Having Fun on ViewSurf
Beach Report and Snow Report are free services for the end user, but Nicolas created ViewSurf in the hope of making some money with it. He's currently trying to sell the service to French Tourism Offices, but it's quite hard; basically, France is lagging in communications and Internet services. Additionally, many French people consider computers and the Internet as American Trojan horses such as McDonald's or Disneyland Paris.
Most French on-line services are available for a low performance Videotex-compatible terminal called Minitel, which was distributed free of charge by France Telecom at the beginning of the 1980s. This technology is obsolete, but France Telecom is currently the only French operator for communications. The Minitel allows them to charge up to several dollars per minute for some on-line services. This could be the reason why most French people don't have a PC at home, and as a result, Internet-based services are not seriously considered.
Nicolas has gotten a contract with the government organization which deals with traffic regulation in Paris. Some French highways have been on the Net since September 1997. If you compare it with other WebCAM systems, ViewSurf gives very good quality for a small data size.
This software would be more easily configurable without editing crontab or shell scripts each time you wished to change the call time or add a new site. To that end, I wrote a set of CGI (Common Gateway Interface) scripts which present a simple and portable interface for the Linux server configuration. The advantage of using CGI instead of standard Linux programs is the capability to configure the server from any forms-capable browser running on any operating system.
Another crucial option is to have the ability for several users to look at a “live” video (not recorded files) at the same time. For this, the Linux PC could be used as a server to distribute the live image from ViewCOM to several users connected from the Net. To reach this goal, I wrote a multi-threaded Linux daemon, based on the POSIX 1003.1c LinuxThreads library by Xavier Leroy (http://pauillac.inria.fr/~xleroy/linuxthreads). Actually, this daemon handles only the “video/x-vcr” MIME type and uses two specific TCP ports. The live video can be inserted in an HTML page with a line such as:
<EMBED SRC="http://your_linux_server:daemon_port" WIDTH=320 HEIGHT=240>
The second port is reserved for ViewCOM administration, such as setting brightness or contrast. Additionally, the daemon can control a weather station in order to get real-time information about external temperature, wind speed and other weather information. A VISCA (a standard for video camera remote control) functionality is about to be added to control zoom, pan-and-tilt and other camera parameters directly from the Internet browser. Figure 4 is a snapshot of the Bordeaux/Bayonne motorway on the private COM1 web server.
The ViewCOM is often connected to the PC via a serial line, but one of the most important advantages of the system could be the ability to control a remote ViewCOM. So, it's not necessary to install a PC on the site you want to look at, you just have to set up a ViewCOM connected to a simple phone line or a leased line. In the phone line case, it's possible for the daemon to call the ViewCOM at starting time or only when an HTTP request occurs. In this last case, the daemon hangs up the line when the last client is disconnected.
Free DevOps eBooks, Videos, and more!
Regardless of where you are in your DevOps process, Linux Journal can help!
We offer here the DEFINITIVE DevOps for Dummies, a mobile Application Development Primer, and advice & help from the expert sources like:
- Linux Journal
- New Products
- Flexible Access Control with Squid Proxy
- Users, Permissions and Multitenant Sites
- Security in Three Ds: Detect, Decide and Deny
- High-Availability Storage with HA-LVM
- Tighten Up SSH
- DevOps: Everything You Need to Know
- Solving ODEs on Linux
- Non-Linux FOSS: MenuMeters
- diff -u: What's New in Kernel Development