Meteorology Weather Forecast App is the official mobile application of Turkey, maintained by Turkish State Meteorological Service. Mobile applications are used by over 4 million unique users while the web page has nearly 100 million unique visitors in a year (2021).

I did lead four different teams to develop the following applications and services, and I implemented several components in them:

• Mobile application for iPhones
• Mobile application for Android phones
• Weather data presentation module of the Web application
• Backend services to be consumed by the mobile applications and by the web page of Turkish State Meteorological Service itself.

We implemented the iOS app with Swift and Android app with Java. We designed the backend services with a polyglot persistence mechanism where we used relational (SQL) and document (NoSQL) databases together.

The backend is composed of two different, independently running server applications. One is an ETL application which collects weather forecast related data from various sources and puts into a MongoDB cluster and updates the data in different frequencies and arranges the documents in MongoDB. The ETL application is implemented with Java. The second system is a Node application, coded in JavaScript, utilizing Express and deployed in a distributed fashion with PM2 inline with the MongoDB cluster. We implemented an automatic CI/CD workflow using GitLab CI/CD for continuous integration and deployment to manage the deployment of the backend services to the cluster. There are millions of users of the mobile apps in both platforms and the backend services run smoothly for years.

Some functionalities offered by the mobile applications can be listed as in the following:

• Detailed instant weather information for cities and districts.
• Detailed hourly and daily forecasts for cities and districts.
• Instant weather information and forecasts for the closest location calculated with GPS.
• Push notifications for meteorological alerts.
• Satellite and radar images over map.
• Current sea temperatures and snow ticknesses over map.
• Marine forecasts about weather events in our seas.
• Meteorology Radio.
• Sharing weather information, meteorological alerts and images taken with in-app camera on social media.
• Quick launch with 3D Touch (only in iOS).
• Displaying weather information without launching the app through Widget.