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being a java programmer sometimes feels like being in the movie groundhog day. in the movie, bill murray is stuck in a loop: every morning when he wakes up its the same day (groundhog day). he relives the day over and over again, seemingly without reason. but the days are subtly different: each time he relives the same event, he learns a little bit more about how to be a better person. and, at the end of the movie, bill murray finally gets to move on and live the rest of his life.
but just as bill murray eventually got to experience all of the days that come after groundhog day, we may be on the verge of changing how we build web applications. theres a growing restlessness in the air, and a growing movement towards rich internet applications. in this article, im going to give you a quick overview of laszlo, an open source rich internet application development platform. first ill give a high level overview of what laszlo is, and how it works. then ill give you a quick tour through some of the basic features of laszlo, and talk about whats involved in building an application in laszlo. and, after that, ill talk about where it works best, and when it makes sense to use laszlo. 【程序编程相关:Revenge of the Old F】
similarly, every year, without fail, java developers get to see new programming frameworks and container models. and, in much the same way that bill murray gradually addresses his problems and becomes a better person, the frameworks are getting better, and helping us to become better programmers (or, at least, deliver higher quality applications in shorter time frames). but, in the same way that bill murray keeps seeing the same things happening over and over again, we keep getting presented with frameworks that keep solving the same problems over and over again. while java.sun.com/j2ee/javaserverfaces/index.jsp">javaserver faces looks much better than struts, it doesnt enable anything new: its just a better way of creating the same old html-over-http web applications. 【推荐阅读:The Black Box @ JDJ】
the phrase "rich internet application framework" is a lot like the word pornography: easy to identify (the old "i know it when i see it" standard) but hard to define. generally speaking, when people say "rich internet application," they usually mean something that meets the following criteria: 【扩展信息:From Writing Program】
rich internet applications the application is launched from (or even contained within) a web page. the application provides immediate feedback to users when they interact with the application (instead of a two-to-four-second delay while a response is fetched from a server somewhere). and it eliminates the "white screen while we refresh the page" aspects of existing web applications. the application uses modern user interface controls, such as tree controls or tabbed panels, instead of living with what was current at the time html 4.0 was drafted. the application allows users to perform common "fat client" operations like drag and drop, or using keyboard navigation in a way that feels natural to them. the application has the same the ease of deployment and almost universal reach of existing web applications. the application does all of the above without requiring large amounts of platform- or browser-dependent javascript.youll note that the above list of criteria doesnt include a lot of technological guidance. thats because the field of rich internet applications is wide open, and there are a lot of frameworks and environments out there. some of the leading contenders include:
laszlo, snapp mx, and flex, which build on top of flash. aspx">xaml, the new markup language from microsoft. asperon.com/">asperon, which builds on top of javasoft.com">java. java.sun.com/products/javawebstart/">java web start, which is actually part of java. general interface (recently purchased by tibco), which builds on top of a sophisticated javascript library. ideaburst, which uses svg instead of flash, java, or javascript. kenamea, which replaces http with a custom protocol and uses javascript and dhtml on the client side. xul, the graphical toolkit written by mozilla. in many ways, this is the grand-daddy of the current set of rich internet application architectures. (if youre curious about xul, you might also want to look at planet xul.)however, while they use vastly different technologies, platforms for rich internet architectures have some interesting commonalities. among them are:
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