HTTPClient is a powerful tool for making HTTP requests in C#. It is a versatile library that can be used to make requests to web APIs, download files, and more. However, it is important to use it correctly in order to ensure that your code is secure and efficient.
In this article, we will discuss 10 best practices for using HTTPClient in C#. We will cover topics such as using the correct HTTP methods, using the correct status codes, and more. By following these best practices, you can ensure that your code is secure and efficient.
1. Use the HttpClientFactory
The HttpClientFactory provides a way to manage the lifetime of your HTTPClients, which is important because creating and disposing of them can be expensive.
The HttpClientFactory also allows you to configure your clients with specific settings such as timeouts, headers, etc., so that all requests made using the same client will have the same configuration. This makes it easier to debug issues since you don’t need to worry about different configurations causing unexpected behavior.
Finally, the HttpClientFactory helps improve performance by reusing existing connections instead of creating new ones for each request. This reduces the overhead associated with making multiple requests and ensures that resources are used efficiently.
2. Dispose of your HttpClient object when you’re done with it
When you create an HttpClient object, it creates a connection to the server and keeps that connection open until you explicitly close it. This means that if you don’t dispose of your HttpClient object when you’re done with it, then the connection will remain open and can cause memory leaks or other performance issues.
To avoid this issue, make sure to always call the Dispose() method on your HttpClient object when you’re done using it. This will ensure that the connection is closed properly and any resources associated with it are released.
3. Don’t use a single instance of HttpClient for all requests
When you use a single instance of HttpClient, it can lead to connection pool exhaustion. This is because the underlying TCP connections are not released back into the pool when requests complete. As more and more requests come in, the number of available connections decreases until eventually there are none left.
To avoid this issue, create a new instance of HttpClient for each request. This ensures that all connections are properly released back into the pool after they have been used. Additionally, if you need to make multiple requests at once, consider using an asynchronous approach such as async/await or Tasks.
4. Set up a timeout value on your HttpClient object
When you make an HTTP request, the server may take a long time to respond. If your HttpClient object doesn’t have a timeout value set, it will wait indefinitely for a response from the server. This can cause your application to hang and become unresponsive.
By setting up a timeout value on your HttpClient object, you ensure that if the server takes too long to respond, your application won’t be stuck waiting forever. You can also use this timeout value to determine how long your application should wait before giving up on the request and trying again.
5. If you need to make multiple calls, consider using async/await
When making multiple calls, it’s important to ensure that the requests are sent out in a timely manner. If you use synchronous calls, then each request will be sent one after another, which can lead to delays and timeouts. On the other hand, if you use async/await, then all of the requests can be sent at once, allowing for faster response times. Additionally, using async/await also allows your code to remain more organized and readable.
6. Consider adding Polly to handle transient errors
Polly is a .NET resilience and transient-fault-handling library that allows developers to add robustness to their applications by adding retry logic. This means that if an HTTP request fails due to a transient error, such as a timeout or network issue, Polly will automatically retry the request until it succeeds. This helps ensure that your application remains responsive even in the face of intermittent errors.
7. Add Polly as part of the HttpClient pipeline
Polly is a .NET resilience and transient-fault-handling library that allows developers to add robustness to their applications. It helps with retrying failed requests, circuit breaking, timeouts, and more. By adding Polly as part of the HttpClient pipeline, you can ensure that your application will be resilient in the face of network failures or other issues. This will help keep your application running smoothly and prevent any downtime due to unexpected errors.
8. Make sure you have proper logging in place
Logging allows you to track the requests and responses that are sent and received by your application. This is especially important when debugging, as it can help you identify any issues with your code or configuration quickly and easily.
Logging also helps you monitor performance, so you can see how long each request takes and if there are any bottlenecks in your system. Additionally, logging can be used to detect security threats such as malicious requests or unauthorized access attempts.
Finally, having proper logging in place will ensure that you have a record of all activity related to your HTTPClient usage, which can be invaluable for auditing purposes.
9. Avoid making synchronous calls from an ASP.NET Core controller
When a synchronous call is made from an ASP.NET Core controller, the thread that handles the request will be blocked until the response is received. This can cause performance issues as requests pile up and threads become unavailable to handle new requests.
To avoid this issue, it’s best practice to use asynchronous calls instead. Asynchronous calls allow the thread handling the request to continue processing other requests while waiting for the response. This helps ensure that your application remains responsive even when making multiple HTTP requests.
10. Use the IHttpClientFactory interface instead of creating your own HttpClient instances
The IHttpClientFactory interface provides a way to create and manage HttpClient instances in an efficient manner. It allows you to reuse existing connections, set timeouts, and configure other settings that are important for performance. Additionally, it helps prevent memory leaks by disposing of unused resources. This is especially important when dealing with long-running applications or services.