Unit6

030010401 BCA 4th Semester
Preeti P Bhatt Department of Computer Science, UTU. 1 | P a g e
030010401- GUI Programming
Unit-6: Introduction to .NET Framework
BCA 4th Semester
Note: - This material is prepared by Ms. Preeti P Bhatt. The basic
objective of this material is to supplement teaching and discussion
in the classroom. Student is required to go for extra reading in the
subject through library work.

Topic Covered
 .NET framework: Evolution and Benefits
 Architecture of .NET framework
 Common Language Runtime:
– CLR functions, managed code, unmanaged code, memory management
 .NET Framework Class Library
 Common Language Specification
 Metadata and Assemblies:
– Assembly contents, manifest, GAC, strong name assembly, private and shared
assemblies, side by side execution

1. .NET Introduction
Definition: .Net is a collection of tools and technologies and language that all are work
together in a framework to provide a solution need for develop application.
.NET is Microsoft’s strategy of software that provides service to people any time, any place, on
any device.
.NET is a new framework for developing web-based and windows-based applications within the
Microsoft environment.
It also known as Software Platform or Language neutral
Benefits Of .NET
• Consistent programming model: -
– .NET provides a consistent object oriented programming model across different
language.
• Cross – platform support:-
– Any windows platform that supports CLR can execute a .NET application.
• Language Interoperatibility:-
– It is a feature that enable program written in different languages to interact with
each other.
– This allows reusability of code and improves the efficiency of development
process.
– You can inherit visual basic class in C#.
• Automatic management of resources:-
– You do not need to manually free the application resources, such as file,
memory, and network and database connection.
• Ease of deployment:-
– It make task of deployment easier.
– Easy deployment of application by installing new application.

2. .NET Framework
The .NET framework exposes numerous classes to the developer. These classes allow the
development of rich client applications and Web based applications.
.Net Framework component
 Common Language Runtime(CLR)
 Base Class Library (BCL)
 ASP. Net and XML
 Web form and Window Form
 Common Language specification (CLS)
Block Diagram of .NET Framework
C++ C# VB Perl J# ..........
Visual
Studio
.NET
Common Language Specification
(CLS)
ASP.NET
Web Forms, Web
Services
Windows
Form
ADO.NET (Data and XML)
Base Class Library (BCL)
Common Language Runtime (CLR)
Operating System
2.1 Common Language Runtime
At the base is the common language runtime.
It is the heart of the .Net Framework; it is the engine that compiles and run the application.
It uses MSIL (Microsoft Intermediate Language) format code which is language independent
for execution. The MSIL code is translated by JIT (Just in Time Compiler) compiler.
CLR manages code execution at runtime.
It include
 Common Type System
• It include common type, standard interface convention, make cross language
inheritance.
 Memory Management
• Allocation and management of memory
 Life cycle Monitoring
 CLR also does reference counting for object and handles garbage collection.

2.2 Base Class Library (BCL)
It is a second entity of .NET framework which is designed to integrate with CLR.
It is also known as Framework class Library (FCL).
The Base Class Library (BCL) is a standard library available to all languages using the .NET
Framework.
Class libraries implement a large number of common functions such as
 File reading and writing,
 Graphic rendering,
 Database interaction,
 XML document manipulation.
The .NET class libraries are available to all CLI (Common Language Infrastructure) compliant
languages.
The .NET Framework class library is divided into two parts:
 Base Class Library
 Framework Class Library
2.3 ASP. Net and XML
It is also known as Data Access Layer. With this we can access relational databases.
It work with XML and provide the Disconnected Data Model
This layer includes the next generation of standard system service such as ADO.NET and
XML.
It is a part of BCL. It consists of two parts:
1) Data Provider: Connection, Command, DataAdapter, Data Reader
2) DataSet
These services are brought under the control of framework, making them universally
available and standardizing their usage across language.
2.4 Web form & Web Services and Window Form
a. Web form & Web Services
• Web forms
It provide toll for web application. It is a part of ASP.NET.
 Manageable code
 Logical evolution of ASP (compiled)
• Web service is a method of communication between two electronic devices over
the web.

b. Window Form or Win Form
It used to create the GUI for windows desktop application.
It has rich variety of windows controls and user with win Forms.
2.5 Common Language specification (CLS)
Common Language Specification (CLS) is a set of basic language features that .Net Languages
needed to develop Applications and Services, which are compatible with the .Net Framework.
It is a set of rules and constraints that all languages must follows which want to be
compatible with .NET framework.
Language Support VB, C++, C#, J#, JScript
3. Common Language Runtime
At the base is the common language runtime.
It is the heart of the .Net Framework; it is the engine that compiles and run the application.
It uses MSIL (Microsoft Intermediate Language) format code which is language independent
for execution. The MSIL code is translated by JIT (Just in Time Compiler) compiler.
CLR manages code execution at runtime.
It include
 Common Type System
• It include common type, standard interface convention, make cross language
inheritance.
 Memory Management
• Allocation and management of memory
 Life cycle Monitoring
 CLR also does reference counting for object and handles garbage collection.
Component of CLR

• Common Type System (CTS)
• It is responsible for interpreting the data types into the common format.
• IL compiler (Intermediate Language)
• The IL Compiler takes in the IL code and converts it to the host machine
language.
• Security
• Security component in the CLR ensures that the assembly (the program being
executed) has permissions to execute certain functions.
• Garbage Collector
• Its function is to recover the memory when the object is no longer in use, this
avoids memory leaks.
• Class Loader
• Purpose is to load the classes needed by the executing application.
Working of CLR
Code running under the control of the CLR is often termed managed code.
Two step of compilation
1. Compilation of source code to IL (Intermediate Language)
• The .Net program is compiled in to special type of code called the Microsoft
Intermediate Language (MSIL)
– When .NET code is compiled, the output of compiler is not an executable
file but a file that contains special type of code called MSIL code, which is
a special low-level set of instructions understood by CLR.
2. Compilation of IL to platform-specific(native code) code by the CLR
• This MSIL is turned into executable code using a JIT (Just In Time) complier.
– When .NET programs are executed, the CLR activates JIT compiler.
– The JIT compiler converts MSIL code into native code on a demand.

Benefits of CLR
• Automatic memory management: -
– The CLR provides the Garbage Collection feature for managing the life time of
object.
• Standard Type System: -
– The CLR Implement a formal Specification called the Common Type System (CTS).
CTS are important part of rules that ensures that objects written in different
language can interact with each other.
• Language interoperability: -
– It is the ability of an application to interact with another application written in a
different programming language
• Platform Independence: -
– The Compiler compiles code language, which is CPU-independent. This means
that the code can be executed from any platform that supports the .Net CLR.
• Security Management: -
– In .Net platform, Security is achieved through the code access Security (CAS)
model.
• Type Safety: -
– This feature ensures that object is always accessed in compatible ways.
Therefore the CLR will prohibit a code from assign a 10-byte value to an object
that occupies 8 bytes.
– Versioning and deployment services: -
– It supports side - by - side execution of multiple version of the same component,
even within the same process.

Important Terms
 Manage Code
“The code that is developed with a language compiler that target the CLR is
called manage code”.
Managed Code in Microsoft .Net Framework, is the code that has executed by
the Common Language Runtime (CLR) environment.
Manage code is code that is executed directly by CLR. The application created by
manage code automatically have CLR services, such as type checking, security
automatic garbage collection.
 Unmanaged Code
“The code that is developed without considering the conventional and
requirements of the CLR is called unmanaged code”.
Unmanaged code directly compiled to the machine code and runs on the machine
where it has been compiled.
CLR does not provide services, such as type checking, security automatic garbage
collection to unmanaged code.
Unmanaged code executes in CLR environment with minimal services.
For example, unmanaged code may run with limited debugging and without
garbage collection process.
Manage code consists of MSIL and Metadata
 Memory management
One of the important services that CLR provides during managed executions is
automatic memory management.
CLR uses garbage collection to manage the allocation and release of memory.
 MSIL Code
NET programs are compiled by the language compilers into assemblies that
consist of Microsoft Intermediate Language (MSIL) instructions.
MSIL: It is a CPU-independent set of instructions that can be efficiently converted
to native code.
MSIL is also known as IL or CIL.
CLR compiles MSIL in just-in-time (JIT) manner – each function is compiled just
before execution.

JIT Compiler
Just in Time (JIT) Compiler gets its name because it compiles your managed code
into executable native code on the fly. That is, it compiles the IL just as it's
needed.
During the code execution time, the Managed Code compiled only when it is
needed, that is it converts the appropriate instructions to the native code for
execution just before when each function is called. This process is called Just In
Time (JIT) compilation, also known as Dynamic Translation.
4. Base Class Library (BCL)
The .Net Framework class library provides the core functionality of .Net Framework
architecture.
The .Net Base Class Library (BCL) includes a huge collection of reusable classes, interfaces,
and value types that provide access to system functionality.
Framework class library (FCL) is huge library of reusable types meant to be used by
managed code.
It is an object oriented library used in component based application.
Important Point in FCL:
 The classes, interface, structures, and enumerated value are collectively referred
as type.
 Different type in .NET framework is arranged in hierarchy of namespace.
 The system namespace is root namespace in .NET framework.
 All class have base class including user defined types.
Namespace
Namespaces are the way to organize .NET Framework Class Library into a logical grouping
according to their functionality, usability as well as category they should belong to.
Namespaces are logical grouping of types for the purpose of identification.
The .NET Framework Class Library (BCL) is a large collection of thousands of Classes. These
Classes are organized in a hierarchical tree.
The System Namespaces is the root for types in the .NET Framework.
We can uniquely identify any Class in the .NET Base Class Library (BCL ) by using the full
Namespaces of the class .

5. Common Language Specification (CLS)
Common Language Specification (CLS) is a set of basic language features that .Net
Languages needed to develop Applications and Services, which are compatible with the .Net
Framework.
When there is a situation to communicate Objects written in different .Net languages, those
objects must expose the features that are common to all the languages.
Common Language Specification (CLS) ensures complete interoperability among
applications, regardless of the language used to create the application.
“The CLS defines a superset of the CTS to enable cross-language interoperability”.
The CLS defines a (large) superset of the CTS that a language must obey if it wishes to
interoperate with other CLS-compliant languages.
For example, the CLS requires support for most CTS value types, including Boolean, Byte,
Char, Decimal, Int16, Int32, Int64, Single, Double, and more.

Common Type System
Common Type System (CTS) describes a set of types that can be used in different
.Net languages in common.
That is the Common Type System (CTS) ensure that objects written in different .Net
languages can interact with each other.
These types can be
 Value Types
 Reference Types.
The Value Types are passed by values and stored in the stack.
The Reference Types are passed by references and stored in the heap.
Common Type System (CTS) provides base set of Data Types which is responsible for
cross language integration.
6. Metadata and Assembly
Metadata
A data about data is known as metadata.
It describes program that is in the form of binary information stored in CLR portable
executable (PE) file or in memory.
– When compilation of code take place in PE file, the metadata is inserted into one
part of the file,
– While code is converted in to MSIL and inserted in to other part of file.
Metadata contains the following:
– Assembly Information:
• Its identity like name, version, culture public key, the type of assembly,
other assembly and security permission.
– Information about Type

• Name, visibility, base class, interface used, and members.
– Attribute information
• This modifies the type and members of class.
Assembly
Microsoft .Net Assembly is a logical unit of code, it contains code that the Common
Language Runtime (CLR) executes.
When you compile an application, the MSIL code created is stored in an assembly.
Assembly: It is a collection of types and resource information that are built to work
together and form a logical unit of functionality.
Every Assembly you create contains one or more program files and a Manifest.
There are two types’ program files.
 Executable (EXE) and
 Dynamic linking Library Assemblies (DLL).
Assembly can be divided in two types
– Static Assembly: It includes interface, classes, and resources and stored in PE
files on a disk.
– Dynamic Assembly: you can create dynamic assemblies that run directly from
memory; therefore there is no need of saving them on disk before execution.
o After execution you can store then in a disk.
Manifest Assembly:
An assembly manifest is a text file containing metadata about .NET assemblies.
– Manifest describes the relationship and dependencies of the components in the
assembly,
– Versioning information, scope information and the security permissions
required by the assembly.
– Information stored in assembly manifest
• Assembly name, version number, culture, list of all file in assembly.
GAC: Global Assembly Cache
• It is a central place for registering assemblies, so that different application on the
computer can use it later on.
• Assembly must be made sharable by registering them in GAC only, when needed,
otherwise the assembly must be kept private.
• Deploy assembly in GAC using any one of the following
– An installer that is designed to work with GAC

– The global assembly cache tool known as Gacutil.exe
– Window explorer to drag assemblies into cache.
Strong name assembly
A strong name assemblies contains the assemblies' identity
– Assembly’s name, version number, culture information, public key and digital
signal.
Using private key, the assembly file containing the manifest generates the strong name.
Benefits of strong assembly
– Provides uniqueness to the names by generating a private key.
– Ensures that the version you are using comes from the same publisher that
creates the version.
– Facilities integrated checks, which ensures that content of assembly have not
changed since last build.
Private and Shared assembly
Private Assembly
When single application uses assembly, it is called private assembly.
Example: You have created a DLL containing information about your business logic and
placed it in same folder in which the client application has been installed. So DLL can
only be used by your client program.
Shared Assembly
Shared assembly are placed in the global assembly cache so that they can be used by
multiple application
Example: You have created DLL that needs to be reused in different application. Instead
of downloading copy of DLL in each and every client application, the DLL can be placed
in global assembly cache.
Side – by – Side Executions
It is a process where multiple version of an application or component are stored and
executed on the same computer.
Means you have multiple version of application and component that uses a particular
version of runtime on same computer at same time.

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