Enhancing the library with TAF

May 9, 2011 at 8:31 PM

Hi there

First of all thanks for your excellent work with this project.

I did a Windows Phone 7 application to retrieve airport weather from around the globe. At the moment I use the experimental webservices from ADDS (http://weather.aero/) to download METAR and TAF information. Those infos arrive in XML format and are roughly decoded. However there are some errors in the decoded values. The other issue is data loading time, since it takes much longer to download the decoded XML than just the METAR or TAF string.

I am looking for a better method now to parse the METAR and TAF strings and to display them accordingly in the app (www.airportweather.ch - by the way). That's how I found your project.

Do you have plans to implement the TAF portion as well. Or would you like me to contribute to add the TAF portion in the same manner you did the METAR?
Is there a reason you did not decode TAF in your project, I just ask because most of the time METAR and TAF data is neccessary.

Regards,
Marcel

Coordinator
May 10, 2011 at 10:06 AM

Hi, Marcel.

Thank you for your post and support. 

This project is supporting one of my other apps, which is aimed on Air Traffic Controller simulation (yet not available). I had no need to decode TAF for that, so I did not implement this part of information. To decode METAR I found pdf document on web which is precisely describing the content of METAR message string. Currently, I have no idea how TAF is decoded and I was not looking for this. 

However, both options you suggested are possible. I can check and implement TAF into this library, but I'm not able to give it any time before end of May. Or, if you are interested, you may build your own TAF decoder and we can put it together to one project.

 

Have a nice day

Engin

May 11, 2011 at 7:04 PM

Hi Engin

TAF is decoded in a similar way. If you reference the document of the WMO (Manual No. 306) where you found the precise content of the METAR string then there is a section about TAF in the same document. Otherwise I will be able to send the description to you py PM or eMail.

At the moment I try to figure out how you decode the METAR and how you implemented all this nice functionality. (REGEX, classes and stuff). I will tell you if I'm able to add the TAF decode functionality myself. If I succeed I will then share it with you so you could add it to your codebase. If not, I'm happy to wait till end of May to let you look into it (you might be much faster anyway).

I will keep you updated!

Stay well,
Marcel

Coordinator
May 12, 2011 at 8:04 AM

Hi,

well, I'm not sure if my approach was the good one :-)

Basically, the main idea is based on principle that METAR consists of several parts (time, location, wind, etc). For each part I define the regex in group. The, the regexes are joined together to one huge, really disgusting regex, containing all parts. The source string is passed over this regex, groups are found and every part (wind) is testing its group content.

Im not very sure if this way is correct, after this experience. There are two major disadvantages - a) it is really really difficult to find an error in the regex and decoded string; b) the application can take partial or incorrect metar string. I'm not sure if this behavior is correct. However, I did that this way and I had no time to test other alternatives.

Have a nice day

Engin

Coordinator
Jun 9, 2011 at 11:21 AM

I added implementation of TAF report in the 2.0 version. Check download section.

Jun 11, 2011 at 3:44 PM

Hi Engin

You are a hero!

I do not have the time to check it out right now, but I will asap.
Will tell you my findings (if there are any :-)).

Thanks,
Marcel