Kelvinweb

Internet

Scheduled Appointments
Kelevinweb is developing an appointments scheduling package for the NHS to allow a doctor to obtain an appointment for a patient with a consultant over the internet using a standard web browser. This appointment is then used to log when the consultant sees the patient and other statistical information.
Scheduled Ticketing
Kelvinweb has also designed a ticket sharing system to allow timed advance ticket sales on the internet or local intranet with timed tickets sold locally. This is for sites where there is a limited availability of seats or places and it is to stop over-selling of tickets. All ticket sales are done using a PC and local printer.
This system is ideal for stately homes where a limited number of visitors are allowed each day or period or where safety limits apply.
Data transfer and control.

Data transfer over the Internet
Data transfer can be done over the Internet but there are problems. The main problems are :
  • Security and data privicy.
  • Inconsistent action or response time.
  • Unreliability. sometimes response is so slow a timeout occurs.
  • Complicated interfaces.
Data transfer over the Intranet
Data transfer can be done over a local Intranet. An Intranet is a private internet system. Some of the problems with this sytem are:
  • Less reliable than a hardwired connection.
  • Inconsistent response time is less of a problem here.
  • Complicated interfaces.
Data transfer over modem links
There are several types of modem links available:
Normal Dial-up. ADSL types. Other dedicated hard wired links using modem type interfaces.
Data transfer can be done over these links but again problems.
  • Dial modems up can be slow to establish the link and relies on the telephone system.
  • ADSL and other dedicated links are faster and cost more and are always present. They can share lines with other services such as telephone lines.
Data transfer over radio & mobile phone links
GPRS (mobile phone link) These are becoming more of a possibility. With GPRS charges are proportional to the data transferred so if small data packets need to be sent this can be a use full data transfer method where good mobile phone coverage is available. A 3 k block of data costing 1p to transfer.
Control Systems
For normal transfer of data where there are no constraints to the response time any of the above methods might be OK. Problems occur when data transfer is used for control systems. Here a slow response might be unacceptable.
TCP/IP
TCP/IP is the system used to transfer data over the Internet/Intranet/ADSL links. It can also be used with dial up and hard wired links using PPP. TCP/IP forms the data into packets and sends the data to a specific address attached to the packet. Any data can be sent using this method as the data is split up into small packages and re-assembled at the other end. The software for this is very complex but is available as libraries for various languages and is included in many operating systems.

FTP: File transfer Protocol over TCP/IP. A program for transfering files between computers. It is not secure. Telnet: A program for connecting to a remote computer over TCP/IP SSH: Secure Shell: A secure method of connecting to a remote system using TCP/IP. SCP is part of SSH and allows secure copying thus eliminating FTP.