The dojo.Deferred module has long been a central component of Dojo, providing a powerful interface for asynchronous operations like HTTP requests. Dojo’s Deferreds are a form of promises, providing a separation of concerns between the mechanics of calling a function and the interface for interacting with the eventual asynchronous future result. Passing callbacks directly to functions tightly couple the interface with asynchronous semantics, but using Dojo’s Deferreds (promises) keeps the concerns separate for robust asynchronous code. Furthermore promises can greatly simplify interaction, allowing one to easily get the eventual result of an operation whether it has already finished, or if it is yet to be finished. While the Deferred module has existed in Dojo for some time, version 1.5 introduces some valuable enhancements.
Posts Tagged ‘Deferred’
Robust Promises with dojo.Deferred 1.5
Monday, May 3rd, 2010Queued: Demystifying Deferreds
Tuesday, March 31st, 2009At SitePen, we work very hard to to provide our customers and fellow developers with useful web app development services. We’re currently deconstructing the development of Queued, our Netflix Queue management application built with Dojo and Adobe AIR. Having presented on dojo.deferred and related topics at the Ajax Experience, and having heard that the Queued team ran into a few problems with them, I thought it would be interesting to review problems that are sometimes encountered when using Deferreds. What is the source of these problems, are these problems related to bugs or because there are misunderstandings, and how should we address this going forward?
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