That seems to be the way that Websphere does it too.
Another question: can a load balancer like 3 DNS from F5 load balance encrypted
traffic? What if the request/response conversation between client and
server-servlet goes over SSL? Would certificates pose further trouble?
dave.
Randy Belknap wrote:
> My understanding is that both WebLogic and Dynamo (and probably others)
> can do the following: Each webserver has an app server plugin that
> directs requests from the webserver to the appserver (If you are using
> Netscape Enterprise Server, then the plugin is a NSAPI module). The
> plugin is intelligent enough to direct a sessions requests to the
> correct app server so that you don't need to 'stick' the user to one
> particular webserver. In otherwords, if you have three webservers and
> two app servers - a particular session will get tied to a particular app
> server, but can use any of the three webservers; the stickiness is at
> the app server level. They do this by encoding which app server to use
> in the session id. Obviously if the app server goes down, they have
> mechanisms for passing control to another app server.
>
> Shashank Phadke wrote:
> >
> > Hi all --
> >
> > To add to Dave' questions, I would also be very much interested in the way
> > people have tackled this problem.
> >
> > I havent played around with how webserver load balancing works (I am not
> > sure about the word they use for that - routing ??) But I would like to know
> > if anyone has tried that ? What are my options - software/hardware ??
> >
> > If the requests can be spread across multiple webservers, to maintain state,
> > requests from a user need to be routed to the same webserver the next time.
> > Can this be achieved by webservers themselves ? Its like some session info
> > maintained in the webserver. If yes, then one can continue with one
> > webserver <--> one servlet engine combination.
> >
> > If not, how do I associate a user to the particular instance of servlet
> > engine ? Is there any inbuilt support for this in any of the servlet engines
> > ?
> >
> > Writing my own session management servlet and routing servlet would be the
> > last thing I would like to do ...
> >
> > Thanks for any inputs ...
> >
> > Shashank
> >
> > >From: David Mossakowski <[EMAIL PROTECTED]>
> > >More specifically now,
> > >
> > >I have noted two possible set ups:
> > >
> > >1. Simpler round-robin algorithm to choose web server at the DNS level
> > >and then have the web server load balance (with session awareness) to
> > >servlet engines as it seems to be the case with Apache.
> > >
> > >2. Have DNS itself be session aware (3-DNS from F5) and load balance to
> > >HTTP server which would have only one instance of servlet engine.
> > >
> > >I guess it comes down to: should one web server have many instances of
> > >servlet engine on it? It seems that it is a good idea since it will
> > >take much less for the HTTP server to relay request to servlet engines
> > >and then send back a ready-made reply. It would seem a waste to have
> > >just one servlet engine instance on one HTTP server. Is this assumption
> > >correct?
> > >
> > >It seems that the Apache way is better. In the second approach if DNS
> > >is session aware then it would send request to a given web server and
> > >the web server would again have to check the session ID to direct the
> > >request to correct instance of the servlet engine?
> > >
> > >Am I making sense here? Are there other setups? Can someone who has
> > >done this share their knowledge?
> > >
> > >dave.
> > >
> > >--
> > >David Mossakowski _||_ e-mail: [EMAIL PROTECTED]
> > >Instinet Corporation __||||_|_||__||_ tel: 212.310.7275
> > >Programmer __||||__||_|||__|||||_|__ fax: 212.583.7780
> > >
> > >_||__|__"I don't sit idly by, I'm planning a big surprise"
> > >
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David Mossakowski [EMAIL PROTECTED]
Programmer 212.310.7275
Instinet Corporation
"I don't sit idly by, I'm planning a big surprise"
___________________________________________________________________________
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