AWS re:Invent 2025 - Vibe modernize your .NET applications using AWS Transform and Kiro (MAM343)

Modernizing Legacy .NET Applications with AWS Transform and Kiro

Challenges of Legacy .NET Applications

• Many organizations still manage legacy .NET Framework applications built over the past 20 years
• These applications often rely on Windows-specific components and infrastructure like SQL Server and MSMQ
• Modernizing these applications is crucial to take advantage of cloud-native architectures and technologies

Key Modernization Steps

1. Code Modernization: Port legacy .NET Framework applications to the latest .NET versions (e.g. .NET 8, .NET 10)
2. Architecture Modernization: Migrate from monolithic to microservices-based architectures
3. Infrastructure Modernization: Move from Windows-based hosting to cloud-native platforms like Linux, containers, and serverless

Using AWS Transform and Kiro for Modernization

AWS Transform for .NET

• Agentic AI service that automates the process of porting .NET Framework applications to newer .NET versions
• Analyzes the codebase, performs the transformation, and validates the output
• Supports bulk modernization of multiple applications at once

Kiro AI IDE

• AI-powered IDE that helps developers fix compilation issues and build modernized .NET applications locally
• Uses natural language prompts to guide the development process
• Supports both VIP coding (prompt engineering) and spec-driven development workflows

Modernizing the Kontoso University Application

1. Code Modernization with AWS Transform:

   • Ported the .NET Framework 4.8 Kontoso University application to .NET 8
   • Automated the transformation process, resulting in a new branch with the modernized codebase

2. Fixing Compilation Issues with Kiro:

   • Used Kiro's natural language prompts to identify and resolve package version conflicts and other build errors
   • Iteratively built and tested the .NET 8 application locally

3. Replacing SQL Server with Amazon Aurora Postgres:

   • Leveraged Kiro's spec-driven development to migrate the application's database from SQL Server to Amazon Aurora Postgres
   • Automatically updated the data access code, connection strings, and other related components

4. Migrating from MSMQ to Amazon SQS:

   • Used Kiro's spec-driven development to extract the notification service into a separate microservice
   • Implemented the new SQS-based notification system, preserving the existing API interfaces

5. Refactoring the UI to React:

   • Leveraged Kiro's spec-driven development to migrate the Razor view-based UI to a React-based frontend
   • Automatically generated the necessary API controllers, data transfer objects, and other supporting components

6. Deploying to AWS with CDK:

   • Created a CDK project in C# to provision the required AWS infrastructure, including EC2 instances, Aurora Postgres, SQS, and CloudFront
   • Automated the deployment process, including steps to update the React application with the correct API endpoint URLs

Key Takeaways

• AWS Transform and Kiro provide a powerful, AI-driven approach to modernizing legacy .NET applications
• The combination of automated code transformation, local development support, and spec-driven architecture design streamlines the modernization process
• By migrating from Windows-specific components to cloud-native services like Aurora Postgres and SQS, the modernized application becomes more scalable, resilient, and cost-effective
• The use of microservices and React for the UI improves the application's flexibility and maintainability
• The CDK-based deployment automation ensures a reliable, repeatable, and infrastructure-as-code approach to hosting the modernized application on AWS

Real-world Impact

• The modernization techniques demonstrated can be applied to a wide range of legacy .NET applications, helping organizations unlock the benefits of cloud computing and modern software architectures
• By reducing the technical debt and operational complexity of legacy systems, companies can focus more on delivering value to their customers and driving business growth
• The AI-powered tools like AWS Transform and Kiro lower the barrier to entry for .NET modernization, making it accessible to a broader range of development teams

Conclusion

The presentation showcased a comprehensive approach to modernizing legacy .NET applications using a combination of AWS Transform, Kiro AI IDE, and AWS CDK. By automating key steps in the modernization process and leveraging cloud-native services, organizations can unlock significant benefits in terms of scalability, resilience, and maintainability of their .NET applications.