Bill (Vasileios) Barekas

Technical Product Manager / Senior Software Architect

  • Highly motivated and reliable professional with a strong passion for software development and technology in general, engineer at heart.
  • Enthusiast in building software products after a 25-year old experience in various roles across the Software Development Life Cycle process, in companies ranging from early-stage startups to well-established organizations.
  • Delivering, architecting, and technical leading software products that have been released worldwide, serving millions of users. Ranging from mobile applications to scalable network services for SaaS Platforms and carrier-grade network servers using state-of-the-art technologies.
  • Hiring, managing, technical leading, and mentoring multiple cross-functional software engineering teams (backend, frontend, native, QA). Agile Scrum methodology advocate.
  • Tuned analytical skills, proven in translating complex customer requests into product requirements and providing time-efficient solutions to customer issues. Efficient collaboration with multi-function teams and customers across time zones and geographies.
  • Expert in designing scalable, high-performance network services, multithreaded programming, and asynchronous/multiplexing I/O technique.
PERSONAL STATEMENT
EXPERIENCE
Director of Product Developement
wappier Ltd., Athens, Greece
  • Supervising the development of new web3-based products targeting the simplification of using NFTs on games and brands. Delivery of the development of a white label NFT Marketplace, a self-service NFT collection and drop page setup portal and a couple of customer NFT collection launches.
  • Collaborating with Product Managers on the PRD preparation, UI/UX designers for optimal flows, and Technical Leaders for the implementation details. Responsible for the product roadmap, backlog refinement process and the preparation of USTs for four development teams.
  • Gaining a deep understanding of blockchain, smart contracts, NFTs, and cryptocurrencies for EVM compatible and Solana L1 networks and emerging technologies used in the web3 ecosystem.
  • Improving wappier SaaS platform by adding Promotional Pricing product and better interaction with App Store for iOS-based programs. Leading the integration with a major customer's management console using S2S API and wappier Unity SDK.
  • Participation in pre-sales activities by providing technical knowledge and support as required, including giving demonstrations and assisting with customer integrations and RFP responses.
Sep 2021 - present
Senior Software Architect
wappier Ltd., Athens, Greece
  • Member of the founding team of wappier.
  • Leading the software development team and expand it to more than 25 software and QA engineers. Responsible for the management, mentoring, and coaching of the team and the selection of technical solutions for the development of wappier Platform.
  • Architecting and designing wappier SaaS platform supporting 3 different products: price optimization, gamification tactics and next best action, all driven by end-user data tracked via wappier SDK or S2S API. Serving millions of users, collecting and processing about 100 million events daily.
  • Spearheading Agile Scrum framework across 5 separate development teams (backend, frontend, native, QA). Applying best practices across all stages of the Software Development Life Cycle.
  • Product owner for all wappier products and projects, collaborating with Business stakeholders, Customer Success, Data scientists, and UI designers to prioritize the most impactful features and transform them into USTs for the development teams.
  • Leading the deployment of the Live services on cloud services and maintenance operations, like flawless platform migration from Azure to AWS. Introduction and setup of the DevOps tools for efficient collaboration and CI/CD. Integration and support for the internal wappier teams (Ops, Data Analytics, Data science).
  • Architect and technical lead for the development of an innovative product for building a gaming community and promoting mobile games. Involving a custom high performance backend service, custom native applications and SDK for 3rd party native applications. Integration with 3rd party applications and mobile tracking SDKs.
Jan 2015 - Sep 2021
Principal Software Engineer
Velti SA, Athens, Greece
  • Engineering manager for the Product Development & Innovation remote team, in charge of 6 software engineers working for R&D projects and products.
  • Technical leader for an HTML5/Javascript based, media authoring and publishing environment for building mobile sites, web applications and rich media ads (MRAID) for mobile ad networks.
  • Architect and designer for a native application building service, enabling users to export a mobile-friendly web application as a native application, running on various mobile platforms.
  • Technical leading research projects for web, mobile app and multichannel analytics platforms. Performance evaluation of big data processing for campaign data analysis using Graph DBs.
Apr 2012 - Jan 2015
Principal Software Engineer
Bytemobile EDC, Patras, Greece
  • Development of a core network element, providing adaptive data traffic management capabilities to mobile operator networks.
  • Designer and technical leader for the IPv6 support of this product. Integration with IPv6-enabled RADIUS, LDAP and PCRF interfaces. Integration with in-house Analytics platform.
  • Architect, designer and technical leader of a novel Content Adaptation product for mobile network operators, enabling access to complex web pages for any mobile device. Product deployed on a number of mobile operator networks worldwide.
  • Designer and technical leader of a high performance multi-threaded proxy, responsible for handling high volumes of concurrent adaptation transactions. Integration with a third-party content adaptation engine. Integration with centralized cluster management and data storage.
  • Designer and technical leader, for the implementation of in-house content adaptation engine based on Mozilla, capable to apply adaptation algorithms on the DOM tree.
  • Tight and efficient collaboration with engineers, QA, architects, product management, customer support and customers across company sites and geographies (EMEA, US, APAC).
  • Product presentation and training to the Professional Services/Presales teams of the company.
  • Debugging and troubleshooting complex customer related issues on Bytemobile products.
May 2006 - Mar 2012
Senior Software Engineer
Bytemobile EDC, Patras, Greece
  • Redesign of the Bytemobile optimization client, supporting new features and portability between Symbian OS and Windows. Technical lead for the Symbian variant of the client.
  • Implementation of performance analysis tools for Symbian OS. Including prototype packet sniffer for the Symbian OS, installable as a device driver in the device network stack.
  • Design and implementation of an experimental device driver for Symbian OS, for the transparent forwarding of TCP packets between the device browser and the optimization client.
  • Performance tuning of the Bytemobile optimization client for Symbian 9.x. Instrumentation and profiling using custom tools and techniques.
Jan 2004 - Apr 2006
Senior Software Engineer
Daedalus Networks Ltd, Patras, Greece (Acquired by Bytemobile Inc., in Jan 2004)
  • Member of the founding team of Daedalus Networks Ltd.
  • Architect and technical leader for the implementation of a scalable traffic/event reporting system, gathering and on-the-fly correlating data from an IP gateway in a mobile operator network.
  • Architect and lead developer of a prototype Performance Enhancement Proxy (PEP) for Mobile, ISP and Corporate Data Networks.
  • Design and implementation of a high performance logging library, suitable for use with multithreaded applications.
2001 - Dec 2003
Software Engineer / Researcher
High Performance Information Systems Lab, CEID, University of Patras
  • Design and implementation of a resource scheduler for SMP platforms, at the kernel level, as a loadable kernel module.
  • Design and implementation of a user-level threads library for Windows 2000.
  • Implementation and evaluation of scheduling policies of a user level resource manager.
1997 - 2002
EDUCATION
Master in Computer Science
Computer Engineering and Informatics Dept., University of Patras
Thesis: Implementation of a user-level threads library for SMPs.
Sep 1998 - May 2001
Diploma in Computer Engineering and Informatics
Computer Engineering and Informatics Dept., University of Patras
Dissertation: Implementation and evaluation of scheduling policies on SMPs.
Sep 1993 - Jul 1998
SKILLS
  • Linux, Android, iOS, Mac OS, MS Windows – Oldies: Solaris, Symbian OS, FreeBSD, IRIX, QNX
Operating Systems
  • Expert: C, C++, Rust;
    Good: Javascript / Node.js, Python, Golang, Bash;
    Basic: Java, PHP, C#, Perl, Objective-C, Kotlin, Swift, HTML, CSS;
    In fact, I can understand/edit almost any piece of code in any modern language.
Programming
Languages
  • MongoDB, Postgres, Redis, SQLite, Cassandra/ScyllaDB, MySQL, memcache, Neo4j, Clickhouse, LMDB
Databases
  • POSIX, UNIX, ISO C, IPC, WinSock, Win32, OpenMP, MPI, SunRPC, Protobuf, MRAID, GTK, DOM, NPAPI
APIs
  • HTTP/S, REST, gRPC, GraphQL, SOAP, POP, IMAP, FTP, SNMP, WSGI, DNS, ICMP, IP, TCP, UDP
Network Protocols
  • AWS: EC2, ECS, EBS, ELB, S3, MSK, VPC, Cloudfront, RDS, ElasticCache, ECR, EKS, Cloudwatch,
    Azure: VMs, Storage, ApplicationGateway, DocumentDB, EventHubs, StreamAnalytics
    GCP: Compute Engine, Cloud Run, Cloud Storage, GKE, BigQuery,
Cloud Platforms
  • SDLC: JIRA, Aha, Gitlab, Github, Git, Testrail, Webdriver, Appium, Browserstack, JetBrains IDEs ...
    DevOps: Docker, Kubernetes, Gitlab CI, Ansible, Sentry, Prometheus, Grafana, ELK, Nexus ...
    Documentation: Confluence, Docusaurus, OpenAPI, Gitbook, Swagger, UML, Draw.io
    Data: Spark, Parquet, Airflow, Kafka, Tableau, Vector, RabbitMQ, Hadoop
    Other: SonarQube, Valgrind, JMeter, nginx, Tsung, gdb, dbx, tcpdump, Wireshark, VMWare ESXi
Tools
  • Agile, Scrum, Kanban, Waterfall
Methodologies
  • First-Time Managers, 3-parts on-site training, Ken Blanchard, Spring 2022
    Certified Scrum Product Owner, Scrum Alliance, June 2019
    Getting More out of Agile and Lean, Greece Summit 2016 Workshop, Sept 2016
    Architecting with Amazon Web Services, GK4502, Global Knowlwdge, June 2015
    Management Academy, Linkage Management Seminar, Autumn 2014
Certifications
& Trainings
  • Power-efficient computing with SBCs (Raspberry Pi) and microcontrollers (ESP32/8266, Arduino)
    Electronics and Robotics
    Nspector.AI - An AI-driven user identification toolkit.
Free-time
Projects
  • Greek (native), English (fluent), French (basic)
Communication
PUBLICATIONS
  • A Multiprogramming Aware OpenMP Implementation. V. K. Barekas, P. E. Hadjidoukas, E. D. Polychronopoulos, T. S. Papatheodorou. Scientific Programming, Volume 11(2), pp. 133-141, 2003.
  • An OpenMP Implementation for Multiprogrammed SMPs. V. K. Barekas, P. E. Hadjidoukas, E. D. Polychronopoulos, T. S. Papatheodorou. In Proceedings of the 3rd European Workshop on OpenMP (EWOMP2001), Barcelona, Spain, September 2001.
  • A Portable Kernel-Mode Resource Manager on Windows 2000 Platforms. P. E. Hadjidoukas, V. K. Barekas, E. D. Polychronopoulos, T. S. Papatheodorou. In Proceedings of the 12th IASTED International Conference on Parallel and Distributed Computing and Systems (PDCS 2000), Las Vegas, Nevada, USA, November 2000.
  • Nanothreads vs. Fibers for the Support of Fine Grain Parallelism on Windows NT/2000 Platforms. V. K. Barekas, P. E. Hadjidoukas, E. D. Polychronopoulos, T. S. Papatheodorou. In Proceedings of the 3rd International Symposium on High Performance Computing (ISHPC 2000), LNCS No. 1940, pages 146-159, Tokyo, Japan, October 2000.
RESEARCH PROJECTS
  • USEMP: User Empowerment for Enhanced Online Presence Management, Programme: FP7-ICT-2013.1.7, Project reference: 611596
  • OpenI: Open-Source, Web-Based, Framework for Integrating Applications with Social Media Services and Personal Cloudlets, Programme: FP7-ICT-2011.1.2, Project reference: 317883
  • DIG: Digital Interactive Graffiti, Programme: FP7-SME-2011, Project reference: 286927.
  • POP: Performance Portability of OpenMP, Long Term Research IST Project No. IST-2001-33071.
  • High Performance Computations for Scientific and Multimedia Applications, Greek General Secretariat of Research and Technology Project 99ΕΔ-566.
  • NANOS: Effective Integration of Fine-Grain Parallelism Exploitation and Multiprogramming, ESPRIT EC-DGIII Basic Research Project 6634.
OTHER ACTIVITIES
  • Long-distance running, photography, cycling, reading and being environmentally friendly