{"id":1032,"date":"2019-12-03T19:15:00","date_gmt":"2019-12-03T18:15:00","guid":{"rendered":"http:\/\/cmagazine.test\/net-async-await-and-its-catches\/"},"modified":"2019-12-03T19:15:54","modified_gmt":"2019-12-03T18:15:54","slug":"net-async-await-and-its-catches","status":"publish","type":"post","link":"https:\/\/www.codemotion.com\/magazine\/backend\/net-async-await-and-its-catches\/","title":{"rendered":".NET Async\/Await and its catches"},"content":{"rendered":"

Since the introduction of the Task-based Asynchronous Pattern<\/b> (or TAP) with .NET 4.0 programmers have enjoyed a simpler and streamlined approach to asynchronous programming in .NET<\/strong>, improving performance and readability of their code.<\/p>\n

If you are already familiar with .NET TAP basic concepts, don\u2019t miss the opportunity to learn more from an expert: Brandon Minnick<\/b>, developer advocate with Microsoft<\/strong>, will address some in his talk \u201cCorrecting Common Async\/Await Mistakes in .NET<\/em>\u201d at Codemotion Milan 2019<\/a><\/b> – check the agenda<\/a>. Hurry up as tickets are still available<\/a>!<\/p>\n

Was it worth the Await?<\/h2>\n

Before TAP, .NET programmers had several alternatives to write non-blocking code:<\/p>\n

    \n
  • Using the Asynchronous Programming Model<\/b> (APM), with its Begin*<\/code>, End*<\/code> methods and its IAsyncResult<\/code> interface;<\/li>\n
  • The Event-based Asynchronous Pattern<\/b> (EAP), which is the legacy event-based model introduce with .NET 2.0;<\/li>\n
  • Writing code at a lower level using Threads<\/b> and the related synchronization primitives (Mutex<\/code>, Semaphore<\/code>, etc).<\/li>\n<\/ul>\n

    All of these alternatives are somewhat cumbersome and difficult to handle compared to the Async\/Await paradigm introduced with TAP. They all require a lot of boilerplate just to get things up and running, with the obvious consequence of hurting readability and maintainability.<\/p>\n

    TAP is instead very simple to grasp, as far as parallel programming can go. It is modelled around the concept of Tasks as the name implies. A Task is simply a generic asynchronous operation, some piece of code we want to run without blocking the caller or other tasks.<\/p>\n

    An async Hello World<\/h2>\n

    So let\u2019s get started with a simple \u201chello world<\/b>\u201d example with the Async\/Await constructs. The goal of this simple program is to perform a few HTTP GET<\/i> requests against a list of servers. A simple synchronous version would be:<\/p>\n