Re: Freeing cyclic refferences
On Wed, 20 Dec 2000, Radovan Semancik wrote: I have perl objects with cyclic refferences to each othen in mod_perl environment. I know that these objects will never be freed unless I break the refference cycle. But, how to do it transparently for user of object? What you need to do is to have a "starting" node in your reference cycle that doesn't have anything pointing to it. Such as the "head" pointer of a linked list. If the DESTROY method of this object were to explicitely call some clean-up method of yours that is in the regular node objects (clearing internode references), then the whole process should be transparent to the user because all they have to do is remove any references to the starting node, and they all vanish. If your entire set of linked objects is encapsulated in another one, then that would effectively be your "start". // Darren Duncan
Re: slight mod_perl problem
On Wed, 20 Dec 2000, Jamie Krasnoo wrote: Ok, it seems that my startup.pl is being run twice on server start. Since configuration scripts can include other scripts, you probably have more than one other script that includes startup.pl, or more than one script that includes something that includes startup.pl, or other such. This is a commonly encountered situation in programming. What you need to do is scan your other relevant config files to look for multiple includes of another file and remove one. Or, if this isn't feasible, then there may be some conditional that you can use to check if you already ran a script, and then not do it again. Of course, there could be a different reason that this is happening... // Darren Duncan
Re: HTTP authentication based sessioning with logout ability
I have also been doing problem solving related to session handling and I will briefly share my ideas for a solution. What I am about to say is just the logic or protocol behind my solution without getting into implementation details. I don't know if it'll help you, but here goes: Essentially I had a server-side data store that tracked 4 pieces of information on a client session for authentication purposes: 1. session code or login name (primary key) 2. the "realm"/cookie that the client got on the last log in 3. the date and time of their last log in or request 4. the IP address (or something) of the client machine when last logged in The above information is checked each time the client makes a request. If any is not acceptible then they are prompted for their user id and password again. "acceptible" means that the realm and IP are the same as before, and that less than a certain amount of time passed since they were prompted for a password. If users log out then the "realm" is reset to nil so that they would have to be prompted on a log-in later. HTTP authentication can be used to gather the login name and password, or an html form could be used (greater compatability). It doesn't really matter. The back-end data store also remembered the cumulative effect of whatever users did during the session, so it doesn't all need to be passed back and forth by the browser. So if the web browser crashes or they move to another computer or their session times out, all they have to do is answer the new prompt for a username/password and they can continue right where they left off. This also means that their short-term workflow is remembered, so they have the same screen they left with. The actual commitment of their changes is only done at certain times, such as when they request to save changes. Meanwhile, the actual back-end data isn't left in a volatile state. I think that my solution has advantages of convenience, security, data integrity, compatability and so forth. Also, web browsers have very little that they need to remember. The catch is that users need to have login ids and passwords, and that their activity is tracked by the server (at least short term). But my solution was designed for users who were registered and approved to edit the database, not anonymous individuals. Although, this methodology could still be adapted for anonymous uses... FYI: My requirements were to facilitate a web-accessible resource that could be edited by multiple registered people at once, and as such, each person would have their own login name and password. Fairly standard so far, right? But in addition to that, it needed to let them do their work at a public station or office where the same user could be sitting at several different computers in one day, and several people could use the same computer. Additionally, an editing task could be either simple or quite involved, meaning that the user may have to abandon their session and continue where they left off later. I needed precautions against the browser crashing or it being left open after the user leaves for others to see. Finally, the edited information would be hierarchical, often requiring multiple screens, as well as going up a path and then returning, with what they did up the path being remembered. The same user may even want to edit several unrelated pieces of information at once, doing first one, then stopping and doing something else, and then returning to what they were doing before. Now, I don't know if any of this has helped you or not, but it certainly has helped me. Good days, // Darren Duncan
Document contains no data
I have been having a problem with my scripts during the where I periodically get a Netscape 4 error saying "Document contains no data" when they run under mod_perl, but not with the same script under CGI. And this only happens sometimes; other times the pages return fine. However, the problem happens very often, even while not all the time. At some points it happens many times sequentially. The problems started soon after I switched to mod_perl on my server using this in the .htaccess file (files named .cgi run as CGI): Files *.pl SetHandler perl-script PerlHandler Apache::Registry Options +ExecCGI /Files I did a search in the Guide for this error and otherwise looked in the troubleshooting sections, but could find nothing. So I am hoping that you all can forgive me for asking help on this problem. Everything else is working fine as near as I can tell. I do not use any global variables explicitely, so I don't see how there could be persistant variable issues. I also print my entire output with headers in a single print statement. I am printing the "HTTP/1.0 200 OK\r\n" ahead of the other headers when running under mod_perl as I am supposed to. And when pages do display they show evidence of this (no extra header text appears). I believe that my mod_perl set-up has about 10 child processes in it, and site traffic is on the order of about 300-1000 hits per day. Stop/Starting the server did not make a difference. Non perl files still are served fine so far and so are .cgi files. Help? // Darren Duncan
Re: greetings and questions
Thanks to everyone who answered my questions in some form or other. As it is, I *had* been reading whatever manuals I found, but those were the documentation that came with the mod_perl distribution on CPAN. I was not aware of the existence of "http://perl.apache.org/guide/" and if I had been then I would have looked there. I had seen a number of documents on the perl.apache.org server, but not that one. So thanks to those of you who pointed it out. And no, I'm not offended by any "RTFM" comments. I can fully understand that many of you would have seen the same questions asked over and over by people that didn't read the FAQs first. So while I had read some FAQs it seems like I missed the important one. Chalk it up to my first posting on a new listserv. So I will look at The Guide now. Thank you, // Darren Duncan P.S. Tom Brown, what a small world this is?
