Multi-tenancy with SQL/WCF/Silverlight
We're building a Silverlight application which will be offered as SaaS. The end product is a Silverlight client that connects to a WCF service. As the number of clients is potentially large, updating needs to be easy, preferably so that all instances can be updated in one go.

Not having implemented multi tenancy before, I'm looking for opinions on how to achieve

 - Easy upgrades
 - Data security
 - Scalability

Three different models to consider are listed on [msdn][1]

 1. Separate databases. This is not easy to maintain as all schema changes will have to be applied to each customer's database individually. Are there other drawbacks? A pro is data separation and security. This also allows for slight modifications per customer (which might be more hassle than it's worth!)
 2. Shared Database, Separate Schemas. A TenantID column is added to each table. Ensuring that each customer gets the correct data is potentially dangerous. Easy to maintain and scales well (?).
 3. Shared Database, Separate Schemas. Similar to the first model, but each customer has its own set of tables in the database. Hard to restore backups for a single customer. Maintainability otherwise similar to model 1 (?).

Any recommendations on articles on the subject? Has anybody explored something similar with a Silverlight SaaS app? What do I need to consider on the client side?

  [1]: http://msdn.microsoft.com/en-us/library/aa479086.aspx
Multi-tenancy with SQL/WCF/Silverlight
===

We're building a Silverlight application which will be offered as SaaS. The end product is a Silverlight client that connects to a WCF service. As the number of clients is potentially large, updating needs to be easy, preferably so that all instances can be updated in one go.

Not having implemented multi tenancy before, I'm looking for opinions on how to achieve

 - Easy upgrades
 - Data security
 - Scalability

Three different models to consider are listed on [msdn][1]

 1. Separate databases. This is not easy to maintain as all schema changes will have to be applied to each customer's database individually. Are there other drawbacks? A pro is data separation and security. This also allows for slight modifications per customer (which might be more hassle than it's worth!)
 2. Shared Database, Separate Schemas. A TenantID column is added to each table. Ensuring that each customer gets the correct data is potentially dangerous. Easy to maintain and scales well (?).
 3. Shared Database, Separate Schemas. Similar to the first model, but each customer has its own set of tables in the database. Hard to restore backups for a single customer. Maintainability otherwise similar to model 1 (?).

Any recommendations on articles on the subject? Has anybody explored something similar with a Silverlight SaaS app? What do I need to consider on the client side?

  [1]: http://msdn.microsoft.com/en-us/library/aa479086.aspx