Java Developer in San Francisco, CA, United States
Member since February 27, 2015
Denys is a seasoned software engineer, engineering manager, and entrepreneur with over 11 years of experience. He specializes in distributed and scalable web applications targeted to run in the cloud. Has a track record of using diverse programming languages and technologies with Java being a favorite one. Since the start of his career, he has been an advocate for readable, maintainable, and testable code.
Denys is now available for hire
Portfolio
- Cisco SystemsJava, JavaScript, Go, Python, Spring, Ruby, Jersey, Docker, AWS, Kafka...
- Max2 (via Toptal)Java, Kafka, Scala, Play Framework, Akka, Redis, MySQL
- BSDvmJava, PHP, Python, AngularJS, Play!, Apache Thrift, ZeroMQ, Akka, HTML, CSS...
Experience
- Java, 10 years
- Docker, 5 years
- NoSQL, 5 years
- Spring, 3 years
- AWS ECS, 3 years
- Algorithmic Trading, 3 years
- Natural Language Processing (NLP), 2 years
Availability
Part-time
Preferred Environment
IntelliJ IDEA, Git, MacOS, AWS, Linux, Docker
The most amazing...
...thing I've coded was a MapReduce that could process and modify the data of more than a billion records in less than 10 minutes.
Employment
Senior Software Engineer
2015 - PRESENTCisco Systems- Built an API gateway and data processing/aggregation microservices using Springboot for a distributed monitoring solution.
- Made key contributions to the design and implementation of a Java auth framework based on Oauth2.
- Implemented a project management system on top of Openstack API.
- Increased stability and security of an open sourced monitoring Ruby-based agent by refactoring and implementing the authentication layer.
- Boosted performance of the data ingestion service by 60% by analyzing code with profiling tools and fixing identified issues (decreased auth overhead, optimized payload processing).
- Implemented product licensing capabilities in monitoring solution by building middle-tier services and integrating with licensing service.
Technologies: Java, JavaScript, Go, Python, Spring, Ruby, Jersey, Docker, AWS, Kafka, Elasticsearch, Redis, Postgres, Apache Avro, Apache Mesos, MongoDB, AMQP, OpenstackJava Developer
2015 - 2016Max2 (via Toptal)- Hardened mobile app Java back-end API security by introducing a signed request feature (Amazon API like).
- Boosted performance of API back-end pagination requests by 50% by implementing Redis-based pagination.
- Increased the robustness of the API by introducing JSON schema and automated payload field validations.
- Made code more reliable and testable by refactoring and applying testability best practices.
Technologies: Java, Kafka, Scala, Play Framework, Akka, Redis, MySQLFounder and Lead Developer
2014 - 2015BSDvm- Designed and implemented a VPS infrastructure orchestration layer in Python.
- Built a cloud provisioning system based on a custom work queue implemented with Java and Akka.io.
- Designed and implemented a cloud control panel with PHP and AngularJS.
- Built integration with Amazon AWS via Java API.
- Created the main company website.
Technologies: Java, PHP, Python, AngularJS, Play!, Apache Thrift, ZeroMQ, Akka, HTML, CSS, VMware, Amazon AWSEngineering Manager
2012 - 2014Google (via EPAM)- Implemented a number of BI system plugins for proprietary file systems, databases, and data warehouses.
- Designed and implemented a web application that served as a metadata dictionary for the data delivered to multiple data warehouses.
Technologies: Java, JavaScript, AngularJS, GWT, HTML, CSS, Protocol BuffersSoftware Engineer
2011 - 2012Google (via EPAM)- Developed a multi-purpose Java query tool based on MapReduce.
- Participated in the migration of the application from a MySQL to a NoSQL database.
Technologies: Java, Python, JavaScriptSoftware Engineer
2010 - 2011Google (via EPAM)- Implemented a GWT front-end framework that served as the basis for application development for a CRM administration application.
- Implemented a quick search feature that improved the UX.
- Re-engineered the application's mail queue administration view.
- Covered the application functionality with functional automated tests.
Technologies: Java, GWT, Python, Protocol Buffers, MapReduce, MySQL, NoSQLSoftware Test Engineer
2006 - 2010GlobalLogic- Developed a testing framework in Java/Selenium for a web application.
- Created a number of JavaScript extensions for the Java/Selenium testing framework.
- Wrote a parser in Perl that helped to fix thousands of legacy automated tests written in Tcl.
Technologies: Java, Python, Perl, JavaScript, WebDriver, Selenium
Experience
- Java Quant/algorithmic Trading Framework (Development)
The framework is implemented based on Interactive Brokers Java API and open sourced back-testing engine. Allows to easily implement new trading strategies and backtest them, using historical data from multiple sources: Interactive Brokers API, Yahoo Finance API, Database, CSV files.
- Albumica (Development)
A web application that allows for sharing of photo albums across multiple social networks. Technologies used include Facebook API, Instagram API, VK API, AngularJS, Redis, and Play!
- GammaCloud (Development)
Developed a PaaS for PHP, RoR, Python, and Java app deployment. Technologies used include Go!, Ruby on Rails, MongoDB, and Docker.
- Building Modern Web Applications with AngularJS and Play Framework (Publication)Building robust web applications is often a lot about choosing the right tools. Doing so with a combination of tools that ensure both a modern, flexible front-end, and a solid, reliable back-end is something everybody wants. This article demonstrates exactly that trick by combining AngularJS and Play Framework to build a simple blog application.
Skills
Languages
Java, Python, Go, CSS3, PHP, JavaScript, HTML5, SQLFrameworks
Spring, Play Framework, AngularJS, Jersey, Bootstrap 3, Apache Thrift, DjangoLibraries/APIs
Interactive Brokers' API, ZeroMQ, Instagram API, Facebook API, jQueryTools
AWS ECS, Mesos, Amazon Virtual Private Cloud (VPC), IntelliJ IDEA, Git, VirtualBox, VMware, VagrantPlatforms
Docker, Linux, AWS Lambda, AWS EC2, FreeBSD, MacOSOther
Algorithmic Trading, Quantitative Finance, Natural Language Processing (NLP), Protocol BuffersParadigms
Agile Software Development, MapReduceStorage
NoSQL, MongoDB, MySQL, H2, PostgreSQL, Redis
Education
- Master of Science degree in Radio Electronics Engineering1999 - 2004Khmelnitsky National University - Ukraine
