Portfolio

Fixing sync issues in the SWING interface of a Teledyne Optech mobile lidar

Back in 2016 when I was still working at Excelsior, I found and fixed a memory leak in the SWING interface of mobile lidars produced by Teledyne Optech, one of Excelsior’s clients. So when in summer 2017 Teledyne Optech reached out to Excelsior again with some issues in that app, the job was handed over to me on a subcontract basis.

The app was initially developed by an intern who hasn’t been able to find a sound implementation of thread synchronization. This was causing the app to be extremely unstable.

Because of the large-sized code base, I decided it would be more efficient to develop a Kotlin-powered tool based on the Java Debug Interface. The tool would detect all the spots that need to be synchronized, as well as all GUI requests coming outside the Main flow.

Tomcat 8.5 and 9 support in Excelsior JET

One of my last tasks before leaving Excelsior was to provide support for Tomcat 8 in Excelsior JET. So when in October 2017 they had to add support for Tomcat 8.5 and 9, Excelsior handed this job over to me on a contract basis. For this task, I had to reverse-engineer the web apps class loader in Tomcat and replicate its work the compiler and Excelsior JET’s runtime.

This project had me work with the code of Java Virtual Machine’s certified implementation. What’s more, I got the chance to dive deeply into all the minutiae of JVM’s and Tomcat’s class loaders.

R&D of a video capture system for custom camera, The Siberian Center of Transport Technologies

The Siberian Center of Transport Technologies is the company developing high-tech tools for the Russian Railways. Their flagship products were based on Windows, but in spring 2018, they decided to also give Linux a try. That’s why they went to me. For the pilot project, they chose to make a prototype of a video capture system for a custom camera that would receive signals from one of their existing devices.

This project turned out to be one of the most fascinating and complex ones I’ve ever worked on. First, it was the first–and so far the last–commercial experience I’ve had with C. Second, I got the chance to do some work with hardware directly. That’s a whole different experience :) Finally, I tried my hand at multithreaded and network programming with a language that has no synchronized block or garbage collector.

The system’s workflow was supposed to look like this:

Dynamically configuring proxy server for Oboz

Back in winter 2019, Siberian.Pro was developing a mobile app for Oboz. In this project, the client wanted to have a small proxy powered by Spring Boot that would act as a liaison between the mobile app and the client’s system. The proxy’s main task was to dynamically receive the configuration from Consul.

Siberian.Pro’s Java engineers were all busy working on other tasks, which is why they handed this job over to me on a subcontract basis.

Siberian.Pro was satisfied with the quality and pace of my work. So once they needed a Java developer again, they reached out to me.

Company "X", project "L": a server for a business hypothesis validation app

In winter 2021, Siberian.Pro started working on a new project for Company "X", a gambling provider. The client wanted the back-end system to be powered by the Java platform. Siberian.Pro reached out to me again.

At the time of me writing this text, Project "L" is still in the development stage. The project is to validate a business hypothesis regarding the efficiency of a new game translation mechanic. For that reason, Project "L" delegates most of its functionality to the main system.

Here are some interesting spotlights:

A system to protect & license a cryptocurrency trading algorithm

Trading Club has developed a unique Python-powered algorithm for crypto exchange trading. In winter 2019, they reached out to me to have 3 things done. I was to:

To protect the algorithm from reverse-engineering, I decided to compile the script to native code via Cython. Native code per se is a tough nut to crack in terms of reverse-engineering. Things get much harder if we’re talking native code generated from a code snippet written in a high-level dynamic language.

For licensing, I developed a license server and added a license check into the algorithm.

Finally, I developed a GUI with QT. To keep the user from bothering with installing a Python interpreter, I packed the app with pyinstaller.

For now, this is my only commercial project written with Python.

Data Transfer server

Once they were done with the app, Trading Club switched to developing a mobile app that could keep track of their bot’s work. In summer 2020, Trading Club decided they want to arrange all the disparate parts of the app into a solid whole. That’s why they reached out to me again.

The project consisted of developing a server that would provide three APIs:

Android and iOS app prototypes for validating a business hypothesis

In spring 2019, GameOn Production asked me to develop a prototype of an Android app that was to validate a business hypothesis.

The app’s idea was to store specific user data and use it to autofill similar web forms on various websites.

It was clear from the start that writing and maintaining form-filling scripts powered by WebView’s standard API would cost too much time and money. For that reason, I developed a DSL based on Kotlin Coroutines that allowed to describe the process of filling out a form in a declarative style.

While working on the scripts, I had to come up with a way to fill forms out automatically on websites powered by modern web frameworks. Naturally, I had to do extensive research into the frameworks' structure to do so.

Initially, the client wanted an Android app only. In a bunch of months of development, though, he decided he needs an iOS one as well. I knew that the scripts were the project’s most expensive part. For that reason, I decided that instead of porting these to iOS, I’d better take a risk and put both the DSL and the scripts into a multiplatform module.

I had encountered some issues while connecting the KMM module to the iOS app. Still, I’m quite sure this decision saved my client around 50% to 100% of the project’s final cost.

Reingeneering the reporting module

One of Brooma’s products is Threads, an end-to-end solution for handling customer communication via chats and messengers. In spring 2019, Brooma wanted Threads' report module reingeneered. They didn’t have enough hands in-house for that back then, which is why they reached out to me.

Originally, the module had about 20 caching-related issues that were hard to diagnose. It would consume too much memory when running, which was causing the main app to fail.

To solve the problem, I:

Setting up the data streamline and interacting with JDBC directly allowed to resolve the original module’s problems, significantly improve on its performance, and fix all the memory-related issues.

The project took much longer than expected. Nonetheless, we continued to work together on an outstaff basis and kept it going for one year and a half.

Reengineering the routing module

In summer 2020, I promptly reengineered the routing module for Brooma. The routing module is the system’s 'heart' acting as an intermediary between the clients and the operators. If it’s down, the entire system is as well.

Over the development years, the module had accumulated much technical debt, which eventually led to some serious performance issues. This has taken its toll on one of Brooma’s strategic clients who noticed a significant drop in their service quality.

In two weeks, I brought the first reengineered version of this module in full accordance with the ergonomic approach’s principles. This allowed for quite impressive 300x growth in the system’s throughput with no functional losses. Naturally, this in turn helped Brooma to retain their strategic client.