İsa is available for hire

İsa Ölmez

Verified Expert in Engineering

Full-stack Developer

Location

Izmir, İzmir, Turkey

Toptal Member Since

August 13, 2020

İsa is a software engineer with more than a decade of experience. While İsa is a full-stack developer whose areas of expertise are with Java, Spring, and Spring Boot, he would describe his past work as primarily back-end development with exposure to the front end. İsa also has robust OOP skills and ample experience in software design. İsa can successfully develop his section of a project as well as thoroughly explain the most relevant parts of his source code, so he works well in teams.

Back-end Java Unit Testing Apache Maven Spring Spring MVC Spring Boot Java 11 Web App Development Cloud Distributed Systems Message Queues Database Design MySQL Relational Databases

Portfolio

Eldermark

Groovy, Vue, Amazon Web Services (AWS), Spring Boot, Spring Security...

Syngenta

Java, Spring Boot, Apache Kafka, PostgreSQL, Spring MVC, Spring Cloud...

Priceline

Java, Spring, Spring Boot, Oracle Database, REST APIs, JDBC, SQL...

Experience

Java - 12 years Spring - 8 years APIs - 8 years Message Queues - 6 years Spring Boot - 6 years Amazon Web Services (AWS) - 5 years Azure - 2 years Kubernetes - 2 years

Availability

Part-time

Preferred Environment

Linux, IntelliJ IDEA, Java, Spring, Amazon Web Services (AWS), Azure, Spring Boot, NoSQL, Relational Databases, Message Queues

The most amazing...

...thing I've participated in is the development of real-time data processing pipelines that consumed 50+ million events per day.

Work Experience

Senior Full-stack Developer

2023 - 2024

Eldermark

Developed the MVP in ten months, contributing to all parts of the application development process.
Implemented the security layer using OAuth2 to integrate with different third parties.
Created a webhook system that captures the entity updates and notifies the related integration parties.

Technologies: Groovy, Vue, Amazon Web Services (AWS), Spring Boot, Spring Security, Spring MVC, Amazon Simple Queue Service (SQS), Amazon RDS, OAuth 2, Amazon Cognito, TypeScript, HTML, CSS, Jira, Confluence, Scrum, Microservices

Java Developer

2022 - 2022

Syngenta

Enhanced the data migration system to become more resilient when processing 45+ million messages.
Added a bootstrap mechanism to start a specific entity's data migration process.
Implemented a migration validation application for performing various checks for the data-migration process.

Technologies: Java, Spring Boot, Apache Kafka, PostgreSQL, Spring MVC, Spring Cloud, Spring Data JPA, Amazon Web Services (AWS), Kubernetes, Docker, Spring Security, Java 11, Unit Testing, Integration Testing, C#, Jira, Confluence, Scrum

Senior Full-stack Developer

2021 - 2022

Priceline

Initiated and developed a major integration with another travel agency.
Worked on the migration of the direct database calls to an internal REST API in multiple modules.
Implemented several infrastructural enhancements to the project to be used by multiple modules.

Technologies: Java, Spring, Spring Boot, Oracle Database, REST APIs, JDBC, SQL, RESTful Services, Back-end, Cloud, Relational Databases, Distributed Systems, Microservices, APIs, Java 11, Unit Testing, Integration Testing, Jira, Confluence, Scrum

Senior Full-stack Developer

2020 - 2021

Fortune 100 North American Construction Equipment Manufacturer

Participated in enhancing the application performance to handle new clients, sending around one million requests per day.
Refactored an existing application and implemented the new features covering Spring Boot, Azure Function Apps, and React.
Created monitoring support for the application using Azure Application Insights.

Technologies: Azure, Azure Functions, Azure Cosmos DB, Azure Blobs, Spring Boot, Spring Security, OAuth 2, React, Angular, Spring Data JPA, Selenium, OpenID Connect (OIDC), Azure App Service, Continuous Integration (CI), Hibernate, Full-stack, REST APIs, JDBC, SQL, RESTful Services, Back-end, Cloud, NoSQL, Relational Databases, JavaScript, Microservices, APIs, Java 11, Unit Testing, Integration Testing, C#, .NET, AngularJS, HTML, CSS, Jira, Confluence, Scrum

Senior Full-stack Developer

2019 - 2020

FlexEngage

Refactored the existing messaging infrastructure to work with Amazon SQS instead of ActiveMQ which increased the throughput.
Enhanced the logging infrastructure to preserve critical correlation data between more than 20 different messaging applications as a result, traceability was improved.
Built a testing infrastructure using Cucumber to test back-end services.

Technologies: Cucumber, Continuous Delivery (CD), Apache Maven, Stream Processing, Spring Security, Database Design, ActiveMQ, Message Queues, Amazon Web Services (AWS), Hibernate, Scrum, Git, Linux, MySQL, Jenkins, Docker, Amazon Kinesis, Amazon Simple Queue Service (SQS), Amazon DynamoDB, Amazon S3 (AWS S3), JMS, Spring Boot, Spring, Kotlin, Java, Spring Data JPA, Karate API Testing, Continuous Integration (CI), Jenkins Pipeline, Full-stack, REST APIs, JDBC, SQL, RESTful Services, Back-end, Cloud, NoSQL, Relational Databases, JavaScript, Relational Database Services (RDS), Distributed Systems, Microservices, APIs, Unit Testing, Integration Testing

Senior Full-stack Developer

2017 - 2019

Emakina Group (Belgium)

Implemented an event-driven middleware application to process legal investigation requests. The application collected data from multiple data sources using Spring Boot and Spring JMS.
Participated in the integration phase of Belgium's two big telecom companies, Base and Telenet, working on every application stack layer.
Implemented the monitoring functionality, which supports JMS endpoints/clients and REST endpoints/clients, thus improving traceability.

Technologies: Cucumber, Continuous Delivery (CD), Apache Maven, Spring Security, Database Design, Message Queues, Jenkins, Hibernate, Scrum, Git, Linux, Spring, Angular, MySQL, Oracle Database, Oracle, MongoDB, ActiveMQ, JMS, Spring MVC, Spring Boot, Java, Selenium, Spring Data JPA, Jenkins Pipeline, Continuous Integration (CI), Full-stack, REST APIs, JDBC, SQL, RESTful Services, Back-end, NoSQL, JavaScript, Relational Databases, Distributed Systems, Microservices, APIs, Unit Testing, Integration Testing, HTML, CSS

Senior Full-stack Developer

2016 - 2017

Emakina Netherlands

Implemented new features for the Unilever Food Solutions website, Ufs.com, which was rolled out in more than 50 countries.
Developed event-driven applications for the asynchronous processing of online customer data, which improved the system's fault tolerance.
Enhanced the search layer using AWS CloudSearch to support new business features.

Technologies: Apache Maven, Spring Security, Database Design, Redis, Amazon Web Services (AWS), Hibernate, Scrum, Git, Linux, Spring, Amazon CloudSearch, Amazon DynamoDB, Amazon S3 (AWS S3), MySQL, Spring MVC, Spring Boot, Java, Selenium, Spring Data JPA, Full-stack, REST APIs, JDBC, SQL, RESTful Services, Back-end, Cloud, NoSQL, JavaScript, Relational Database Services (RDS), Relational Databases, APIs, Unit Testing, Integration Testing, HTML, CSS, Jira, Confluence

Founder

2015 - 2016

Datacrow Software

Created a process management system for a local foundation using the .NET framework in two months.
Implemented prototype recommendation services using the latest machine learning and big data technologies.
Worked on big data systems and their applications using real-world scenarios.

Technologies: Apache Maven, Spring, Linux, Git, MySQL, Spring MVC, Java, Hibernate, SQL, Back-end, Relational Databases, Unit Testing, Integration Testing, C#, .NET

System Architect

2013 - 2015

Comodo

Reimplemented the existing legacy solutions with the latest modern technologies for an advertising network that has more than 20 million views per day.
Created the big data pipelines from scratch using Apache Storm, Apache Hadoop, Apache Kafka, and others.
Guided the whole team in the adoption of the newly introduced big data technologies.

Technologies: Apache Maven, Stream Processing, Apache Cassandra, Apache Storm, Database Design, Message Queues, Scrum, Git, Linux, MySQL, RabbitMQ, Redis, MongoDB, Apache Kafka, Hadoop, Spring, Java, JDBC, SQL, REST APIs, RESTful Services, Back-end, NoSQL, JavaScript, Relational Databases, Distributed Systems, Microservices, APIs, Unit Testing, Integration Testing

Software Engineer

2010 - 2013

STM Software

Implemented new features for the command control and information systems of NATO.
Developed a plugin system for a chat application used by the military personnel.
Developed an Eclipse RCP-based application for a network simulation project.

Technologies: Hibernate, Spring, Java, Back-end, Relational Databases, JavaScript, Unit Testing

Software Engineer

2009 - 2010

Soft Tech Software

Maintained existing banking applications for one of the biggest banks in Turkey.
Participated in the transformation of legacy Cobol-based applications into Java-based solutions.
Created reports using SQL and PL/SQL to provide insights about banking operations.

Technologies: Oracle Database, JDBC, Java, Back-end, Relational Databases

Experience

FlexEngage

https://www.flexengage.com/

FlexEnagage is an application designed to collect receipts from various clients via different web services. As one of the senior back-end developers, I developed new features and refactored the system to handle the increasing load. The application stack was composed of Java, Kotlin, Spring, Spring Boot, and AWS services.

Base Telecom Web Applications

https://www.base.be

Base Telecom's web application suite serves end-users, branch offices, and government offices. As a senior back-end developer, I developed new features and new integrations. During this period, I successfully worked with various technology stacks while collaborating with different teams.

Javabyexamples.com

http://www.javabyexamples.com/

Javabyexamples.com is a technology blog focusing on Java- and Spring-related topics. I am the founder of the site, and it operates on a Kubernetes cluster. I migrated the site from WordPress to Spring MVC to fully control the development process.

Education

2001 - 2006

Bachelor's Degree in Computer Science

Bilkent University - Ankara, Turkey

Certifications

DECEMBER 2022 - DECEMBER 2025

Certified Kubernetes Application Developer (CKAD)

The Linux Foundation

JUNE 2022 - JUNE 2024

Confluent Certified Developer for Apache Kafka

Confluent

SEPTEMBER 2021 - SEPTEMBER 2022

Microsoft Certified: Azure Developer Associate

Microsoft

SEPTEMBER 2020 - SEPTEMBER 2023

AWS Certified Developer Associate

AWS

OCTOBER 2019 - PRESENT

Pivotal Certified Spring Professional

Pivotal Software, Inc.

MARCH 2016 - PRESENT

Certified Developer on Apache Cassandra

Datastax

FEBRUARY 2015 - PRESENT

Cloudera Certified Developer for Apache Hadoop (CCDH)

Cloudera

JUNE 2013 - PRESENT

Oracle Certified Professional, Java SE 7 Programmer

Oracle

Skills

Libraries/APIs

JMS, REST APIs, JDBC, Jenkins Pipeline, React, Vue

Tools

Apache Maven, Git, ActiveMQ, Jenkins, IntelliJ IDEA, Amazon Simple Queue Service (SQS), RabbitMQ, Amazon Simple Email Service (SES), Terraform, Cucumber, Karate API Testing, Apache Storm, Azure App Service, Amazon Cognito, Jira, Confluence

Frameworks

Spring, Spring Boot, Spring MVC, Hibernate, Spring Security, Selenium, Angular, Hadoop, OAuth 2, AngularJS, .NET

Paradigms

Unit Testing, Object-oriented Programming (OOP), Database Design, Scrum, Microservices, Continuous Integration (CI), Continuous Delivery (CD)

Languages

Java, Java 11, SQL, JavaScript, Kotlin, Groovy, TypeScript, C#, HTML, CSS

Storage

MySQL, Amazon S3 (AWS S3), Amazon DynamoDB, Spring Data JPA, NoSQL, Relational Databases, MongoDB, Redis, Datadog, Azure Cosmos DB, Azure Blobs, PostgreSQL

Platforms

Linux, Amazon Web Services (AWS), Azure, Kubernetes, Docker, Oracle, Oracle Database, Apache Kafka, Amazon EC2, Azure Functions

Other

Back-end, Integration Testing, Web App Development, Message Queues, RESTful Services, Cloud, Distributed Systems, APIs, Apache Cassandra, Stream Processing, Amazon Kinesis, Relational Database Services (RDS), Amazon CloudSearch, OpenID Connect (OIDC), Full-stack, SOAP, Spring Cloud, Amazon RDS, Domain-driven Design (DDD)

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