On 7/10/07 11:07 PM, "Andre Garzia" <[EMAIL PROTECTED]> wrote:
Hi Andre, > usually when building Revolution web aps, people use apache cgi interface, > so for each web request, apache will launch an instance of the revolution > engine. If you have two concurrent requests, you will have two instances > running. Each with their own V4REV external loaded. What happens if they > both try to access the same Valentina database. > > SQLite have built in methods for locking the file if they are opened by more > than one application at the same time, so all transactions are atomic. You > still have the problem of one instance overwritting the changes of the other > instances, but you can guarantee that both accessess will happen and will go > thru without file corruption. > > What I am to say is that using SQLite you can build a minimal web > application if you're clever enough to build a locking mechanism to prevent > overwritting other users changes. My SQLite will guarantee the transactions > or in other words, the multiple client access to the file. > > Now, since I really like Valentina, can we do something similar with V4REV, > can more than one application access the same database file without using > Valentina Server? Short answer: YES. Long Answer: * History: MAC OS 9 - did have exclusive open for files Windows also did have it and DO have it. OS X like linux - do not have it. * Unix world and APPLE on its site recommend "fight" with this using LOCK FILE. For example, When app opens a Valentina db, you check if exists in the same disk location dbname.lock file. If not exists - you make it and open db. So other user will see file and will wait until it go away. Yes more headache for developers thanks to *nix way. How hard make it for you in REV? 5-6 lines of code? * Should I explain how much better to use VSERVER instead of such way? :-) I sure you understand that loading of V4REV or SqlLite plugin in each Apache copy means init/kill each time cache. Working with Valentina Server cache not dies. Also time on open/close of db file. ... -- Best regards, Ruslan Zasukhin VP Engineering and New Technology Paradigma Software, Inc Valentina - Joining Worlds of Information http://www.paradigmasoft.com [I feel the need: the need for speed] _______________________________________________ use-revolution mailing list use-revolution@lists.runrev.com Please visit this url to subscribe, unsubscribe and manage your subscription preferences: http://lists.runrev.com/mailman/listinfo/use-revolution