
Sergio Penén
Verified Expert in Engineering
Software Developer
Edinburgh, United Kingdom
Toptal member since July 14, 2022
Sergio considers himself a creative, curious, focused, and self-managed professional. He is always looking for the best way to resolve technical problems or develop new features. Sergio is comfortable working as part of a team and alone. Although most of his work experience is in the payment industry, he is always keen to learn new things and is open to opportunities in other sectors as well.
Portfolio
Experience
- C++ - 20 years
- Linux - 20 years
- Databases - 20 years
- Java - 12 years
- JPA 2 - 12 years
- Amazon Web Services (AWS) - 10 years
- REST - 6 years
- Spring Boot - 3 years
Availability
Preferred Environment
Linux, Spring Boot, Microservices Architecture, Java 11, Redis, ISO 8583, C++14, MySQL, EMV, MasterCard IPM
The most amazing...
...project I've developed is a payment switch cluster system called PayOne, which consists of a real-time message broker developed in C++, Redis, Java, and JPA.
Work Experience
Back-end Developer | CTO
Telmos Consulting Ltd
- Started working in this company in 2019, and my main task was to build the back end, which I did within one year. The back end was fully scalable, PCI DSS compliant, and decentralized.
- Integrated our system with five acquirer networks using ISO 8583 protocol for four and APACS protocol for the fifth one while working as a back-end software developer. Settlement files were either base-2 or similar to Mastercard IPM.
- Became a CTO and acquired the ADVT Visa Level 2 and security certification for POS on commercial off-the-shelf (COTS) devices, including PIN on glass.
Back-end Developer and Payment Systems Specialist | CTO
Quadrisoft
- Designed and developed a cluster-based credit and debit card transaction processing system with a secure message broker and HA using C++, Java, and JPA for business logic. It is mission-critical, fault-tolerant, flexible, and fully customizable.
- Performed installations of the PayOne system for several clients, some of which are banks with stringent security rules and service level agreements.
- Designed and developed a cluster management tool specifically for the PayOne system, capable of managing individual processes and cluster nodes.
Payment System Specialist
Fidelity National Information Services
- Implemented Mastercard Maestro in collaboration with other team members. It was a downsizing project, and our system successfully became Brazil's main credit and debit card transaction processing system, reaching high transaction numbers.
- Implemented the clearing system for Mastercard credit transactions for Brazil in IPM format files in collaboration with the team. This meant that we completed a process that had been in production for many years.
- Participated in the initial design and development of the Visa online transaction processing implementation.
Software Developer
Siemens
- Developed the Windows application for the ATCS tool designed to automate testing using a proprietary language. The tool communicated with testing devices using a proprietary protocol RS-232.
- Maintained proprietary tools to support the development environment.
- Developed proprietary tools to convert WAV files into a proprietary format for the switch exchange system.
Experience
Acquirer Payment System Simulator (Dissertation project)
Maxa payments backend
PayOne System
Education
Master of Science Degree in Computer Science and International Business
University of Cumbria - Online
Engineer's Degree Coursework in Systems Engineering
National University of La Matanza - Buenos Aires, Argentina
High School Diploma in Electronics technician
Instituto San José (A-355) - Buenos Aires, Argentina
Skills
Libraries/APIs
Standard Template Library (STL), JPA 2, JDBC
Tools
Amazon Virtual Private Cloud (VPC), Git, Apache Tomcat, Amazon ElastiCache, Apache Maven, AutoTools, CMake, AWS Key Management Service (KMS), AWS SDK, AWS CodeCommit, AWS CloudFormation, AWS CLI
Languages
Java 8, Bash, Java, XML, C++98, KSH, CSH, C++, Java 11, C++14, Assembly Language, C++11, Stored Procedure
Paradigms
Object-oriented Programming (OOP), Software Testing, Automated Testing, Scrum, Kanban, REST, Windows App Development, Microservices Architecture
Platforms
Linux, Amazon EC2, Windows, AWS Elastic Beanstalk, Oracle Database, Software Design Patterns, AIX, Amazon Web Services (AWS), Firebase, IBM WebSphere
Storage
Databases, PostgreSQL, JSON, SQL Stored Procedures, Redis, Sybase, MySQL, MongoDB, SQL Server 2017, Amazon S3 (AWS S3), Spring Data JPA, Google Cloud
Frameworks
JUnit, Spring Boot, Qt 5, JPA
Other
ISO 8583, MasterCard IPM, Operating Systems, Software Development, Amazon RDS, DUKPT, Multithreading, IPC, Pinblock Translation, 3DES, Transport Layer Security (TLS), Fintech, Firmware, Hardware Security Modules (HSMs), RFID, Base II, AWS SSH Keys, EMV, Internet of Things (IoT), CI/CD Pipelines, Digital Marketing, Microcontrollers, Digital Circuit Design, Android POS, Android Development, RS232, PCI DSS, MySQL DBA, HSM
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