Raymond, I think you're on the right track by considering global variables but you have to be careful. See comments below.
Raymond Wan wrote: > > What is a global variable in Mason? Are global variables accessible by > all components in a request, all requests from a single user (this one > doesn't make sense), or global for all users? > A global variable is one that is available from all components and it's value may persist across all requests served by the same perl interpreter/web server process. > Even worse, if User 1 sets the value to "100" upon reading index.html > and user 2 sets it to "200", if user 1 goes to next.html, is it foolish > to rely on the fact that x must be "100"? > In most cases yes it is foolish to assume that the value will persist from request to request or user to user. The foolishness of this depends on your configuration. If you're running an Apache web server with a normal configuration there are actually a number of apache processes running that serve requests. Each one of these processes contains it's own perl runtime with it's own memory. When you store data in a global variable it is only stored in the memory of the process that served the request. This value will persist for every other request that this process serves. In my experience Apache usually serves consecutive requests from the same IP address with the same process. Thus if my first request hit process #3456 then my second request will most likely (no guarantees) hit process #3456. Any requests from your IP address may also go to that process or they may go to process #3460 which has a completely different memory allocation. If your apache configuration only spawns one process to handle requests then the memory will persist for all requests and all users and relying on this will not necessarily be foolish. But this type of configuration can be perhaps a different kind of foolishness in a high traffic configuration. > In the Mason Book, they seemed to have used user names and DB access > ($User and $Schema) as a global, but they "limit their lifetime via the > use of local()". In the context of Mason, what does local have the > effect of doing? > Declaring a variable using local creates a blank version of a variable. This guarantees that code following the 'local' declaration will have a clean slate. This is a fairly standard way to use global variables. In my experience there is a top level autohandler or system handler which clears out every global variable that exists. With all this in mind you can use a combination of cookies and global variables to store your id. Storing the id in a cookie ensures that the browser will send the value with each request. Your code can store the value of the cookie in a (cleared out) global variable which will be accessible by any component for the duration of the request. If you have the time I would recommend looking into the Apache::Session module. This allows you to store various information about a user session in a location that will persist for the same user across requests. The storage location can be in a relational database or other server side persistent container (e.g.: file) Good Luck, -- BenRifkah ------------------------------------------------------------------------- This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2005. http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/ _______________________________________________ Mason-users mailing list Mason-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/mason-users
