WebLink
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[User Guide]

WebLink is the module which allows users to access NTMC via the internet. With WebLink operators can:

1. Configure NTMC to expose the desired portions of its database to the internet, thus making them visible to the rest of the world via web browsers,
2. Allow users to monitor, and issue commands to NTMC via web browsers,
3. Configure WebLink so NTMC can send e-mail to users who are interested in special events monitored by the control system.

To manage the above operators use WebLinkManager's (see the Architecture section below) configuration page shown in the following screen caption:

In addition, WebLink provides a programmatic interface to the outside world via the internet. This means that other control systems, or other software in general, anywhere in the world, can call NTMC functions over the internet without any software supplied by BTE. Furthermore, these NTMC function calling programs do not have to be Windows based programs - they can be programs running on any platform which can consume Microsoft .Net Web services.

Architecture

WebLink consists of three components:

1. WebLinkManager (WLM), which runs alongside other NTMC components in the control room, or at least on the same LAN, and is responsible for overall WebLink configuration management, replication of relevant portions of database to BTE internet server, downloading of commands coming from web browsers and forwarding them to the rest of NTMC components for processing, and e-mail / SMS message dispatching.
2. WebLinkService (WLS), which runs on BTE internet server, implemented as a Microsoft ASP.NET 2.0 Web Service, and is responsible for server database management, server-side security enforcement, and communications between itself, WebLinkManager, and WebLinkPublisher.
3. WebLinkPublisher (WLP), which runs on BTE internet server, implemented as a Microsoft ASP.NET 2.0 application, and is responsible for serving web pages to the requesting web browsers. These pages display real-time content obtained from the server-resident NTMC databases via WebLinkService.

This is illustrated in the figure below.

Some of the benefits of this architecture are:

1. Easy installation on customer site. Only WebLinkManager runs on customer site. Since WebLinkManager is designed to always initiate conversation with WebLinkService, the program works as soon as internet is available on the host computer. No firewall, local server, or network security issues need to be re-addressed. 
2. The company running NTMC does not need to own and / or operate its own internet server. This means faster and simpler initial installation, and no internet server management issues. The latter are taken care of by BTE via a professional service provider^*. Economies of scale thus allow BTE to run the server for a smaller cost, and the savings are passed on to NTMC users.
3. Security - WebLinkManager is actually a client, not a server, continuously polling WebLinkService. Even incoming commands are solicited this way. This means that only requested data come into the master, and local network security can be as tight as desired. Furthermore, because client - server conversations are poll-based, operators in the control room know within seconds if and when the internet server 'goes down'.
4. BTE server software updates benefit all customers conversing with the server.
5. WebLinkService provides a programmatic interface to NTMC already described above.
6. Although WebLinkService and WebLinkPublisher run on the same server, they do not have to. In principle, WebLinkPublisher can run on the customer's own server where the customer's own programmers can custom-modify web pages as per their needs.

^*BTE server is managed for BTE by DiscountASP, a Los Angeles, CA based professional internet domain hosting company specializing in Windows web hosting, and using the latest security measures and infrastructure. When accessing NTMC via the internet, all communications between BTE Sever and your browser, as well as all communications between BTE server and NTMC Operator master station computer are encrypted using the latest SSL technology.