iam developing a module in Drupal, which needs to have a locking machanism, When one user operating on form submission other should nt take action,
How do i can achieve this in php/drupal
iam using mysql database with MyISAM/INNODB
Please help me
Thanks in advance
Kamal
Drupal 6.16 implemented a locking framework.
http://api.drupal.org/api/drupal/includes--lock.inc/6
If you're in a situation where there's a good possibility where there will be two users trying to do something, outright locking will annoy people.
You can be a lot more clever, storing locks in a database, having the client poll in from the form to let the system know it's still connected, alert other users trying to access the page (by reading the database) and you could even add a notification system so users could click "notify me when I can submit" that stores their session key in another table with a reference to the lock...
Their client keeps polling for notifications and when the lock finishes or expires, you either let them know they can get a lock or automatically give them a lock.
Whatever you do, don't just add some code in that stops the form being processed. It'll make people monstrously unhappy.
Related
I have an inline chat application which I got from Ajax Chat, which is working brilliantly. The application allows a user to chat with users that are registered on the system. Ie:
Now I need to show if the user is online or offline.
So my question is how do I show online users using PHP?
Thank You
Basically what you need is a way to register users activity.
One way you can do this is doing it by sessions within PHP, and you log these. There are tons of ways to register then your activity in a log. If the activity is not updated for example in 5 minutes, the user is offline. Bassically you just need then a sessionId, and a timestamp (and i would recommend this also to hang to a userid). If offline, there is no userId assigned and when online you add a userId. If you have those, its pretty easy. Its a matter of updating them constantly when a new page is loaded and if they log out, you simply destroy the session, or update it so it wont be linked to the user.
It may not be the best system, but it works, and it might help you.
I don't know your specific needs. Pardon me, If I am wrong.
If Jabber support is there with Ajax Chat, why not try ejabberd kind of XMPP servers rather than re-inventing the wheels on your own. And you could have a look at Apache Vysper too, since it has support of extension modules too. If XMPP server is there, users presence handling and message transfer would become a cake walk.
What you need is a constantly update for a table in your database that save the last change in an user and save the date time... so if that date is more than 5 or 10 min, the user ir off..you can do it with ajax...
What i would do is have a script that the clients run to do an ajax call to update a entry in your database with a time stamp for last seen. Not too often or you will overload your server.
you can also put some if statements where it checks for keystrokes, mouse movement, and if the window is active if you really want to get technical and do a away status.
then in active chats just check the time stamp for active messages or when the user list is open. anything outside a acceptable range will show the user as off line. 5 minutes seems pretty long to me. poll for a check every 10 seconds maybe?
I am helping develop a web application for one of the departments in the company I work for.
I was asked to look into a way to log off every user that might be on the application at once, so that if updates to the Web App are pushed out, people aren't working with an old version of it.
My problem is that as I am not very savvy with PHP, JQuery, AJAX, etc. which is what we're using, I have not known exactly what to look for.
We have a timer script running every couple seconds in the background, so I was thinking that I could add an admin button that updated a field in the database which this script could check every so often, and if the field was set, the logoff script could be executed. But this seems like a hack to work around the issue.
The guy I'm working with suggested I look into custom SESSION handlers.
What do you guys think? Any ideas?
Any help would be appreciated. Even if it's an idea on what to start searching for.
Thanks in advance!
EDIT: I should mention that this is a one-page web app. The user is not following any links or leaving the page.
Make an entry for logged in users in your database of choice, maybe memcached if performance is a criteria.
Use a custom Session save handler which stores the sessions in database or file. When you want to destroy all sessions, you can clear the storage (be it database, or file).
Start from - http://php.net/manual/en/function.session-set-save-handler.php
What I ended up doing was the following:
I added a field into one of out database tables and checked its value every time our browser tick came through (about every minute or so). If the field is set when the tick comes through, their page is refreshed, thus logging them off the application and destroying their session (We destroy the session when someone leaves the page).
The users cannot log back in until that field has been reverted to '0'
The admin account can change that field with the click of a button. Therefore their field in the database remains as a '0'
It might be kind of a hack, but it's what I could come up with even after everyone's help. The only issue is that it takes a bit to log everyone off. Problems of pulling vs pushing I guess.
And yes, an email will be sent out some time before logging everyone off so they don't lose work.
Thank you all for your help!
This is a common problem about sharing data.
As i am building a system that allow user share their mailing list to their colleague.
I suspect there is a problem when userA open the page ,
userB open the same page and edit the data,
after that user A edit the data and submit and the changes of userB will be cancel.
As i am using PHP , is their any way to prevent this kind of error??? Thank you.|
Are there any coding example provided in php /jquery??? Thanks a lot
Make editions log, so user A will update conent ver. 123 to ver. 124 , user B will try too to update ver. 123 in his own way, but on server there is already ver. 124, so you will show message to user B, that content was recently modified by another user.
This principe is used in SVN for example.
There are a few solutions.
The simplest would be to have a "lock" field on a database which is set to true when someone is looking at a page, and refuses to let anyone else enter the page while it is locked. This isn't a great idea because it's difficult to capture when someone has left the page, so the page might remain locked forever.
You can get around that problem by using a little AJAX call that sends a message to the server to lock the page every ten seconds or so, and the page locking has a thirty-second time limit.
Perhaps the best method (although this depends on the system) is to use AJAX to dynamically reload components of the page when they are edited by another user (and to put a message next to them when they are being edited), and to warn both users if they are editing the same field at the same time.
This is my first post on these forums, however I've been using them for years in looking for solutions to my coding challenges...thank you for all for sharing your knowledge.
Ok, to the point...I need a nudge in the right direction for a theory of a solution to the below problem.
Desired Result:
Current existing structure: FLEX RIA that communicates with MySQl DB via PHP.
We basically, have a RIA that is part of a software solution we provide to our customers, we want to restrict login sessions to one/username, which we did successfully by setting a value in our MySQL DB...the point of this was to restrict the use of username(s) to one application access point and create the ability for us to charge for additional usernames, if so desired by our customer.
Problem:
Although, we successfully restricted user logins to one session, we ran into a problem when the RIA connection with the DB was inadequately terminated (eg., browser crash, OS crash, flash player error, etc). When these crashes happenned the value that was set in the DB for the user, showing them logged in, would persist and thusly lock them out of our software application. We would have to go into the database and manually reset their logged in status.
What I am looking for:
I need some suggestions or some areas to look into/research for a solution to this problem
Any help you might provide is greatly appreciated,
Thank You
Dignified Dude
When the Flex app pings your server for the first time; create a server side session. When that session expires, flip the value of the database automatically, regardless of whether or not the user has logged out. You may also want to add some form of timer to the UI to automatically log the user out.
I assume there is some way to run code in PHP when the server side session expires. Here are some approaches that came up in a Google Search:
Run query after session expire
http://forums.digitalpoint.com/showthread.php?t=1320013
PHP session timeout callback?
http://www.google.com/search?q=Run+code+when+PHP+session+expires&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:en-US:official&client=firefox-a#sclient=psy-ab&hl=en&safe=off&client=firefox-a&rls=org.mozilla:en-US%3Aofficial&source=hp&q=run+code+on+PHP+session+expire&pbx=1&oq=run+code+on+PHP+session+expire&aq=f&aqi=q-w1&aql=&gs_sm=e&gs_upl=9504l13039l1l13162l32l12l0l0l0l0l1160l5043l2-4.2.1.3.0.1l11l0&bav=on.2,or.r_gc.r_pw.r_cp.,cf.osb&fp=9fb4160009134867&biw=1200&bih=786
I have a social website in developmenti n PHP codeignitor and MySQL. I am storing user sessions in the database to handle a multi-server enviornment. Currently there is only 1 database.
1) To handle multiple databases (+ the multi server) how and where will the user session be stored? I assume database wont work in a multi-database env.
2) The session ID given to the user, is it an auto increament from the database or generated from the application logic? I assume it should be a GUID?
3) Along with the session ID I have a user_session table which logs all session related details like login_datetime, logout_Datatime, if user was on web/mobile, etc. So this table has to be written to in 2 stages: When the user logs in and again when the user logsoff. The questions is when the user logsoff what is the logic the system should follow to write the date? Like how will the system know which user_session to write the data to since this PK ID is a database driven autoincreament value and created after the main session ID is created. So at end it will need to query user_session table to find the user_Session ID and then write.
Your comment gave me some clues about the best way to solve this problem for you.
First, if the site is launching soon but not live yet, the best way to solve your problem is: don't worry about this problem yet. Just host everything on one server with one database for the time being. Your idea, no matter how brilliant, will need to solve lots of problems with its first few real users before demand picks up enough to require more hardware.
Second, your image and video servers probably don't need a user's session information. If a user requests a web page with a video, and they have enough access to view the web page, then you can probably just send along the video without further auth checking. This choice will also enable you to use a content delivery network (I personally like RackSpace Cloudfiles, with has a partnership with Akamai) for a much-improved user experience over using your own servers.
Good luck!