On Apache Tomcat courses, I find myself explaining "single login" models and on some Java courses I explain single threaded models. In both cases, there are times that newcomers to the technologies ask "does it matter".

Answer - for a small and quiet application suite, probably not - but as the application suite grows, a single login to cover all applications is a boon to your users, and in contrast the single threaded model should be avoided as it will limit traffic - keeping users waiting at the "starting gate" until the previous visitor to the application has completed his current interaction.

We have developed a number of applications for internal use here at Well House Consultants and Well House Manor over the years that rely on staff members logging in to get [full] use of the application code, and I am in process of applying a single login model to them retrospectively ... since they're internal, I'm afraid I can't publish log in details to give you a demonstration, but I can give you some pointers.

• 1. We're noting logins at the start of each of the applications via a common set of PHP functions that we have written and include in each application: pwtest to see if the user is already logged in, and return account info pwcheck to check if a user name and password pair are valid pwlogin to log a user in pwlogout to log a user out   • 2. On the exit from each application, any session is destroyed but the longer term login cookie is retained   • 3. On the user selecting a general logout button, session cookies for all applications grouped under the single login facility are destroyed in order to avoid any security holes being left open.   • 4. Cookies for the single common login are specifically set up for the root directory or any folder below it so that they will be seen by all the sharing applications, and are initially configured to allow a user to remain logged in for a period of rather longer that a regular session, but not for months or years!

What applications are we serving with the system so far?

Our Staff Resources Front Page (where extra links are provided for staff who are logged in)

Our hotel room availability page (if you're not logged in, you just get a room status report and an invitation to book. When logged in, we can see details of room allocation right down to the staff member on duty being given a checklist of anticipated arrival times!)

Our new incident book system through which we report anything from breakages to notes of customer preferences between ourselves - the public facing pages are read only, and only show items we have chosen to mark "public".

Our wiki (sample page) that is extensively used for both internal and customer facing pages that change frequently.

Our traffic monitor (last 5 minutes) and most popular pages (last 24 hours) reports reveal more information to logged in staff

And our security monitor page - when logged in suitably, certain team members can view the web cams. If not logged in, You'll see a display of some static photographs instead.
(written 2008-01-04, updated 2008-01-08)

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  [1550] Java (JSP and Servlet examples) live on our server - (2008-02-23)
  [1909] javax.servlet cannot be resolved - how to solve - (2008-11-26)
  [2183] Servlet life cycle, and Java Servlet variable scope - (2009-05-16)
  [2652] Reading and writing cookies in Java Servlets and JSPs - (2010-02-26)
  [2717] The Multiple Inheritance Conundrum, interfaces and mixins - (2010-04-11)
  [3044] Changing a Servlet - more that just editing and compiling - (2010-11-12)
  [3293] Distributing the server load - yet ensuring that each user return to the same system (Apache httpd and Tomcat) - (2011-05-18)
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  [4432] Java web application for teaching - now with sessions and clustering / load balancing demonstrations - (2015-02-20)

H202 - PHP - Case Study
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  [4691] Real life PHP application using our course training MVC example - (2016-06-05)

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)
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  [1496] PHP / Web 2 logging - (2008-01-06)
  [1505] Script to present commonly used images - PHP - (2008-01-13)
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  [1518] Downloading data for use in Excel (from PHP / MySQL) - (2008-01-25)
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  [3432] 3 digit HTTP status codes - what are they, which are most common, which should be a concern? - (2011-09-11)
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  [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)
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