1. CS4540 Special Topics in Web Development Introduction to .NET
Chengyu Sun
California State University, Los Angeles

2. Libraries
Collections of programs that perform specific tasks, e.g. I/O, GUI, network communication, implementations of various data structures and algorithms …

3. Libraries Cannot Be Shared By Different Languages
Java Program
C++ Program
Python Program
Java
Libraries
C++
Libraries
Python
Libraries
The same functions have to be implemented again and again for different languages
Programmers have to re-learn the API of the same functions when they use a different language

4. The .NET Platform … .NET Programming Languages .NET Platform Visual
Basic C# F#
Base Class
Library (BCL)
I/O
GUI
Networking
DB Access
Security
.NET
Platform
Common Intermediate Language (CIL)
Common Language Runtime (CLS)

5. … The .NET Platform
.NET applications run on Common Language Runtime (like JVM for Java)
.NET applications can be written in many different languages
Compiled into Common Intermediate Language
Share the same Base Class Library
Additional cross-language support

6. Additional .NET Terminology
Common Type System (CTS) specifies all possible data types and programming constructs supported by CLR
Common Language Specification (CLS) is a subset of CTS that all .NET languages must support

7. .NET Family of Frameworks

8. So Which Framework to Use?
.NET Core when possible – it's basically a new version of the .NET framework that is open-source, cross-platform, and modular
Xamarin for mobile app development
.NET Framework for Windows desktop applications that require Windows-specific libraries such as Windows Forms or Window Presentation Foundation (WPF)

9. .NET 5 …

10. … .NET 5 Announced in May 2019 To be released in Nov 2020
Based on .NET Core with all the capabilities of .NET and Xamarin/Mono
Single framework for all platforms

11. Readings Pro C# 7: Chapter 1
.NET Core, .NET Framework, Xamarin – The “WHAT and WHEN to use it”
Introducing .NET 5