Server errors in class room

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Agajon

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Oct 10, 2019, 11:25:27 AM10/10/19
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Hello everyone, 

I'm a big fan of the App Inventor Project and I've used App Inventor yesterday and today in class with students. 
Unfortunately we had a lot of technical issues with the page. 

  1. It was quite a challenge even to start developing: The login page did not load (blank page) or we got an 503 server error. When we got to the projects overview it was rarely possible to create a project – often the server responded with unable to create or unable to load project errors like "Server error: could not retrieve project information. Please try again later!". Yesterday it took us about half an hour full of reloading the page to get alle the groups ready for development (8 groups at 8 PCs). Today it was impossible: only one group reached the designer/block-view, all other teams resigned after about 45 minutes of trying. 
  2. We also had problems connecting test-devices. The bar reached 20% (establishing secure connecting) and after a while it failed. 
Some background information
  • We are located in Germany and used the german language-edition.
  • We worked in a computer classroom within a school network – are there any limitations by the server, if there are too many connections from one IP? The overall internet connection at school was fine, we could use other websites without limitations.
  • We used the app inventor from 9:00 to 11:30 a.m. yesterday and today from 9:00 to 10:15 a.m. (Berlin time zone, UTC +1) – have there been too many requests in this timeframe, delaying the server?
  • Edit: We used Chrome and Firefox on linux-based computers.
Have there been other users experiencing similar problems? 

Looking forward, hearing from you!

Greetings
Florian

SteveJG

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Oct 10, 2019, 11:43:24 AM10/10/19
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Regarding connecting devices, a magic 'fix' might be to check the Use Legacy Connection on the Companion before scanning the Qr code.  Please try that.   What happens?
Make sure you are connecting to App Inventor using Chrome or Firefox.   Do not use Edge, it is incompatible with App Inventor.  Using Edge seems to work but then, unexpectedly strange things happen...perhaps what you are experiencing?


This Forum discussion might help you discover a solution to your class issues Florian  https://groups.google.com/forum/#!category-topic/mitappinventortest/yqmrlll8qqo

You  said "are there any limitations by the server, if there are too many connections from one IP? The overall internet connection at school was fine, we could use other websites without limitations."   App Inventor uses WebRTC, it is not a web site, it is a Web app.      Yes, there possibly are too many connections on your network, this will depend somewhat on your school's Internet provider.  A  503 Service Unavailable error is an HTTP status code that means the website's server is simply not available right now. Most of the time, it occurs because the server is too busy or because there's maintenance being performed on it.  MIT has several servers, when the load becomes heavy, it provides additional servers so MIT is probably providing adequate access.   If that were not true, all users would have this issue; that is not the case

Please read the link and the links within the link.  There might be something in that discussion that will help you.





BodyMindPower

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Oct 10, 2019, 3:14:38 PM10/10/19
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Evan Patton

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Oct 10, 2019, 3:58:15 PM10/10/19
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Nothing on our end shows that there were server failures yesterday. Do you also experience these errors from home? You may want to check with your school IT to see if you are using App Inventor from behind an HTTP proxy. If it was struggling with the load that would explain the 503 errors. Other error messages are likely caused by that as well. We had over 2000 users access App Inventor from Germany yesterday, so I'm not sure you would have been alone in these issues if it were a server-side problem.

Regards,
Evan

Agajon

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Oct 11, 2019, 3:24:38 AM10/11/19
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Hi Anke, 

thanks for your advice. I'll give it a try with the offline version. 
To get it right: Do you run the server within your school network, so students access the app inventor without having to use the internet? 
Or is the use case to run it on each computer – one instance for each team? 

Grüße
Florian

Agajon

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Oct 11, 2019, 3:59:57 AM10/11/19
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Thanks for your tipps, I'll give it a try by using the legacy connection. 
We've used Chrome and Firefox on a linux-based system and experienced the issues with the server in both browsers. 

Your links were very helpful, especially when I found this document for preparing the school network: https://docs.google.com/document/d/1GMXO_GoCRj3052Pg93dzEzJ5sXido9Ul7Xrn6HYU6Xs/edit
Is it necessary to have both the computers and the smartphones within the same network/Wifi as described? Because currently there is no WIFI at school – so we used cellular connections of the phones. I did test with with my computer within my own WIFI and tried to connect to my phone with WIFI turned off – and it worked? 

Agajon

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Oct 11, 2019, 4:04:57 AM10/11/19
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Hi Evan, 

thanks for checking the server. 
I had some minor issues with app inventor from home, but there were less and I could use it overall. Sometimes I got some project could not be saved-errors, but I did not experience as much trouble as in computer lab. 
I'm going to check with our IT guy, if there is any HTTP-proxy causing issues within our school network. 

BodyMindPower

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Oct 11, 2019, 8:33:10 AM10/11/19
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Hi Florian,

yes, it is a local installation that does not require internet connection. Download the zip file, extract it to a directory and start the servers locally.

Open your browser (Firefox, Chrome) an enter
http://localhost:8888/

see also my post in this thread:

Note: Use the USB connection (AI2_Starter) to connect your device to the PC:


Greetings,
Anke

Evan Patton

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Oct 11, 2019, 1:22:31 PM10/11/19
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Please note that the offline version is not something produced by MIT and may be out of date with our production version.

Regards,
Evan

BodyMindPower

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Oct 11, 2019, 2:10:28 PM10/11/19
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Yes, that may happen, but ramiro updates the offline versions very soon. The current version is nb180, the same as the live version.

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