Part 9: Error Handing and Chaining From Page to Page
The example introduced the subroutine PLW.PAGE(...,...,...) and
used this subroutine to chain to error pages. PLW.PAGE is actually the
main PicLan-IP web server subroutine that is used to process a page transaction.
When you call PLW.PAGE, you are actually recursively calling the subroutine
that is itself calling your program. This operation give you great flexibility
in controlling page flow. The important thing to remember about calling
PLW.PAGE is that you will usually want to include a RETURN statement
so that the new pages result will be used and not the merge results from
the current page.
Because of the way that PLW.PAGE(...) allows you to chain from page
to page, may web designers choose to build a PicLan-IP web application
using the same page name for all of the pages. The logic within this main
page then reads variables and branches to other pages depending on
the applications current status. While this may seem confusing, it effectively
prevents the user from bookmarking an application mid-stream and insures
that users always start at the beginning.
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