Navatec's approach to Internet bandwidth transition
Internet Bandwidth
Although most main global population centres now have access to the Internet the number of people with direct access and who use it regularly is something like 15% of the world's population.
The speed with which data can flow to and from a user's PC varies with the Internet link being used (fee footnote 2). The normal range of capabilities varies from 28.8 Kbps using a modem up to some 1.544 Mbps for ADSL (asymmetric digital subscriber line). 
Navatec Voyager - the world's first Virtual Client |
ADSL has a capacity of transmission some 54 times greater than someone using a 28.8 Kbps modem. With ADSL data can be received at a rate of around 1.5 to 9 Mbps and data can be sent at the rate of around 16 to 640 Kbps. This asymmetry represents the reception capability being some 45-90 times larger than transmission capability. This makes sense because, in practice, a user's browser sends quite small command signals to servers whereas the response from the server is normally more information.
The standard html page can be something like 15-25k meaning that even with a 28.8 Kbps modem a page appears within the user's browser with no more than 2 seconds delay. Today, websites make a lot more use of dynamic content such as Adobe-Macromedia Flash, server end JavaScript processing and various forms of images including video. In practice the full benefits of such content can not be obtained with 28.8Kbps systems because of the delays in transmitting all of this information. In addition if a network has this limited capacity, multiple users can drain the real capacity available ending up with an unacceptable system's response for all users.
In reality the are many parts of the work where Internet bandwidth restrictions limit the use of centralised remote servers.
Navatec's bandwidth transition solution
Dynamic content can be useful and therefore to deliver this on low bandwidth with a responsive systems operation requires a different approach. One of the ways this can be achieved is to use Virtual Client Technology (VCT) a range of techniques developed by Navatec.com.
The VCT Client Package combines low network bandwidth with high speed local operations
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VCT can locate processing power for web-based systems where it is needed while minimising the use of the network. In the case of most low bandwidth systems processing power can be moved from the remote server to the user's PC. This is achieved by using a small server within user PCs which works with a sophisticted interface known as a Virtual Client. The first Virtual Client, the Navatec Voyager, was launched by Navatec early in 2006 and is illustrated above on the right. The Navatec Voyager runs within a user's PC under the MS Windows Operating System and runs scripts written in JavaScript which are interpreted by the local server. The remote server is used as the source from which to download updates in content used at the client end. If the system is carefully designed the size of updates should be relatively small so as to avoid long download delays.
In such a case the Virtual Client downloads updates for the main web content from the remote server and then uses the PC bus to deliver the full web content to the monitor. Such an arrangement provides a per machine response to program commands which is far faster than ADSL.
Applications which can make use of this architecture include support operations which have regularly updated content such as distance education, corporate bulletins and technical support manuals such as operational guidelines and help systes.
An example - training through simulation & active dialogues
One of the key issues in distance education and training managers, for example, in new operational guidelines, is trying to assess whether the individual has understood and is able to apply what is required.
An effective way to achieve a practical evaluation is to first of all provide a demonstration of how, for example, a new form should be completed under some new guidelines.Navatec's VCT low bandwidth architecture
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First of all a simulator can show the user how a form is filled in a step by step fashion. JavaScript and its extensions such as Action Script (Flash) and others are a very good basis for achieving this. The "learner" can then be asked to fill in a form using data supplied. The form can be an "active dialogue" within which error checking is live on all fields to be completed so the number of errors can be counted as the form is filled in. The error event would be shown immediately to the person filling in the form and advance to the next field is only possible when the correct input is received. The objective would be for the "learner" to fill in the form in a faultess fashion according to the new guidelines. Form in this context can signify any document such as a project proposal, an M&E task, evaluation exercise, accounts, financial evaluations and many other essential management tasks.
The attractive part about this basis of learning is that each individual can pace themselves and each will know when they have mastered any specific task. Where problems persist then the individual might refer to more detailed descriptions or email an individual responsible for support. Free voice communications within the systm using the Voice Over Internet Protocol (Voip) can also be used to get instant replies to queries.
Transition to higher bandwidth
As the overall Internet provisions within a country or region move towards higher bandwidth, then at some point it is more rational to migrate the main operations to a central server since this reduces overall operational overhead and the cost of ownership as the number of people served increases.
Footnote 1: Useful links on this topic:
Some background on JavaScript
New approaches to the Internet
The Navatec Voyager site
The economics of server-based management
Behind the scenes of Navatec Voyager
Footnote 2: Common Internet bandwidths
- 1.544 Mbps ADSL, T-1, DS-1
- 128 Kbps ISDN
- 64 Kbps DS-0, pulse code modulation
- 56 Kbps 56flex, U.S. Robotics x2 modems,
- 33.6 Kbps 56flex, x2 modem communications rate
- 28.8 Kbps V.34, Rockwell V.Fast Class modems
- 20 Kbps Level 1 cable, minimum cable data speed
- 14.4 Kbps V.32bis modem, V.17 fax
Where the following units of measurement are being used.
bit= smallest unit of digital information, i.e. ones & zeros
byte= a set of bits
bps= bits per second
Kbps= kilobits per second =1000 bits per second
Mbps = Million bits per second =1,000,000 bits per second |
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