In an ever-changing world, it is easy to think that “things just happen”.
Change, even of seismic proportions, is constant but not random. Most of the time it takes a certain sequence of events.
This blog post discusses 2 frameworks for understanding the mechanics behind change.¹

In this post I will

  • cover modern payment “rails”,
  • blockchain-based systems, and
  • close the “trilogy” with some parting thoughts on the future and how the unfolding Covid-19 pandemic will accelerate the evolution of the payment systems.

In the previous 2 instalments (part 1, part 2) of this series, I talked about the history behind payment systems and described how domestic and international payments work.



Mobile money (or M-Pesa as is widely known from its initial Kenyan incarnation) is the answer to the question

How do you provide digital financial services to third world populations, where the only technological device available…

Take a look around you.
Try to count how many items are not imported. Chances are you have not managed to count many.

With international trade so prevalent, money crossing borders is crucial to keep our world connected. But how does water turn into oil?¹

In the previous instalment of this series, I talked about the history behind payment systems and described how domestic payments work. In this post I will cover

International payments — Nostro/vostro

The oldest form of cross-border payment mechanism is via correspondent banking (a.k.a. nostro/vostro accounts).

You are on holiday in another country. You want to buy a coffee.
You get your card out, swipe or type your pin and presto! Coffee paid for your enjoyment.

Congratulations! You just participated in the modern marvel of international payments.
The simple action described above requires levels upon levels of financial structures and instruments.

This series of 3 posts will attempt to give a high level intro on the history, the “what”, the “how” and, when possible, the “why” of modern payment systems.

Can I has payment?

Some definitions

Other than the neighbourhood bakery and garage, pretty much every modern-day organisation worth its salt is a technology company. As software is eating the world at an increasing pace, focus is on delivery and pushing features out the door.
That is the only way to stay ahead of the competition. Deliver X% more than your rivals each day/year and through the compounding interest effect of features and efficiency you will win.

One aspect which is almost always an after-thought is that of documenting the systems and their interactions.

Here are some ideas of mine on the subject, after a few…

A fast-growing company has all kinds of good problems.
One of them (admittedly the smallest) is the frequent question of new-joiners: “where does everyone sit in this new office?”.

Luckily, regular hackathons give the opportunity to address all the issues (big or small) stacking up.

This post will show a slightly expanded version of a desk reservation prototype we worked on during that day, using some simple image processing and a Kotlin Spring back-end.

Problem statement

A couple of years ago I had the great privilege of partaking in the excellent Enterprise Engineer Program in RBS. This was jointly organized by Digital Engineering Services and Catalyst.

The amount of knowledge, lessons and skills I took out of it is a future post by itself.

What I would like to share with you is my end-of-course TED-style presentation.

The subject

The subject of my presentation is something I had to learn (and still learning) the hard way: wealth and money.
Is there something I could distill as knowledge? Something which could be useful and actionable?

The recorded presentation is…

I have been using Slack quite a lot this last year for my day-to-day work.
Late adopter as I am, I have been using it both in a geographically distributed startup as well as a tightly-knit mature company.

In both cases, it is a force multiplier.

The benefits it brings are pretty well documented and I will not go over them here.

What I will cover is how to easily utilize Slack’s API for historical data processing.

The use case

PostgreSQL is an extremely performant database.
We are using it heavily and to great effect in my current place of work. However the internal design choices of Postgres mean that you may be faced with performance degradation if not careful.

From an application developer’s point-of-view there is an easily accessible treasure trove of optimisation hints: the pg_stat_user_indexes view.

Some background info

What is your phone really doing?
More specifically, what are the apps installed on your phone really doing?
Do they just sit there? Do they constantly send data to their servers?

Do you even know what is sending data where and how often?

I had to answer this question recently for a little pet project.

I had no intention of rooting my phone, nor did I have unlimited time to tinker with its internals (I still need it during the day).

So? How do I do it?

Enter Wireshark.


Stelios Gerogiannakis

Life-long learner, happy father, trying to do some software engineering on the side.

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