Designing databases and applications for hosted / cloud solutions

Question

Are there any resources available that can guide someone on how to 'think' about the various components of a hosted / cloud solution before going ahead and starting to make a hosted application? If that made no sense, what I mean to ask is are there any guidance books/websites on what things need to be considered when making a cloud application?

I am attempting to make a hosted CRM-style software application that will serve many hundreds of customers. The application is powered by a SQL server database with many tables and a ColdFusion, HTML5, CSS, Javascript front-end. If I was installing this application and its components at each client site, then each installation is unique to that customer. But somehow I have to replicate this uniqueness in the cloud which is baffling me.

Only two things have come to mind so far:

1. The need for a unique database per customer in SQL server
2. The need to change DB connection strings per customer in the web application

My thought process has come to a block when I am trying to envisage how to design the application to serve so many different customers. Even though the application that all customers use will is the same (same DB tables, same front-end), the data that they store and retrieve will be specific to them. So I was thinking that surely each customer needs a separate database creating for them? Is it feasible to create a replica database for each customer? If I need to update some tables or add a new table, how would I do this for hundreds of different databases?

From the front-end I guess each unique customer log-in would change DB connection strings so that they can only access their database. Other than this I can't think of anything else that needs to change per customer basis.

When a new customer wants to sign up, it needs to be clear to me what I need to create for them to have access to the application. I guess this is ultimately what I need to think of but I'm stuck.

If anyone can suggest some things to think of or if there is a book or website on this kind of thing that someone could point me to I'd really be very thankful.

EDIT: I was looking at an article about Salesforce.com and it says

"In order to ensure privacy of data for each user and give an effect of each having their own database, the data from different users are securely isolated from one another."

Anyone know how this is achieved or how it may be done?

Answer 1

Found some great information here. It is called multi-tenant database design and seems to be a common topic. Once I get the database designed then the application can sit nicely on top.

https://dba.stackexchange.com/questions/1043/what-problems-will-i-get-creating-a-database-per-customer