more on persistent cgi modelsand support in python for things such as fastcgisearch the web or consult web-specific resources combining techniques naturallythese techniques may be combined to achieve variety of memory strategiesboth for interaction sessions and for more permanent storage needs for examplea web application may use cookies to store per-user or per-session key on the clientand later use that key to index into server-side database to retrieve the user' or session' full state information even for short-lived session informationurl query parameters or hidden form fields may similarly be used to pass key identifying the session from page to pageto be used by the next script to index server-side database moreoverurl query parameters and hidden fields may be generated for temporary state memory that spans pageseven though cookies and databases are used for retention that must span sessions the choice of technique is driven by the application' storage needs although not as straightforward as the in-memory variables and objects of single process gui programs running on clientwith creativitycgi script state retention is entirely possible the hello world selector let' get back to writing some code again it' time for something bit more useful than the examples we've seen so far (wellmore entertainingat leastthis section presents program that displays the basic syntax required by various programming languages to print the string "hello world,the classic language benchmark to keep it simplethis example assumes that the string is printed to the standard output stream in the selected languagenot to gui or web page it also gives just the output command itselfnot complete programs the python version happens to be complete programbut we won' hold that against its competitors here structurallythe first cut of this example consists of main page html filealong with python-coded cgi script that is invoked by form in the main html page because no state or database data is stored between user clicksthis is still fairly simple example in factthe main html page implemented by example - is mostly just one big pull-down selection list within form example - pp \internet\web\languages html languages hello world selector the hello world selector