Re: Update on National Hurricane Center Products and Services for 2018
Posted by
Chris in Tampa on 4/21/2018, 11:27 pm
Yep, this is going to be fun. I just tried to decode the new format in my decoder to see what would happen and it decodes it wrongly rather than rejects it. I'll have to go ahead and write temporary code that rejects the new format until I can rewrite the vortex decoder. The vortex decoder is very complex because of all the information it can contain, or not contain, going back decades. Things in it have changed over the years and it needs to remain backwards compatible, being able to decode every valid vortex message since 1989. Sometimes information is missing in a message. Sometimes additional information is on a line after the normal content the line should have. That means I can't require a specific set of characters for a line. If I can't decode a line for some reason I add "(Undecoded)" to an undecoded line rather than reject the whole message because many older messages, and maybe even some newer ones, would never decode properly.
I hate making changes to the vortex decoder because there is a lot of testing that needs to take place. Other parts of the system reject content when it can't decode something, but the vortex decoder just can't work like that which makes it problematic since I need to make sure it decodes everything correctly. And since there are about 2,400 lines of code for the main code in that decoder specifically it should be fun. (Though mostly double spaced code.) There is an additional 1,100 lines that decode just the remarks section in vortex messages, but I shouldn't need to change much there.
Hopefully it won't be as hard as I think. Many of the decoding features still work, they just need to be moved to individual sections of code that allow me to call a specific decoding feature that I need depending on whether it is a new or older message. So if I get to line "D" I will call what decodes a wind if it is an older message or call what decodes a pressure if the newer format. Then I can label what information the line is displaying. I'll process the message first just to determine if it is a newer or older message and have the script then go through and try to decode it. While the newer messages usually contain a year, older messages don't. So I'll have to look at a variety if options to determine if the message is newer or older. (including if there is a line "U" if newer) And there is such old changes like line "N" used to be reported as line "O" and line "O" used to be reported as line "P". (Those old messages used to use line "N" to repeat the coordinates)
I had planned to rewrite the vortex decoder anyway, but I was thinking more about doing it in 2019 or 2020.
Maybe I'll get that part done by June. I'm going to work on it now, then continue the layout changes to the recon system to try to make it more mobile friendly in the future. I have made too many changes to go back to the old layout, so I have to finish that up to. It's likely no one sees the layout difference when I make it live, because I'm not going to make the header and footer mobile friendly yet, so I probably won't have the page change how content appears until I do that.
I also need to verify that the new code to map recon missions works as it should. No visible changes to people really, there was just a rare issue when HDOB messages stopped for a mission, and sondes or RECCO messages continued, the plane would appear in the wrong place in some maps, where the HDOBS stopped. That involved a bunch of changes to correct and I still want to test more. Plus I was initially going to rewrite the NOAA radar feature but I haven't yet. So I need to restore the old code and replace the new sections of code I had put in that don't work.
Then I have to test everything.
I'm glad Cypress posted about the change. I had been checking on whether it would happen this year but then figured it probably wasn't since I hadn't seen anything since the NHC asked the public for comments on changing it last year. If my first indication had been when the first mission of the season occurred, I would be throwing things right now. |
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