modernizing/migrations

Question 1

Tell me about a system modernization or migration project you’ve worked on

Answer 1

• Migrated SQL Server databases to Azure Managed Instances.
• Optimized stored procedures

Question 2

Have you migrated a legacy .NET Framework/WinForms system?

Answer 2

• Experience maintaining legacy WinForms.
• Approach: decouple UI/business logic, create APIs, migrate modules incrementally.

Question 3

How do you decide between .NET Framework vs .NET Core

Answer 3

• Default to .NET Core for performance, cross-platform, new features.
• Only use Framework if legacy dependencies require it.

Question 4

Experience building or consuming REST APIs

Answer 4

• Enhanced AML REST APIs (~20% more data exposure).
• Integrated third-party APIs (FactSet, ICE).

Question 5

Optimizing SQL queries & stored procedures

Answer 5

• indexes
• query plans
• large joins

Question 6

Writing testable & resilient C# code

Answer 6

• Separate business logic from UI/data access.
• Use dependency injection and interfaces for mocking.
• Unit tests for edge cases; single-responsibility methods.

Question 7

Experience managing builds & deployments

Answer 7

• DLL updates on IIS (Vertafore).
• TeamCity pipelines for builds/tests/deployments (ACA Group).

Question 8

How would you ensure quality during modernization?

Answer 8

• Implement unit tests that capture legacy behavior
• Serves as safety net during refactoring

Question 9

Unit/Integration/Regression Testing

Answer 9

• Unit Tests: Focus on a single function, fast feedback.
• Integration Tests: Ensure API, DB, and services interact correctly.
• Regression Tests: Preserve legacy system behavior during modernization.

Question 10

Strangler Fig Pattern

Answer 10

• A technique to replace a legacy system incrementally.
• Wrap the old system with new components and gradually route traffic to the new services.
• Eventually “strangles” the old system until it can be fully retired.
• Helps avoid big-bang rewrites and reduces risk.

Question 11

How to break apart a monolith

Answer 11

• Identify seams/boundaries: modules with clear domain ownership (billing, quotes, policies).
• Extract services starting from low-risk areas or read-only functionality.
• Replace shared DB patterns with domain specific DBs (Claims DB, Billing DB, etc)
• Introduce eventing or messaging as systems become decoupled.

Question 12

How to reverse-engineer undocumented logic

Answer 12

• Analyze queries, stored procedures, and UI workflows.
• Use debugging tools, call tracing, and logs.
• Ask SMEs and senior engineers.
• Document as you go (sequence diagrams, flow diagrams).