Microsoft .Net - FAQ

9. What is Interoperability? How does Microsoft .Net provide Interoperability?

Interoperability is the ability of diverse/different components to work together (inter-operate).

Because interaction between new and older applications is commonly required, the Microsoft .NET Framework provides means to access functionality that is implemented in programs that execute outside the .NET environment, e.g COM components. Access to COM components is provided in the System.Runtime.InteropServices and System.EnterpriseServices namespaces of the framework, and access to other functionality is provided using the P/Invoke feature (Platform Invoke).

10. What is Simplified Deployment in Microsoft .Net?

Once the .Net Application is developed, it must be installed on client machines or on the server. Installation of the Application must be carefully managed to ensure that it does not interfere with previously installed software, and that it conforms to stringent security requirements. The Microsoft .NET framework includes design features and tools that help address these deployment requirements.

11. What is Portability ?

Application Portability is one of the key concepts of Microsoft .Net. Application Portability means to be able to reuse the existing code instead of creating new code when moving Applications from one environment to another.

The design of the .NET Framework allows for it to be cross platform compatible. This means, that a program written to use the Microsoft .Net Framework should run without change on any type of system for which the framework is implemented. Microsoft's commercial implementations of the framework cover Windows, Windows CE, and the Xbox 360. In addition, Microsoft submits the specifications for the Common Language Infrastructure (which includes the core class libraries, Common Type System, and the Common Intermediate Language), and the C# language, and the C++/CLI language to both ECMA and the ISO, making them available as open standards. This makes it possible for third parties to create compatible implementations of the framework and its languages on other platforms.

12. How does Microsoft .Net implement Security for Applications?

The Microsoft .NET Framework has its own security mechanism. The security mechanism in Microsoft .Net has two general features: Code Access Security (CAS), and validation and verification. CAS is based on information that is associated with a specific assembly. The information is the source of the assembly. CAS uses information to determine the permissions granted to the code. Other code can demand that calling code is granted a specified permission. The demand causes the CLR to perform a call stack walk: every assembly of each method in the call stack is checked for the required permission and if any assembly is not granted the permission then a security exception is thrown.

When an assembly is loaded the CLR performs various tests. Two such tests are validation and verification. During validation the CLR checks that the assembly contains valid metadata and CIL, and it checks that the internal tables are correct. Verification is not so exact. The verification mechanism checks to see if the code does anything that is 'unsafe'. The algorithm used is quite conservative and hence sometimes code that is 'safe' is not verified. Unsafe code will only be executed if the assembly has the 'skip verification' permission, which generally means code that is installed on the local machine.