The Mechanics of HTML Applications in the UcompOS RPF

When I set out to build the application (the Educator 2 E-Learning Enterprise Management System) that led me to build the UcompOS RPF, I was operating under some very simple premises.

One such premise is, to the maximum extent possible, I didn’t want to be handcuffed exclusively to any one particular technology.

While I did make the decision to make the UcompOS Portal (i.e. the “Main Container”) a Flex 4 application (and I am very comfortable with this decision), as far as the sub-applications that would be launched inside or alongside the UcompOS Portal, I simply felt I absolutely needed to be able to work with as wide of a canvas as possible and for me this includes Flex, Flash, HTML/JavaScript/CSS, Adobe AIR for desktop UcompOS applications and even Microsoft Silverlight.

But any of these technologies need be able to interact with each other seamlessly such that what particular technology a UcompOS application or sub-application was constructed with was irrelevant in the context of the overall UcompOS Continuum.

In a full-fledged UcompOS implementation that has multiple UcompOS Applications all working in conjunction with each other, each application, sub application, and the UcompOS Portal itself is a player I refer to as an entity.

For an entity to be able to talk to other entities or execute API commands on other entities, it must have the UcompOS SDK installed.  The download for the UcompOS SDK contains 3 resources for Flash/Flex, AIR, and JavaScript developers.

The Flash/Flex SDK is a SWC that has no Flex dependencies so you can use it interchangeably in Flash as well as Flex applications, however, the Flash/Flex SDK is based on ActionScript 3 and at this point I don’t yet have any intention to release an ActionScript 2 SDK (though there still are ways to involve ActionScript 2 applications in UcompOS implementations and that will be covered in a future posting).

The AIR SDK is a SWC file that has some AIR 2.0 dependencies so that will only compile in an application that has the AIR 2.0 SDK at its disposal.

The JavaScript SDK is comprised of 2 files: UcompOSSDK.js and UcompOSSDK.swfUcompOSSDK.js needs to be included in a UcompOS HTML Application <SCRIPT/> element and the file can be placed on any webserver – even on a domain different than the domain hosting the UcompOS Application.

However, the UcompOSSDK.swf file MUST be served on the SAME domain as the domain that is serving the UcompOS HTML Application.

By default, the UcompOS SDK will look for the UcompOSSDK.swf file in the root of the webserver – i.e. at an absolute path of /UcompOSSDK.swf.  This however can be changed by setting the basePath variable in your HTML Application’s JavaScript code to a relative or absolute path – for instance:

basePath = ‘./’;

would tell the UcompOS SDK that the UcompOSSDK.swf file can be found in the same directory as the HTML Application.

In my post yesterday I discussed the fact that for browser based content, UcompOS applications use the LocalConnection infrastructure of the Flash Player as their communication medium (UcompOS AIR Applications use the new AIR 2.0 ServerSocket implementation).

So if the UcompOS Continuum is based on the LocalConnection which is a Flash Player implementation, how then do UcompOS HTML Applications participate in UcompOS transactions?

The answer is using the UcompOSSDK.swf as a Proxy to the UcompOS Continuum.

When the UcompOSSDK.js file is implemented into a UcompOS HTML Application, the UcompOSSDK.swf file is loaded as an invisible element into the page via DHTML.

The UcompOSSDK.swf file is actually a UcompOS Application with the UcompOS SDK incorporated into it.

The UcompOSSDK.swf application utilizes a Proxy Component (more on Proxy Components in a future post) called JavaScriptCommand.  The UcompOS JavaScript SDK serves as a traffic manager between a UcompOS Application’s internal implementation and the UcompOSSDK.swf application.  Then the UcompOSSDK.swf application and its JavaScriptCommand Proxy Component serves as a proxy to the UcompOS Continuum.

If all this sounds complicated, well, it is.  It took a lot of time to think through the implementation details and to develop, test, and perfect them.  But once you get your head around it, it is very easy to implement.

For the most part, the mechanics involved with leveraging the UcompOS JavaScript SDK are very similar to those involved with the UcompOS AIR and Flash/Flex SDK.

ActionScript 3 and JavaScript are different languages though.  For starters, ActionScript 3 is a strongly typed language and JavaScript is not.  Also, implementing Object Oriented design patterns in JavaScript is more convention than strict procedure so there are subtle differences I’ll cover in this blog as the project evolves.

To get started building simple UcompOS HTML applications, you really only need to know a very basic amount of JavaScript.  To build full fledged powerful UcompOS HTML applications however that implement Services Dictionaries and Proxy Components (I’ll devote separate postings to each of these exciting topics in the next week), you do need to invest some time into learning Object Oriented Programming conventions in the JavaScript programming language.

About Edward Mansouri
Edward Mansouri is the CEO and Founder of Ucompass.com, Inc., a company focused on building scalable and profitable e-Learning enterprises. His expertise is in building e-Learning software, as well as in building visual frameworks such as the Enrich Content Enrichment System and the newly announced UcompOS Rich Experience Framework. He has been working with Flash since 1998, building Flash applications since 2002, and working with Adobe AIR since its private alpha release in 2006. He authored the site AIRApps.net (later renamed to O2Apps.com) dedicated to providing leadership in building Adobe AIR applications. In 2010, he is building and releasing a new e-Learning platform called Educator 2 which is built entirely upon the UcompOS Rich Experience Framework. Since 1999, over 1,000,000 students have taken courses served with his original e-Learning platform, Educator 1.

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