Assembly

1.What is an assembly ?

it is unit of deployment.It is a file generated on successful compilation of .Net application. it can be either a DLL or an EXE.

2.what are the features of Assembly?

a) They are self descrining. They consists of metadata which tells what are the methods,propeties etc present in the assembly.

b)Assembly can be loaded side-by side thus achieveing side by side execution.

c)installation of an assembly is easier.

d)Assemblies solve the DLL HELL problem.

2.Whats the diff bt a DLL and and EXE 

    

DLL	EXE
Dynamic Link Library with .dll extension	Executable with .exe extension
Can have many entry points	Has only one entry point
Does not contain UI	Contains UI
It is an in-process file.that means it runsin someone else’s memory	It is out-process file.It  can run independently. Its standalone.

2.What the physical location of assembly ?

 c:\Windows\assembly

3.Different types of  Assembly ?

a)Private Assembly

An assembly used by a single application is called private assembly. Its present in the bin folder.

b) SharedAssembly

An assembly used by more than one application.Its present in GAC.

c)Satellite Assembly

These are resource files which are compiled to assemblies.

4.What is DLL Hell ?

DLL HELL is a problem which arises when a new version of application with a new set of DLL overrides the older version.The application which are using older version of DLL crashes because those have been replaced by new DLL which are not compatible with the old applicaitons.

5.How is DLL Hell solved in .Net?

It is solved with the help of Assemblies.Assemblies allow different versions of DLL to co-exist among themselves.This feature is called Versioning.

6.What is Process ?

Instance of computer program that is being executed.

6.What are Application domains?

The domain in which your application runs. They provide isolation for running applications.

They are hosted inside Process.Single process can have more than one application domain. Communication between them can be achieved with the help of proxy.

7.How are Application domains created in C#?

static void Main()
{

    // Create an Application Domain:
    System.AppDomain newDomain = System.AppDomain.CreateDomain("NewAppDomain");

    // Load and execute an assembly:
    newDomain.ExecuteAssembly(@"d:\HelloWorld.exe");

    // Unload the application domain:
    System.AppDomain.Unload(newDomain);
}

8.What is PE file ?

Portable Executable File is either a DLL or an EXE.It is generated when a program is compiled.It consists of 3 part-

PE Header

MSIL

Metadat

8.What are the contents of an Assembly ?

An assembly consists-

a)Manifest

b)IL Code

c)Resource Files

d)Metadata

9.What is manifest ?

Manifest of an assembly contains the following-

a)Identity--consists of Assembly Name,Version No,Culture and Public Key Token.

b)List of File present in Assembly.

c)A list of referenced assemblies.

d)A set of permission requests.

10.What is metadata ?

Contains all the type and member information present in the code.

11.What is Single File and MultiFile assembly ?

Single File Assembly-it consists of only one file.

Multifile Assembly-consists of more then one files like- module(.netmodule), resource file(x.jpg) etc.All of them can be linked to form one assembly.

12.Whats the diff bt assembly and module ?

Assembly contains the manifest info.

modules does not have manifest info.They only contain metadata.They cannot be created in VS.

13.Can you compile an assembly with more than one file ?

Yes 

14.What is ILDASM ?

Its a tool used to view contents of an assembly.

15. what is ngen.exe ?
Native Image Generator.It compiles the entire assembly during installation.
It creates native images that are nothing but files so that the next time compiles compiles it picks up these images instead of files from JIT.
This helps in faster compilation.It can be used only if ngen is used for all the assembly in the application. 

16.What is GAC ?

It a a cache for assemblies which are globally available. For assemblies to be loadede in GAC they must have a strong name.Strong name ensures that assemblies with same name exists in GAC.

17.How do install and uninstall assembly in GAC ?

install- gacutil -i <assembly name>

uninstall-gacutil -u <assembly name>

18.What is strong name ?

Its  a .Net assembly name that consists of foll-

Name,Version,Culture Info and Public Key token.

It is used to help different versions of same assembly co-exist in GAC.

18.what is strong name key file?How is it created?

The snk.exe utility generated a public/private key pair that is stored in file called snk file(<name>.snk).it can be created by going to command prompt and typing-

                             snk -k <name>.snk

19.What do you mean by signing  a assembly

it means ensuring your software does not fall into wrong hands. this is done by creating a .snk file for the assembly and then it is used to sign the assembly by giving it a strong name.

.Net uses digital signature to safe guard the integrity of an assembly .it follows Public-key cryptography.

20.Explain how public key cryptography works.
In this method both the sender and receiver will have set of keys know as public keys(which is used to encrypt a assembly) and private key(used to decrypt an assembly).when you sign an assembly using snk utility these two keys are embedded into the assembly. the assembly gets signed by the pubic key ,public key is freely distributed. the user who wants to use it must have the private key which is used to decrypt this assembly.

21.What is delay signing  ?

22.What is satellite assembly ?

satellite assembly consists of resource files which for a specific language.it can be used for localization and globalization.
read more about them here ads

23.what is shfusion.dll?
Its a dll that allows you to see the contents of GAC very easily.go to run command and type assembly ,it opens up a windows which shows the contents of assembly.

16.How Windows diff win32 exe and managed exe ?

18.  What is probing ?

19.What is side by side execution ?

20.How can you run assembly without .Net Framework ?

22.What is AL.exe and Resgen.exe