The page displaying time, temperature, and a view out the window is assembled and served by three machines. Our Web server (River.Clarion.Edu) serves a page (Outside.html) that is created once a minute by a remote Mac. That page has, embedded in its' center, a "pushed" image provided through a second Web server. The time and temperature are inserted into the page by the remote Mac.
The Image is served from a remote machine (Outside.at.clarion.edu) running WebCamTurbo. WebCamTurbo is freeware that provides "pushed" images as fast as the connection permits. We have it configured to push no faster than 2 images each second, although the software is able to go far faster.
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The "image" machine is an Apple 7100 running at 66 Megahertz. This machine is also running MacDNS and provides EtherTalk access to files for our lab (which explains why we want the images to be served in a leisurely manner).
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The camera is an old Videolabs gooseneck color camera. It interfaces with the Mac 7100 through the S-video port on the AV card.
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The time and temperature are generated on another machine (an old PowerBook 160). That machine, once a minute, reads the time and temperature and writes a file (Outside.html) to our Web server. This timing is done through an AppleScript program (maybe 10 lines long). The same script initializes an ADB I/O interface (below, right) to read the voltage passing through a thermistor. The thermistor is on the end of a wire, dangling from my window, on the North side of Harvey Hall. The voltage is transformed to degrees F and inserted into the HTML file so that it displays correctly. |
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Except for the 1-2 seconds the file is being written, the Web server has access to a static document. Doing the same thing through a CGI would tie up the Web server for variable periods of time. Additionally, having two remote machines (one for video the other for time & temperature) allows us to move the sensors well away from the Web server.
On the down side, if the PB 160 loses its' AppleTalk connection to the Web server, the same page will be served over and over --- frozen in time and temperature, if you will. Also, the way we do this ties up a bunch of equipment, though most of it is obsolete. Finally, the time is never refreshed. It reflects the time of connection, not the actual time. The same is true for the temperature. No matter how long you look out the window, the temperature will not change --- until you refresh the page.
Future plans are to see if we can move the temperature sensor and AppleScript to an old SE, and to see if we can serve the page through an alias... Also, we plan to put the camera on a swivel and run a CGI so remote users can point the camera. Finally we are probably moving to Java for the time and temperature to allow real-time updates.
Take me back to the outside view.
