Job Description
Job Title: Principal C#/.NET Engineer Mainframe Modernization & EF Core
Job Id :26-05086
Location: Hamilton, NJ
Duration: 09 months' contract
Description:
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.
Position Summary
We are modernizing a large, mission-critical Client 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
Job Id :26-05086
Location: Hamilton, NJ
Duration: 09 months' contract
Description:
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.
Position Summary
We are modernizing a large, mission-critical Client 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
Skill Table:
| 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 |
Compensation:
The hourly rate for this position is between $56.00-$60.00 per hour.
Factors which may affect starting pay within this range may include [geography/market, skills, education, experience and other qualifications of the successful candidate].
Benefits:
Sunrise offers ACA compliant medical coverage/dental insurance/vision insurance to all employees. We also offer Sick time benefits as required per State regulations.
Contact:
Jaya Balaji: jayabalaji.s@sunrisesys.com | (732) 515-5373 | URL: www.sunrisesys.com
Numbers & Facts
| Location | Hamilton, NJ |
| Industry | Staffing/Employment Agencies |
| Salary | $56–$60 Per Hour |
| Company Size | 100 to 499 employees |
| Year Founded | 1990 |
| Website | http://www.sunrisesys.com/ |
About Company
Sunrise Systems was founded in 1990 with a clear vision to deliver world-class staffing service solutions in all labor categories, including IT consulting and solutions; all with the commitment to provide service that exceeds expectations and become the most trusted name in the industry. More than two and a half decades later, we pride ourselves on being at the forefront of the staffing industry. Combining our deep industry expertise, insights, and global resources, we have partnered with our clients to connect them with top professionals across several different industries.
We provide cost-effective Managed Staffing Solutions, Information Technology and Information Technology Consulting Services to several Fortune 500 companies and U.S. Government agencies. We provide our clients with flexible engagement models and customized products that are budget and time specific. Understanding the challenges that every business faces, we offer our services either on-site at the clients' site or from one of our globally distributed technology centers. Our onshore and offshore development capabilities ensure that we excel at meeting customer requirements every single time.
Our collective business experience spans over two and a half decades and ranges from:
- Business, management, and technical fields
- Information technology consulting and software solutions.
- Providing strategic support for the development and long-term growth of new business ventures across several industries including but not limited to; accounting, banking, finance, and recruitment.
- Motivating technology staff and establishing partnerships with Fortune 500 companies
Sunrise Systems has a vast range of competence in:
- Design, development, and support of cloud-based solutions from simple to highly complexed
- Database administration of multi-platform applications, complex databases, and web-based environments that include all aspects of installation, planning, maintenance, and monitoring.
- Data processing and data migration
- Application re-engineering and platform migration
- Working with the Information Systems and end-user communities at all levels to resolve issues and establish consensus.
Skills
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