Upload a base64-Picture-String via event message (thinedge) to Cumulocity

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What product/components do you use and which version/fix level are you on?

latest

Is your question related to the free trial, or to a production (customer) instance?

production

What are you trying to achieve? Please describe it in detail.

I try to upload a picture to cumolocity. It is converted to a base64-String and I try to send it via an event message as a normal dictionary payload → image_string

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event_msg_dict = {
	"time": event_time,
	"event_type": event_type,
	"child_type": self.MessageTopic,
	"text": text,
	"lot": HIBC_Code_Contents.LOT_Number,
	"ref": HIBC_Code_Contents.ProductCode,
	"producer": HIBC_Code_Contents.ManufacturerCode,
	"udi-type": udi_type,
	"udi-code": self.Content_String,
	"quality": self.ScanQuality,
	"test_status": self.TestStatus,
	"reason": self.Reason,
	"image_string": self.image_string,
	"location": location
}

Do you get any error messages? Please provide a full error message screenshot and log file.

grafik
grafik1767×837 295 KB

The text over the error is part of the string for internal debug purposes. The Error below is ocurring, when we try to send a dictionary with this string included. If we try to send it without the string (simply commented out the entry but didnt change anything else) it will send the event-message just fine.

Have you installed all the latest fixes for the products and systems you are using?

yes

2

Since the issue comes from that FS_Peripherals.py it makes sense to share that code.

Could you give some more infos why you want to do that? You could also add images via the file repository as well.

3

Specifically, the Event API supports attachments. That way the file is attached to the life cycle of the event.
https://cumulocity.com/api/10.14.0/#tag/Attachments

My guess is that the body of your request is too large an rejected by the HTTP server. How large is the image you are trying to attach?

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The Picture is aproximately 64KB, it varies a little bit depending on the actual object it is taken from.

Since we are using Thinedge to send our Data to Cumolocity, can you please specify under which MQTT-topic and with which payload we have to publish in order to upload the picture as a binary in the first place?

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Ok, I assumed you were using HTTP. The API I linked to is not available via MQTT.

For MQTT the maximum message size is 16KB, so I assume you run into that limit:
https://cumulocity.com/guides/device-sdk/mqtt/#overview

1 Like
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Ok, then how do I upload pictures with thinedge to Cumolocity?

or please suggest best practise to stream real images coming from devices.

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Could you please tell us a bit about the use case.

Images can not be uploaded via mqtt directly but via Rest. There is currently an feature request open for that:

https://github.com/thin-edge/thin-edge.io/issues/1315

However you could handle the RestCall in your own plugin and attach it to an event. @Harald_Meyer referenced the API call already for that.

8

Is it possible through Device Integration using Smart Rest Templates?

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We have now published image through thin edge topic and can be retrieved through events (UTF-8 Encoding)

Use case was simple, we need end to end streaming for our images through thin edge.
Still there is no component which supports decoding of image real time on UI

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