Building CMS architecture - centralised or not

Question

I have a dedicated server and I'm in need for building new version of my personal PHP5 CMS for my customers. Setting aside questions whether i should consider using open source, i need your opinions regarding CMS architecture.

First approach (since the server is completely in my control) is to build a centralized system that can support multiple sites from single administration panel. Basic idea is that I am able to log-in as super user, create new site (technically it creates new web root and new database, and maybe some other things), assign modules and plug-ins for specific customer or develop new ones if needed. If customer log-ins at this panel, he/she sees and can manage only their site content.

I have seen such a system (it was custom build), it's very nice to bug fixes and new features affects all customers instantly without need of patching every CMS that can also be on other hosting server...

The negative aspect I can see is scalability - what if i will need to add second server, how do I merge them to maintain single core.

The second is classical - stand-alone CMS for every customer.

What way will you go and why?

Thank you for your time.

Answer 1

If you were to have one central system for all clients, scalability could become easier. You can have one big database server and several identical web servers (probably behind a load balancer), and that way you don't have to worry about dividing the clients up into different servers. Your resources are pooled so if one client has a day with heavy traffic it can be taken up by several servers, rather than bringing one server (and all other clients' sites on it) to its knees.

You can get PHP sessions to work across multiple servers either by using 'sticky sessions' on your load-balancing configuration, or by getting PHP to store the data somewhere accessible to all servers (e.g. a database).

Keeping the web application files synchronised to one code base shouldn't be too difficult, there are tools like rsync that you could use to help you.

Answer 2

It really depends on the types of sites. That said, I would suggest that you consider using version control software to manage multiple installations. In practise, this can give you the same as with a centralised approach, but it gives you the freedom to postpone update of a single (or a number of) sites.