our web server is actually programmed to return these codes to certain intrusion attempts in the (perhaps vain) hope that those intrusion attempts will think there's nothing there and give up. Easy enough to do, but it does mean that my figures here need a little more careful reading than you might have expected.

Status codes covered in the web sections of many courses. They're particularly mentioned and used on the Deploying LAMP, Deploying Apache / Tomcat and PHP courses. A little ironically, the sample program that I've used here comes as a follow up from last week's Ruby course.





The following extra codes may be seen very occasioanlly. Most of them are module / vendor specific extensions, and / or no longer used. Code 418 was an April Fool's joke ... RFC 2324, the Hyper Text Coffee Pot Control Protocol - [see here].

Processing - 102
Checkpoint - 103
Request URI too long - 122
Multi-Status - 207
IM Used - 226
Switch Proxy - 306
Resume Incomplete - 308
I'm a Teapot - 418
Unprocessable Entity - 422
Locked - 423
Faild dependency - 424
Unordered Collection - 425
Upgrade Required - 426
No Response - 444
Retry With - 449
Blocked by Windows Parental Control - 450
Client Closed Request - 499
Varient also negotiates - 506
Insufficient storage - 507
Bandwidth limit exceeded - 509
Not extended - 510
(written 2011-09-11)

 
Associated topics are indexed as below, or enter http://melksh.am/nnnn for individual articles
R114 - Ruby on the Web
  [1891] Ruby to access web services - (2008-11-16)
  [2605] Ruby on Rails - a sample application to teach you how - (2010-01-30)
  [2607] Answers on Ruby on Rails - (2010-01-30)
  [3431] Ruby at both extremes of your website - (2011-09-10)
  [3623] Some TestWise examples - helping use Ruby code to check your web site operation - (2012-02-24)
  [3773] Ruby on the web - a simple example using CGI - (2012-06-22)
  [4003] Web and console - same principle, same code - Ruby example - (2013-02-14)
  [4502] Reading and parsing a JSON object in Ruby - (2015-06-01)

H112 - PHP - Further Web Page and Network Handling
  [220] When to use Frames - (2005-02-19)
  [314] What language is this written in? - (2005-05-17)
  [345] Spotting a denial of service attack - (2005-06-12)
  [356] Sudoku helper or sudoku cheat - (2005-06-23)
  [372] Time calculation in PHP - (2005-07-08)
  [376] What brings people to my web site? - (2005-07-13)
  [410] Reading a news or blog feed (RSS) in your PHP page - (2005-08-12)
  [425] Caching an XML feed - (2005-08-26)
  [443] Server side scripting of styles to suit the browser - (2005-09-12)
  [451] Accessing a page via POST from within a PHP script - (2005-09-26)
  [484] Setting the file name for a downloaded document - (2005-11-03)
  [537] Daily Image Santafied - (2005-12-22)
  [542] Morning image, afternoon image - (2005-12-26)
  [565] Using PHP to output images, XML, Style sheets, etc - (2006-01-15)
  [603] PHP - setting sort order with an associative array - (2006-02-13)
  [675] Adding PHP tags to an old cgi program - (2006-04-08)
  [767] Finding the language preference of a web site visitor - (2006-06-18)
  [789] Hot answers in PHP - (2006-07-02)
  [847] Image maps for navigation - a straightforward example - (2006-08-28)
  [904] Of course I'll tell you by email - (2006-10-25)
  [936] Global, Superglobal, Session variables - scope and persistance in PHP - (2006-11-21)
  [1009] Passing GET parameters through Apache mod_rewrite - (2006-12-27)
  [1114] PHP Image upload script - (2007-03-21)
  [1183] Improving searches - from OR to AND? - (2007-05-11)
  [1187] Updating a page strictly every minute (PHP, Perl) - (2007-05-14)
  [1210] PHP header() function - uses and new restrictions - (2007-05-30)
  [1355] .php or .html extension? Morally Static Pages - (2007-09-17)
  [1379] Simple page password protection - PHP - (2007-10-04)
  [1485] Copyright and theft of images, bandwidth and members. - (2007-12-26)
  [1495] Single login and single threaded models - Java and PHP - (2008-01-04)
  [1496] PHP / Web 2 logging - (2008-01-06)
  [1505] Script to present commonly used images - PHP - (2008-01-13)
  [1515] Keeping staff up to date on hotel room status - (2008-01-22)
  [1518] Downloading data for use in Excel (from PHP / MySQL) - (2008-01-25)
  [1549] http, https and ajp - comparison and choice - (2008-02-22)
  [2632] Shipping a test harness with your class in PHP - (2010-02-12)
  [2679] How to build a test harness into your PHP - (2010-03-16)
  [2729] Uploading a document or image to its own URL via a browser - (2010-04-18)
  [2918] Downloading a report from the web for further local analysis - (2010-08-13)
  [3036] Sending out an email containing HTML from within a PHP page - (2010-11-07)
  [3540] Easy session example in PHP - keeping each customers data apart - (2011-12-06)
  [3568] Telling which ServerAlias your visitor used - useful during merging domains - (2012-01-04)
  [3918] Multiple page web applications - maintaining state - PHP - (2012-11-10)
  [4070] Passing variable between PHP pages - hidden fields, cookies and sessions - (2013-04-26)
  [4483] Moving from mysql to mysqli - simple worked example - (2015-05-03)

A207 - Web Application Deployment - HTTP
  [1378] Etag in http headers - what is it? - (2007-10-03)
  [1503] Web page (http) error status 405 - (2008-01-12)
  [2321] Uploading and Downloading files - changing names (Perl and PHP) - (2009-08-04)
  [2596] Http protocol - what does a web server send - (2010-01-24)
  [2738] What is all this SESSION stuff about? (PHP) - (2010-04-25)


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or
Horse's mouth home
Forward to
Exceptions - a fail-safe way of trapping things that may go wrong
Some other Articles
Moving from scripting to Object Orientation in Python
Sorta sorting a hash, and what if an exception is NOT thrown - Ruby
Sundays - and over eating
Exceptions - a fail-safe way of trapping things that may go wrong
3 digit HTTP status codes - what are they, which are most common, which should be a concern?
Sigils - the characters on the start of variable names in Perl, Ruby and Fortran
Searching through all the files in or below a directory - Ruby, Tcl, Perl
How many days to Christmas?
What is on the Melksham Agenda?
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This is a page archived from The Horse's Mouth at http://www.wellho.net/horse/ - the diary and writings of Graham Ellis. Every attempt was made to provide current information at the time the page was written, but things do move forward in our business - new software releases, price changes, new techniques. Please check back via our main site for current courses, prices, versions, etc - any mention of a price in "The Horse's Mouth" cannot be taken as an offer to supply at that price.

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