Azure-docs: Empty chart

[martinfierz]

I ran the example - everything seemed to work as intended, except that in the end the graph is empty. A little more information on how to see where data might be stuck would be helpful

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Document Details

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• ID: 681e10a1-05d3-5761-2afd-42602a7efecf
• Version Independent ID: f72e21b1-3530-8554-f1f1-fc66b222a485
• Content: Real-time data visualization of sensor data from your Azure IoT hub – Web Apps
• Content Source: articles/iot-hub/iot-hub-live-data-visualization-in-web-apps.md
• Service: iot-hub
• Product: unspecified
• GitHub Login: @rangv
• Microsoft Alias: rangv

[mike-urnun-msft]

@martinfierz Thank you for your feedback! We have assigned this issue to the content author to review and take the right course of action.

[anthtone]

I am having the same issue. I have noticed the iothub.js file was recently updated, however there was no backup required. A little help would be great.

[martinfierz]

I found my problem! In step 2 of the example

Azure.IoT.IoTHub.ConnectionString | Obtained from iothub-explorer
-- | --

I had the wrong IoThub connectionstring. It would be nice if you could show where to find this string, to give an example for how it looks, and it would also be nice if some error reporting happened somewhere visible when the connectionstring is wrong. I assume the webapp could display an error message in the webpage if the connection fails.

[anthtone]

Thanks for the heads up Martin.

Is it the one under

IoT Hub -> <> -> Settings -> Shared Access Polices -> iothubowner -> primary connection string?

[martinfierz]

Yes, that's the one. I found it mentioned in
https://blogs.msdn.microsoft.com/iotdev/2017/05/09/understand-different-connection-strings-in-azure-iot-hub/

[satishkrishnam]

Hi, I am getting blank chart. I followed the steps as suggested in Microsoft Documentation. I tried all IOT
hub connection strings... But did not yield the desired result. Can someone please suggest the steps to rectify this? Thanks in advance.

[satishkrishnam]

@martinfierz did you get the chart? What did you do? How did you fix it? Please reproduce the steps. Thanks in advance.

[anthtone]

I still have not got it working. Even with the primary connection string given above. Not sure why.

[alejandroandreatta]

Same issue here. Followed all the steps, connection string is correct, sample app on device working properly and messages are being received by the IoT Hub but the web page is either blank (Firefox) or shows error 500 (Explorer).
Another piece of info: if I try
iothub-explorer monitor-events --login ""
I cannot see the device to cloud messages
Help please

[thomas-kinnari]

Hi,
I also experience a blank chart. However, when I check the app service editor output I get:

Fri Aug 03 2018 11:27:51 GMT+0000 (Coordinated Universal Time): Application has thrown an uncaught exception and is terminated:
D:\home\site\wwwroot\node_modules\azure-event-hubs\dist\lib\rhea-promise\connection.js:141
    async createSender(options) {
          ^^^^^^^^^^^^
SyntaxError: Unexpected identifier
    at Object.exports.runInThisContext (vm.js:76:16)
    at Module._compile (module.js:542:28)
    at Object.Module._extensions..js (module.js:579:10)
    at Module.load (module.js:487:32)
    at tryModuleLoad (module.js:446:12)
    at Function.Module._load (module.js:438:3)
    at Module.require (module.js:497:17)
    at require (internal/module.js:20:19)
    at Object.<anonymous> (D:\home\site\wwwroot\node_modules\azure-event-hubs\dist\lib\rhea-promise\index.js:16:20)
    at Module._compile (module.js:570:32)

I tried reading up on the errors but no luck...
Any pointers as to how to proceed? I must admit I am rather new to node.js and this type of frontend work :)

Thanks in advance!

[Fenn-CS]

@thomas-kinnari I had the exact same error! It made me clone the repository and run locally it worked but it's on linux. During creation of the webapp select linux as environment OS.

However the graph worked for a few seconds then stopped only for me to find the epoch error on terminal the number keeps increasing as time passes. I have created a consumergroup and don't understand why MS tutorials or libraries should be so faulty.

At least one receiver for the endpoint is created with epoch of '38', and so non-epoch receiver is not allowed. Either reconnect with a higher epoch, or make sure all epoch receivers are closed or disconnected. TrackingId:050b400e-303e-4511-803d-9833b4a4b10a_B19, SystemTracker:iothub-ns-elechub-565119-333eafefdf:EventHub:elechub~8191, Timestamp:8/4/2018 10:58:24 PM Reference:f477f057-a23d-4d1d-9e7f-e686576452c8, TrackingId:758669db-498d-4d47-9322-1e2a96ca36bc_B19, SystemTracker:iothub-ns-elechub-565119-333eafefdf:eventhub:elechub~8191|$default, Timestamp:8/4/2018 10:58:24 PM TrackingId:f23c4f4734dc45f59ea8cc0b3beb8a1e_G15, SystemTracker:gateway5, Timestamp:8/4/2018 10:58:24 PM

[thomas-kinnari]

@Fenn-CS Thanks for the reply - I have now created a linux app, but I still see no graphs. How do I check that data is being read? And what about the format of the application setting keys and values for linux?

[Fenn-CS]

@thomas-kinnari did you set the environment variables? In the tutorial you asked to set Azure.IoT.IoTHub.ConnectionString and Azure.IoT.IoTHub.ConsumerGroup obtained from iothub-explorer. However those names are not valid identifiers of the Linux operating system so you would have to change them to ConnectionString and ConsumerGroup then create a clone of the project and modify how it is read, by modifying the names in server.js I implemented check it out here.

https://github.com/Fenn-CS/ElecHubWeb/blob/ca2b01e08d76cc58c64bf81af00d49785c36f72d/server.js#L34

In case you are considering cloning my code repo, I have removed the tutorial and implemented mine with vue.js what is really important to you is the server.js file.

[Fenn-CS]

Additionally if you get the epoch error I mentioned above, that is because the so called ConsumerGroup is requested by the app but not supplied with the request to the IoTHub you would have to add that yourself also! But get it to at least show you the graph first.

[thomas-kinnari]

Sweet! That did it! Changing the strings to ConnectionString and ConsumerGroup was what I needed to do.
I am now seeing a nice graph being updated in real time with temp and humidity data. Thanks for the help!

[Fenn-CS]

Cool 👍

On 7 Aug 2018 7:52 a.m., "Thomas Kinnari Strudsholm" <
[email protected]> wrote:

Sweet! That did it! Changing the strings to ConnectionString and
ConsumerGroup was what I needed to do.
I am now seeing a nice graph being updated in real time with temp and
humidity data. Thanks for the help!

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[npa62]

Two questions:
1) If you change something in the web-app, do you have to deploy it again?
2) Does this only work if you have a physical device that sends data, and not the PI simulator?

[thomas-kinnari]

Hi!

Ad 1) Yes, i.e. that was what I did at least. I pulled my code from my
github repo and changed it, then deployed to the webapp.

Ad 2) It also works with simulated data. As long as data is pushed into the
event hub, and the webapp reads from the right stream. That should do it
(works for me).

Cheers!

[rajeshn1802]

Blank chart gets displayed eventhough Azure.IoT.IoTHub.ConnectionString and Azure.IoT.IoTHub.ConsumerGroup are valid. Any other setting needs to be done in the portal?.
Can someone help me in this issue?

[SMARTHON]

Thanks!!!

it works for the below!

IoT Hub -> <> -> Settings -> Shared Access Polices -> iothubowner -> primary connection string

Very confused if the article haven't mentioned it

[asergaz]

We will now proceed to close this thread. If there are further questions regarding this matter, please tag me in your reply. We will gladly continue the discussion and we will reopen the issue.