Using asyncstreams to call a web service

.Net Core 3.0 includes Asynchronous streams.

Basically IAsyncEnumerable is an asynchronous version of IEnumerable. To use it in a you await a foreach loop to consume the elements

await foreach (var location in GetISSLocationSequence())
{
    Console.WriteLine(location);
}

GetISSLocationSequence is an async function which yield 20 IIS locations. It waits 1 second between getting locations

Public static async System.Collections.Generic.IAsyncEnumerable<string> GetISSLocationSequence()
{
    using HttpClient http = new HttpClient();
    for (int i = 0; i < 20; i++)
    {
       var json = await http.GetStringAsync("http://api.open-notify.org/iss-now.json");
       await Task.Delay(2000);
       yield return json;
    }
}

One other thing I would like to point out was the format for the using statement. Notice in this function I am using a using statement to make sure the HtppClient get disposed of when we done with it. Notice we no long have to put the code is {}. The HttpClient will dispose at the end of the function

To demo this I put the code in a .net core console application. To allow

await in the sub main I changed it from a void to async Task

class Program
{
    static async Task Main(string[] args)
    {
  
         await foreach (var location in GetISSLocationSequence())
         {
             Console.WriteLine(location);
         }
    }