Browser security prevents a web page from making requests to a different domain than the one that served the web page. This restriction is called the same-origin policy. The same-origin policy prevents a malicious site from reading sensitive data from another site. Sometimes, you might want to allow other sites to make cross-origin requests to your app.

AspNetCoreRateLimit is an ASP.NET Core rate limiting solution designed to control the rate of requests that clients can make to a Web API or MVC app based on IP address or client ID. The AspNetCoreRateLimit package contains an IpRateLimitMiddleware and a ClientRateLimitMiddleware, with each middleware you can set multiple limits for different scenarios like allowing an IP or Client to make a maximum number of calls in a time interval like per second, 15 minutes, etc. You can define these limits to address all requests made to an API or you can scope the limits to each API URL or HTTP verb and path.

When consuming a web API, understanding its various methods can be challenging for a developer. Swagger, also known as OpenAPI, solves the problem of generating useful documentation and help pages for web APIs. It provides benefits such as interactive documentation, client SDK generation, and API discoverability.

ASP.NET Core gives provides the ability to write middleware, which is logic inserted into the pipeline that the framework runs for every request that is received by the application. ASP.NET Core ships with core middleware components that enable things like rendering MVC pages, defining endpoint routes, and adding authentication support, and these things are configured in the application’s Startup class, where you can also add your own custom middleware components. This ability to easily configure and customize how ASP.NET Core processes requests is tremendously useful and powerful.

We will be creating exception-handling middleware to catch and handle any exceptions that are thrown during the execution of a request to our service.

In ASP.NET Core, background tasks can be implemented as hosted services. A hosted service is a class with background task logic that implements the IHostedService interface. This topic provides three hosted service examples:

• Background task that runs on a timer.
• Hosted service that activates a scoped service. The scoped service can use dependency injection (DI).
• Queued background tasks that run sequentially.

In many projects we want to call external APIs and use their results in our application. In this article, we will address the following:

• HttpClientFactory
• Refit
• Polly