Back-end Developer in Istanbul, Turkey

I contributed to the development and architecture of a supervisory control and data acquisition (SCADA) system for the industrial IoT market.

The back end was designed to contain distributed microservices that were loosely coupled and communicate using RabbitMQ with domain events for specified DDD (domain-driven design). The front end was developed using React framework with Redux functions to provide application scale prop storage.

To communicate with remote terminal units (RTU), sector standard protocols like DNP3, Modbus, and IEC were implemented and used. Kubernetes 1.20 and Red Hat OpenShift 4.6 were used for both development and production environments. Helm charts were used for CI/CD processes to automate operational works.

I worked as a technical team leader and developer of a project that aimed to convert monolithic applications into microservices. This required re-platforming applications from WebLogic 12c to the RedHat OpenShift 4 Container Platform.

We used new robust CI/CD pipelines for the application lifecycle and test purposes. Spring Boot 2 framework and its side dependencies were used for new microservices. This project was viewed as an exemplary effort for the rest of the company to modernize the entire department's applications.

This project involved the development of a Spring Boot 2 application that constructed a bridge between other microservices and the airline reservation system.

I was the only developer. HTTP (RESTful) and custom TCP protocols were supported. Stateful tokens were stored on Couchbase for better performance. The application connected the airline reservation system via IBM MQ 8. RedHat OpenShift 4 was used for the runtime. I created a Jenkins pipeline for CI/CD operations and all deployments were automatically done by Git Hooks with no downtime.

The system was designed for handling a massive RPS load from different applications.

I contributed to the development of a Java application with JAX-WS and JAX-RS endpoints. The app provided major sales channel operations (e.g., websites, mobile applications, agencies) such as before-after tickets, payments, check-ins, and reissuing. It was developed with Spring and Hibernate frameworks and Maven was used for dependency control. Deployments were done with Jenkins pipelines and Oracle WebLogic 12c was used for runtime. I also integrated with many other systems with SOAP, Rest, IBM MQ, and TCP protocols.

A Spring Boot microservice that virtualizes other applications' dependencies for robust CI/CD flows with scenario-based records. It simply worked between two applications, listened to traffic, and simulated real systems when the CI/CD flow was working. The application was designed especially for stateful flows, where the sequence was important for response messages. An Oracle database was used for storing input and output messages.

This complete system consists of several microservices for detecting errors, which were abnormally increasing during a specific amount of time in the application logs from Elasticsearch and the database. It was designed for catching unnoticed production errors which are crucial for sales operations. Spring Cloud Data Flow for Kubernetes was used as the engine of the system. Custom microservices were developed for analyzing errors with standard deviation and RNN (recurrent neural network) algorithms. The design was patented with the Turkish Patent Authority (TR 2019/02123).

I developed a set of back-end microservices for an agency website that was integrated with another service provider to sell tickets from multiple airlines. Spring Boot was used for microservices. Calendar service and other ticketing services were designed for fault-tolerant structure. AWS EC2 and BeansTalk were used for the runtime. To collect applications' logs and illustration, AWS Beanstalk and Kibana were used.

I developed a Spring Boot application that manages the lifecycle of tickets and reservations of an airline. There were CRUD operations for electronic documents like display and cancel. A pipeline for Jenkins was created to build, test, and deploy the application. The package could be running on both RedHat OpenShift with environment variables and WebLogic 12c with system variables.

I developed a Spring Boot 2 application that contains profile and SSR (special service request) operations for the airline. Meal, baggage, identity request, and profile creation integrations were operated with SOAP and REST endpoints. Jenkins pipelines were used to manage the application lifecycle. RedHat OpenShift was used for the runtime.

I implemented a microservice that contains pricing features and integrations for an airline including sensitive ticketing pricing calculations, currency conversion, and stateful logic. Jenkins pipelines were created for building, testing, and deploying application to runtime and RedHat OpenShift was used as the runtime platform.

The Toptal React Academy is an exclusive learning program that teaches the React framework to select members of the Toptal network. After a month of study, all graduates are tasked with completing a 30-40 hour final project to build and deliver a React app from scratch. The above is a walkthrough of my final project.