.NET framework is an environment that facilitates Object Oriented Programming Model for multiple languages. It wraps Operating System and insulates Software Development from many Operating System specific tasks such as file handling, memory allocation & management.
It has two main components CLR (Common Language Runtime) and .Net BCL (Base Class Libraries).
As you can see in Figure, the .NET Framework sits on top of the operating system, which can be a few different flavors of Windows and consists of a number of components. .NET is essentially a system application that runs on Windows.
The most important component of the Framework is something called the CLR. The CLR activates objects, performs security checks on them, lays them out in memory, executes them, and garbage-collects them. The CLR supports all languages that can be represented in the Common Intermediate Language (CIL). A conceptual difference between the two infrastructures is that Java code runs on multiple platforms with a JVM, whereas .NET code runs only on the Windows platforms with the CLR (at the time of this writing).
An assembly is the basic unit of deployment and versioning, consisting of a manifest, a set of one or more modules, and an optional set of resources.
Metadata is machine -readable information about a resource, or "data about data." Such information might include details on content, format, size, or other characteristics of a data source. In .NET, metadata includes type definitions, version information, external assembly references, and other standardized information.
In order for two components, systems, or objects to interoperate with one another, at least one must know something about the other. In COM, this "something" is an interface specification, which is implemented by a component provider and used by its consumers.
In .NET, metadata is a common mechanism or dialect that the .NET runtime, compilers, and tools can all use. Microsoft .NET uses metadata to describe all types that are used and exposed by a particular .NET assembly. Metadata includes descriptions of an assembly and modules, classes, interfaces, methods, properties, fields, events, global methods, and so forth.
.NET assemblies are deployable units and manifests are the metadata that describes the assemblies.
An assembly contains the IL code that the CLR executes at runtime. The IL code typically uses types defined within the same assembly.
There are four types of assemblies in .NET:
Static assemblies: These are the .NET PE files that you create at compile time. You can create static assemblies using your favorite compiler: csc, cl, or vbc.
Dynamic assemblies: These are PE-formatted, in-memory assemblies that you dynamically create at runtime using the classes in the System.Reflection.Emit namespace.
Private assemblies: These are static assemblies used by a specific application.
Public or shared assemblies: These are static assemblies that must have a unique shared name and can be used by any application.
The CLR allows any versions of the same-shared DLL (shared assembly) to execute at the same time, on the same system, and even in the same process. This concept is known as side-by-side execution.
Manifests: Assembly Metadata
An assembly manifest is metadata that describes everything about the assembly, including its identity, a list of files belonging to the assembly, references to external assemblies, exported types, exported resources, and permission requests. In short, it describes all the details that are required for component plug-and-play. Since an assembly contains all these details, there's no need for storing this type of information in the registry, as in the COM world.
An assembly can be a single-module assembly or a multi-module assembly. In a single-module assembly, everything in a build is clumped into one EXE or DLL, an example of which is the hello.exe application that we developed earlier. This is easy to create because a compiler takes care of creating the single -module assembly for you.
A multi-module assembly is one that contains many modules and resource files. To create it you have to use the Assembly Linker (al.exe) that is provided by the .NET SDK. This tool takes one or more IL or resource files and spits out a file with an assembly manifest.
Any .NET language may be converted into IL, so .NET supports multiple languages and perhaps multiple platforms in the future (as long as the target platforms have a CLR).
Interfaces support exactly the same concept as a C++ abstract base class (ABC) with only pure virtual functions. An ABC is a class that declares one or more pure virtual functions and thus cannot be instantiated. If you know COM or Java, interfaces in .NET are conceptually equivalent to a COM or Java interface. You specify them, but you don't implement them. A class that derives from your interface must implement your interface. An interface may contain methods, properties, indexers, and events. In .NET, a class can derive from multiple interfaces.
The Common Language Specification (CLS):
The CLS specifies a series of basic rules that are required for language integration.
The JIT compilers convert IL to native code so that it can execute on the target operating system. The compiled, native code lies in memory until the process shuts down and until the garbage collector clears off all references and memory associated with the process.
You can treat each .NET assembly as a component that you can plug into another component or application, without the need for source code, since all the metadata for the component is stored inside the .NET assembly. While you have to perform a ton of plumbing to build a component in COM, you need to perform zero extra work to get a component in .NET, as all .NET assemblies are components by nature. Remember, we're using the term "component" as a binary, deployable unit, not as a COM class.
Unlike private assemblies, if shared assemblies used once, they must be published or registered in the system Global Assembly Cache (GAC). When you register your assemblies against the GAC, they act as system components. Again, unlike COM, we don't have to store any information in the system registry for clients to use these shared assemblies.
A pool is technical term that refers to a group of resources, such as connections, threads, and objects. Putting a few objects into a pool allows hundreds of clients to share these few objects. Pooling is a technique that minimizes the use of system resources, improves performance, and helps system scalability.
A data reader is a new object providing fast, forward-only, and read-only access to data. This is similar to an ADO Record set with server-side, forward - only, and read-only cursor types.
Even though each Data Adapter maps only one Data Table in the Dataset, you can have multiple adapters to fill the Data Set object with multiple Data Tables.
The .Net framework provides several core run-time services to the programs that run within it. For example exception handling and security.
What is an Assembly?
Assemblies are fundamental building blocks of .Net Framework. They contain the type and resources that are useful to make an application. Assemblies enables code reuse, version control, security and deployment. An assembly consists of: Manifest, Type Metadata, MSIL and resource file.
Assemblies are Private and Shared. Private are used for a single application and installed in application’s install directory or its sub-directory. Shared assembly is one that can be referenced by multiple applications and resides in GAC.
Metadata and Manifest:
Manifest describes the assembly itself. Assembly name, version, culture, strong name, list of files, type reference and reference assembly. While Metadata describes contents within the assembly like classes, namespaces, interfaces, scope, properties, methods and their parameters etc.
It is a virtual process that serves to isolate an application. All object created within the same application scope are created within same application domain.
It is Automatic Memory Manager for .Net Framework. It manages the memory allocated to .Net Framework.
When a variable is defined it gets a space in memory (stack) and when an object is created memory for the object is allocated in heap. When an object is assigned to a variable it increments the reference counts for the object and when program control comes out of the function the scope of variable gets ended Or NULL is assigned to variable it decrements the reference count of object by 1. When reference count of one object becomes zero GC acts call destructor of object and then releases the memory acquired by the object.
Can .Net Components can be used from a COM? Yes.
How does .NET Remoting work?
It involves sending messages along channels. Two of the standard channels are HTTP and TCP. TCP is for LANs only and HTTP can be used on LANs or WANs (internet). TCP uses binary serialization and HTTP uses SOAP (.Net Runtime Serialization SOAP Formatter).
There are 3 styles of remote access:
SingleCall: Each incoming request is handled by new instance.
Singleton: All requests are served by single server object.
Client-Activated Object: This is old state-full DCOM model. Where client receives reference to the remote object and keep until it finished with it.
Situations where we have to put same name Dlls in single directory where are Dlls are of different versions.
Boxing and Un-Boxing:
Implicit (automatic) conversion of value type to reference type is known as Boxing And Explicit (manual) conversion of Reference type to value type is said to be Un-boxing. (conversion of Integer variable to object type)
.Net Object Oriented Programming Concepts
Class is concrete representation of an entity. It represents a group of objects, which posses similar attributes and behavior.
Provides Abstraction and Encapsulations. A category name that can be given to group of objects of similar kind.
Object represents/resembles a Physical/real entity. An object is simply something you can give a name.
Object Oriented Programming:
It is a Style of programming that represents a program as a system of objects and enables code-reuse.
Binding of attributes and behaviors. Hiding the implementation and exposing the functionality.
Hiding the complexity. Defining communication interface for the functionality and hiding rest of the things.
In .Net destructor can not be abstract. Can define Either Finalize / Destructor. For Destructor access specifiers can not be assigned. It is Private.
Adding a new method with the same name in same/derived class but with different number/types of parameters. Implements Polymorphism.
When we need to provide different implementation than the provide by base class, We define the same method with same signatures in the derived class. Method must be Protected/Protected-Friend/Public for this purpose. (Base class routine can be called by Mybase.Method, base.Method).
When the method is defined as Final/sealed in base class and not overridable and we need to provide different implementation for the same. We define method with Shadows/new.
Mean by more than one form. Ability to provide different implementation based on different no./type of parameters. A method behaves differently based on the different input parameters. Does not depend on the Return-Type.
Make an method abstract/virtual in base class. Override it in Derived Class. Declare a variable of type base class and assign an object of derived class to it. Now call the virtual/abstract method. The actual method to be called is decided at runtime.
Calling an non-virtual method decides the method to call at compile time is known as Early-Binding.
Identifiers/Access Specifies and scope:
VB.NET: Private, Protected, Friend, Protected Friend, Public.
C#: private, protected, internal, protected internal, public.
What is a Delegate?
A strongly typed function pointer. A delegate object encapsulates a reference to a method. When actual function needs to be called will be decided at run-time.
Static Variable and Its Life-Time:
VB.NET: Public Shared VAR As Type.
C#: public static Type VAR;
Life time is till the class is in memory.
Special Method Always called whenever an instance of the class is created.
Called by GC just before object is being reclaimed by GC.
Different Types of Caching?
Output Caching: stores the responses from an asp.net page.
Fragment Caching: Only caches/stores the portion of page (User Control)
Data Caching: is Programmatic way to Cache objects for performance.
Authentication and Authorization:
Authentication is identifying/validating the user against the credentials (username and password) and Authorization performs after authentication. Authorization allowing access of specific resource to user.
Different Types of Directives:
Page, Register, Control, OutputCache, Import, Implements, Assembly, Reference
Difference between Server-Side and Client-Side:
Server-Side code is executed on web-server and does not transmitted to client, while client-side code executed on client(browser) and is rendered to client along with the content.
Difference Server.Transfer and Response.Redirect:
Both ends the processing for the current request immediately. Server.Transfer start executing the another resource specified as parameter without acknowledgement to client(browser) while Response.Redirect intimate client that your requested resource is available at this location and then client request for that resource.
Different Types of Validators and Validation Controls:
RequiredFieldValidator, RangeValidator, RegularExpressionValidator, CompareValidator, CustomValidator, ValidationSummary
How to Manage State in ASP.Net?
Client based: ViewState, QueryString and Cookies Server based: Session, Application.
Difference between User Control and Custom Control:
CUSTOM Controls are compiled code (Dlls), easier to use, difficult to create, and can be placed in toolbox. Drag and Drop controls. Attributes can be set visually at design time. Can be used by Multiple Applications (If Shared Dlls), Even if Private can copy to bin directory of webApp add reference and use. Normally designed to provide common functionality independent of consuming Application.
3 Types of
StateServer (Server, Port stateConnectionString="tcpip=server:port"),
SQLServer (sqlconnectionstring) and Off.
What is ViewState and How it is managed, Its Advantages/Benefits?
ViewState is a special object that ASP.NET uses to maintain the state of page and all webcontrols/ServerControls within it. It is in this object preserves the states of various FORM elements during post-backs. It is rendered to client(browser) as a Hidden variable __VIEWSTATE under
COM Callable Wrapper
Common Language Infrastructure. This is a subset of the CLR and base class libraries that Microsoft has submitted to ECMA so that a third-party vendor can build a .NET runtime on another platform.
Common Object File Format
Discovery of Web Services. A Web Service has one or more. DISCO files that contain information on how to access its WSDL.
Distributed interNet Applications Architecture.
Globally Unique Identifier
Interface Definition Language
Microsoft Distributed Transaction Coordinator
Online Transaction Processing
Online Analytical Processing
Rapid Application Development
Runtime Callable Wrapper
Simple Mail Transfer Protocol
Transport Control Protocol
Uniform Data Format
Uniform Resource Locator
Universal Description, Discovery and Integration
Wireless Access Protocol
Web Services Definition Language
Wireless Markup Language