How to develop a web application that is load-balance friendly

Starting to develop to actual code to my webs开发者_开发百科ite and wanted to know how do i develop or design the website that is load balance friendly. I read a post on stackoverflow regarding scalability and the selected answer stated: "Make sure you consider load balancing when developing your application". How do I go about this?

Your decision will come down to environment. If this is a product for sale, you will not have any control over the load balancing implementation. This means that "sticky sessions," where a user is bound to the same server for the duration of a session, cannot be guaranteed. Sticky sessions allow just about any application to be load-balanced, but they are not as efficient.

If you cannot guarantee an implementation with sticky sessions, avoid the usage of Session state altogether, or look into a shared-session solution.

1) do not use static fields to store data, statistics, ...

2) use session with care - you can still use in-process with sticky ssessions but I do not like it.

3) Do not rely on the IP of the server

Well, one answer is to reduce reliance upon session variables. It's possible to share session variables between servers via session server, but that means all your servers have a single point of failure on the session server then, plus reducing performance.

Basically, just try to make each page as stand-alone and stateless as possible, and you'll be good.

This might be obvious to most of you, but actually was an issue in our environment when we started to use a load balancer / several web servers: Do not rely on the IP addresses of your web server.

We had a production environment that used a switch and a set of internal IP addresses, including the one of the web server (our products usually run in a closed off environment, not the open Internet). If you have several web servers that becomes a problem.

Make sure you have a development/QA environment where you can test your software in a load balanced environment and see the issues in your code as you develop it rather than waiting until the deployment day.

One thing to take into account is the usage of Session data to maintain state.

As your application subsequent requests can be handled by other servers in the balance line you can not use InProc mode and StateServer mode.