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Asked: 2026-05-11T04:07:38+00:00

We’re building a Silverlight application which will be offered as SaaS. The end product

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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. 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?

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  1. Depends on the type of application and scale of data. Each one has downfalls.

    1a) Separate databases + single instance of WCF/client. Keeping everything in sync will be a challenge. How do you upgrade X number of DB servers at the same time, what if one fails and is now out of sync and not compatible with the client/WCF layer?

    1b) ‘Silos’, separate DB/WCF/Client for each customer. You don’t have the sync issue but you do have the overhead of managing many different instances of each layer. Also you will have to look at SQL licensing, I can’t remember if separate instances of SQL are licensed separately ($$$). Even if you can install as many instances as you want, the overhead of multiple instances will not be trivial after a certain point.

    3) Basically same issues as 1a/b except for licensing.

    2) Best upgrade/management scenario. You are right that maintaining data isolation is a huge concern (1a technically shares this issue at a higher level). The other issue is if your application is data intensive you have to worry about data scalability. For example if every customer is expected to have tens/hundreds millions rows of data. Then you will start to run into issues and query performance for individual customers due to total customer base volumes. Clients are more forgiving for slowdowns caused by their own data volume. Being told its slow because the other 99 clients data is large is generally a no-go.

    Unless you know for a fact you will be dealing with huge data volumes from the start I would probably go with #2 for now, and begin looking at clustering or moving to 1a/b setup if needed in the future.

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