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Posted by John Kleeman
If you are choosing a platform for online assessments, what is your most important criterion? Probably that the system is reliable and trustable. An online assessment is only useful if participants, instructors and other stakeholders trust the results.
But if you are building an assessment system, how do you make sure it is reliable? How do you ensure scores are added up correctly, results don’t get lost, reports are accurate and that your system doesn’t get broken when a new browser comes out?
One of the things we’ve learned at Questionmark is that using a three-tier architecture helps hugely with QA and reliability. In much of the Questionmark software, there are three tiers, which we regard as key ingredients for trustable assessment management.

  • The Presentation tier deals with the user interface. For example, it formats assessments for display
  • The Business tier contains the business logic. For example, the scoring of an assessment
  • The Data tier records results and other data in a robust database

(Questionmark also has a Services Layer between the Presentation and Business tiers, which allows the business logic to be called from other applications and for testing purposes.)

Questionmark 3 tier architecture, presentation tier, business tier, data tier and services layer

So why does this matter? Why should you care if your assessment application has three tiers? Here are four reasons:
1. It gives a way to test the logic in the Business tier independently. So you can set up a range of automated tests with a variety of input/output at the business tier and test this thoroughly, independently of the user interface. If you don’t automate testing, then mistakes will creep in; if you automate at the UI level, you have to change the test scripts whenever browsers change.
2. You need to be able to update the Presentation tier frequently to take account of changes in browsers, new mobile devices and so on, without having to also change and risk errors in the Business tier.
3. Three tiers make an important difference to security. The Presentation tier protects the other tiers from inappropriate calls, and you can put firewalls between each tier, to protect the data and integrity of the system.
4. A tiered system is much easier to load-balance and scale. You can assign the right number of servers to each tier, and when you get a bottleneck, increase the number of servers in that tier.
So if you’re looking for a platform to run online assessments on, it’s worth asking your supplier:

  • Do you have a three-tier architecture?
  • Do you do automated service testing under the user interface layer?

If the answers to these questions are “no”, you might want to ask how they can be sure their system will stay reliable as they update it.