The middle of the RIA spectrum is occupied by runtime engines, development tools, and libraries that do more on the client than simple AJAX, and do it more quickly, but don't have the overhead of the .Net Framework or the Java JRE. Adobe Flash, Flex, and Shockwave are midsized RIA engines. Curl falls in this category, as does OpenLaszlo, although OpenLaszlo can generate both AJAX and Flash applications.
Adobe Flex 3.0 promises much faster runtimes than Flex 2.0, and Adobe AIR pledges a cross-operating system runtime that allows developers to use their existing Web development skills to build and deploy rich Internet applications to the desktop. Meanwhile, Google Gears gives you a LocalServer, a Database, and a WorkerPool so that you can make Web applications run on the desktop.
Hands-on reviews of the rich Web toolkits
InfoWorld has reviewed a number of RIA toolkits and frameworks, including open source AJAX packages Dojo, Ext, Google Web Toolkit, JQuery, MooTools, Prototype, Scriptalicious and Yahoo User Interface Library; enterprise AJAX tools JackBe Presto and Nexaweb Enterprise, as well as Backbase, Bindows, and Tibco General Interface; Microsoft Silverlight 1.0; Adobe Flex 2.0; and Curl 6.0. Many of these reviews include links to recorded screencast demos that show just what the tools can do.