Publication
Building Business Rules Engines with Drools - Power to the SMEople
https://www.toptal.com/developers/java/rules-engines-power-to-the-smeople
Jeff is available for hire
Hire JeffJeff Marin
Verified Expert in Engineering
Software Architect and Developer
Lake Mary, FL, United States
Toptal member since August 21, 2014
Bio
With 30+ years working as an engineer, project manager, and director, Jeff is able to combine exceptional communication skills with superior technical abilities. While working in the high-tech, financial, entertainment, manufacturing, and medical industries, he has built a large store of knowledge.
Portfolio
MatchBay
React, Node.js, TypeScript, ChatGPT, Build.AI, Claude.AI, Tailwind CSS...
Intrepid Networks
React, TypeScript, Grails, Groovy, Full-stack, HTML5, Material UI, Front-end...
Medtronic
TypeScript, React, Full-stack, HTML5, Front-end, REST APIs, Architecture...
Experience
- HTML - 19 years
- JavaScript - 13 years
- Front-end - 6 years
- React - 5 years
- Next.js - 4 years
- GraphQL - 3 years
Work Experience
Senior Full-stack Developer
2025 - PRESENT
MatchBay
- Developed ways to automate the current hiring experience by utilizing AI.
- Built a UI in React and TypeScript with help from Build.AI and Claude.AI.
- Started work on training LLMs to interview potential candidates and employers.
Technologies: React, Node.js, TypeScript, ChatGPT, Build.AI, Claude.AI, Tailwind CSS, API Integration, Web Applications, OpenAI API
Senior Full-stack Developer
2024 - 2024
Intrepid Networks
- Worked on Intrepid Response, software for first responders.
- Implemented front-end features in React, TypeScript, and Material UI.
- Worked with back-end technologies, including Grails, Groovy, Postgres, and Spring Boot.
Technologies: React, TypeScript, Grails, Groovy, Full-stack, HTML5, Material UI, Front-end, SQL, REST APIs, Architecture, Full-stack Development, Web Development, CSS, HTML, Back-end, Back-end Development, Figma, APIs, Databases, Software Architecture, Git, API Integration, SDKs, Web Applications, Data Modeling, REST, RESTFul APIs
Senior Full-stack Developer
2022 - 2023
Medtronic
- Worked with a front end written in React/TypeScript and a microservices back end where REST services and REST workers were written in TypeScript and PostgreSQL.
- Built Teneo MDM, a mobile device management platform currently supporting iOS and Android devices.
- Created this app so users can control all aspects of company devices, including applications and their managed configurations, stolen mode, lost mode, passwords, and view device history and locations.
Technologies: TypeScript, React, Full-stack, HTML5, Front-end, REST APIs, Architecture, Full-stack Development, Web Development, CSS, HTML, Back-end, Back-end Development, Healthcare, APIs, Minimum Viable Product (MVP), Databases, Software Architecture, Git, API Integration, SDKs, Web Applications, SQL, Data Modeling, RESTFul APIs
Chief Architect
2015 - 2023
BioReference Laboratories
- Worked with a genetic counselor to implement family history-based rules within the Drools rules engine using Java. Rules include health insurance coverage.
- Created a JSON web service to accept family tree information and output rules that, when triggered, recommended genetic tests and health insurance coverage.
- Created a front-end application to allow genetic counselors to create, test, and modify rules. The application includes a pedigree chart using GoJS and a rules editor using Ace.
Technologies: Jersey, Apache Tomcat, MySQL, Ace Editor, GoJS, Ext JS, Jakarta EE (Java EE or J2EE), JBoss Drools, Front-end, Architecture, Web Development, HTML, Back-end, Back-end Development, Healthcare, APIs, Minimum Viable Product (MVP), Databases, Software Architecture, Git, SDKs, Web Applications, SQL, Data Modeling, REST, RESTFul APIs
CTO | Full-stack Developer
2022 - 2022
Always Near TeleHealth
- Worked with web applications and a Raspberry Pi C# controller built with Angular, Ionic, Google Cloud Functions, Firebase, Google Cloud IoT, Rasberry Pi, C#/.Net, and MQTT protocol.
- Performed this using IoT sensors monitoring for safety conditions, especially falls. Additionally, daily activities are recorded for preventive health solutions.
- Worked on this solution that allows senior citizens to live in place.
Technologies: C#, Google Cloud Platform (GCP), Firebase, Angular, Full-stack, Front-end, Architecture, Full-stack Development, Web Development, HTML, Back-end, Back-end Development, Healthcare, APIs, Event-driven Architecture, Minimum Viable Product (MVP), Databases, Software Architecture, Git, Web Applications, SQL, RESTFul APIs
CTO | Full-stack Developer
2021 - 2021
Dynaboost
- Set technical direction and full stack developer on a website that uses Artificial Intelligence to generate human-like text.
- Worked with technologies such as React, TypeScript, OpenAI, and MySQL.
- Allowed the saving of searches and allowed re-rendering of lists.
Technologies: TypeScript, React, OpenAI, MySQL, Full-stack, OpenAI GPT-4 API, Front-end, REST APIs, Architecture, Full-stack Development, Web Development, Express.js, CSS, HTML, Back-end, Back-end Development, APIs, Generative Artificial Intelligence (GenAI), Large Language Models (LLMs), Databases, Artificial Intelligence (AI), Git, SQL, REST
Tech Lead | Full-stack Developer
2021 - 2021
Securus
- Created architectural solutions, mentored junior developers, interviewed potential BAs and developers, and implemented full-stack solutions.
- Worked with AWS, Dojo, TypeScript, TypeORM, and MariaDB technologies.
- Collaborated with these projects that were included in the Jail Management System and Reconnect, a platform to transition incarcerated individuals back into society.
Technologies: TypeScript, Node.js, Dojo, Front-end, REST APIs, Full-stack Development, Web Development, CSS, Back-end, Back-end Development, Databases, Git, SQL, REST
Senior Node.js Developer
2020 - 2021
Driven By Safety
- Debugged existing Python scripts running in Google App Engine and wrote new Python scripts to automate data handling.
- Debugged and extended existing Node.js/Angular applications using JavaScript.
- Worked with AWS, Digital Ocean, SashiDo, and MongoDB.
Technologies: MongoDB, Amazon Web Services (AWS), Angular, JavaScript, Python 2, Python, Web Development, Back-end, Back-end Development, Lambda Functions, Heroku, Event-driven Architecture
Full-stack React Developer
2020 - 2020
RV For Fun
- Performed front-end development including Next.js, TypeScript, custom React components, CSS, GraphQL calls, and Ant Design components.
- Performed back-end development, including Nest.js, TypeScript, TypeORM, DB design, GraphQL components, and authorization.
- Created Nest.js entities, models, resolvers, and services.
Technologies: React, GraphQL, PostgreSQL, Antd, Next.js, NestJS, TypeScript, Web Development, Back-end, Back-end Development, Headless CMS, Prisma, Prismic
Architect
2020 - 2020
NetQuest
- Created Java/Spring Boot middleware with a REST interface.
- Contributed to the development of React front-end code.
- Serialized and deserialized code using Apache AVRO.
- Communicated with the back end using Unix Sockets.
Technologies: React, Java, Spring Boot, Back-end Development
Back-end Developer
2019 - 2019
Virtual Real Estate
- Supplied back-end API methods for front-end developers using Node.js.
- Worked with MySQL and MLS data.
- Worked with AWS S3 for image handling.
- Researched data vendors and selected best fit.
- Created AWS RDS for the project.
Technologies: Data, RETS, Amazon S3 (AWS S3), Amazon EC2, MySQL, Node.js, Back-end Development
Chief Architect for Platform Engineering
2018 - 2018
ByteCubed
- Created direction and documentation for a serverless architecture that complied with 12-factor app mandates, microservices included.
- Implemented and deployed Spring ConfigServer and other Spring Cloud Technologies.
- Modified existing and created new pipelines in Concourse CI.
- Used Docker and Docker Compose to create ELK stack for data analysts.
Technologies: Java, Spring Boot, Concourse CI, Docker Compose, Docker, Microservices, CI/CD Pipelines
Chief Architect
2016 - 2017
LiveSchool
- Using Node.js, designed and implemented Insights, a warehousing engine to provide teachers, admins, and parents advanced analytics.
- Created microservices for front-end developers.
- Created extremely complex ad-hoc MySQL queries to control ordering and record selection.
- Created and ingested AWS SQS messages.
Technologies: Amazon Web Services (AWS), Analytics, Microservices, Data Warehousing, Data Warehouse Design, ECMAScript (ES6), MySQL, Node.js
Chief Architect
2015 - 2015
ToutApp
- Created dozens of web crawlers utilizing Node.js and AWS Lambda. Implemented the web crawlers to parse APIs and raw HTML results.
- Created a Chrome extension to query LinkedIn via Google (XRay Search) and create candidates for potential inclusion within the end-user ToutApp sales campaign.
- Worked with a 500 node proxy server pool to parallel process LinkedIn XRay results.
- Created a front-end application in Node.js and Express.js to monitor web crawler status.
- Utilized the Node.js CRON library to schedule daily and weekly web crawlers.
- Stored the results of the scraped information in MongoDB.
Technologies: MongoDB, AWS Lambda, Node.js, Web Scraping, Serverless Framework
Senior Architect
2014 - 2015
veEDIS Clinical Systems (via Toptal)
- Converted home-grown rules-based architecture to Drools standards.
- Converted rules (over 500) to the Drools Rules Language.
- Added state-of-the-art subject matter expert rules editing tools.
- Created custom accumulators for medical scoring rules and added the ability to perform longitudinal medical rules.
- Added mapping to SNOMED, RxNorm, and other medical standards.
Technologies: Jersey, Ext JS, Jakarta EE (Java EE or J2EE), JBoss Drools
Consultant
2014 - 2014
Amazon Web Services
- Created a Windows client to communicate with Amazon AppStream server applications. The client included customized captions using windows non-client messaging.
- Customized DirectX implementation to display low network levels.
- Worked on an AppStream Android client. The solution included JNI/NDK interface with AWS DLLs and GLSurfaceView implementation.
- Created a customized AppStream eligibility server. Both clients communicated with the eligibility server for authorization and available AppStream applications. Both clients monitored network latency, download speed, dropped frames, and displayed warnings when stats were below minimum acceptable levels. Both clients submitted survey results to Kinesis service.
Technologies: Amazon Web Services (AWS), Jetty, Visual Studio, Eclipse, Android NDK, Accessory Development Kit (ADK), C++, Amazon AppStream, JNI, Java
Director of Accelerator Products
2008 - 2014
iRise
- Designed, implemented, tested, and maintained a suite of products to complement iRise core products.
- Created iRise CodeGen, which creates software code from iRise simulations, reducing customer efforts to create code by up to 70%.
- Created iRise Importer, which converts existing web pages to iRise simulations, reducing customer efforts by up to 90%.
- Worked on project management, technical architecture, and application development.
- Worked on iRise Adoption Center and connectivity products to requirement management systems, including HP Quality Center and Borland Caliber.
Technologies: Agile, Jira, Apache Maven, JxBrowser, JavaScript, MySQL, Apache Tomcat, Jakarta Server Pages (JSP), Java SE (Core Java)
Project Manager/Enterprise Architect
2007 - 2008
Ibeza
- Created Synapse, a rule-based web application to determine insurance reimbursement eligibility in real time. Synapse allowed medical, non-technical personnel to enter complicated medical eligibility rules through a simple-to-use web interface.
- Provided project management, technical design, and application development services.
Technologies: Ajax, JavaScript, Telerik, Microsoft SQL Server, VB.NET, C#.NET, BizTalk Server 2009
Project Manager/Senior Software Architect
2006 - 2007
Symantec
- Worked on new front- and back-end architecture to increase revenue from Norton customers.
- Provided project management, technical design, and application development services.
- Worked on Norton presentation layer and website storefront back-end code.
Technologies: Hibernate, Enterprise Java Beans (EJB), Java, IBM WebSphere
Senior Software Architect/Technical Liaison
2006 - 2006
Yahoo!
- Assisted Yahoo Search Marketing in rolling out Panama SDK to their multi-million dollar Yahoo accounts.
- Traveled through the US, visiting key customers and helping them with software implementation and deployment issues.
- Prepared Yahoo/Google Internet Ad implementation comparison read by Jerry Yang, CEO.
Technologies: .NET, Jakarta EE (Java EE or J2EE), Web Services
Senior Software Architect
2005 - 2006
Sony
- Worked on application development for Sony CONNECT Music Store, using Sony's digital rights management system.
- Performed batch processing to convert music from various sources and formats.
Technologies: Digital Rights Management (DRM), Java
Project Manager/Architect
2004 - 2005
Axium Entertainment Payroll Services
- Worked on a production accounting system, which has been live, with over a billion dollars of activity.
- Managed a system consisting of more than 500 thousand lines of Java code, dozens of stored procedures in MS SQL servers, and dozens of reports running on Crystal Enterprise.
Technologies: Crystal, Citrix, Microsoft SQL Server, Java
Project Manager/Architect
2003 - 2004
Suzuki
- Worked on the warranty claim review system, certified user car program, and WebSphere portal, where users perform delegated user administration tasks.
Technologies: Jakarta EE (Java EE or J2EE), Jakarta Server Pages (JSP), Apache Struts, WebSphere Application Server
Director of Technical Education/Architect
2001 - 2003
Gamma Enterprise Technologies
- Created and delivered J2EE-centric courses.
- Architected and implemented Gamma's Java to SAP enterprise connectivity.
- Presented at computer conferences on technology, and co-authored "WebLogic Server 8.1 Unleashed."
Technologies: Java
Project Manager/Architect
2000 - 2001
Peoplelink
- Created HomePage builder, an advanced applet to allow non-programmers to create web pages using WYSIWIG.
Technologies: Java
Project Manager/Architect
2000 - 2000
Seren Systems
- Created advanced ATM machines with scanning capabilities.
Technologies: Java
Director of Strategic Development
1999 - 2000
Craftclick
- Worked on online auction front- and back-end code.
Technologies: Microsoft SQL Server, Adobe ColdFusion
Project Manager/Architect
1996 - 1999
Eagle Creek Systems
- Created TexCAD, a CAD system used in creating fabrics for the textile industry.
Technologies: OpenGL, C++, Microsoft Foundation Class (MFC) Library, Microsoft Foundation Classes (MFC), CAD
Senior Systems Analyst
1994 - 1995
Salomon Brothers
- Worked on applications to support internal financial planning/budgeting.
Technologies: C++, Microsoft Foundation Class (MFC) Library, Microsoft Foundation Classes (MFC), IBM Informix
Systems Analyst
1993 - 1994
Merrill Lynch
- Worked on applications to help brokers with their day-to-day operations.
Technologies: Visual Basic, C++, Microsoft Foundation Class (MFC) Library, Microsoft Foundation Classes (MFC)
Programmer Analyst
1987 - 1992
Gruntal, Inc.
- Created reports for equity clearance services.
Technologies: PL/1
Project History
iRise Web Importer
I developed an iRise Studio plugin that injects introspective JavaScript into any existing web page, to ascertain its contents, and then recreates them in iRise studio.
iRise CodeGen
iRise CodeGen creates software code from iRise simulations, and can reduce customer efforts to create code by up to 70%.
Production Accounting System
Accounting System for the Entertainment industry, consisting of over 500K lines of Java code.
Education
1990 - 1992
Coursework in Artificial Intelligence/Natural Language Processing
New York University - New York City, USA
1983 - 1987
Bachelor of Science Degree in Computer Science
State University of New York - Stony Brook, NY, USA
Certifications
JANUARY 2007 - PRESENT
Professional Project Manager
Project Management Institute
JANUARY 2002 - PRESENT
BEA WebLogic Server Developer and Administrator
BEA
JANUARY 1995 - PRESENT
Novell Certified Network Engineer
Novell
Skills
Libraries/APIs
React, jQuery, Node.js, NinjaScript, REST APIs, OpenAI API, Google API, YUI, jQuery UI, JxBrowser, Microsoft Foundation Class (MFC) Library, OpenGL, GoJS, Antd, Microsoft Foundation Classes (MFC)
Tools
Git, Ace Editor, Eclipse IDE, Docker Compose, Concourse CI, JBoss Drools, Apache JMeter, Apache Maven, Microsoft Visual Studio, Jira, Figma, Prisma, CAD, Apache Tomcat, Amazon AppStream, Accessory Development Kit (ADK), Android NDK, Visual Studio, Jetty, ChatGPT
Languages
SQL, TypeScript, HTML, CSS, Java, JavaScript, HTML5, ECMAScript (ES6), XML, C++, C, C#, Python, Java SE (Core Java), Crystal, Visual Basic, C#.NET, VB.NET, PL/1, Python 2, GraphQL, Groovy
Frameworks
Next.js, Express.js, NestJS, Spring, Ext JS, Grinder, JUnit, Hibernate, Jersey, Material UI, Tailwind CSS, Serverless Framework, Jakarta Server Pages (JSP), .NET, Apache Struts, JNI, Spring Boot, Angular, Bootstrap, TestNG, Dojo, Grails
Paradigms
REST, Agile Software Development, Object-oriented Programming (OOP), Event-driven Architecture, Microservices, Asynchronous Programming, Distributed Programming, Service-oriented Architecture (SOA), Agile
Platforms
Ubuntu, Windows, AWS Lambda, Docker, Amazon Web Services (AWS), Heroku, Java EE (Jakarta EE), IBM WebSphere, Jakarta EE (Java EE or J2EE), Citrix, Adobe ColdFusion, Eclipse, Telerik, Amazon EC2, Google Cloud Platform (GCP), Firebase
Storage
PostgreSQL, MySQL, Databases, Amazon S3 (AWS S3), JSON, MongoDB, Microsoft SQL Server, IBM Informix
Industry Expertise
Project Management, Healthcare
Other
Scraping, Multithreading, Offshore Development, Software Engineering, Front-end Development, Full-stack, Front-end, Architecture, Full-stack Development, Web Development, Back-end, Back-end Development, APIs, Minimum Viable Product (MVP), Web Scraping, Software Architecture, API Integration, SDKs, Web Applications, Data Modeling, RESTFul APIs, WebLogic, Data Mining, Chrome Extensions, GlassFish, OpenAI GPT-4 API, Headless CMS, Lambda Functions, Generative Artificial Intelligence (GenAI), Large Language Models (LLMs), CI/CD Pipelines, Artificial Intelligence (AI), Web Services, Digital Rights Management (DRM), WebSphere Application Server, BizTalk Server 2009, Ajax, Data Warehousing, Analytics, RETS, Data, Data Warehouse Design, Enterprise Java Beans (EJB), OpenAI, Build.AI, Claude.AI, Computer Science, Prismic
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