Pavel Klimenkov

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Professional skills and knowledge:

‍Programming skills: ‍Ruby, Ruby on Rails, PostgreSQL, MySQL and other databases, Unix, Action Script 3 , Java, Node JS, Python, Git, SVN and other CVS, Redmine , Jira and other issue trackers.

Technical skills:‍

• Architect development of applications from scratch to production
• Strong capability of development multi component systems
• Good knowledge of databases and SQL
• Ability to develop high loaded server apps
• Strong knowledge of VCS
• Believer in automatic testing
• Knowledge in isometric and 3d engines like Unity3D and UnrealEngine 4

Language Capabilities: Ukrainian – native, Russian – native, English – upper - intermediate.

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Education:‍

2013, East Ukrainian National University, Mathematics and Informatics faculty Specialist

2010, East Ukrainian National University College, Applied Mathematics faculty Specialist Junior

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Working experience:

Individual Subcontractor

Dates of Employment: Apr 2017 – Now

Position: Full stack Ruby on Rails developer, with wide responsibilities across applications.

Responsible:

• Designing and maintaining RESTful API for variety of services.
• Developing application with Ruby 2 + and Ruby on Rails.
• Working with high loaded databases (PostgreSQL, MySQL).
• Building stats application from scratch with algorithms to collect data from real app and store persistently, pre compile to front end and store in redis.
• Developing front end applications with React JS, Backbone JS.
• Securing applications from CSRF and JS injections.
• Working with third party APIs.
• Working with wide spread teams across many time zones.

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AirBlackBoxLtd

Dates of Employment: Jun 2016 - Apr 2017

Position: Team Leader

Lead for the back-end of ABB low cost flight connection api. Managing team of 3 developers, from recruiting to project finish.

• Developing application with Rails 4 and ruby 2.2. Building an application from scratch with Rails 4, PostgreSQL and Redis to provide special services.
• Parsing NDC XML from airline request
• Finding special services with requested params from Redis cache and database
• Building NDC XML with Nokogiri
• Developing public api with Grape to manage service from main Admin panel.
• Developing admin tool with ActiveAdmin for main application as well as Service app. Using Her&Faraday combo on remote admin application for Service app
• Developing OAuth authentication for service app.
• Construction of event system to track on actions within the system with Sidekiq async jobs and PostgreSQL database, developing module for admin panel to make sense on events.
• Working with close integration with front end on Node JS with AngularJS, Gulp and Bower.
• Managing and improving multilingual system through multi app system.
• Construction of customers emails with ERB, HTML and WickedPDF for itinerary.
• Parsing SSIM emails coming to mailbox with Mastiff and searching for bookings that are affected by schedule change or flight canceled. Marking those bookings with async Sidekiq task and emailing to airline with list of booking that should have been refunded via flight cancellation or connection no longer possible.
• Deploying application with Jenkins to Docker VM on Amazon Cloud.
• Working with BitBucket and Jira integrated into HipChat. Writing wiki in Atlassin Confluence.
• Providing highly covered code with automated testing. Using Rspec for main test framework with Capybara and Cucumber as for web testing. Involved with Phython unit testing scripts.
• Providing readable and conventional code. Checking code with Reek and Rubocop for violations.

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NewFolderGames

Dates of Employment: Jun 2016 - Oct 2016 (part time)

Position: Server side developer

Working among other start-upers in close team Developing server side application with Java 1.8 with Spring, Hibernate and Maven. Developing Support with User Chat. Using Hibernate with PostgreSQL to store messages. For front-end using Freemarker and HTML. Chat was done with HTTP requests to Java Spring controller from Javascript running in client browser. Feature ownership on item modification. Spring controller with Hibernate Entity on storing changes. Traversing configs from YAML to JSON as Maven task to then importing them to application as JSON configs. Feature ownership on extracting game configs from Google Spreadsheet to YAML with changing only crucial fields. Done with Ruby 2.0, regular expressions and Google API on authentication. Working with saving user state to file. Used Hibernate with Jackson serializer to catch all Entity data to JSON and then restore back to Entities Working with XSOLLA payments and transaction system. Covering controllers with Unit testing.

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Social Quantum Kiev (AvenueGames studio)

Dates of Employment: Jan 2014 - Jun 2016

Position: Team Leader/ Lead server side developer.

Managing team of 3 developers.

Developing HTTP game server for online game Wild West. We were starting with old solution on Ruby 1.8.7 with Postgres 8 which we migrated to Ruby 1.9.2 and later 1.9.3 to provide support for latest PostgreSQL. While working with old server we were continuously improving and reorganizing entire application. So at the end we had almost brand new server that hold up to 3000 active users per instance. According to Ruby GIL limitation we were faced the necessity to run multiple processes of game servers which became our advantage that our system was able to be scaled to 500 instances running on different servers. Working in group of multiple feature teams.
Working on gathering statistics closely with game designers. Writing ruby scripts to collect and make sense of data. Collecting data from production database to teach artificial user for testing purposes. Writing Python socket server to control multiple testing bots. We used Python 3.2 with web sockets to achieve as many bots as possible. Our stress test were run on 10000 bots and it was fine. Writing and teaching Bayesian network based artificial user. We used Adobe Air to be able to run on any
given device as well as take some configs from real game client written on Action Script 3. We successfully achieved our goal of mimic median user in his behaviour.
Feature ownership on neighborhoods. We made a system of 3 server application running and communicating with one another providing user an interacting experience of socket connection on the basis of HTTP server side. Writing an extension to SmartFoxServer on Java 1.7. We had to have some logic on our socket server that is in sync with real game configs so we made a script that generates property files from YAML and then applied them in extension. We did chat message storing to provide user that joins the room with 50 last messages as well as system event storage. We stored rooms and their properties to PostgreSQL and were storing chat to Mongo DB. Writing NodeJS application as agent between Ruby game server and SmartFoxServer for online interactions. We were using Express as HTTP request handler with PBKF2 auth and SmartFox JS library. Application was made with multiple environment configuration to work with multiple env game server. Configuring Capistrano deploy for all application to Unix server. Writing good covered code with Rspec autotests. Using isolation with Mock and Stub to test different parts of game logic.

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iLogos inc.

Dates of Employment: Jan 2014 - Jun 2016

Position: Team Leader/Ruby Tech Lead

Developing AS3 client-side games with pure Ruby, PHP, Java server-side. Managing teams of up to 7 developers.

Developing Action Script 3 game clients with Adobe Flash integration. We were developing full application from scratch to ready for production. For the most part we were using Adobe Flash for UI and were developing AS3 code for all game logic Integration of applications to Facebook, VK, OD, Mail.ru Developing AS3 applications for POGO.COM with basically re-creating Java 1.6 game to modern looking and smooth running application Developing game server on PHP for role play game with almost no interaction between users. Providing content through static file transferring with Nginx. Authentication with social network and game logic. Developing AS3 game client for isometric farming simulator. Using Iso3d engine to handle graphics and Interactive PNG to get it all smooth looking. Making cutscenes with Adobe Flash and importing them to game client. Developing Java 1.7 server for farming simulator. We were using Spring for request controlling and Hibernate for database support. We were writing it from scratch to finish with JSON requests and responses Developing game servers with Ruby 1.8 and Ruby 1.9 for farming simulator and city builder simulator. Starting as content developer working on YAML and AS3 look I them became a leader of core team that worked on basic game mechanics as well as optimization of existing server. Optimization of Ruby Sprout deployment of AS3 application which caused us to override Sprout gem to run with our needs. Working on optimization of ruby server to be able to run on windows platform which was actually ticket to become a core server developer. Working as a tech leader for Ruby and being involved into HR process. Checking CVs, providing and reviewing test tasks. Interviewing developers. Helping to integrate Capistrano deployment to other projects.

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East Ukrainian National University

Dates of Employment: Jun 2010 - May 2011,

Position: Technical-programmer

Responsible:

• Supporting university’s network. Supporting university’s website.
• Holding and managing telecommunication system on all university.
• Developing MySQL database of telephone lines of all university phone line and cable systems
• Working on admin panel of telecom database.Using PHP and MySQL adapter to achieve easiness of finding right cable of the client.
• Managing University’s local network, working with 2 internet operators to connect both University itself and hostel.
• Supporting and maintaining network.

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Freelance

Dates of Employment: Jun 2008 - Jun 2010

Position: Programmer

Responsible:

• Developing casual mobile games.
• Developing training application on desktop and mobile
• Developing casual mobile games with Java 1.6 mobile. Using free images from internet and built in J2ME modules programming games from scratch to finish.
• Developing Delphi 7 application to speed up learning process for students. Providing complex solutions for mostly mathematical tasks.
• Indie development of mobile versions of programs that solves mathematical tasks that students could and did use for speeding their homework and mostly for cheating on exams.
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Achievements: Developing high load server application for SocialQuantum games. We started basically from scratch and built server that holds tremendous DAU. We used Ruby with Thin and created well optimized game server that handles all game logic for applications. Because oj GIL we had to use multiple instances so our server
is built on idea complete independence of each instance and communication between them was achieved through memcached and async jobs monitoring crucial points.
Working with highly sharded and spreaded database (up to 64 shards) and maintaining ability to interact between users from different shard. We used PostgreSQL and did the best we could with it. Collecting statistical data on users through writing heavy and optimized SQL requests. Constructing async event system to collect and view data on users in system for SocialQuantum and then replicating and polishing it for ABB. I used Sidekiq as async system to perform sending events to stats database. And i constructed entire new application to make sense of the data (it was done at ABB as for SQ had their own) Creating artificial user to test social interactions between real users. We were choosing between deep neural networks and Bayesian network which we choose last. We achieved pretty accurate mimic of users behaviour through playing the game. To train the network we used real data from our stats database. We build a system server on Python that control up to 10000 bots at a time. We built our bots with Adobe Air as it can be executed regardless of platform so it really can be much more of AU doing their job of interacting with each other.
Working and improving e-commerce API to connect low cost airlines with each other to provide lowest price possible to customer. I am feature owner of a module for providing data on airline’s special services like wifi or meals for airlines that aren't actually having those data themselves. Like China West A or KLM international. We used Rails 4 for application, Active Admin for admin panel. We had built controllers that parse NDC XML from airline request and provide with correct NDC response depending on such variables as flight number, origin, destination, frequent flier etc. Setting up full stack application on Unix web server. Usually it is Ubuntu with Nginx, RVM, Git, Eye, PostgreSQL and Capistrano. Also done with Node JS and NPM, SmartFoxServer and Java. Working with Amazon Web Server. Deploying ABB application through VM on cloud service (docker) Feature owning of neighborhoods for SocialQuantum. Setting up SmartFoxServer for immediate
interactions between users. Writing Java extension for controlling and securing user operations on server. Writing Node JS application as agent between HTML Ruby game server and SmartFoxServer socket server. We used Express for Node JS and SmartFoxServer js api (which we mostly rewritten by ourselves to work smoothly). Process of connecting user to neighborhood was like connecting to game server via HTTP and doing authentication, then getting list of not overloaded (below 85% loaded) SmarFoxServer shards, then client chooses best ping and connects to chat with PBKF2 auth. Continuous integration deployment with TeamCity. Setting up and managing all deployment with TeamCity CI and capistrano.

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Projects portfolio:

I’m homeless (Я - Бомж)

RPG game that is about being homeless in CIS region

Responsible:

• client-side development with AS3
• VK integration client-server cooperation development content loading optimization

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Sweet Tale (Сладкая Сказка)

Classic farm game styled like in the movie “Charlie and the Chocolate Factory (2005)”

Responsible:

• database development
• architect development
• client-server cooperation
• iso engine integration
• mail.ru integration
• client-side development with AS3
• server-side development with Java SE

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Wild West (Дикий Запад)

Classic farm game with wild west style.

Responsible:

• content development
• client-server cooperation
• client-side development with AS3
• server-side development with pure Ruby
• cut-scene development

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Wild West: New Frontier (Дикий Запад: Новые Земли)

Classic farm game with wild west style. Now in 3D developing game server on pure Ruby admin console with Sinatra deploying with capistrano

Responsible:

• PostgreSQL database
• Git as version control system
• Python socket server for automatic testing
• Adobe Air AI testing application
• TeamCity for deployment
• SmartFoxServer for chat and online interaction
• Node JS for management and control

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Sandon (Песчаные Короли)

Web based low graphics RPG. Long forgotten but still playable developing game server Java SE developing web interface with Freemarker

Responsible:

• Maven
• Spring
• Git as version control system
• Hibernate and PostgreSQL as for database
• Memcached for cache purposes

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ABB api

• Api for connection many small lowcoster airlines to provide joint journeys
• Developing application with Rails 4 and ruby 2.2
• Developing api with Grape
• Developing admin tool with ActiveAdmin
• Redis
• PostgreSQL as database
• Deploy with jenkins and docker
• Sidekiq for async tasks
• Her&Faraday combo for app administration through another app admin tool.