1.to develop different types of applications like windows web mobile games embedded cloud computing 2.all types of applications in a unified model(similar development style) 3..net support 40+ languages moreover all languages can use these libraries
Full interoperability with existing code Complete and total language integration A common language runtime engine shared by all .net supported languages a base class library easy deploymnet code management and code securit Good maemory management thorugh GC
*Interoperability: To have better interface between new and old applications, .net has p/invoke feature. In addition to this, it has access to COM components that are provided in the system. * Common Runtime Engine ? For security purpose and proper management of memory and other exception handling, .Net has virtual machine component. * Language Independence - .Net framework has common type system that supports the exchange of different types of programs written in .Net languages. * Base class library- For using different languages, .Net provides classes for providing a summary of common functions. This also helps in interaction of database and XML document manipulation. * Simplified Deployment of software programs helps in providing conformity to security requirements. It has design features and various tools to address the needs of the professionals.
The following are major features of .NET. We will use these features throughout out journey. Here is just a brief introduction to all key features of .NET.
An assembly is either a .DLL or .EXE that forms a part of an application. It contains MSIL code that is executed by CLR. The following are other important points related to an assembly:
1. It is the unit on which permissions are granted. 2. Every assembly contains a version 3. Assemblies contain interfaces and classes. They may also contain other resources such as bitmaps, file etc. 4. Every assembly contains assembly metadata, which contains information about assembly. CLR uses this information at the time of executing assembly. 5. Assemblies may be either private, which are used only by the application to which they belong or Global assemblies, which are used by any application in the system. 6. Two assemblies of the same name but with different versions can run side-by-side allowing applications that depend on a specific version to use assembly of that version.
The four parts of an assembly are:
Assembly Manifest - Contains name, version, culture, and information about referenced assemblies.
Type metadata - Contains information about types defined in the assembly.
MSIL ? MSIL code.
Resources - Files such as BMP or JPG file or any other files required by application.
Note: Assembly that contains only resources is called as Satellite assembly.
Common Type System
Common Type System (CTS) specifies the rules related to data types that languages must follow. As programs written in all languages are ultimately converted to MSIL, data types in all languages must be convertible to certain standard data types.
CTS is a part of cross-language integration, which allows classes written in one language to be used and extended by another language.
.NET provides support for language interoperability. However, it doesn?t mean every program written in a language can be used by another language. To enable a program to be used with other languages, it must be created by following a set of rules called Cross Language Specifications (CLS).
Cross-language inheritance is the ability to create a class in C# from a class created in VB.NET.
When an exception is raised by a program written in C#, the exception can be handled by VB.NET. This kind of exception handling is called cross-language exception handling.
.NET has brought a set of new features which are to be understood by every programmer developing applications for Windows. There is no way any Windows programmer can ignore .NET, unless he is desperate to be outdated. Microsoft will provide .NET as part of its operating systems in future releases. It is the platform for programmers. It is not new OS from Microsoft or a new language. It is the environment for which you develop applications. It is rich in terms of features. Believe me, programming using VB.NET is fun and it is more productive than VB 6.0.
The following are different types of applications that can be developed in .NET:
Windows applications ? typical Client/Server applications.
Web applications ? Web sites and Intranet applications.
Web services ? Programs that are accessible from anywhere using universal protocols like HTTP and SOAP.
Console Applications ? Simple console based applications without any GUI. Run from command prompt. Best suited to learn fundamentals and also for applications such as server sockets.
Mobile Applications ? Contain web pages that run in mobile devices such as PDAs (Personal Digital Assistant) and Cell phones.
When multiple users are working on one application, the SQL/Oracle statement gets locked when one user is working, thus another user cannot work simultaneously. How can multiple users work. Thus give me syntax for freeing SQL/Oracle queries in order for working of multiple users.