Adrian van den Houten
Software Engineer III at Takealot
CV
Skill Set
Technology Experience
- Experience in developing Angular applications using RxJS, NGXS/NGRX, and Ionic.
- Experience in developing production ready React and NextJs applications with Tailwind CSS.
- Experienced in building Native and Hybrid (Capacitor) mobile applications for Android and iOS platforms.
- Experience in building enterprise backend microservices and monoliths using Python, Node.js and Java following the 12-factor principles.
- Experience with architecture design such as Domain Driven Design, Event Sourcing, Microservices, Orchestration and Choreography workflows.
- Experience with DevOps processes and cloud infrastructure.
- Experience working with GCP, Firebase, GKE, CloudSQL, BigQuery, Google Workspace, etc.
- Experience provisioning AWS resources such as EC2, ECS, ELB, S3, RDS, VPC, CloudFront, and Route 53, etc using Terraform for application deployments.
- Experience with Varnish, OpenResty, Nginx, Docker, Kubernetes, Apache Kafka and RabbitMQ.
- Experience with Git, GitHub, GitLab and BitBucket source code control management platforms.
- Skilled in building robust multi-environment CI/CD pipelines using GitHub Actions, automating deployments for Angular and Node.js applications.
- Experience with Jenkins, Bitbucket, and GitLab, employing Docker-based build and deployment pipelines.
- Experience with database management systems such as PostgreSQL, MySQL, MongoDB, and Key-value stores such as Redis and Memcache.
- Experience in creating technical specifications including design artifacts using UML, ERDs, Process Flows, and Mermaid diagrams, etc.
- Experience in participating and leading Event Storming workshops.
- Disciplined practitioner of Test-Driven Design, utilising testing frameworks such as Jest, Mocha and Cypress (for NodeJs); PyTest and Tox (for Python); JUnit and Cucumber BDD (for Java).
Industry Experience
- Supply Chain through ecommerce. Exposure to software systems that orchestrate warehouse operations such as Picking, Packing and Shipping parcels for delivery.
- Financial technology. Exposure through involvement in the development of software platforms for esteemed institutions like Standard Bank.
- Blockchain technology. I had to up-skill extremely quickly to be able to solve my previous company's needs, and therefore became the technical lead in this technology.
- Drone Aviation and legal compliance. Experience in designing and building a software platform related to this.
Distributed Systems Experience
During my time at Takealot and Zailab I've gained skills and experience related to the following:
- Design, deployment and debugging of applications running on Kubernetes.
- Extensive hands-on experience with Microservices architecture and implementing various Orchestration and Choreography workflows.
- Experience using event streaming platforms like Kafka and message queue technologies like RabbitMQ.
- Experience with and practical application of event-based architectures, including Event Sourcing and Event Replaying (Axon framework, BigQuery, etc).
- Experience working with MongoDB and other NoSQL databases.
- Experience with 3rd-party integrations and designing for resiliency and outages.
- Implementing Observability for applications through graphs (Grafana), logging (Kibana & Elasticsearch) and tracing (Jaeger).
- Implementing service SLAs for expected throughput (p95, p99, failures) with alerting (OpsGenie).
Consulting Project Experience
During my time at Byte Orbit, I gained valuable experience and contributed to various Django and Angular projects within a consulting capacity. I worked on the following projects:
- FlyteZone: AutonoSky drone GIS application. Implemented features such as real-time tracking of airborne drones, complex Google Maps integrations, and built a majority of the platform's secure asset management.
- Standard Bank Corporate & Investment Banking: Helped design and implement the Messaging Centre feature (a simplified version of Gmail) on the backend and frontend implementation using Angular.
- Edge Banking: Standard Bank Business Banking for entrepreneurs and accountants. Helped design and implement the major features of the platform, including document asset management, until the EOL of the project.
- Byte Orbit Website: Successfully revamped the company website using Wagtail CMS.
- HouseRules: Byte Orbit Internal HR management system. Implemented many admin/staff features, including reporting tools such as a monthly leave report.
- Feenix: Collaborated on the development of the Standard Bank Student education crowdfunding platform.
- Dine4Six: Contributed to the Byte Orbit social dining platform. A social website to reserve dining experiences with others at restaurants.
Craftsmanship & Standards
- Proficient in Object-Oriented Design principles, encompassing roles, responsibilities, and collaborations, as well as adhering to OOP, SOLID, and Component Principles to ensure robust and maintainable codebases.
- Strong understanding and practical experience in implementing Design Patterns.
- Extensive experience using Test-Driven Development, producing clean self-documented code, including writing thousands of tests.
- Adequate skill set with Algorithms and Data structures.
- Demonstrated ability to research, design and implement robust and scalable solutions to problems.
Interpersonal Skills
- Strong communication skills, adept at effectively collaborating within teams of any size, ranging from small to large.
- Excel in working in an Agile environment and running Scrum ceremonies to drive collaborative and iterative development.
- Strong time management skills and prioritisation of work.
- Demonstrates a strong work ethic and takes pride in delivering features to clients, going above and beyond to ensure that work is completed to the team's definition of "DONE".
- Committed to continuous learning and actively invests significant effort in improving both my strengths and weaknesses.
- Passionate about mentoring junior developers.
- Great at teaching and upskilling myself as well as fostering the growth and development of team members, even if it requires working overtime to meet deadlines.
- Excited to share new technologies and better practices with my team.
- Consistently driven to enhance team throughput and velocity.
- Value respect, open communication and constructive feedback, promoting a positive and collaborative work environment.
Work Experience
Takealot
Software Engineer 3
Aug 2023 - Present (1 year, 9 months)
Takealot is South Africa's largest ecommerce website and provides world-class supply chain and logistics infrastructure and systems.
I am currently in the Supply Chain Outbound (SCO) team that maintains systems to enable the shipment of 100k parcels every day across their combined distribution centres.
Contributions since joining:
- Developed and deployed new microservices to facilitate new product enhancements and new architectural standards set by the Group Fulfilment division.
- Designed technical specification artifacts for new product enhancements within the domain, including collaborating with other division teams to support system integrations.
- Implemented full observability (metrics, logs and traces) within new and legacy services using StatsD, Jaeger, Grafana and design new alert SLAs for service metrics.
- Enhanced the feature functionality of the division's internal portal (build with React) for operational efficiency.
- Made significant contributions in the design and development of a native Android application and a supporting BFF (backend for frontend) to support merchant return operations within the warehouse.
- Lead discussions and presentations to the Group Fulfilment division on the new standards for Supply Chain.
- Shared techniques and tips for developer productivity within our team's weekly knowledge share.
- Improved test coverage from 0% to 90% on various legacy microservices.
- Debug applications locally and used tools such as Okteto to debug remotely on the staging Kubernetes cluster.
- Lead Scrum ceremonies such as daily standup and retrospectives where required.
Key Responsibilities
- Write clean and beautiful code using either functional or an object-orientated design approach, abiding by the SOLID principles (different teams maintain different paradigms within the division).
- Work within a collaborative team and support team member velocity through code review, QA and support.
- Participate in monthly rotations in the division's support (hot desk) team to address critical production issues and investigations. This also includes maintaining existing and new playbooks for repeated hot desk issues.
- Be on rotation for the on-call roaster to answer alerts (through OpsGenie) and diagnose production incidents such as network latency degradation (p95, p99), workflow failures and Kubernetes pod health (memory failures, HPA scaling, etc).
Takeaways from Takealot
Takealot is an exceptionally large platform consisting of multiple divisions each with multiple development teams such as, DevOps, RET Engineers, Database Engineers and an army of talented QA engineers to provide consistent high quality product increments to its customers.
To support the increasing scaling demand, Takealot has multiple production Kubernetes clusters and stacks written in both Python and Java. I have learned an exceptional amount and greatly improved my technical and interpersonal skills not only by working within my team but also across the division to deliver projects.
Seeing how Takealot has implemented microservices at mass scale (especially during "season" - Black Friday, Cyber Monday, Christmas, etc) has enhanced my understanding of distributed systems and Kubernetes even further. I now have a better answer when it comes to choosing between sync vs async communication (different pros/cons). I have increased my depth of knowledge around Kubernetes, Prometheus, Kafka, MySQL, Terraform and many of the technologies used by Takealot.
Technology stack:
- Backend: Large-scale microservices (1000s) architecture built with Python 3, Pyramid, gRPC, Memcached, MySQL, and Apache Kafka spanning across multiple Kubernetes clusters.
- Architecture style: Microservices, BFF, API Gateway, Event-driven, and various others.
- Frontend: Various projects using React.
- Cloud Infrastructure: GCP using managed MySQL (CloudSQL), Kubernetes (GKE), Varnish, OpenResty, Helm, Terraform & Chef, etc.
- Observability: Opsgenie, Jaeger, Prometheus, Grafana, Kibana & Elasticsearch.
- CI/CD: Jenkins, GitLab, SonarQube & Docker.
- Issue Tracker, Wiki & Repository: Jira, Confluence, Notion and GitHub.
- Tooling: PyCharm, WebStorm, MacBook Pro 16-inch M1 Pro.
Momint
Senior Software Developer
Jan 2023 - Aug 2023 (8 months)
Momint is the NFT marketplace for alternative investments where users can invest in fractionalised assets such as solar energy, art, and whiskey.
A few months after joining, I become the "go to" person for Blockchain network integrations. I saw this gap in the company as a previous senior with blockchain experience had left. I read "Mastering Blockchain 3rd edition" within a matter of weeks to achieve this.
Past contributions:
- Designed, developed and deployed smart contracts on the Polygon network to enable monthly revenue payouts to the platform users using USDC. Also wrote unit tests for new smart contracts to ensure the expected behaviour was kept.
- Wrote a robust and reusable blockchain module that handles essential functionalities such as native token top-ups, gas estimation (EIP-1559), payouts, and ERC20 transfers. This module supports Ethereum, Polygon and Gnosis networks.
- Implemented multiple frontend (Angular) and backend feature flows using Clean Architecture.
- Integrated Bitrefill onto the platform to allow users to purchase vouchers for stores such as Checkers, Woolworths, Engen, and Takealot.
- Integrated with multiple fiat and cryptocurrency payment gateways, including Circle Payments, Flutterwave and Meld.io.
- Developed internal admin tools such as a CSV data exporter and data tables to enable better operational efficiency.
- Wrote and executed MongoDB database migration scripts for new feature development.
- Refactored and rewrote legacy code to improve code quality, maintainability and performance.
- Consistently delivered numerous user-facing features on the frontend (Angular) to enhance the overall product experience.
- Actively contributed to leading the team in Agile planning and estimation ceremonies, providing valuable insights and guidance.
Technology stack:
- Blockchain: Gnosis, Polygon, Smart Contacts (ECR721, ERC1155, etc), Solidity, Ethers.js & Hardhat.
- Backend: Node.js, Express.js, TypeScript, RabbitMQ & MongoDB.
- Frontend: Angular 10+, NgRx, Ionic, TypeScript, SCSS.
- Cloud Infrastructure: Azure, Docker & MongoDB Atlas (Clustered Mongo).
- Observability: Sentry.
- CI/CD: Azure Pipelines.
- Issue Tracker & Repository: Azure Boards, Notion & Github.
- Tooling: WebStorm, MacBook Pro 16-inch M1 Pro.
Byte Orbit
Intermediate Software Developer
Mar 2022 - Dec 2022 (10 months)
Software Developer
Jul 2019 - Mar 2022 (2 yrs 9 mos)
Byte Orbit is a trusted partner specialising in Fintech software solutions, renowned for delivering exceptional design and implementation. Throughout my time at Byte Orbit, I had the opportunity to contribute to a variety of projects, gaining valuable experience and honing my skills in the following areas:
Projects and Experience:
Please refer to the "Consulting Project Experience" section above.
Technology Stack:
- Backend: Django, Django Rest Framework (DRF), Python, Huey, Celery, Redis, and PostgreSQL.
- Frontend: Angular 10+, NGXS (state management), TypeScript, and SCSS.
- Cloud Infrastructure: AWS services such as EC2, Elastic Beanstalk, S3, RDS, VPC, CloudFront, Route 53, as well as Nginx, Redis, PostgreSQL, Docker, and Kubernetes.
- Observability: Sentry.
- CI/CD: GitLab Pipelines, BitBucket Pipelines, and Jenkins for continuous integration and deployment.
- Issue Tracker & Repository: Jira, BitBucket, and GitLab for efficient project management and version control.
- Tooling: PyCharm, WebStorm, MacBook Pro 14-inch M1 Pro.
Zailab
Software Developer
Oct 2017 - Jun 2019 (1 year, 9 months)
Zailab is a globally recognised Cloud-Based Contact Centre solution catering to Sales, Cx, and Marketing Teams.
The application is built upon two distinct technology stacks: the RTC stack, responsible for handling VoIP-based phone calls, and the Application stack, encompassing various customer-oriented features, workflows, and 3rd party integrations. The application adopts a CQRS Event-Driven Microservices architecture, to enable Event Sourcing and Event replay. Built with the Spring Boot, the Axon framework, Kafka, MongoDB, and an Aurelia front-end.
I was actively involved in the foundational architectural design and development of CRM integrations with Salesforce and Zendesk. These integrations enabled real-time and bulk import contact syncing between Zailab's customer contacts and the other 3rd party CRM platforms.
Here are some highlights of my contributions:
- Liaised with CRM integration partners (Cloud Elements) during the development of CRM integrations.
- Developed a proof of concept and handled the initial development efforts for CRM integrations with Salesforce and Zendesk.
- Created a microservice dedicated to managing integrations between each CRM provider, including OAuth authentication for contact syncing and call logging.
- Designed and implemented an AWS S3 Kafka Connector proof of concept, enabling bulk contact imports from CSV files.
- Enhanced the existing capabilities of their custom Kafka message filter service to enable better routing of Kafka messages based on Spring SPeL expressions.
- Designed and implemented a scalable messaging pipeline to support bulk contact syncing from 3rd party integrations.
- Worked in an Agile environment. Used both Kanban and Scrum respectively on different projects.
Technology stack:
- Backend: Java 8, Spring Cloud microservices comprised of two Kubernetes Clusters (Asterisk, Axon, Apache Kafka, MongoDB, Redis, MySQL, PostgreSQL).
- Frontend: Aurelia and TypeScript.
- CI/CD: Jenkins.
- Cloud Infrastructure: AWS (EC2, S3, VPC, CloudFront, Route53) self-managed Kubernetes clusters.
- Observability: Sentry and DataDog.
- Tooling: IntelliJ IDEA, Linux Mint