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Halil Ayyildiz
Verified Expert in Engineering
Software Developer
Ankara, Turkey
Toptal member since October 22, 2020
Bio
Halil is a software developer with in-depth and broad expertise in back-end systems and cloud services. He also has hands-on experience in the reliability and scalability of cloud systems. Halil is a lifelong learner and software expert who chooses the proper tools and algorithms to best solve business problems.
Portfolio
Google
Google Cloud Platform (GCP), Go, Python, Cloud, Linux
TomTom
Redis, Amazon Web Services (AWS), NoSQL, API Integration, REST APIs...
Siemens
Redis, NoSQL, RabbitMQ, API Integration, REST APIs, Oracle, TypeScript...
Experience
- Back-end Development - 12 years
- Java - 12 years
- JavaScript - 10 years
- Cloud - 8 years
- Spring - 8 years
- Kubernetes - 4 years
- Go - 4 years
- Python - 4 years
Work Experience
Senior Software Developer
2022 - PRESENT
- Identified and improved reliability metrics for top cloud customers.
- Contributed to planet-scale tools that monitor and improve the reliability metrics of cloud customers.
- Developed workflows to monitor and calculate the SLO performance of top cloud customers.
Technologies: Google Cloud Platform (GCP), Go, Python, Cloud, Linux
Senior Software Developer
2018 - 2022
TomTom
- Developed APIs for developers which provide information about places in TomTom-powered maps, libraries, applications, and services worldwide and are published at Developer.tomtom.com/search-api.
- Built four new microservices from scratch, including parking spaces, fuel prices, Rich POI, and charging availability services.
- Improved data release duration from more than eight hours to two hours by optimizing the data storage method and storing data in an embedded database (RocksDB) instead of a file system-based structure.
- Switched the infrastructure from an Azure VM-based custom solution to an AKS (Azure Kubernetes Service) based one, which decreases cost and improves the reliability of the services.
- Designed a processing pipeline for regularly fetching and parsing Foursquare data and incorporating it into the TomTom Rich POI service.
- Supported the product owner with the design of API fields to maintain the readability of the response and flexibility for further changes.
Technologies: Redis, Amazon Web Services (AWS), NoSQL, API Integration, REST APIs, Microservices, Protobuf, gRPC, Gatling Load Testing, Karate API Testing, Jenkins, Spring Boot, Java, Helm, Docker, Kubernetes, Terraform, Azure, Node.js, Back-end Development, Apache Kafka, TypeScript, SQL, APIs, Git, Memcached, GraphQL, Cloud, Linux
Senior Software Engineer and Technical Lead
2012 - 2018
Siemens
- Managed the software development activities of a team of five to seven developers using Agile software development methodologies for the projects executed in several countries, including Turkey, Austria, Saudi Arabia, Spain, and Norway.
- Developed an outage management system that detects and manages electricity outages in smart grid networks and integrates with the electricity distribution company's ERP systems.
- Guided the software development team that developed the core components, such as outage management and mobile outage management system, and built the integration with customer systems, including SAP PM, SAP WFM, and SAP CRM.
- Participated actively in technical customer-facing meetings to collect requirements and decide design approaches.
- Supported external projects in other countries, such as requirements collection in Spain and the implementation of the outage management module in Norway.
- Proposed new ideas to deal with customer requests in modeling low voltage network model of utility companies with more than two million customer feeding points.
- Introduced innovative extensions to an outage management system, such as a mobile application for customers. The source code for a simple prototype can be found at github.com/halilayyildiz/outagetracker.
Technologies: Redis, NoSQL, RabbitMQ, API Integration, REST APIs, Oracle, TypeScript, Spring Integration, Spring, Spring Data JPA, Node.js, Angular, JavaScript, Java, Back-end Development, Amazon Web Services (AWS), Kubernetes, SQL, APIs, Git, Linux
Software Development Engineer
2010 - 2012
Anelarge
- Developed a data augmentation engine that augments any given text content by using linked data sources and semantic web technologies.
- Implemented linked data vocabulary, information extraction, text mining algorithms, such as NER, WSD, and more, and recommendation system algorithms like collaborative filtering.
- Contributed to an open-source software project, DBpedia, by implementing mappings for Turkish Wikipedia: Mappings.dbpedia.org/index.php/Mapping_tr.
- Published a whitepaper and presented it at Proceeding SWIM '11 Proceedings of the International Workshop on Semantic Web Information Management in Athens, Greece: Dl.acm.org/doi/10.1145/1999299.1999305.
Technologies: REST APIs, MySQL, Spring, Java, Back-end Development, SQL, APIs, Git, Memcached, Linux
Back-end Software Developer
2008 - 2009
Sebit A.S.
- Contributed to the Vitamin project back-end team, which serves online educational content, such as animations, learning objects, games, exams, and so on, to 800,000+ users.
- Implemented an online testing platform where 100,000+ students take online tests concurrently and calculate the results afterward.
- Developed web-based online education components on top of a distributed, scalable, and fault-tolerant infrastructure.
Technologies: REST APIs, JavaScript, PostgreSQL, Java, Back-end Development, SQL, Git, Memcached, Linux
Project History
TomTom Search API
Developed four new microservices from scratch and was responsible for the products from end to end, from software design to final deployment, including on-call duty. I've made a remarkable impact on the cost optimization of the cloud environment without sacrificing service availability.
TomTom has a broad list of location technology products. One major group is the search product unit, responsible for providing online search services on the top of map data.
I've been working on the search product unit to provide extended search APIs to the customers. Those APIs cover a list of different capabilities, including parking space availability, fuel prices, electric vehicle charging station availability, and rich data services. All of these products are available worldwide via highly available, distributed, resilient cloud deployments located in multiple geographical regions to serve low latency APIs to the customers. These services are being used by cars and Azure maps back-end developers who have acquired the developer API key via the TomTom developer portal.
TomTom has a broad list of location technology products. One major group is the search product unit, responsible for providing online search services on the top of map data.
I've been working on the search product unit to provide extended search APIs to the customers. Those APIs cover a list of different capabilities, including parking space availability, fuel prices, electric vehicle charging station availability, and rich data services. All of these products are available worldwide via highly available, distributed, resilient cloud deployments located in multiple geographical regions to serve low latency APIs to the customers. These services are being used by cars and Azure maps back-end developers who have acquired the developer API key via the TomTom developer portal.
Siemens OMS | Outage Management System
Siemens Outage Management System is an on-premise software solution for utility companies that tracks outages in the electricity network, providing full lifecycle management of the outages, starting from outage detection on the grid up to report generation for power loss calculations of the customers.
I managed a team of five to six developers. We handled the extension of the global product according to local market rules. We also implemented the integration layer for external ERP systems, including SAP-PM, SAP CRM, SAP WFM, and smart meters. I actively participated in the collection of customer requirements and the design and development of the product. I also designed an integration medium that supports two-way communication between the OMS and customer ERP systems.
I've successfully delivered and customized OMS to four different utility companies in Turkey and one another in Saudi Arabia. Moreover, I've supported Siemens branches in Spain and Norway for their local OMS solutions.
At the end of these projects, I successfully designed the outage management workflow and reduced response time and average outage duration of reported failures. I also generated monthly and yearly reports that comply with local regulations.
I managed a team of five to six developers. We handled the extension of the global product according to local market rules. We also implemented the integration layer for external ERP systems, including SAP-PM, SAP CRM, SAP WFM, and smart meters. I actively participated in the collection of customer requirements and the design and development of the product. I also designed an integration medium that supports two-way communication between the OMS and customer ERP systems.
I've successfully delivered and customized OMS to four different utility companies in Turkey and one another in Saudi Arabia. Moreover, I've supported Siemens branches in Spain and Norway for their local OMS solutions.
At the end of these projects, I successfully designed the outage management workflow and reduced response time and average outage duration of reported failures. I also generated monthly and yearly reports that comply with local regulations.
Education
2011 - 2013
Master's Degree in Software Engineering
Middle East Technical Univesity - Ankara, Turkey
2004 - 2008
Bachelor's Degree in Computer Engineering
Middle East Technical Univesity - Ankara, Turkey
Certifications
SEPTEMBER 2016 - PRESENT
Certified Professional for Software Architecture
International Software Architecture Qualification Board (ISAQB)
Skills
Libraries/APIs
Node.js, REST APIs, Protobuf
Tools
Gatling Load Testing, Karate API Testing, Git, Terraform, Jenkins, Helm, RabbitMQ
Languages
Java, SQL, JavaScript, TypeScript, Python, Go, GraphQL
Frameworks
Spring, Spring Boot, gRPC, Angular, Spring Integration
Paradigms
Microservices
Platforms
Azure, Kubernetes, Docker, Amazon Web Services (AWS), Oracle, Apache Kafka, Linux, Google Cloud Platform (GCP)
Storage
Redis, Memcached, PostgreSQL, MySQL, RocksDB, NoSQL, Spring Data JPA
Other
Cloud, RESTful Web Services, API Integration, Back-end Development, APIs
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