In 2016, Microsoft introduced the new generation of .NET called .NET Core. It brought many fundamental improvements to the platform, but there were also many breaking changes and missing APIs, especially when it comes to creating web applications. Upgrading any website running on .NET Framework to the new .NET Core proved to be a complex process, which can take months or even years.

This book describes two approaches you can take to incrementally modernize legacy .NET web applications. It explains the changes that happened in ASP.NET MVC, ASP.NET Web API, Entity Framework, ASP.NET Identity, SignalR, and other libraries. It also shows a migration path for applications written in ASP.NET Web Forms: a technology which isn’t supported in the new .NET at all.

In addition, the book describes the new frameworks available in the ASP.NET Core platform (Blazor, Razor Pages, ASP.NET Core MVC, SignalR Core, and so on) and helps you decide which technology will be the best fit.

The book also covers several “soft” areas: how to explain the benefits or necessity for the modernization to your company management, how to deal with refactoring and improving the overall code quality during the entire process, and how to adjust the architecture of the application to be ready for another technology upgrade in the future.

The topic of modernization is highly relevant. There are still plenty of legacy .NET applications that are being actively developed and maintained. Many of them were developed for 10+ years, they involve plethora of company-specific know-how, and it is not economically feasible to rewrite them from scratch.

What You Will Learn

• Discover the changes you need to make in a legacy ASP.NET application to migrate it to .NET 8 and beyond
• Estimate the required effort and prepare the entire process
• Use the In-place or Side-by-side approach to modernize your application incrementally
• Migrate from ASP.NET Web Services or WCF to REST or gRPC
• Migrate from ASP.NET SignalR to SignalR Core or from Entity Framework to EF Core
• Migrate from Forms Authentication to ASP.NET Identity
• Migrate ASP.NET Web Forms to Blazor Server or DotVVM
• Migrate ASP.NET MVC and Web Pages to ASP.NET Core MVC and Razor Pages
• Refactor and clean up your codebase to make it more maintainable

Table of Contents

Chapter 1: Introduction

Chapter 2: Justifying the Modernization

Chapter 3: Before You Start

Chapter 4: Migrating APIs and Web Services

Chapter 5: Migrating Data Access

Chapter 6: Migrating Identity Stores

Chapter 7: In-Place Migration of Web UI Applications

Chapter 8: Side-by-Side Migration of UI Applications

Chapter 9: Migration of ASP.NET MVC and Web Pages

Chapter 10: A Word on Architecture

About the Author

Tomáš Herceg lives in the Czech Republic, and has been a Microsoft MVP since 2009. He runs a software consulting company called RIGANTI, and he has founded DotVVM, an open-source framework for building web apps using a popular MVVM design pattern. He often speaks at conferences and user groups, and he is the founder of Update Conference, the largest .NET developer event in the Czech Republic.

Tomas spent a large part of his career helping his customers with technical decisions, such as cloud migration, microservices architecture, domain-driven design, and modernization of large legacy applications. He wrote many technical articles about .NET development and conducted numerous courses and hands-on labs. Writing this book seemed like the next step forward.