Comments on: Client-side Load Balancing Web 2.0 Apps is Voodoo

By: leforge

leforge — Mon, 15 Oct 2007 13:18:44 +0000

Lucas Chan: Good point about it being an issue for both methods. I’ve gotten so use to the server-side method having tools to handle all that for you that I forgot, it indeed, DOES need handling. I do a little PHP, but most of my work is done in .Net and there’s a simple setting that you have to flip and a database that you have to create that takes care it. All-in-all it takes just a few minutes to do. Hmmm.. if client-side loadbalancing catches on it, seems that it would be a good idea for M$ and the php people to come up with a simple (flip-a-switch) solution to this. Thanks for the response. I’ll have to crack open my PHP books and take a look. :).

By: Lucas Chan

Lucas Chan — Mon, 15 Oct 2007 00:03:48 +0000

leforge: You are right, this can be tricky. When storing form data in a user session variable you will run into problems if you’re using file-based sessions. The way to combat this is to make your PHP session handler store data in a database or on some sort of shared file system (same goes for file uploads). For what it’s worth this is an issue for both methods of load balancing.

By: leforge

leforge — Fri, 12 Oct 2007 14:36:04 +0000

Hmmm… how would passing form data from page to page work with this? It seems like the article says that at anytime, the client-side scripting can push a browser from one server to another. Wouldn’t the servers need to keep track of various form values/properties and send that info to the other servers?

Seems like it not only complicates the client-side work, but also the server-side as well. I don’t know… am I having a brain-fart on this or am I right?

By: saumendra

saumendra — Fri, 12 Oct 2007 05:10:07 +0000

Lucas , is right in point out the client side Load balancing demerits. This ius simply true that forcing your client to wait multiple times on multiple servers is annoying one and the well established server side counterpart, i.e Server side Load balancing is the one which makes the path clear

By: mrsmiley

mrsmiley — Sun, 07 Oct 2007 23:20:28 +0000

@Federico That may be true that they add an extra layer of complexity, but there comes a point when software design alone will not solve your stability problems. If you have a “very high” volume site, or require real time redundancy in your application/site, then load balancing is pretty much essential.

By: plumsauce

plumsauce — Sun, 07 Oct 2007 06:21:23 +0000

Hardware load balancers are cheap and effective.

This sounds very much to me like a solution looking for a problem.

By: Ren

Ren — Sat, 06 Oct 2007 11:39:06 +0000

Heh, this reminds me of the SuperProxyScript thats been about since 1996.

That used client side hashing of urls, to determine which proxy server to make a request to.

By: Federico

Federico — Fri, 05 Oct 2007 20:58:25 +0000

Load balancers add an extra layer of complexity to the system, so my advice is to spend some time planning and designing the architecture of the system. Consider using the database when working with sessions and web services, and another server as your main file repository.

By: brothercake

brothercake — Fri, 05 Oct 2007 07:30:59 +0000

There are things that client-side is good for, and things that server-side is good for. Load balancing most definitely falls into the latter category.

I think it’s counter productive to think in terms of doing things on the client simply because you don’t have easy access to the resources for doing it on the server; if that’s the case, then the problem is missing resources. The client should not be used to make up for lack of server capability, the server capability should be upgraded.

By: mrsmiley

mrsmiley — Fri, 05 Oct 2007 06:55:09 +0000

I absolutely agree with you on the hardware side of things. Just saying that I can see how client side load balancing could be an option for some people. Strange how the two main arguments put forward by the author aren’t really that big a deal. Cost can be an issue, but as you mentioned, there are cheap ways to do it say through a two machine HA-Linux cluster, and the other was related to concurrent requests. If your load balancer cant cope with the level of requests, then there is a good chance a single app server is going to fall in a big heap too. No amount of client balancing will fix that.