Using wview

Are you fascinated with weather? Do you often find yourself checking local weather conditions? Is the weather your favorite part of the news broadcast? If so, you may be a weather geek, and wview may be the application for you.

wview is an open-source weather application that retrieves sensor readings from a weather station. The sensor data is stored in SQLite3 databases. Aggregate data, such as minimums, maximums and averages, are computed and stored in the database back end. Optional uses of the stored data include weather Web site generation; generic file generation for external applications; data submission to third-party organizations, including Citizen Weather Observer Program (CWOP) and Weather Underground; and store-forward to remote data collection centers. A user-friendly HTML interface is provided for configuring your weather station as well as for optional features.

To set up your weather station and publish your data with wview, you need a weather station. Supported stations include Davis Vantage Pro/Pro2 (Figure 1) or Vantage Vue, Texas Weather Instruments, Vaisala WXT510/520, Oregon Scientific WMR9X8 and La Crosse WS-23XX. Next, you need a platform to host the wview application. Desktop computers of any vintage work well, but it often is desirable to host wview on a low-power, unattended system. The now discontinued Linksys NSLU2 has been a popular choice. The new SheevaPlug quickly is gaining popularity as a wview host also. Industrious people even have used a Western Digital Worldbook NAS as their wview host. Because wview is modular and designed for embedded applications, it can be hosted on low-horsepower systems.

Next, you need to install a Linux distribution of your choice. The Debian (and derivatives) wview packages provide the most idiot-proof installation path, but source installs also are straightforward for any Linux distribution.

Finally, you need an interface cable. This may be a simple 9-pin serial cable or perhaps a USB-serial adapter if your host has no serial ports.

Figure 1. Dave Vantage Pro2 Weather Station

To configure wview, open your favorite browser and point it to the wview management Web site, typically http://[your_wview_server]/wviewmgmt/login.php. An HTTP server is required on the wview host (this will be installed automatically if you use the APT packages). Use the default administration password “wview” (you can change this later). After logging in successfully, the System Status page is displayed (Figure 2). The System Status page displays the current state of all wview services as well as other status information.

Figure 2. System Status

Configuration is broken up into logical sections with context-sensitive help available by mousing over the configuration items. Click the Station tab to configure the station parameters (Figure 3).

Figure 3. Station Configuration

The critical parameters here are the station type and the interface characteristics. Select Save Changes when you are done. Next, click the Services tab (Figure 4).

Figure 4. Services Configuration

This page provides the configuration of wview services, log verbosity for the services and e-mail alerts. Services available are File Generation, Alarms, CWOP, HTTP (Weather Underground and Weatherforyou), File Export (SSH or FTP) and Process Monitoring. For now, let's not enable any additional services until you have confirmed your station interface.

Now, let's proceed to the station interface verification. Open a shell on the system that is running wview, so you can follow updates to the system log. At the prompt, enter the following:

$ sudo tail -f /var/log/syslog

This displays new system log messages as they are generated. Here, you will monitor wview startup and status messages. Open another shell, and execute the following:

$ sudo /etc/init.d/wview stop
$ sudo /etc/init.d/wview start

You will see a flurry of activity in the system log from the wview processes as they start up. It is a good idea to familiarize yourself with these wview log messages, as a wealth of detail is included that can be very helpful.

Return to the System Status page and observe the status of the station interface and the file generation. If both are not status “green” and “Running”, further investigation in the system log file will be required to find any configuration or station interface issues.