Hack Day 2017: Onwards Defrosted Tuna

Hack Day 2017, ‘Let’s Get Physical’, required that every entry contain a hardware component. To meet this requirement, the ‘Onwards Defrosted Tuna’ team decided to leverage the Caplin Platform to enable a web application to initiate and terminate calls on a user’s smartphone.



Any good hack day entry has the following qualities: it has to be achievable within 24 hours and it has to have the potential to deliver real business value.

We drew our inspiration from a previous Caplin trial project that explored integrating the Caplin Platform with trading turrets to enable traders to initiate and receive calls in Caplin web applications:

Why was this trial project an interesting idea?

  • Phone numbers could be stored in the Caplin Platform; sales traders would not need to keep all their clients’ phone numbers.
  • The Caplin Platform could record statistics, such as call duration, and persist them for later auditing.
  • Notification, client profiles, and rates could be presented automatically when a client called.

The idea never took off, but the trial project became the inspiration for our Hack Day entry. Could we implement a modern version of the project using smartphones instead of turrets?

Hack Day

We managed to create a minimal viable solution in under 24 hours. We wrote a mobile app that initiated and terminated calls on a trader’s smartphone in response to messages sent by a web application over the Caplin Platform.

No turret was required, and all we used was the standard Android SDK and Caplin Platform libraries.

Our solution consisted of the following:

  • Mobile app:
    • Initiate and terminate calls
    • Relay information to and from the Caplin Platform
  • Front-end:
    • A grid to display available clients
    • Phone calls initiated by selecting a client from the grid.
    • Display status and caller details on the grid
  • Back-end:
    • An adapter to receive and execute instructions from the front-end

The main technical hurdles we faced were as follows:

  • Requesting the mobile app’s access to phone features and setting the correct security settings
  • Rather than running a monitoring background process, the mobile app needed to be kept alive in the foreground. This was not ideal, and given more time we could have solved this.

Final Word


Onwards Defrosted Tuna achieved first place and lifted the coveted Hack Day Cup!

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