Introduction

Microsoft introduced Dot Net programming concepts in the year 1999. Dot Net contains a collection of languages like VC#.Net, VB.Net, VJ#.Net, VC++.Net, ASP.Net(specification)...etc. All the Dot Net programming languages works based on a common platform called Dot Net framework.

Dot Net Framework Main Objectives:

1. Supports platform independent concepts
2. Supports language independent concepts
3. Supports language interoperability concepts
4. Supports pure OOPs concepts
5. Supports to develop background processes with the help of windows services
6. Supports to work with databases with the help of ADO.NET
7. Supports to develop 3-tier architecture with the help of Dot Net remoting
8. Supports to develop game programming with the help of multi-threading
9. Supports to work with link programming
10. Supports to work with WPF for developing animations

Platform independent concepts: As .exe and .dll files work in any operating system with the help of CLR, hence .Net is called as platform independent. (.exe) is executable file, it consists of executable code, and (.dll) is dynamic link library file it consist of reusable code. .exe and .dll files contains the code in the format of bytecode is also called as MSIL (microsoft intermediate language) code. Machine language is also called as native code. CLR is common language runtime, CLR software converts byte code into native code. Dot Net is platform independent but CLR software is platform dependent. One question arises if we go in detail, that is either Dot Net is pure platform independent or not? Answer is Dot Net is partially platform dependent, as of now CLR software's are not available for DOS operating system and Windows 95.

Language independent concepts: As Dot Net programming logic can be developed in any Dot Net framework compatible languages; hence Dot Net is called as language independent. Microsoft is introducing approximately 40 languages into Dot Net framework, out of which as of now approximately 24 languages and one specification are released.
Ex: VC#.Net,VB.Net,VC++,VJ#,VF#,PHP,COBOL,PERL,PHYTHON,SMALLTALK,JSCRIPT...etc
One specification is ASP.Net. VC#.Net is case sensitive, VB.Net is not case sensitive, and ASP.Net case sensitivity depends on integrated language.

About DLL Files: We can create DLL files with the help of Dot Net(C#,VB...etc), and also we can create with the help of visual studio 5.0 or 6.0 (VB 5.0/6.0, VC++ 5.0/6.0..etc)

What is DLL as per VB 6.0 or VC++ 6.0?

• VB 6.0 or VC++ 6.0 DLLs contains the reusable code in the format of machine language.
• VB 6.0 or VC++ 6.0 DLLs are called as COM(component object model) components.
• Every COM component must be registered for a class ID.
• Class IDs are unique.
• Class ID is a part of registry.
• As regestry is a part of Windows OS, hence COM components are platform dependent.

What is DLL as per Dot Net?

• Dot Net DLLs contain the reusable code in the format of byte code.
• Dot Net DLLs are platform independent.
• Dot Net DLLs are called as assemblies.
• A collection of classes is called as Namespace.
• A collection of Namespaces is called as assembly.
• A collection of assemblies is called as FCL(Frame Work Class Library) or BCL(Base Class Library).