Explanation of Tenant Load Balancer in SaaS maturity model level 4

Question

I've already done some research about SaaS maturity level based on Gianpaolo SaaS maturity model.

Right now I got confused about SaaS maturity level 4. It said, it has a "Tenant load balancer" that dynamically calls a new application instance to serve load balancing for a SaaS application.

I want to know what this "Tenant load balancer" really means. How do we implement this "Tenant load balancer" in the real world or in an application server?

Can anyone give me some good explanation and an example, like an implementation in Java EE technology?

Answer 1

One way to implement Tenant Load Balancer:

1. Create multiple instances of the application - say A,B,C. Each with its own database.
2. Create one meta-database - this database has info on accounts, logins, etc.
3. Login interface is single. ie everyone logs on to same web interface.
4. When a user signsup, allocate him to one of the app instances (A,B or C).
5. When user logs in, authenticate against the meta-database and then redirect to specific instance.

So for example:

1. Login site is setup at www.example.com
2. App instances are available at a.example.com, b.example.com, c.example.com
3. To signup, user goes to www.example.com
4. To login, user goes to www.example.com
5. After successful login, user is directed to a.example.com or whatever his instance is.

This is how Salesforce.com does it. They have different instances for different regions and allocate clients these.