David MacCallum

Experience

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  Retail IT

  Jul 2004 - Jul 2007

  Software Developer

  Retail IT is a Retail Software and Professional Services company. Clients include United Colours of Benetton, Diesel, Dr Martins Shoes and Jimmy Choo.I was privileged to start my career here. I joined as a Delphi Software Developer working on point of sale (POS) software. I learned about the retail domain and experienced all parts of a small software company including working on the help desk, on site support, store rollouts and business development.eCommerce Link:The eCommerce Link project integrated our POS system with the online shop website of a customer (Sweaty Betty :-). This was a great education in eCommerce. I got to experience eCommerce operations from order through fulfilment and returns. My role on the project was to integrate the POS system, the source of truth for stock levels and prices, with the online shop website.Skills: Delphi, ASP Show less

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  Accenture

  Jul 2007 - Jul 2012

  Technical Architecture

  My five years at Accenture were a great learning experience. I worked at two media companies and one telco. I spent two years at Accenture UK and then moved to Accenture SA.ITV Enterprise Architecture:ITV Plc is the UK's largest private broadcaster. As part of the Enterprise Architecture team I worked closely with highly skilled Data, Security, Process and Integration Architects. A great learning experience. I joined the team as an integration developer building common components for logging and error handling (Oracle SOA Suite). I was promoted into an integration governance role which included:- Responsible for SOA services management.- Responsible for SOA middleware platform operations and offshore operations team.- Responsible for ensuring integration standards and guidelines are adhered to.Finally I was promoted to Solution Architect where I implemented a large (£330k) SOA project integrating a 3rd party application with ITVs core systems.Skills: Service Oriented Architecture, Solution Architecture, IT Operations, IT Governance, BPMN, BPEL Show less

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  E-Insight

  Jul 2012 - now

  Software Development and Systems Integration

  e-Insight is a company I created to provide tailored software development and systems integration services.TV License Payment Website:The SABC TV Licence PayNow website processes about R3M of payments per month. The requirements for the website was to make it as easy as possible for people to make this grudge payment. The user experience (UX) we created allows a customer to make a payment in just five clicks on their mobile. I was responsible for design, integration and development. The website was built using Java Servlets, JSP, responsive web design and is integrated with a AS-400 mainframe.Full Stack Development: I did several full stack development projects including an auction app, a crime reporting app and a tablet based system for managing field service technicians. See the Projects section of my LinkedIn profile for details.Skills: Grails, Android, iOS, Java Servlets, JSP, C#, AWS, MS SQL Server Show less

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  PrivySeal Limited

  Sept 2017 - Jul 2019

  Chief Technology Officer

  PrivySeal is a rapidly growing digital certification platform allowing professionals to showcase their qualifications and expertise in real-time. For more information go to www.privyseal.com.Architecture Review:PrivySeal's technical architecture served the company well for five years but became a bottleneck as the company started to scale up. My role was to analyse the As-Is architecture and define a scalable To-Be application architecture. Through intensive engagement with stakeholders we decided to replace the existing monolithic PHP system with a NodeJS microservice architecture.Technical Leadership:PrivySeal asked me to step into the CTO role to drive through the transformation project. This included:- Full stack software development.- Setting up the new infrastructure (Docker on AWS) and a CI/CD pipeline to enable us to move fast.- Intensive change management including creating many how-to videos for the legacy team. Giving them a pathway to up skill.- Recruiting new team members.- Participating in the fund raising due diligence processes.- Taking responsibility for security and data privacy. Implementing applicable General Data Protection Regulation (GDPR) requirements.- Making sure we maintain 99.99% uptime amidst all of this change. The new architecture was very effective. Through standardising the integration process the time to integrate a new data source was reduced from months to weeks or days.This was a very stressful period of my life. Some of the most important skills I learned are soft skills. I grew in empathy and in my ability to manage stress.Skills: NodeJS, React, Docker, Elasticsearch, Kibana, Ansible, MongoDB, RabbitMQ, AWS, Jenkins, CI/CD, Microservice Architecture Design, Event-Driven Architecture Design Show less

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  Centbee

  Jul 2019 - Mar 2020

  Senior Software Engineer

  Centbee is a high energy startup focused on making Bitcoin real by enabling people to use their Bitcoin to buy everyday things. During my time at Centbee I developed a basic understand of how Bitcoin and the Blockchain works. I also gained experience in the financial domain, specifically payments.I was responsible for the development of ScanPay, a standards based payment system enabling merchants to accept Bitcoin at point of sale (similar to Zapper or SnapScan). ScanPay enables merchants to take payment in Bitcoin and get paid out in fiat currency. The platform consists of a NodeJS backend, an Angular portal for merchants and an Ionic mobile app for the point of sale. Play store link: https://play.google.com/store/apps/details?id=com.centbee.scanpayRoles and Responsibilities:* I had end to end responsibility for the ScanPay project. * Led a small dev team. * Driving the functional design through regular steering workshops with the business. Skills: Angular, NodeJS, AWS Lambda, Ionic Show less

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  Takealot.com

  Oct 2020 - Oct 2022

  Takealot.com is South Africa's largest online retailer. Takealot have used a microservices architecture, CI/CD and devops to enable them to grow their engineering team and deliver new code into production at a blistering pace. Their engineers are amongst the smartest I have ever worked with.I was the manager of the Logistics Engineering Operations Team. This included a first line support team of three and a second line root cause fix team of five. In this role I learned a lot about managing people including mentoring, performance management and recruitment. I set up a Jira Service Desk instance and helped to refine our service desk processes. I also ran a SRUM based second line root cause fix team. This included sprint planning, retrospectives, grooming etc.Skills: Management, Agile, SCRUM Show less A big part of my job is migrating functionality out of the legacy monolithic application into microservices without any interruption to the business. A difficult task given the high volume of transactions.At Takealot I have learned how to work in a large development team. I have experienced Agile practices like daily standups, backlog grooming, sprint planning and retrospectives. I have experienced the devops practice of making developers responsible for 24/7 operational support. With developers taking turns on call. I participated in the architecture forum and specifically championed consistent service documentation. My microservice architecture skills have deepened and matured at Takealot. Experiencing a microservice architecture at scale has highlighted what works and what does not. A key lesson learned is observability using metrics, which can be easily turned into graphs and alerts. Another key lesson learned is the importance of having good coding standards and guidelines up front.Skills: Agile, Kubernetes, team work, Grafana, PostgreSQL, microservices, legacy software migration Show less

  • Engineering Manager

    Nov 2021 - Oct 2022

  • Senior Software Engineer Logistics

    Oct 2020 - Nov 2021