Preface

Microsoft has released the second major version of its open source and cross-platform web application framework, ASP.NET Core. This runs on top of .NET Core, which is also open and is now, likewise, at version 2. ASP.NET Core is primarily used with the C# programming language, but F# and VB.NET can also be used. You are no longer tied to using Windows with ASP.NET, and you can now develop on a Mac and deploy to Linux. The new platform also offers much higher performance.

Version 2 is what version 1 should have been, as the first stable release was not really production ready. Major changes were made very late in the release candidate stage. Thankfully, things have stabilized with the new tooling, and you can now use ASP.NET Core in earnest.

In today's world, a web application that only performs well on a developer's workstation and fails to deliver high performance in production is unacceptable. The way that web applications are now deployed at scale has changed, and development practices must adapt to take advantage of this. By reading this book, you'll learn about the modern way of making high-performance web applications, and how to do this with ASP.NET Core.

This is a high-level book that provides performance tips that are applicable to web application development with any programming stack. However, it focuses specifically on C# and ASP.NET Core. The reader should already know how to build a web app, though not necessarily in .NET Core.

This book addresses web application performance improvement techniques, from both a general standpoint (HTTP, HTTPS, HTTP/2, TCP/IP, database access, compression, I/O, asset optimization, caching, message queuing, and other concerns) and from a C#, ASP.NET Core, and .NET Core perspective. This includes delving into the details of the latest frameworks and demonstrating software design patterns that improve performance.

Common performance pitfalls will be highlighted, which can often occur unnoticed on developer workstations, along with strategies to detect and resolve these issues early. By understanding and addressing the challenges upfront, any nasty surprises can be avoided when it comes to live deployment.

Many performance improvements will be introduced, along with the trade-offs they entail. We will strike a balance between premature optimization and inefficient code by taking a scientific and evidence-based approach, focusing on the big problems, and avoiding changes that have little impact.

We assume that you understand the importance of the performance for web applications, but we will recap why it's crucial. However, you may not have had any specific or actionable advice, or much experience of performance problems occurring in the wild.

By reading this book, you'll understand what problems can occur when web applications are deployed at scale to distributed infrastructure, and you will know how to avoid or mitigate these issues. You will gain experience of how to write high-performance applications without having to learn about issues the hard way, possibly late at night.

You'll see what's new in ASP.NET Core, why it's been rebuilt from the ground up, and what this means for performance. You will understand the future of .NET Core and how you can now develop and deploy on Windows, macOS, and Linux. You'll appreciate the performance of new features in ASP.NET Core, including updates to the Razor view engine, and you will be aware of cross-platform tools such as Visual Studio Code.