There are several new features in IIS 7.0 as compared with IIS 6.0/IIS 5.0. IIS 7.0 has been re-engineered at its core to deliver a modular and extensible web server platform, forming the foundation for learn, low-footprint Web servers that power customized workloads and Web applications. The new extensible architecture enables the Web server to be completely customized; we can select only the required IIS features and add or replace them with new Web server features and leverage the new rich extensibility application programming interfaces (APIs). In addition, the Web server enables the use of a new distributed configuration system and management tools that simplify Web server deployment and management. The core feature set of IIS 7.0 continues to leverage the reliability and security-focused architecture established by its predecessor, IIS 6.0, and it adds additional improvements to enhance the reliability and security of the Web server platform. IIS 7.0 also includes extended support for application frameworks, including better integration with ASP.NET and built-in support for FastCGI-compliant application frameworks.

Among its many improvements, IIS 7.0 delivers the following:

Modular Web server architecture:

Unlike its monolithic predecessors, IIS 7.0 is a completely modular Web server, containing more than 40 components that the administrator can individually install to create low-footprint, reduced surface-area Web server deployments that play a specific role in the application topology. Furthermore, the new extensibility architecture enables any of the built-in modular features to be replaced with customized implementations that Microsoft and third parties provide.

.NET Extensibility through ASP.NET integration:

The new ASP.NET integration capabilities enable you to develop IIS 7.0 features with the power of ASP.NET and the .NET Framework, reducing development and maintenance costs for custom Web server solutions. You can use existing ASP.NET services in this mode to enhance any application technologies, even those that were not developed with ASP.NET in mind. These abilities enable Web applications using IIS 7.0 to further customize the Web server to their needs without incurring the higher development costs associated with the previously used Internet Server Application Programming Interface (ISAPI).

Enhanced application framework support:

In addition to improved ASP.NET integration for extending the Web server, IIS 7.0 provides more options for hosting other application frameworks. This includes the built-in support for the FastCGI protocol, a protocol used by many open source application frameworks such as PHP Hypertext Preprocessor (PHP) so that they can be reliably hosted in a Windows environment.

Distributed configuration system with delegation support:

IIS 7.0 replaces the centralized meta base configuration store with a new configuration system based on a distributed hierarchy of XML files, which enables applications to control their own configuration. The new configuration system enables simplified application deployment without the overhead of required administrative involvement and provides the foundation for more flexible Web server configuration management.

Improved management tools:

IIS 7.0 offers a host of management tools that leverage the new configuration system to provide more flexible and simpler configuration management for the Web server. This includes a brand new task-based IIS Manager tool, which offers remote delegated management; a new tool for command line management (Appcmd); and several APIs for managing Web server configuration from scripts, Windows Management Instrumentation (WMI), and .NET Framework programs.

Enhanced diagnostics and troubleshooting:

IIS 7.0 provides diagnostic features to help diagnose Web server errors and troubleshoot hard-to-reproduce conditions with a failed request tracing infrastructure. The diagnostic tracing features are integrated with ASP.NET applications to facilitate end-to-end diagnostics of Web applications.