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AJAX, Adobe’s Flex 2 & Navatec’s VCT AJAX AJAX seemed to become an issue of discussion following an article published in February 2005 by Jesse James Garrett, which described the bundle of existing Internet systems development resources as being capable of asynchronous communication of data. Basically the key point is that server based data, or output from background processing, can be pushed to the client end. The backbone scripting being JavaScript or ECMAScript. Adobe's Flex 2 Recently Adobe launched a product called Flex 2 which many see as a competitor to AJAX. Adobe's push technology is considered to be the highlight of Flex 2 by eliminating the need for polling between the client and server. Some consider that Flex’s ability to push data to the client is completely original. Adode consider Flex 2 to provide an enterprise solution for developing applications in the context of SOA, with clients using services provided by a back-end system. On this basis Adobe believes it is offering the most technically elegant, sophisticated and most complete way to develop rich Internet applications.
Flex Builder's visual layout capability has been improved as well, being based on Eclipse with WYSIWYG functionality. Skinning and styling capabilities also have been revamped, enabling developers to apply their own customized look and feel to an application. Navatec's VCT Virtual Client Technology is a product of the Systems Engineering Economics Lab (SEEL) which achieves all that AJAX and Flex 2 accomplish using a different and user orientated architecture. VCT has three components:
The servers used to support the Virtual Client’s control are also DScript servers which can run at the server end or at the client end within the PC. DScript provides the foundation VCT is the product of a dedicated applied R&D programme known as Seel-Telesis and which is coordinated by Hector McNeill. McNeill says that, “We have been working on AJAX-type functionality for some 7 years now. The way we use the equivalent resources has followed a different systems engineering approach however. We already have several proven commercial applications. We chose DScript as the foundation script because of its modularity in design but more importantly, DScript has had asynchronous communications capability built in from the start; it is a relatively easy implementation. This can run in the background or foreground. DScript also enables cross access between scripts so that it is possible for one script, if it has the necessary authorization, to read the contents of a specific node in another script in real time. DScript has also had the capability to read and present online dynamic content such as commodity quotes and financial rates. We find it puzzling that such capabilities are being currently considered to be some new capability by those who are reviewing AJAX and Flex 2. But these capabilities, in a very robust and operational form, have been available to DScript users for well over 7 years.” Concerning the process involved in developing VCT, McNeill said, “We worked for the first three years perfecting the operational linkages between local pages, the Virtual Client and servers. At that time we were only working with our Virtual Clients, a proprietary technology, and DScript products. Once that was proven with real busines applications, in early 2004, we began to investigate the feasibility of integrating all other ECMAScript-based extensions, techniques and scripting variants. Naturally with the effectiveness of the then MacroMedia Flash in the graphics and dynamic presentation areas we began to integrate ActionScript and an Australian variant, SwishScript. I have to say that we found these scripts to be variants in the real sense of the word in that they are not totally faithful versions of ECMAScript, but through the use of “intermediation” carried out in DScript, which is a more robust interpretation, we have been able to integrate these scripts completely.” "We have also found that for data intensive applications it is better to rely on scripts designed for this purpose, such as DScript. ActionScript and SwishScript are fine for presentation and dynamic graphic interface effects including video, and other forms of presentation, however DScript does all the data processing and presentation of data in formats accessible by these other scripts. DScript even generates the clients containing the other scripts. For heavy duty commercial applications where there are multiple simultaneous sessions involving data input dialogues and reports and things like document flow management, intensive read and writing of data, DScript handles this well" Which should you use? There are differences in the availability of AJAX, Flex2 and VCT. AJAX and Flex2 are essentially development kits which are generally available. AJAX is the currently available Internet resources making AJAX a sort of low cost open source system. Flex 2 is an Adobe developer's kit with a pricing model which is sensitive to the fact that AJAX is virtually free. AJAX implementations are extremely recent and largely unproven on heavy duty commercial and business applications. Indeed, there are arguments in the media that several applications stated to be AJAX-based are not in fact based on AJAX. Flex 2 has only just been launched. As a result, heavy duty commercial applications are yet to be proven. On the other hand, VCT has the longest track record of proven business applications. But VCT is not supplied as a developer's kit but rather as an online business applications service. McNeill says that the feasibility of providing VCT as a development kit is being looked into but for the moment no decision has been made on this score. Cost-effectiveness? The cost of ownership of these three approaches for sophisticated business applications is lowest with VCT simply because it is available as an online service provided through Navatec.Com. The high end Flex2 systems, designed for business aplications, have a development kit price of some $15,000 before purchase of servers and any design, development and implementation effort. It is likely that for a company to get to the point of commissioning an application based on Flex 2 we are talking about a minimum outlay of around $30,000. Such an outlay and the associated risks for what would be an unproven application can be avoided using the Navatec.Com service. Their service fee rates fall within a range of $50-$150/month per client staff member seat. Where customers have large customer bases Navatec.Com provide very competitive rates for the maintenance of customer specific data in online databases. Customer-specific services One of the criticisms leveled at online business applications services has been the inability of such services to deliver truly customised services. Navatec.Com however have proven the market wrong by adopting a sophisticated system whereby their online applications service can deliver user-specific services. This is achieved by integrating customer-specific design and development costs into a futures contract. This contract is an undertaking, on the part of the customer, to use the service for a minimum period of time enabling Navatec.Com to recover development costs. For this to work however, customers need to know they will get the functionality they need. Navatec.Com address this issue through a service support designed to minimise customer risks through the use of a Internet Systems Prototyping Service (ISPS) based upon a new standard methodology known as Critical Functional Analysis (CFA). This allows customers to test any new functionality they require for their applications using an online prototype so as to establish feasibility. McNeill explains that, "Our ISPS service based upon CFA is unique. It provides potential customers with provability of service adapted to their specific needs before committing to a large project. It is also in our interests because this process enforces transparency on customer requirements and avoids misunderstandings." On the other hand the monthly fee remains within that competitive range of between $50-$150/month/client staff-member seat. Some Examples The DScript structures illustrated above are from two successful applications of VCT. The one of the left is a module from AP Europe's online news service. Since introducing a parallel VCT operation AP Europe's online ratings, starting in February 2006, have gone up some 300% and the number of unsolicited user emails making positive comments has increased by 60%. The other script, on the right, is a VCT application used by commodity traders which provides VoIP services as an integral part of closing deals. This service has been well received and runs using what is known as Navatec Voyager basic (illustrated above) and which, in spite of its name is the most sophisticated Virtual Client released to date. Other applications include private corporate networks and the use of bar coding for online applications for document flow control and consignment tracking and traceability. References & links: AJAX: Jesse James Garrett's article on AJAX: Ajax: A New Approach to Web Applications and a general website on this topic: Ajax Matters Adobe Flex 2: The Adobe Flex website Navatec Voyager: Navatec Voyager website Navatec.Com online services: The Navatec online services website DScript: The DScript website at Vanguard Software Seel-Telesis®: The website of the Systems Engineering Economics Lab |
