What is 'NET

1
What is .NET?

• The .NET Framework is an integral Windows
  component that supports building and running the
  next generation of applications and XML Web
  services.

2
Defining .Net( cont)

• .Net targets on some objects
• .Net is a new platform for the development and
  deployment of modern, object-oriented, managed
  applications
• Fully function. Net can be developed using any
  programming language that targets the .Net
  runtime( C, VB. Net, managed C, JScripts )
• .Net provides a comprehensive framework of
  language-neutral class libraries
• .Net supports multilanguage integration,
  cross-language component reuse , and
  cross-language inheritance
• .Net introduces a new way to develop Web-based
  and Window-based

3
.Net Framework

• The .Net framework includes
• Common Language Runtime (CLR) provides an
  execution environment that incorporates features
  such as
• Code verification and complication
• Security management
• Memory management
• .Net Framework class library is a library of
  class, interfaces, data structure and delegates
  intended to provide the foundation for .Net
  applications, components, services and controls

4
.Net Framework
5
.Net Framework- Managed code

• Software that uses the .Net Framework (and thus
  relies on the CLR) is referred to as managed code
• In object-oriented paradigm, these codes/objects
  are known as managed objects
• Objects written in any CLR-based language can
  inherit and use the librarys code
• Some managed code languages includes C, VB.NET,
  Jscript.NET, Managed C

6
.Net Compact Framework

• The .NET Compact Framework is a smaller version
  of the .NET Framework
• It can be used with smaller devices , such as
  mobile phones, PDAs, set-top boxes.
• It takes less memory so MS eliminates some part
  of the .NET Framework class library
• It can be developed in other environments and
  language like .NET Framework
• Its also an important piece of Microsofts
  overall .NET strategy

7
What the CLR Defines?

• The CLR defines a common set of semantics that is
  used by multiple languages such as common set of
  data types( integer, string , classes,
  interfaces), specifications for how inheritance
  works, common set of semantics for language built
  in it

8
Using CLR

• The CLR supports many different language and
  targets on these features
• Compilation and Verification
• Security
• Memory Management

9
Using CLR- Compilation and Verifying

• CLR is the fundamental for everything in .NET
  Framework.
• It supports the creation and execution of managed
  code
• It offers the building, compiling, organizing,
  executing these managed code
• Building Managed Code The Common Type System
  (CTS)
• Compiling Managed Code MSIL and Metadata
• Organizing Managed Code Assemblies
• Executing Managed Code JIT compilation

10
Building Managed Code Common Type System (CTS)

• The Common Type System defines core semantics but
  not syntax
• The CTS defines reference and value types. Both
  inherit directly (reference type) or indirectly
  (value type) from a type called Object( System.
  Object)
• All value types inherit from ValueType, different
  from Object , value types cannot act as a parent
  type for inheritance. In CLR, value types are
  said to be sealed
• The Common Language Specification (CLS) defines a
  (large) subset of the CTS that a language must
  obey if it wishes o interoperate with other
  CLS-compliant languages

11
Using CLR- Compilation and Verifying

• Building Managed Code The Common Type System
  (CTS)
• Compiling Managed Code MSIL and Metadata
• Organizing Managed Code Assemblies
• Executing Managed Code JIT compilation

12
Compiling Managed Code MSIL and Metadata

• When a managed code is compiled , two things are
  produced
• Code in Microsoft Intermediate Language (MSIL).
• Metadata, information about those instructions
  and the data they manipulate.
• Both the MSIL and the metadata are stored in a
  standard Window portable (PE) file. This file can
  be either a DLL or an EXE, and generally called
  module.

13
Compiling Managed Code MSIL

• MSIL is a CPU-independent set of instructions
  that can be efficiently converted to native code
• MSIL is full, stack-based language that you can
  use to implement .NET components
• MSIL is not an object-oriented language.

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Compiling Managed Code MSIL

• MISL instructions and what theyre used for
• Add adds the top two values on the stack and
  pushes the result back onto the stack
• Box Converts a value type to a reference type
  that is , it boxes the value.
• Br Transfers control (branches) to a specified
  location in memory
• Call calls a specified method.
• Idfld Load a specified field of an object onto
  the stack.
• Idobj Copies the value of a specified value type
  onto the stack
• Newobj Creates a new object or a new instances
  of a value type
• stfld stores a value from the stack into a
  specified field of an object
• Stobj Stores a value on the stack into a
  specified value type
• Unbox Converts a boxed value type back to its
  ordinary form

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Compiling Managed Code MSIL

• // A C example
• interface IMath
• int Factorial(int f)
• double SquareRoot( double s)
• class Compute IMath
• public int Factorial(int f)
• int i
• int result1
• for (i2iltfi)
• resultresulti
• return result
• public double SquareRoot( double s)

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Compiling Managed Code MSIL

• .method public hidebysig static void
  Main(string argv) cil managed
• .entrypoint
• .custom instance void mscorlibSystem.Diagnost
  ics.DebuggerNonUserCodeAttribute.ctor() ( 01
  00 00 00 )
• // Code size 25 (0x19)
• .maxstack 1
• .locals init (class vshostutilVSHostUtil.Host
  Proc V_0)
• IL_0000 call class vshostutilVSHostUt
  il.HostProc vshostutilVSHostUtil.VsHostAppDomain
  Managerget_HostProcListener()
• IL_0005 stloc.0
• IL_0006 ldloc.0
• IL_0007 callvirt instance void
  vshostutilVSHostUtil.HostProcSetVSEvent()
• IL_000c ldloc.0
• IL_000d callvirt instance class
  mscorlibSystem.Threading.AutoResetEvent
  vshostutilVSHostUtil.HostProcget_EventRunAssem
  bly()
• IL_0012 callvirt instance bool
  mscorlibSystem.Threading.WaitHandleWaitOne()
• IL_0017 pop
• IL_0018 ret
• // end of method EntryPointMain

18
Compiling Managed Code Metadata

• Compiling managed code always produces MSIL and
  metadata. Metadata is information about the types
  defined in the managed code . It is stored in the
  same file as the MSIL.
• This information is loaded into memory when the
  file itself is loaded, making the metadata
  accessible at the runtime.
• Metadata can also be read directly from the file
  that contains it, making information available
  even when code isnt loaded into memory
• The process of reading metadata is know as
  reflection
• What metadata contains
• The types name
• The types vibility, which can be public pr
  assembly
• What type this type inherits from
• Any interfaces the type implements

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Using CLR- Compilation and Verifying

• Building Managed Code The Common Type System
  (CTS)
• Compiling Managed Code MSIL and Metadata
• Organizing Managed Code Assemblies
• Executing Managed Code JIT compilation

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Organizing Managed Code Assemblies

• An assembly is one or more files that comprise a
  logical unit.
• Metadata for Assemblies Manifests.
• An assemblys manifest contains the assemblys
  name, its version number, list of other
  assemblies it depends on and all types and
  resources exposed by the assembly..
• An assembly can be built from a single file or a
  group of files ( modules). With a single-file
  assembly, the manifest stored in the file itself.
  With a multifile assembly, the manifest is stored
  in one of the files in the assembly, while the
  metadata in each module defines the types in that
  module
• The assembly is responsible for declaring the
  security it requires. Request for permissions
  fall into one of three categories required,
  optional, denied. The identity information may be
  used as evidence for determine whether or not to
  approve the security requests

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Using CLR- Compilation and Verifying

• Building Managed Code The Common Type System
  (CTS)
• Compiling Managed Code MSIL and Metadata
• Organizing Managed Code Assemblies
• Executing Managed Code JIT compilation

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Executing Managed Code
23
Executing Managed Code

• Loading Assemblies
• When an application is executed , the assemblies
  that make up that application must be found and
  loaded into memory.
• Founding the application
• CLR determines what version of a particular
  assembly its looking for ( in the manifest)
• CLR checks whether the desired assembly is
  already loaded. If it is, the search is over,
  this loaded version will be used. If the desired
  assembly is not already loaded, the CLR will
  begin searching in various places to find it
• Global assembly cache (GAC), a special directory
  intended to hold assemblies that are used by more
  than one application
• The CLR can next look in the location referenced
  by a codebase element.
• If no codebase element exists , the CLR searches
  in other places URL, directory,
• Assemblies are loaded into memory only when
  needed

24
Executing Managed Code

• Compiling MSILThere is two option exist for
  doing this
• MSIL code can be compiled one method at a runtime
  during execution JIT compilation
• MSIL code can be compiled into native code all at
  once before an assembly is executed NGEN (Native
  Image Generator)

25
Executing Managed Code

• JIT Compilation
• CLR load an assembly and then compile each method
  at the first time that method is invoked, this
  process is called just-in-time compilation
• When a method is JIT compiled, its also check
  for type safety, This process, called
  verification, The CLRs built in security
  features depends on this process
• Only those methods that get called will be
  compiled. If a method in an assembly is loaded
  but never used, it will stay in its MSIL form.
  Compiled code is no saved on disk, JIT
  compilation is carried out each tine an assembly
  is loaded.
• Creating a Native Image (NGEN)
• An assembly MSIL code can be traslated into
  native code for a particular processor all at
  once using the NGEN.
• The assembly will now be loaded as native code
• Using NGEN doesnt make the overall speed of the
  application.
• Note .NET Framework does not include an
  interpreter for MSIL. Executed code is either JIT
  compiled or compiled all at once.

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Executing Managed Code
27
Using CLR Security

• When compiling MSIL to native code, code must
  pass a verification process.
• Verification examines MSIL and metadata to find
  out whether the code is type safe.
• Type safety provides assurance that security
  restrictions on code can be reliably enforced.
• The runtime relies on the fact that the following
  statements are true for code that is verifiably
  type safe
• A reference to a type is strictly compatible with
  the type being referenced.
• Only appropriately defined operations are invoked
  on an object.
• Identities are what they claim to be.

28
Using CRL- Security

• The CLR implements two different types of
  security for assemblies code access and
  role-based security
• Role-based security
• Role-based security gives way to control what an
  assembly is allowed to do based on the identity
  (indicated by an identity object) of the user on
  whose behalf the assembly is running
• The foundation for role-based security is a
  principal object.

29
Using CLR Security- Code Access Security

• Code access security can limit what running code
  is allowed to do
• CLR determines what an assembly is allowed to do
  and an assemblys permissions are checked at
  runtime
• CLR-based code is allowed to do depends on the
  intersection of two things
• What permissions that code requests
• What permissions are granted to that code by the
  security policy.

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Using CLR Management Memory

• Garbage collection
• Every instance of a reference type is allocated
  on the heap. As the application runs, the memory
  allotted to the heap fills up. Before new
  instances can be created, more space must be made
  available. The process of doing this is called
  garbage collector
• When CRL notices that the heap is full, it will
  automatically run the garbage collector
• Garbage objects can appear anywhere in the heap
• Garbage collection can reposition the contents of
  the heap
• The garbage collection view objects in
  generations

31
.NET Framework Class Library

• The .Net framework class library can be used from
  any CLR-based language
• The .Net framework class library is organized as
  a tree of namespaces. Each namespace can contain
  types, such as classes and interfaces, and other
  namespaces.
• The root namespace is System
• The System namespaces contains many different
  types
• The core types defined by the CLR s CTS
• Console
• Math
• Environment
• GC (garbage collector)
• Random

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.Net Framework Class Library

• System.Data The types implement ADO.NET, the
  standard approach to accessing data for .NET
  framework applications
• System.Diagnotics contains a large set of
  classes, interfaces, structures, and other types
  that help with debugging .NET framework
  applications
• System.EnterpricesServices contains types for
  accessing the services provided by COM,
  including support for distributed transaction,
  role-based authorization, and object pooling
• System.IO provides a large set of types for
  reading and writing files, directories, and
  in-memory streams
• System.Net provides types for accessing several
  common protocols, including HTTP and Domain Name
  System (DNS)
• System.Security contains classes, interfaces,
  enumerations, and subordinate namespaces that
  provide various security-related functions. Some
  subordinate namespace
• System.Security.Cryptography contains types for
  using secret and public key cryptography services
• System.Security.Permissions contains types such
  as a class representing each of the possible
  permissions for code access security
• System.Security.Policy defines classes such as
  Site, URL, Publisher, Zone, and others used in
  defining security policy
• Sytem.Security.Principal contains types for
  working with security principals. These classes
  are used by the CLR in implementing role-based
  security
• System.Web, the most important namespaces. It
  implements ASP.NET. The most two important
  children of System.Web are
• System.Web.UI contains types for building
  browser-accessible applications
• System.Web.Services contains types for creating
  applications that exposed Web Services
• System.Windows.Forms contains types used to
  construct local Windows GUIS
• System.XML contains types useful for working
  with XML documents.

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Accessing Data ADO.NET

• ADO.NET lets applications access stored data
• ADO.NET clients rely on a .NET data provider to
  access a DMS. .NET data providers built from
  managed code
• A .NET data provider allows clients to access
  data either directly as rows or through a
  DataSet
• Direct Access to Data (by rows)
• Accessing Data with DataSets
• A DataSet is an in memory cache that can store
  data from various sources
• DataSets allow much more flexible access to data
  than is possible with a DataReader
• A DataSet contains DataTables
• DataSets can also be used with XML-defined data
  and we can translate between DataSets and XML
  Documents

35
Building Web Applications ASP.NET

• Implemented in the System.Web namespace, ASP.NET
  is a major piece of the .NET Framework
• ASP.NET allows the creation of two types of
  applications
• Traditional browser applications accessible via
  HTTP and HTML and execute in files with extension
  .aspx (VB.NET is the default language for .aspx
  pages)
• Web Services applications accessible via SOAP and
  execute in files with extension .asmx

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Web Services

• Allowing software running on other systems to
  invoke operations over the Web directly would
  allow Web applications to provide richer services
  to more diverse clients
• Web services rely on four fundamental
  technologies
• Describing information sent over the network
  Invoking a remote operation commonly involves
  passing in parameters and getting back some kind
  of result. With Web services, this information is
  described using Extensible Markup Language (XML)
• Defining Web services capabilities specify the
  technical details of exactly what services are
  offered. For Web Services, this can be done using
  the Web Services Description Language (WSDL).
  Each WSDL-defined interface contains one or more
  operations, and WSDL itself is defined using XML.
• Accessing Web services Simple Object Access
  Protocol (SOAP) provides a way to identify which
  operation to invoke. SOAP itself defines only
  simple envelope for conveying this information
• Finding Web Services Universal Description,
  Discovery, and Integration (UDDI)- standard
  registry fir storing and accessing this kind of
  information. UDDI allows clients to learn what
  services each provider offers and letting
  creators of clients software learn what they need
  to know to build those clients
• Applying Web services
• Allowing programmatic access to applications
  accessed via the Internet
• Business-to-business (B2B) integration, allowing
  applications from different organization to
  communicate across the Internet
• Applcation-to-application(A2A), allowing
  applications within a single organization to
  communicate across an intranet

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.NET My services

• .Net My services is a set of Internet-accessible
  Web services provided by Microsoft
• .NET My services includes an authentication
  service
• Some services provided by .NET My services
• .NET Alerts
• .NET Calendar
• .NET Contacts
• .NET Inbox
• .NET Documents
• .NET Lists
• .NET Wallet
• .NET Profile
• .NET Presence
• .NET My Services raises many security and privacy
  issues

38
The .NET Framework vs the Java Environment

• Mainstream software development today split into
  two camps
• Microsoft, promoting the .NET framework
• Sun , promoting the Java Environment
• They are similar in some points
• Support the same classes of applications
• JavaServer Pages , JDBC, Swing, Enterprise
  JavaBeans for Java Environment
• ASP.NET, ADO.NET, Windows Forms, Enterprise
  Services for .NET Framework
• C and VB.NET are quite similar to Java
• But they are also different in some points
• Java runs on diverse operating systems.
• .NET framework focuses on Windows

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A .NET example

• Step1 User contacts Passport authentication
  part of .NET My Services to obtain a way to
  identify herself reliably
• Step2 Use browser to access ordering application
• Step3 Order application access .NET My Services
  to acquire information about the customer
• Step4 Ordering Application communicates with
  shipping application (building in BizTalk Server)
• Step5 Ordering application uses SOAP to access
  billing application