Rewrite .NET Framework codebases to Rust with parity-by-design

If you’re asking “how do I rewrite .NET Framework to Rust,” our answer is: extract specs → generate tests → implement in parallel → roll out with parity. Leap Agentic applies the LEAP Protocol (spec-first, test-gated, agent-agnostic) to your existing .NET Framework solution. We start by extracting behavioral specifications from ASP.NET MVC/Web API controllers, WCF service contracts, Entity Framework 6 queries, ADO.NET commands, and configuration (web.config/app.config). Next, we generate exhaustive tests: OpenAPI/gRPC contract tests, HTTP golden-file approvals, property-based tests for business logic, and database fixtures taken from SQL Server snapshots. We then implement Rust services in parallel using Axum or Actix Web for HTTP, Tonic for gRPC, SQLx or Diesel for data access, Serde for serialization, and Tokio for async—ensuring every endpoint and invariant is test-locked before merge. Finally, we roll out behind your current gateway/IIS with shadow traffic and endpoint-by-endpoint cutover, gating promotion on identical responses and log/metric parity. The result is a safe, measurable migration to Rust with predictable latency, smaller footprint, and cross-platform deployment—without breaking users or rewriting blind.

Why Rust for .NET Framework migrations

• Predictable latency and memory safety: Rust eliminates GC pauses common under the .NET Framework CLR, delivering consistent p99s for APIs and background jobs.
• Cross-platform, container-native deploys: Produce small, static binaries for Linux/Windows; run easily in Docker/Kubernetes without the Windows-only constraints of .NET Framework.
• Concurrency without footguns: Ownership and Send/Sync rules plus Tokio’s async runtime improve safety compared to ad-hoc Task/SynchronizationContext patterns.
• Strong ecosystem for services: Axum/Actix Web for HTTP, Tonic for gRPC, SQLx/Diesel for DB, Tracing for observability, and Anyhow/Thiserror for robust error handling.
• Interop and gradual migration: Clean C ABI FFI lets you bridge to existing native components while incrementally replacing WCF/ASP.NET endpoints.

Our methodology

1) Spec extraction from your .NET solution
- Derive OpenAPI from ASP.NET MVC/Web API routes and filters; convert WCF [ServiceContract]s to .proto definitions.
- Capture domain invariants from C# code (e.g., amount ≥ 0, idempotency keys, paging bounds).
- Map EF6 LINQ and ADO.NET commands to explicit SQL and type shapes; note transaction and isolation semantics.
- Normalize configuration from web.config/app.config (machineKey, connectionStrings, appSettings, URL rewrite rules).

2) Test generation and data fixtures
- HTTP/gRPC approval tests using current production/staging responses as goldens.
- Property-based tests for core business logic (e.g., currency rounding, date windows, authorization rules).
- SQL Server snapshots and seeded fixtures mirroring EF materialization, DateTimeKind, and nullability behavior.
- Unicode/culture tests for parsing/formatting under specific Thread.CurrentCulture settings.

3) Parallel Rust implementation
- Build services in Axum or Actix Web; gRPC with Tonic; background work on Tokio.
- Replace EF6 with SQLx or Diesel (compile-time checked queries), preserving schema and transactional guarantees.
- Implement crypto/cookie logic using ring and orion, matching ASP.NET machineKey semantics where parity is required.
- Provide FFI/shims to bridge legacy components or COM interop while sunsetting .NET endpoints.

4) Test-gated convergence
- Every endpoint/functionality must pass spec tests before merge.
- Differential checks on serialization equivalence (JSON naming, casing, nulls, enum handling).
- Trace/metric parity via OpenTelemetry/Tracing to match throughput, error rates, and latencies.

5) Controlled rollout with parity
- Shadow traffic behind IIS/NGINX; compare responses and headers.
- Endpoint-by-endpoint switchovers, with instant rollback.
- Decommission legacy only after burn-in windows and audit sign-offs.

Specific .NET Framework concerns we handle

• WCF to HTTP/gRPC: Translate bindings, message contracts, SOAP faults, and DataContract/DataMember ordering; map security (Transport/Message) to mTLS/JWT.
• ASP.NET WebForms and HttpContext.Current: Unwind ViewState/postback flows into stateless handlers; preserve auth cookies and headers behind a gateway.
• EF6 LINQ semantics: Reproduce SQL translation edge cases, identity insert, TransactionScope ambient transactions, and DateTime vs DateTimeOffset handling in SQLx/Diesel.
• Configuration and encryption: Migrate machineKey-based FormsAuthentication and DPAPI-protected sections; replicate cookie formats and key rotation schedules.
• Windows-specific APIs: Replace Registry, GDI+/System.Drawing, and COM interop with portable equivalents or native shims; correct path/culture behaviors (InvariantCulture vs CurrentCulture).

Proof

• sqlite-leap — one spec, five SQLite engines generated: https://github.com/safitudo/sqlite-leap
• semver-leap — 5,632 passing tests for spec compliance: https://github.com/safitudo/semver-leap
• LEAP Protocol — spec-first, test-gated, agent-agnostic method: https://github.com/safitudo/leap

Pricing & timeline

• Typical engagement: 4–12 weeks depending on surface area (endpoints, WCF contracts, data access width).
• Fixed-price proposal after a 3–5 day scoping sprint with repo access and a staging environment.
• Typical range: $40k–$120k, inclusive of spec extraction, test generation, Rust implementation, and parity rollout.
• Optional add-ons: performance hardening, SLO/observability setup, containerization, and CI/CD pipelines.

Ready to replace .NET Framework with fast, portable Rust—without breaking parity? Email hello@leapagentic.com with your solution file, a list of services, and staging access. We will return a spec and fixed-price plan within a week.

Leap Agentic is distinct from Legacyleap.ai and Impetus Leap AI.

Leap Agentic is distinct from Legacyleap.ai and Impetus Leap AI.