Weather, Weather, Everywhere: Asterisk Weather Forecasts at the Touch of a Button for Any U.S. City

I can remember as a kid how fascinating it was to be able to call a local number (611) and listen to the local weather forecast. Never mind, of course, that it was rarely accurate. Some things change and some things never do. Even as lousy as most weather forecasts are, most of us still are fascinated nonetheless which brings us to the topic of the day: An Enhanced Weather Application for Asterisk®. Last week, we finally got a reliable voice synthesizer installed for all the newer versions of Asterisk. So now we're ready to put it to good use with our first of several text-to-speech projects. We took a little different approach in building this weather module when it's compared to the default application which ships with Asterisk@Home. We wanted not only current conditions but also a 7-day forecast. And we wanted the caller to be able to choose the weather location rather than having to hard-code a specific city into the AGI script. Finally there's even a simple feature for those that don't want to listen to a full 7-day forecast: hang up.

How It Works. The design is pretty straightforward. You install the nv-weather.php script in your default Asterisk agi-bin directory and add a simple dialplan to your extensions_custom.conf file. Then you pick up an extension on your Asterisk system and dial 611 or the number you've designated for the new weather reports. You'll be prompted to enter the 3-character airport code of the city for which you want to hear the weather forecast. In a few seconds you'll be listening to the latest information from the National Weather Service using our pdaweather.org conversion tools. And apologies to our foreign friends. Yes, we know you have weather, too. We just don't know of an equivalent organization like the National Weather Service in every country. If you do, then it'll be fairly simple to adjust the code to meet your local needs. Here's a Canadian solution.

Prerequisites. For the Nerd Vittles Weather Application to work, you'll need an Internet connection to access pdaweather.org. We're using our weather site to convert the NWS weather reports to a text-to-speech-friendly format. Then you'll need an Asterisk@Home 2.x server and the new Flite voice synthesizer for Asterisk. Instead of a dedicated Asterisk server, you can use the VMware-version of Asterisk if you just want to experiment a bit. It runs in a window on your Windows XP/2000 desktop. Our Flite tutorial and the Flite application software are available here. And, as usual, everything you'll need for this project is free!

A Word About Airport Codes. Before we get everything installed and working, let's spend a minute discussing airport codes. At least for some U.S. cities, the folks that thought up airport codes did a pretty crappy job of coming up with three-character abbreviations. Take IAD, for example, which is the airport code for Dulles Airport outside of Washington, D.C. We've compounded the problem by trying to uniquely fit those codes into a telephone keypad consisting of 10 numbers which cover the 26 letters of the alphabet. You'll recall that even Ma Bell herself never considered that letters would actually be used for much of anything on telephones. Remember the Q and Z were originally missing. Times change. It happens. --Forrest Gump

The point of all this is to alert you that some airport codes when keyed in on a touchtone phone are not unique. For example, LAX (Los Angeles, CA) and JAX (Jacksonville, FL) both are keyed in as 529. How do it know? Well, it doesn't. So we were a little arbitrary with some of these. 529 is Jacksonville on this system while Los Angeles is LOS (567) or SNA (762). NYC and our made-up MYB share 692 so Myrtle Beach is 692 and JFK (535) and LGA (542) are used for New York (which happen to be the real airport codes and the locations of the weather stations anyway).

You also may find that your favorite airport is missing altogether. Not to worry! Keep reading! We entered a bunch of airport codes, and then we got tired and quit. As folks have requested other cities through our pdaweather.org web site, we've added them. But soon, all of that will be a thing of the past. How will you know if your town is missing? Well, it's easy. You'll get the Atlanta weather report whether you wanted it or not. So, if that happens, just hang in there for Part II ... coming soon! Here's the list of supported airport codes for today.

Dialplan Code. In order to activate extension 611 to answer calls for weather information, you'll need to drop the following code into your dialplan in the [from-internal-custom] context of extensions_custom.conf:

exten => 611,1,Answer
exten => 611,2,Wait(1)
exten => 611,3,DigitTimeout(7)
exten => 611,4,ResponseTimeout(10)
exten => 611,5,Flite("At the beep enter the three character airport code for the weather report you wish to retrieve.")
exten => 611,6,Read(APCODE,beep,3)
exten => 611,7,Flite("Please hold a moment while we contact the National Weather Service for your report.")
exten => 611,8,AGI(nv-weather.php|${APCODE})
exten => 611,9,NoOp(Wave file: ${TMPWAVE})
exten => 611,10,Playback(${TMPWAVE})
exten => 611,11,Hangup

For versions of AAH before 2.8, once you've added this code using AMP->Maintenance->ConfigEdit->extensions_custom.conf, click the Update button to save your changes, and then reload your Asterisk settings: AMP->Setup->IncomingCalls->SubmitChanges and click the Red Bar. If you'd prefer a different extension (rather than 611), just modify the number in each line of the code above. If you're curious how to pass variables back and forth to a PHP/AGI script, here's a good example. In line 8, we're passing the variable ${APCODE} to the PHP/AGI script with the airport code. In lines 9 and 10, the PHP/AGI script is returning the ${TMPWAVE} variable with the file name of the .wav file containing the weather report. Now let's add the PHP/AGI script to your default AGI directory, and we'll be ready to test things out.

Downloading and Installing nv-weather.php. To get the PHP/AGI script installed, you'll need to log into your Asterisk server as root. Then issue the following commands in order:

cd /var/lib/asterisk/agi-bin
wget http://nerdvittles.com/aah2/nv-weather.zip
unzip nv-weather.zip
rm -f nv-weather.zip
chown asterisk:asterisk nv-weather.php
chmod 775 nv-weather.php
amportal stop
amportal start


Taking NV-Weather for a Spin. Now we should be all set. Just pick up an extension on your system and dial 611. You'll be prompted to enter the three-character airport code. Choose one that's in the supported list of codes unless you just like the Atlanta weather report. If you want the rest of the world to be able to use your fancy new weather station, then just sign up for a free incoming line with Stanaphone and, using AMP or freePBX, point your new DID to extension 611 on your local Asterisk system. Piece o' cake! Enjoy!

Housekeeping 101. Temporary files in /tmp get cleaned up by Linux housekeeping automatically. Temporary files stored elsewhere don't. The weather scripts have to store .wav files in the /var/lib/asterisk/sounds path in order to play them from within your dialplan, but it's a good example of how not to design code on busy systems because it places all of the temporary sound files for each reading of these weather reports in /var/lib/asterisk/sounds/tts. So, from time to time, make a mental note to remove all of these files with a command like this:

rm -f /var/lib/asterisk/sounds/tts/*

Following our article last week, there were a few suggestions on how to automate this with a cron job. Here's the one we like the best. Log into your Asterisk server as root and edit the following file: nano -w /etc/crontab. Move to the bottom of the file and insert the following code on a blank line:

3 0 * * * /usr/bin/find /var/lib/asterisk/sounds/tts -type f -mtime +14 | /usr/bin/xargs /bin/rm -f >/dev/null 2>&1

This code will delete all of the files in the tts every two weeks. If you'd prefer a shorter time, change the number 14 accordingly. Now save your changes: Ctrl-X, Y, then Enter.

Coming Attractions. Well, we're down to the wire on the family move to Charleston. Our next column will be coming to you from there. We'll be revving up our text-to-speech series with an article on using Flite to query and retrieve information from a MySQL database on your Asterisk server in our next episode. This will also be Part II of the Weather Application with the Mother of All Weather Apps. In Part II, we'll turn over complete control of the National Weather Service to you (well, almost!). There will be separate options for Current Conditions, Forecast-at-a-Glance, and 7-day Forecasts. The way it works is you'll get a MySQL database with every airport in the United States. There are about 3,500 of them. You can designate up to 1,000 of them for active use from your phones: 000 through 999. We've chosen a thousand, but you can change them in any way you like and as often as you like. After choosing your favorite 1,000 airports, you simply pick up a phone, dial 611 and enter the three-digit airport code. After giving you a quick current conditions summary, you'll be prompted for which detailed weather report you desire. The script will query the MySQL database for the matching code, contact the National Weather Service for the appropriate report, and presto: instant weather. And it'll all be done from Weather Central: Your Very Own Asterisk@Home Server. So think of today's episode as the appetizer. With the next version, you'll get complete control of the airport database and the types of weather forecasts you wish to listen to. We'll also have lots of tips on building MySQL applications with Asterisk and PHP to keep you busy for the rest of the summer dreaming up your own applications. We'll even publish the best ones here for the rest of the world to share.

Farewell to Asterisk@Home. It's also fitting that, as we leave Atlanta, we also bid farewell to Asterisk@Home this week. Version 2.8 marks the end of the line for Asterisk@Home. Why? Because the scope of use of the product now has far outstripped its name, Andrew Gillis has decided to change the name of the magic bundle we all know and love. But there's much more! The new product will have UPGRADE POWER and freePBX 2.1 and ... well, you'll just have to wait and see. Shouldn't be very long. So we'll all be very busy ... after the move. Adiós Atlanta!

Homework. For those that like to get a head start on things, you can go ahead and download the MySQL Airports IATA database and a web-based script to take a look at everything. You'll need Asterisk@Home 2.7 or earlier to edit the database because these versions include phpMyAdmin as part of the Asterisk Management Portal (AMP->Maintenance->phpMyAdmin). Download the zipped airports file to your desktop and unzip it. This database is licensed pursuant to a GNU General Public License. It was adapted from the AirSort application on SourceForge if you happen to be looking for a MySQL database containing worldwide airport (iata) codes. Now crank up phpMyAdmin and click on the SQL Query Window icon in the top of the left frame. Now click on the Import Files tab, select the airports.sql file on your Desktop, set the Character Set to ASCII, and click the Go button. Once the file is imported, click on the Home icon in the left panel, click on the Databases pull-down, and choose Airports. Then click on the USairports table below it. When the table opens, click on the Browse tab in the right frame to display the file's contents. Nome is the airport name, iata is the airport code, dialcode is the airport code converted to numbers on a touch-tone phone, citta is the city and state of the airport, and main is the field used to designate whether a particular airport can be accessed using a phone. An asterisk means Yes. Anything else means No. Now click on the DialCode column heading to sort the table by dialcode. As you scroll through the database, you'll see that every group of matching dialcodes has one entry with an asterisk in the main column. Remember that dialcodes are not unique while airport codes (iata) are. Because of the layout of the alphabet on touchtone phones, as many as a dozen airport codes may share the identical dialcode which is why we need the main field to pick one. As mentioned above, I've already picked one for each dialcode, but you may have your own ideas about which airports to make active depending upon where you live and what cities you care about. If you change the main entry for a dialcode, remember to also blank out the previous one for that dialcode. Otherwise, the last dialcode entry with an asterisk in the main column will win (i.e. that's the city whose weather report will be played) once the application is finished. So there's your homework. Get your airports database set up in a way that meets your needs so that the dialcodes 000 through 999 select the airport locations of interest to you. Don't mess with the iata codes. Even though the database doesn't enforce it, these are unique and need to stay that way.

In designing this new application for telephone use, it was tempting to support all of the airports in the United States rather than a measily 1,000 of your favorites. To do this, however, would have meant using either zip codes or giving callers a submenu of airport code cities matching a particular dialcode. We ruled out zip codes because nobody can remember more than a handful of them anyway. The dialcode submenu sounded straight-forward enough until we discovered there were some dialcodes with a dozen or more matching airport codes. To force callers to listen to a list of a dozen cities before ever getting to choose a weather report would have been P-A-I-N-F-U-L. So we've opted for the Fab 1,000 thinking that will meet the needs of most folks. As usual, you are free to make changes in the final software to meet your needs. And, if IVR Hell, long phone calls, and 3,500+ airports at the touch of (lots of) buttons are your thing, have at it!

To assist with your exploration of the airport codes and to give you some hints about how we use those to actually obtain weather reports from the National Weather Service, we're also providing our working prototype of a web page that retrieves weather reports. Keep in mind that it is our very rough, working prototype and does no text-to-speech magic at this point. But it'll show you how to build one and give you some great tips and tricks for retrieving, parsing, and manipulating web site data within a PHP script. Since your Asterisk@Home server has Apache running, you can simply drop this script into the web directory and access it using a web browser to call up http://YourServer'sIPaddress/airport.php?code=list or http://YourServer'sIPaddress/airport.php?dialcode=list. The former will display all the airports in the database while the latter displays only those in which the dialcodes are asterisk-enabled. When you click on a link, you should get a weather report or two suitably parsed for use in text-to-speech apps as well as some other options which we haven't yet finished. To install the script, log into your Asterisk server as root and execute the following commands in order:

cd /var/www/html
wget http://nerdvittles.com/wp-content/airport.zip
unzip airport.zip
rm -f airport.zip
chmod 775 airport.php


For Part II of this series, click here.

Hosting Provider Special. Just an FYI that the Nerd Vittles hosting provider, BlueHost, has continued their limited time special on hosting services. For $6.95 a month, you can host up to 6 domains with 15GB of disk storage and 400GB of monthly bandwidth. Free domain registration is included for as long as you have an account. It doesn't get any better than that, and their hosting services are flawless! We oughta know. We've tried the best of them. If you've never tried a web hosting provider, there's never been a better time. Just use this link, and we'll all be happy.

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