C# – How to add request headers when using HttpClient

There are two ways add request headers when using HttpClient: Add headers for all requests using HttpClient.DefaultRequestHeaders. Add headers per request using HttpRequestMessage.Headers. In this article, I’ll show examples of both ways to add request headers. Add an unchanging header for all requests Let’s say you’re adding an API Key header. It needs to be … Read more

C# – Circuit breaker with Polly

In an electrical system, a circuit breaker detects electrical problems and opens the circuit, which blocks electricity from flowing. To get electricity flowing again, you have to close the circuit. The same approach can be implemented in software when you’re sending requests to an external service. This is especially important when you’re sending lots of … Read more

C# – How to use Polly to do retries

Whenever you’re dealing with code that can run into transient errors, it’s a good idea to implement retries. Transient errors, by definition, are temporary and subsequent attempts should succeed. When you retry with a delay, it means you think the the transient error will go away by itself after a short period of time. When … Read more

ASP.NET Core – Log messages to the database in the background

I was reading about logging in ASP.NET when I came across this statement about logging to the database: When logging to SQL Server, don’t do so directly. Instead, add log messages to an in-memory queue and have a background worker dequeue and insert data to SQL Server. Paraphrased from https://docs.microsoft.com/en-us/aspnet/core/fundamentals/logging/?view=aspnetcore-5.0#no-asynchronous-logger-methods In this article, I’ll show … Read more

C# – How to change the HttpClient timeout per request

It’s best practice to reuse the same HttpClient instance for multiple requests. When you’re using the same instance repeatedly, and you want to change the timeout per request, you can pass in a CancellationToken, like this: You can’t change HttpClient.Timeout after the instance has been used. You have to pass in a CancellationToken instead. There … Read more

C# – Newtonsoft extension methods for HttpClient

System.Net.Http.Json provides extension methods that simplify getting and sending JSON with HttpClient. Internally, it uses System.Text.Json for serialization. What if you want to use Newtonsoft instead of System.Text.Json? You can use the following extension methods for that: These are modeled off of the extension methods in System.Net.Http.Json. You can pass in a JsonSerializerSettings object to … Read more

C# – Get and send JSON with HttpClient

The simplest way to get and send JSON with HttpClient is to use the GetFromJsonAsync() and PostAsJsonAsync() extension methods found in System.Net.Http.Json, like this: Note: You have to install the System.Net.Http.Json nuget package if you’re using a framework version before .NET 5. These extension methods use System.Text.Json for serialization. They simplify things by abstracting away … Read more

C# – Switch from using HttpWebRequest to HttpClient

There are many reasons to use HttpClient instead of HttpWebRequest. For one, the MSDN docs strongly recommends against using HttpWebRequest, and using HttpClient instead. That should be enough, but if you need a little more convincing, take a look at the Practical reasons to not use HttpWebRequest section below. In addition to explaining why not … Read more

How to use toxiproxy to verify your code can handle timeouts and unavailable endpoints

When you have code that calls an endpoint, you need to make sure it’s resilient and can handle error scenarios, such as timeouts. One way to prove your code is resilient is by using toxiproxy to simulate bad behavior. Toxiproxy sits between your client code and the endpoint. It receives requests from your client, applies … Read more

Event-driven .NET: How to consume an SSE endpoint with HttpClient

Server-Sent Events (SSE) allow a client to subscribe to messages from the server. It creates a one-way stream from the server to the client. When the server has new messages for the client, it writes them to the stream. This is an alternative to the client polling the server for updates. Use the following to … Read more