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Re: EDDF-Triangle

Postby tdammers » Mon Jan 07, 2019 6:44 am

AAL545 wrote in Sun Jan 06, 2019 11:45 pm:Okay this is what I have found.

remember, the MP protocol has fixed sized packets it sends... if a craft tries to send to much, the packets will be truncated... that could easily lead to problems like this...

Posted by kwitty42.
2017.3 Changes
New property /sim/multiplay/transmit-only-generics, when this is set only the position header, all of the sim/multiplay/generic/ and instrumentation/transponder/ are transmitted over MP. This is intended to allow models to use an alternative encoding (such as the Emesary PropertyNotification) to transmit a well known (to the model) list of properties packed into the generic properties.

The maximum size of a string was also increased to 768 bytes (from 128).

Not sure who posted this one!

Using the Emesary Multiplayer Bridge[1][2] is an effective way to transmit more properties using less space[3]; however if the transmit filter property base[4] is also set to say 10000 or higher then only the really important properties will be available to other craft.


Posted by Richard.



AAL4955


I think the most important takeaways here are these:

- Transmission of properties is not guaranteed, the MP can drop properties at either end; however, how many of them are dropped depends on the FG versions on both ends and is thus difficult, if not impossible, to predict
- Property assignment is specific to an aircraft model and may even change between versions (of that model)
- There is no way to unambiguously identify a model and version over MP, so we routinely get mismatches on the MP system

So we really get two problems interacting: dropped properties, and incompatible aircraft models. Proper solutions to both would, I believe, require breaking changes, and I don't think those will fly given the current state of the FG MP ecosystem.
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Re: EDDF-Triangle

Postby tdammers » Mon Jan 07, 2019 7:00 am

AAL545 wrote in Sun Jan 06, 2019 11:23 pm:Not sure why you guys have to do this in the middle of a topic.
Listen, I appreciate your help here I really do, and you know what, I won't even take it personally if you have an issue with EDDF/ Jomo
even though I fly there almost every weekend, I guess because he's always there but that's my business and your business is your business.


Well, this is the topic titled "EDDF-Triangle", so it seems to me that this is the most appropriate place to discuss the EDDF events. If anything, I'd say the 777 landing gear deserves a separate thread.

Anyway, the reason I brought this up is because I honestly want things to be better for everyone; I'm not coming here to shit on anyone, I just wanted to know what happened, why things went ugly in that particular session, and discuss possible ways of avoiding ugliness in the future. If things go the way they did that day, I don't want to be part of it anymore, but that would be a terrible shame - I'd much prefer a situation where we have a nice event with plenty of people flying in, ideally even including all those who have rage-quit the EDDF sessions in the past. Jomo is doing some awesome work, the amount of time and dedication he sinks into this is worth a medal IMO. But that doesn't change the fact that I don't want to be part of an event where people get randomly yelled at or ignored, and I'm pretty sure I'm not alone in this.

Again, I don't want to shit on anyone, and I certainly don't want to hijack any threads; I'll happily discuss the matter on a separate thread if that's preferred.
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Re: EDDF-Triangle

Postby jomo » Mon Jan 07, 2019 8:02 am

I did think a lot about commenting some more about this issue - but I guess it is getting out of control! And all that because of a "user" (that loves that 777 !!) reports a minor bug of that model. Nobody ever mentioned anything coming near a critic to the designer (except some designers themselves!). As a professional designer over many many years I know that most serious designers would like to get responses from users in order to improve their design even more. In a big company we even hired/payed some students during their summer-timeouts to fool around with our designs - just in order to find some "shortcomings". i.e. we paid for it! I guess we should be thankful to AAL545 for spending his time to help improving -- without embarrassing anybody!
tdammers wrote in Sun Jan 06, 2019 8:56 pm:
BEL ISAAK wrote in Sun Jan 06, 2019 5:38 pm:No pressure, I mainly mentioned this to support the "it's not necessarily 100% the aircraft developer's fault, and you should be more careful blaming people" thing.
Quite frankly: Who (except You) is blaming people/designers?
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Re: EDDF-Triangle

Postby legoboyvdlp » Mon Jan 07, 2019 8:32 am

Your own words could be interpreted as such:

There you see very clearly that the front-Wheel is located correctly on the ground.
Also the center-wheels are correctly centered on the GND - BUT: That are 3 wheels in a row that are tilted when in air and not straightened on GND. i.e. only the center-wheel is placed correctly on the GND, the front-wheel is over GND, and thus the Back-wheel is below GND.
--> Thus that is a design-problem of that model - obviously it was forgotten to level the landing-gear on GND. That is not a problem with FGFS but with the tricky gear-design of that model.
Also the thrust reverse is surely a design-problem of that model - not a FGFS general problem!
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Re: EDDF-Triangle

Postby jomo » Mon Jan 07, 2019 11:32 am

tdammers wrote in Sun Jan 06, 2019 3:24 pm:On a completely different note; I'm curious what happened yesterday. I tried to fly in, but since I wasn't hailed at 60 nm out as usual, I tried to contact ATC multiple times via MP chat. I never got any response though, so I assumed some sort of bug dropping my chat messages, and after about 30 minutes of repeatedly trying to make contact and switching MP servers, I gave up. Watching the films today, however, I noticed to my astonishment that my messages came through just fine, my callsign appeared in the flight strips section, I was visible on the radar, I just got ignored completely - meanwhile lots of other pilots were serviced over MP chat without issues. .....
Nicely spoken - so I tried to find that happening in the movies - spend 2h to search - but did not find something like that. It would have been nice if you could tell us your flight ID + movie and time + etc. Because I do the movies especially for giving everybody a chance to improve.

I am surprised about your definition of VATSIM. In this forum I pointed out several times my definitions of what is what:
1) FGFS is a very nice "game" for people just trying to play
2) About 10 years ago we started with controlled flying i.e. simulating"! (See e.g. TGA: http://transgear.treborlogic.com/ etc.)
-- that is just using the FGFS in an controlled environment - e.g. using ATC's --> this seemed to be an easy way to upgrade abilities
3) A higher class simulating for all Flight-Simulators (FGFS, MS etc.) is VATSIM (https://www.vatsim.net/)
-- they come close to Profis! They request controlled LogIn and classes for all functions prior to be accepted, etc
4) Flying in reality with a real plane and a real certificate (e.g. PPL = Privat-Pilot-Land) (of course the ultimo fun, but expensive)

I did all 4.
Like me you may have noticed the big gap between 2 and 3: The need for LogIns, classroom education, special equipment, etc..
As far as I remember they also do require the use of Radio (no typing, except in emergency!)

I try to offer something similar, on a much lower level. My offer will not attempt to get into competition with VATSIM - but should be a help if you want to join VATSIM. I wonder why you still work in the primitive FGFS-environment - if you really want to work like in VATSIM!

You could help a lot by using the MUMBLE --> you cannot trust that all MP-messages will be noticed/remembered - especially not in an environment were many people are using MPchat at the same time!
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Re: EDDF-Triangle

Postby bugman » Mon Jan 07, 2019 12:00 pm

Hmmm, maybe we need an in-built Mumble client within FG itself... Pity there aren't many MP users who are also C++ software developers.

Regards,
Edward
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Re: EDDF-Triangle

Postby jomo » Mon Jan 07, 2019 2:08 pm

bugman wrote in Mon Jan 07, 2019 12:00 pm:Hmmm, maybe we need an in-built Mumble client within FG itself... Pity there aren't many MP users who are also C++ software developers.

Regards,
Edward
You do not need it! I guess everybody flying with FGFS has a Handy - and mumble is available as an APP!
I used it several times when I had problems with my PC - it worked perfectly!
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Re: EDDF-Triangle

Postby FlugHund » Mon Jan 07, 2019 6:17 pm

jomo wrote in Mon Jan 07, 2019 2:08 pm:[...] I guess everybody flying with FGFS has a Handy[...]


Just FYI:
a) It's called a cell phone or mobile (not your fault, just German idiocracy).
b) You've guessed wrongly (although I know how to handle mumble along with FG perfectly well). I just mention this, because people, usually the wrong ones like certain politicians or Bahnvorstände, just assume everybody owns such a device. Such assumptions can cause serious issues for people who don't. Or, to quote Benny Hill in "The German Professor": You must never assume because when you assume you make an ASS out of U and ME.
https://www.youtube.com/watch?v=Uv-qHlcX0Ig
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Re: EDDF-Triangle

Postby wkitty42 » Mon Jan 07, 2019 6:27 pm

tdammers wrote in Mon Jan 07, 2019 6:44 am:I think the most important takeaways here are these:

good list... one should also remember that the MP protocol is UDP which is not guaranteed to even reach the destination system... if it were TCP, no packets would/could be lost in transit... only if one end or the other truncates for some reason...
"You get more air close to the ground," said Angalo. "I read that in a book. You get lots of air low down, and not much when you go up."
"Why not?" said Gurder.
"Dunno. It's frightened of heights, I guess."
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Re: EDDF-Triangle

Postby AAL545 » Tue Jan 08, 2019 2:12 pm

So we really get two problems interacting: dropped properties, and incompatible aircraft models. Proper solutions to both would, I believe, require breaking changes, and I don't think those will fly given the current state of the FG MP ecosystem.


Did my first attempt at logging and FG crashed, will try again some time.
Regarding the quote, seems to me there are too many changes happening when updating FG and or an aircraft. My father always told me don’t fix what ain’t broke.
Keep in my though, as I have said before, I’m not complaining nor criticising a developer for what was done or not done but rather I’m trying to do my part in improving a great product.


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Re: EDDF-Triangle

Postby tdammers » Tue Jan 08, 2019 3:48 pm

wkitty42 wrote in Mon Jan 07, 2019 6:27 pm:
tdammers wrote in Mon Jan 07, 2019 6:44 am:I think the most important takeaways here are these:

good list... one should also remember that the MP protocol is UDP which is not guaranteed to even reach the destination system... if it were TCP, no packets would/could be lost in transit... only if one end or the other truncates for some reason...


Good point in principle, but if that were the reason, we would see the landing gear prop being dropped randomly, not as consistently as we do - we're usually sending several property updates per second, surely if some of them got dropped, it would 1) correct itself on a subsequent update, when the property gets through again, and 2) affect random properties at random, not this one property consistently. I'm a bit rusty on the details, but IIRC, the protocol works such that each packet will contain a complete property set, if possible; if a packet gets lost, then the entire set update is skipped, not just one or two properties. Someone who is more intricately familiar with the MP protocol should probably jump in and elaborate though.
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Re: EDDF-Triangle

Postby tdammers » Tue Jan 08, 2019 3:53 pm

bugman wrote in Mon Jan 07, 2019 12:00 pm:Hmmm, maybe we need an in-built Mumble client within FG itself... Pity there aren't many MP users who are also C++ software developers.

Regards,
Edward


I run mumble alongside FG without issues; and then I use qjoypad to map a joystick button to "talk". This way, it's much like the real thing. There's also FGExtend, which allows you to control mumble via FG COM radio, though it only works with mumble servers that are set up for it (i.e., not the one we use for EDDF).
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Re: EDDF-Triangle

Postby Richard » Tue Jan 08, 2019 4:01 pm

tdammers wrote in Tue Jan 08, 2019 3:48 pm:Someone who is more intricately familiar with the MP protocol should probably jump in and elaborate though.


Partial UDP packets can't happen however packets that don't contain the full property set are possibly, and if the aircraft is transmitting variable length strings long strings can cause a packet that is nearly full to become full and cause properties at the end to not be transmitted. There are warning messages given on the console of the transmitting aircraft that indicate this. I've not checked the packet size on the B777 - that can be viewed when flying by looking in /sim/multiplay/last-xmit-packet-len - ideally this should be no more than 900 (bytes) to allow for text chat strings.

The non tilting landing gear on the 777 doesn't seem to me from what I've read to fit the profile of a transmission problem - it is more likely a model/animation problem than an MP protocol problem.
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Re: EDDF-Triangle

Postby AAL545 » Tue Jan 08, 2019 4:29 pm

I
I've not checked the packet size on the B777 - that can be viewed when flying by looking in /sim/multiplay/last-xmit-packet-len - ideally this should be no more than 900 (bytes) to allow for text chat strings.


Just had a look and my last-xmit-packet-len = 832.


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Re: EDDF-Triangle

Postby tdammers » Tue Jan 08, 2019 4:53 pm

jomo wrote in Mon Jan 07, 2019 11:32 am:Nicely spoken - so I tried to find that happening in the movies - spend 2h to search - but did not find something like that. It would have been nice if you could tell us your flight ID + movie and time + etc. Because I do the movies especially for giving everybody a chance to improve.


Alright, so the film in question is this one: http://www.emmerich-j.de/EDDF/Films/201 ... 57-157.mp4

I'm flying under my usual callsign of NL256 (I thought the forum tagging gave that away). The first time I appear on screen is around 1:55, though I'm still about 110 miles out at that point. The flight strip pops up around 1:58, at 92 miles out. I'm trying to establish contact at 2:06, the screen shows my chat message at 22:40:31 local time. You can see me make further attempts, e.g. at 2:08; the last one is around 2:26. At 2:12, I fly right through the frame, near the PSA NDB.

jomo wrote in Mon Jan 07, 2019 11:32 am:I am surprised about your definition of VATSIM.

I never mentioned VATSIM. You must mistake me for someone else. I know what VATSIM is, and I never tried to give a "definition".

jomo wrote in Mon Jan 07, 2019 11:32 am:I try to offer something similar, on a much lower level. My offer will not attempt to get into competition with VATSIM - but should be a help if you want to join VATSIM. I wonder why you still work in the primitive FGFS-environment - if you really want to work like in VATSIM!

Put simply: because VATSIM requires non-free software, which is generally a no-go for me. I even made an exception, tried setting things up in Wine, but couldn't get it to work - I have a VATSIM ID that I can log in with, but with the FG setup recommended somewhere on the wiki (which, btw., is pretty hard to track down too), I just get silent failures. If you have any pointers as to how to make it FG + VATSIM work on Linux, I'd be eternally grateful.

But, my complaint isn't about EDDF sessions not being like VATSIM; any level of realism is fine by me, really, as long as the terms are clear. I understand that the purpose, approach, and situation are different; I understand that there are technical and organizational limitations such as incompatible charts and procedures; I understand that you deviate from realism on a few points, such as not using squawks, etc.; that's fine. I just wanted to know why I got no responses.

jomo wrote in Mon Jan 07, 2019 11:32 am:You could help a lot by using the MUMBLE --> you cannot trust that all MP-messages will be noticed/remembered - especially not in an environment were many people are using MPchat at the same time!


I know, and I normally do. However, sometimes mumble is not an option, because I have to keep my ears open for the kids sleeping next door, so I can't put on headphones, and I can't really be talking all the time. If the session had been advertised as "mumble only", or if you had told me "sorry, busy, please mumble only"; fine. But everyone else seemed to be communicating on MP chat just fine, so I figured it must be something with my setup. But it wasn't.
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