Lukas, Hi Thanks for your comments. The "File download" example which I mentioned, was just an example. The big picture would be somehow storing the current state between the user and the web server (independent of the actual web application) so that it is restored (maintained) when one of the web servers goes down. Consider current authenticated user sessions, content posting, etc. When one of the active back-end web servers goes down, the logical connection between the user and the web application is lost; the main question is how is it possible to restore this logical connection when the other back-end web server is used as a replacement by the load balancer? How is it possible to synchronize user sessions, file downloads, active logins, etc. between two master/backup web servers so that the client never feels the switchover? Thanks again for your consideration.
Warm Regards, Ali Majdzadeh Kohbanani *Ali Majdzadeh Kohbanani* *Managing Director* *Abshar Data Processing* *Tel:+982144160700 * * Tel/Fax: +982144160701 * *Cell:+989123614728* *majdza...@abshar.biz * *http://www.abshar.biz* 2013/7/16 Lukas Tribus <luky...@hotmail.com> > Hi Ali, > > > ________________________________ > > Date: Sat, 13 Jul 2013 23:23:08 +0430 > > Subject: Question about a feature that is present in Barracuda Load > Balancer > > From: ali.majdza...@gmail.com > > To: haproxy@formilux.org > > > > Hello List, > > The Barracuda load balancer has feature which enables it to recover a > > broken web connection. Let me explain the scenario; suppose that there > > exist two web servers behind the Barracuda load balancer and the user > > is downloading a file from one of the back-end web servers. Now, > > suppose that the active web server goes down, the Barracuda load > > balancer is capable of continuing the download from where it was broken > > using the other web server. Is it possible to achieve such a behavior > > using HAProxy? Are there exist any open source alternatives which can > > provide the same capability? If not, is anybody aware of any roadmaps > > to achieve the same functionality using open source tools? Considering > > an open source load balancer like HAProxy, what are the required steps > > to follow in order to add such a functionality? > > Thanks in advance. > > With HAProxy the HTTP connection will abort, the client will reconnect > and if the client is smart, he will continue to download where the > connection > was interrupted with byte-ranges. > > If you mean the client shouldn't actually be involved in this switchover > from one backend server to another within a HTTP transaction, then thats > another thing. I'm not sure how this is supposed to work (I can imagine > this > on big static files only) and it sounds like it violates the RFC. > > It will probably cause more problems then it solves. > > Anyway, if you would like to request this commercially, I guess contacting > Exceliance is a good idea: > http://www.exceliance.fr/en/contact > > > > Regards, > > Lukas
