Robert Špendl

OVERVIEW
A scalable IoT integration project capable of handling over one million users with 100,000 requests per second. As the back-end developer and network administrator, I developed custom Nginx modules and optimized networking performance and security.

DELIVERABLES
• Back-end development in Go of account management, two-factor authentication using an SMS service, settings, and any other account-related functionality.
• Architecture, documentation, and Go code for coherent database and memory cache functioning on multiple shards, each serving a subset of accounts.
• Architecture, documentation, and C code for a custom Nginx module that routes requests to multiple back-end instances. Parallel instances, shared memory, decoding JWT tokens, and upstream server diagnostics were all implemented in this module.
• Complex Go performance benchmarking of the Nginx-Go-PostgreSQL mix environment.
• Set up a bare-metal Kubernetes environment on Linux CentOS to run the back end and administration of Docker Swarm during development up to the production phase.
• Architecture of PostgreSQL database consistency verification and a Docker/Bash script to manage upgrade and downgrade processes during development, staging, and production.

OVERVIEW
Custom devices for wastewater treatment and air emission control with custom reactors and scrubbers, including the development of custom electronics, software for the main PLCs, back-end data analysis, and remote management and reporting.

DELIVERABLES
• Design of process flow and equipment (AutoCAD).
• Architecture and design of custom electronic components (microcontrollers and sensors) and set up of processes for serial production and testing (KiCad).
• Firmware for controllers and sensors in C for AVR and ARM processors.
• Python and Rust software for high-level process control and remote access to the facilities.
• Set up a highly available, multi-node Docker swarm cluster.
• Apache Kafka and Rust back end with PostgreSQL for remote data storage.
• Go and Rust back end for centralized management of devices.
• Vue.js front end, providing remote access for wastewater treatment plant operators, with graphic presentation of processes and interactive data visualization.
• Rust and PostgreSQL data-mining tools to perform statistical analysis on millions of records to identify component failures, wear risk, and optimize operating parameters.

OVERVIEW
A software gateway and prototype of hardware to enable communication of charge points that only support local Modbus protocol over RS-485 with a remote server over the internet. This, in turn, enables communication of the client’s electric vehicle charging station with the provider’s server using the Open Charge Point Protocol (OCPP). The final product that will act as a standalone plug-in module is under development.

DELIVERABLES
- Rust software that communicates with charge points and retrieves operations data, charging currents, and user identification on one side, and communicates with the OCPP server on the other side, providing the possibility for real-time control of the charging stations.
- Design of a low-cost, small footprint, and industrial-grade programmable logic controller that can run the gateway software at remote locations.

OVERVIEW
A standardized energy meter that can use a LoRa wireless communication network to enable remote energy consumption metering without using mobile readers.

DELIVERABLES
- Design of the electric circuit for the energy meter device with ultra-low energy consumption (two years of operation from a single battery) and highly accurate and low-noise temperature reading.
- C software to enable LoRaWAN data transfer from the meter and remotely initiated firmware upgrades.

A platform to provide modern analytical, marketing, and payment processing tools to classic offline stores was under development. As CTO, I was responsible for the overall technology and control of the outsourced parts of the codebase.

OVERVIEW
Municipalities partly finance their infrastructure by collecting fees from investors based on the costs of existing and planned infrastructure in the municipality. To calculate the fee, each land lot has to be analyzed for existing and available infrastructure and the costs of construction for any missing infrastructure, such as waterworks or sewage pipelines. As the fees have to be uniform in the whole municipality, it's necessary to analyze tens of thousands of lots where construction is allowed.

DELIVERABLES
- Development of a comprehensive set of PostGIS and Python scripts to enable data import, validation, and spatial data cleanup; perform complex queries; and generate maps.
- Writing of a Vue.js and OpenLayers front end and a Rust back-end MVT tile server, allowing users to view the data and generate reports.

A specialized short task on Tezos smart contract client performance improvements, written in Rust. The work includes low-level improvements of details on memory management and alternative parsing libraries, the performance testing tools I've developed proved these refactoring provided significant speed improvements of the code.