Behind the scenes on the Clarity servers

by | 19 March 2019

Step back 10 years and interacting with a program like Tense Buster on a mobile phone would have seemed very much like magic. Now we take it completely for granted — like the electricity in our houses, or the workings of our kidneys. For those who are interested, I’d like to step back and look at the four processes that enable the delivery of digital learning to work so smoothly.

Step 1: Download the program

A student picks up their phone and types in the Clarity URL. The browser checks it out, and sends a message to the server requesting the Tense Buster images, text (with style), and the code that makes the exercises work. But which server? This message checks out the best one in its geographical location to supply all this data. This flexibility means that you get the fastest possible response whether you are in Brazil or Bhutan.

Step 2: Sign in

Next, our student types in their email and password. The phone sends this to the Clarity gateway — this is a single webpage, again on the nearest server, that sends requests to the correct place. In this case, we go to a server that will check the database to see if this sign-in combination exists. For GDPR reasons, this request can only go to servers in Europe, which has the highest levels of data protection in the world. It goes to an Amazon Europe server, but we don’t know which one as they form a ‘cluster’ which scales itself up and down based on demand. If all is well, we move on into the program.

Step 3: Working on the program

This is really a repeat of Step 2, except the servers do not have to be in Europe. The gateway page sends the messages and requests to the exercise database for the activities and to the score database to save the results.

Step 4: Licensing

The system also runs a set of connections that control licencing and activity. This will figure out if a student in a library has actually stopped using Tense Buster and put their phone in their pocket. If so, it frees the licence for another user. For this we use a protocol developed by telecoms companies to keep phone conversations running no matter what happens in the exchanges. It runs on yet another specialised, secure server.

All of these elements run in a Virtual Private Cloud (VPC), which puts a ring fence around the whole Clarity setup, logically isolating it from other networks in the Cloud. This week we upgraded the final elements of our systems to run under the VPC. This gives us a more up-to-date database engine, providing users of Clarity programs with enhanced security through its faster, encryption-enabled storage.

This is just one more step in Clarity’s ongoing quest to continually improve reliability, speed and safety.

Adrian Raper, Technical Director, ClarityEnglish

Adrian Raper, Technical Director, ClarityEnglish