16-11-2012, 06:01 PM
The Evolution of Web Applications
unit-1_DOTNET.ppt (Size: 304.5 KB / Downloads: 22)
First generation of Web applications -non-interactive content (HTML static content)
Second generation of Web applications - scalable back-end and a richer User Interface. (DCOM, ASP, CGI, Cold Fusion, dynamic content)
Third generation of Web applications (.NET) - using Web protocols and XML to allow better integration between services on the Web
Why the Move to .NET?
DCOM works fine on an Intranet, however:
DCOM does not go through firewalls
Requires too many open TCP/IP ports
Requires Stateful connections
Platform dependent
Portals provide services however:
Non-standard interfaces
Hard to integrate with other applications
Not designed to use outside the scope of the portal
.NET – What Is It?
Software platform
Language neutral
In other words:
.NET is not a language (Runtime and a library for writing and executing written programs in any compliant language)
What Is .NET
.Net is a new framework for developing web-based and windows-based applications within the Microsoft environment.
The framework offers a fundamental shift in Microsoft strategy: it moves application development from client-centric to server-centric.
Common Language Runtime (CLR)
CLR works like a virtual machine in executing all languages.
All .NET languages must obey the rules and standards imposed by CLR. Examples:
Object declaration, creation and use
Data types,language libraries
Error and exception handling
Interactive Development Environment (IDE)
Common Language Runtime
Development
Mixed language applications
Common Language Specification (CLS)
Common Type System (CTS)
Standard class framework
Automatic memory management
Consistent error handling and safer execution
Potentially multi-platform
Deployment
Removal of registration dependency
Safety – fewer versioning problems
Common Type System
CTS is a rich type system built into the CLR
Implements various types (int, double, etc)
And operations on those types
OR
The common type system defines how types are declared,used, and managed in the runtime.
CTS performs the following functions:
1.Establishes a framework that enables cross-language integration,type safety, and high performance code execution.
2. Provides an object-oriented model that supports the complete implementation of many programming language
Intermediate Language (IL).
NET languages are not compiled to machine code. They are compiled to an Intermediate Language (IL).
CLR accepts the IL code and recompiles it to machine code. The recompilation is just-in-time (JIT) meaning it is done as soon as a function or subroutine is called.
The JIT code stays in memory for subsequent calls. In cases where there is not enough memory it is discarded thus making JIT process interpretive.