IIS (Internet Information Services) Handlers are components in the IIS web server that process specific types of requests. They are an essential part of the request-processing pipeline and determine how requests for certain resources (like .html, .aspx, .jpg files) are handled by the server.
Handlers can be thought of as the intermediaries that translate requests into actions that the server can execute, enabling a more organized and efficient processing system.
Handlers are invoked during the "Execute Request Handler" stage of the IIS request-processing pipeline. This stage comes after the request has been authenticated, authorized, and filtered by any applicable modules. When a request reaches this stage, the IIS pipeline looks up the appropriate handler based on the request type and any configured routes or mappings.
IIS comes with several built-in handlers, categorized into three types:
These handlers are responsible for serving static files such as HTML, CSS, JavaScript, and images.
Script handlers process dynamic content. Examples include ASP.NET handlers for .aspx files, PHP handlers for .php files, and so on.
These are user-defined handlers that can be created to handle custom scenarios or specific types of requests not covered by the default handlers.
Custom handlers can be developed to meet specific needs where default handlers fall short. For example, a custom handler could be written to:
Creating a custom handler typically involves implementing the `IHttpHandler` interface in .NET, allowing you to define the logic for processing requests. We will discuss how to create custom handlers and invoke different features of it in the upcoming blog.
Handlers can intercept traffic by hooking into the request pipeline at specific stages. They can inspect, modify, or even abort requests based on custom logic. Here’s how this typically works:
For incoming requests, handlers can:
For outgoing responses, handlers can:
Using IIS handlers offers several advantages:
IIS handlers are particularly useful in scenarios where:
To get the most out of IIS handlers, consider the following best practices:
IIS handlers are powerful tools in the web server’s arsenal, offering the flexibility to handle a wide range of request types and scenarios. Whether you are working with static files, dynamic content, or custom processing needs, understanding and effectively utilizing handlers can significantly enhance your web application’s performance and capabilities.
By adhering to best practices and leveraging the unique advantages of handlers, you can ensure a robust and efficient request-processing pipeline for your applications.
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