NJDHS- DFD Principal C#/.NET Engineer - Mainframe Modernization & EF Core

Lead/Principal C#/.NET Engineer with expert-level Entity Framework Core experience to lead the modernization of a mission-critical legacy benefits system hosted on AWS Cloud.

Will start 100% on site for 30 days & move to hybrid 3 days onsite 2 days remote

Position Summary

We are modernizing a large, mission-critical Honeywell Bull mainframe benefits system (FAMIS) converting ~1.5M lines of COBOL and ~160K lines of JCL to C#/.NET , migrating an IDS-II hierarchical database to PostgreSQL , and deploying on AWS . Converted code is delivered by an automated modernization vendor in an \"as-is\" state. This Lead/Principal role owns the refactoring of that converted code into clean, maintainable, high-performance, production-grade C#/.NET , defines the data-access architecture using Entity Framework Core against PostgreSQL , sets engineering standards for the team, and safeguards functional equivalence to the legacy system. This is a benefits system serving NJ families correctness, performance within the nightly batch window, and maintainability are paramount.

Key Responsibilities

C# / .NET Engineering

• Refactor machine-converted, COBOL-derived C# into idiomatic, maintainable .NET meaningful naming, proper OO/domain design, separation of concerns, dependency injection
• Work in .NET (Core) / .NET (latest version); apply modern C# language features (LINQ, async/await, records, pattern matching, nullable reference types, generics)
• Design and implement service layers, domain models, and APIs (ASP.NET Core Web API) that back the Angular UI
• Refactor legacy batch/procedural logic (converted from COBOL/JCL) into maintainable, testable .NET; handle exact decimal/financial arithmetic (decimal, rounding rules) to preserve benefit-calculation correctness
• Optimize performance to meet the nightly batch window (profiling, memory management, async I/O, parallelism where safe)

Entity Framework / Data Layer

• Own the data-access architecture using Entity Framework Core against PostgreSQL (Npgsql provider)
• Refactor the auto-generated/converted data-access layer into a clean, performant EF Core model
• Design entity models, DbContext configuration, Fluent API mappings, relationships, keys, and indexes reflecting the IDS-II PostgreSQL schema (168 tables, 4,024+ fields)
• Optimize EF Core queries (eager/lazy/explicit loading, projection, AsNoTracking, compiled queries, batching) to avoid N+1 and meet performance SLAs on high-volume batch operations
• Manage EF Core migrations, concurrency handling, transactions, and connection resiliency
• Map legacy data types and semantics correctly (packed decimals, fixed-width, EBCDIC-origin data, condition codes) to PostgreSQL/EF types without behavioral drift
• Contribute to the COBOL-field PostgreSQL-column business-term data dictionary

Technical Leadership

• Define and enforce C#/.NET coding standards, architecture patterns, and refactoring guidelines for the engineering team
• Serve as senior technical authority on the converted codebase; make cross-cutting design decisions
• Mentor mid/junior C# developers; perform code reviews; drive engineering quality

Partner with the Technical Manager/Architect on target architecture and the refactoring strategy

Quality, Testing & Delivery

• Ensure functional equivalence: build unit and regression tests (xUnit/NUnit, Moq) to validate refactored code against the legacy baseline; fix FET-surfaced defects
• Integrate with CI/CD (AWS CodeBuild/CodePipeline), enforce quality/security gates (SonarQube, static analysis, secure coding/OWASP)
• Collaborate with FAMIS SMEs to preserve business logic (eligibility, benefit calculation, payments, EBT)
• Deliver incrementally within Scrum; document design and decisions

Required Qualifications

• 12-15 years of professional C#/.NET software engineering, including senior/lead responsibilities
• Deep expertise in C# and the .NET platform (.NET Framework and .NET Core / .NET 6/8+), including async programming, memory/performance optimization, and modern language features
• Expert-level Entity Framework / EF Core : entity modeling, Fluent API, migrations, query optimization, transactions, concurrency, provider-specific behavior
• Strong relational database skills; PostgreSQL strongly preferred (Oracle/SQL Server acceptable) schema design, indexing, query tuning, stored procedures
• ASP.NET Core Web API design (REST) for front-end integration
• Solid software design: SOLID, design patterns, domain modeling, layered/clean architecture, dependency injection
• Testing discipline: unit/integration/regression testing frameworks; TDD/mocking
• Git, CI/CD, and static code analysis (SonarQube)
• Proven ability to read, reason about, and safely refactor large, unfamiliar codebases
• Exceptional attention to correctness financial/benefit calculation accuracy

Preferred / Nice to Have

• Legacy modernization experience COBOL-to-C#/Java conversion, mainframe migration, or automated-transformation tooling
• Understanding of mainframe concepts (COBOL, JCL, batch processing, hierarchical/CODASYL databases like IDS-II/IMS) to reason about source behavior
• High-volume batch processing performance tuning
• AWS experience (ECS/EKS, Lambda, RDS for PostgreSQL, S3, CloudWatch, IaC/CloudFormation)
• Experience integrating with enterprise job schedulers (Stonebranch, Control-M, CA7)
• Government / benefits / healthcare or other regulated, high-correctness domains
• Npgsql specifics, EF Core performance internals, or ORM migration experience

Success in the First 90 Days

• Establish the C#/.NET and EF Core standards, patterns, and reference implementation the team will follow
• Refactor a representative set of converted programs (including a benefit-calculation and a batch program) to clean, tested, performant C# validated against the legacy baseline
• Define the EF Core data-access approach against PostgreSQL, including query-performance guardrails for batch workloads
• Mentor the team and set the code-review/quality bar

Required/Desired Skills

Skill Required /Desired Amount of Experience
C# Programming Experience	Required	10	Years
.NET Core / .NET 6/7/8/10 Experience	Required	10	Years
.NET REST/WEB API Development Experience	Required	5	Years
Entity Framework Core and LINQ and async/await patterns Experince	Required	10	Years
Solid software design: SOLID, design patterns, domain modeling, layered/clean architecture, dependency injection	Required	5	Years
Angular 17+, Typescript and Node.js experience	Required	5	Years
Strong relational database skills; PostgreSQL strongly preferred (Oracle/SQL Server acceptable) schema design, indexing, query tuning, stored proc	Required	5	Years
unit/integration/regression testing frameworks; TDD/mocking	Required	5	Years
Git and static code analysis (SonarQube)	Required	5	Years
Docker containerization and CI/CD pipeline experience (AWS CODEPIPELINE OR GitHub Actions)	Required	3	Years
AWS cloud native applications (S3, SNS, SQS, ECS, RDS, EC2, Lambda)	Required	3	Years

Questions

No. Question

Question1

Absences greater than two weeks MUST be approved by CAI management in advance, and contact information must be provided to CAI so that the resource can be reached during his or her absence. The Client has the right to dismiss the resource if he or she does not return to work by the agreed upon date. Do you agree to this requirement?

Question2

What is your candidate's email address?

Question3

Where does your candidate currently reside (City & State)?

Question4

If your candidate resides more than 1 hour from the Client site, will your candidate relocate for the position?

Question5

Is your candidate available for a Round 1, in-person interview?

Question6

Do you agree to the maximum hourly Vendor Rate of $$$(excluding the Efficiency Fee)?