Building a robust, web-based application backed by well-grounded software practices

Munich Re's North America Data Engineering team (DE), within the Integrated Analytics group, brings unique models to life. Data Engineers wear many hats: they are designers, developers, and debuggers. Our team creates and maintains the infrastructure that our business partners use to integrate data science insights into pre-existing or novel workflows.

Recently, our team delivered a web-based, client-facing application that is now used in the daily underwriting workflow – allowing the client to receive case data and provide model scores through API requests. In this case study, we explore the many design decisions and technical expertise that made it possible to build and integrate a non-trivial underwriting solution within a short timeframe. This process is the software development and deployment cycle in action, customized to align with the evolving insurance industry and our client's specific needs.

DE devised a secure and robust technology stack that leveraged the best-suited innovations for the task and utilized an Agile software development process to ensure the client's needs were met expediently. The stack consists of two main parts: the backend (a collection of the pieces responsible for processing and storing the data) and the frontend (a client-facing user interface). The table (Technical Components) below highlights a few technical components of the application and the rationale for selection. The design decisions were oriented around a cloud-native architecture. Security received further consideration and concern, which is discussed in detail later in this article.

What is Agile Software Development? Agile is a project management framework that encourages frequent, incremental deliverables and high levels of collaboration. Feature development, testing, and deployment tasks are planned and spread equally amongst team members, allowing quality work to be produced quickly. For this project, as features were developed, they were deployed and made available for the client to test in real-time, resulting in iterative improvements.

The application heavily utilizes Azure Pipeline to build and deploy the application created using Azure App Services. When changes are made to the code, Azure Pipeline runs a predefined series of jobs encompassing the app's components, including automated testing. This process is commonly called continuous integration and continuous deployment (CI/CD), where manual intervention is limited. The testing environments are identical copies of the production environment where the final application runs.

Security is paramount since data submitted to the API contains sensitive information, and the model response is also proprietary. During development, sensitive material was received from the client using Secure File Transfer Protocol (SFTP) rather than email. SFTP provides a secure means of transferring files. As part of the deployment, all traffic to and from the API is securely encrypted. To ensure no malicious user can make API requests, the API endpoint is accessible only to users with an API access key that Azure App Services have authenticated. Also, the production and non-production app instances are isolated and use different databases with different access keys. If a malicious user ever received access to the API key, that user could post requests but would not read any of the information stored in the databases. Logging can also assist in detecting intrusion attempts by detecting a suspicious web crawling pattern, and the app is made temporarily unavailable while the event is investigated.

Finally, the entire Azure infrastructure is contained in a virtual network. A virtual network isolates the resources inside the network from the public. All virtual network resources can communicate using private IP addresses, but the network is generally hidden from the public. Azure Firewall also monitors and controls the incoming and outgoing network traffic based on predetermined security rules. This establishes a barrier between a trusted internal network and untrusted external network, such as the Internet, and provides another security layer.