Mustafa Sen

A dashboard application written in AngularJS and .NET MVC that provides page navigation, authentication, and user authorization and has call-taker application integration functionalities. Vital issues and significant technical depth had increased the application's maintenance costs and discouraged people from modifying the codebase.

I rewrote the application in Angular 9 as a single-page application, along with one of the PrimeNG templates in the new version. This implementation improved maintenance costs, testability, and performance, and the project encouraged others to work on the codebase.

A web-based application written in C #, .NET MVC, and AngularJS to manage the company's internal documents. The system stores documents, tracks versions, and controls access according to the user roles. I designed the system to be scaled horizontally if needed.

Before this application, a shared network directory stored the documents. Users saved documents to the directory and accessed them there without any access control, versioning, or auditing. Also, the documents could not be accessed from outside the network.

After developing the application, documents were stored in the shared directory and other data was migrated to the new system. This application enabled users to access documents from anywhere via a web browser and their usernames and passwords. This also enabled the IT staff to monitor user access and any inappropriate usage and report them to supervisors. Finally, this prevented document losses and security breaches.

Now, millions of documents are stored in the system, and several thousand company employees use it.

A distributed database system running over unreliable and low-bandwidth networks. It provides eventual consistency but is always available to all nodes in the mesh, and any node in the mesh has a backup. When there is no network partition, all nodes are synchronized, and all changes are sent to the other nodes by the center.

However, if there is a network partition, in other words, some nodes do not have a connection to the center, and local changes are stored separately in the nodes. When a connection is established to the center, such local changes are synchronized with the center. Then the center synchronizes these changes to the other nodes. With this strategy, all nodes become available to their clients, even when they are inconsistent.

I designed the system to operate as geographically distributed nodes in unreliable networks. I implemented the system in modern C++ (C++11 and C++14) to run in Linux and used Microsoft SQL Server underneath to store actual data, and I designed the system to also use IP multicasting to share data among the nodes.

An application to track and visualize network equipment, software, and hardware alarms. The system has several protocols to track alarms, such as SNMP to read alarms and receive network equipment and radio-link device traps.

I developed the system in two parts: a WPF-based desktop application to visualize and manage the alarms, written in C#, and a Windows service to track and save the alarms in the background, also written in C#.

A switching system for a professional mobile radio (PMR) system that handles control signaling with radio equipment, real-time switching of voice frames of radio equipment, and the transmission of short message service (SMS) packages.

While co-developing this switching system for DMR, APCO25, and TETRA standards, I focused on implementing push to talk (PTT) service (both group and unit to unit calls), SMS, packet data service, and management of RF resources. The software was first developed in C# and .NET Framework to run as a Windows service. A few of the services were reimplemented in C++ to run in Linux to meet additional performance requirements.