Perils of Async: Introduction

As application communications over lossy networks and “in the cloud” have grown, the necessity of performing these communications asynchronously has risen with them. Why this change has been occurring may be an interesting topic for another post, but a few simple cases demonstrate the point:

  • Web browsers make multiple, asynchronous HTTP calls per page requested. Procuring a page’s images, for example, have been asynchronous (“out-of-band”) operations for at least decade.
  • Many dynamic websites depend on various technologies’ (AJAX, JavaScript, jQuery, etc.) asynchronous capabilities – that’s what makes the site “dynamic.”
  • Similarly, most desktop and mobile applications use technologies to communicate asynchronously.

Previously, developing asynchronous software – whether inter-process, multi-threaded, etc. – required very talented software developers. (As you’ll see soon enough, it still does.) Many companies and other groups have put forward tools, languages, methodologies, etc. to make asynchronous development more approachable (i.e., easier for less sophisticated developers).

Everyone involved in software development – developers, managers, business leaders, quality assurance, and so on – need to be aware, however, that these “tools” have a down-side. Keep this maxim in mind: Things that make asynchronous software development easier also make bad results Ibugs!) easier. For example, all software involving some form of asynchronicity

  • Not only has bugs (as all software does), but the bugs are much, much more difficult to track down and fix
  • Exhibits higher degrees of hardware-based flux. Consider, for example, a new mobile app that is stable and runs well on a device using a Qualcomm Snapdragon S1 or S2 (single-core) processor. Will the same app run just as well on a similar device using (dual-core) Snapdragon S3 or above? Don’t count on it – certainly don’t bet your business on it!

This series of posts, Perils of Async, aims to discuss many of the powerful .NET capabilities for asynchronous and parallel programming, and to help you avoid their perilous side!

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