Each time the user makes a request the program runs, reloads the session file, carries out the chosen action, outputs the updated HTML page, saves the session file and exits. The program cannot assume that the user will retrurn to make another request so there has to be a garbage collection routine which deletes unwanted session files after a timeout period. The program makes use of URLs to keep track of separate sessions. The program generates the opening page for the user and creates URLs for the forms which are specific to the session. The first part of the URL is a standard reference to the program file on the WWW server.
Further information follows.
The effect is that you are following a series of URLs that reveal more information but in reality you are receiving output from the same program over and over again. Becasue the documents you read are generated 'live' you cannot reload them in the usual way and the normal navigation tools should be avoided. You must always use the forms on the most recently downloaded page for the session. The patient is defined by a text file. This contains a list of the tests that will be availble and all the test results.