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Comment by thatcherc | Hacker News Reader

I was wondering if something like could be done to upload sensor data without a data connection and it looks like that's exactly what the authors here had in mind!:

> Potential use cases

> While I was mostly just curious about whether it would be possible, I wouldimagine the most common use case to be uploading sensor readings or any data from IoT devices without a broadband modem, SIM card, data plan or Wifi connectivity.

The use case I had in mind is gathering sensor data from boat out in a harbor (away from wifi) that other boats with iPhone-bearing crew pass by frequently. This ESP32 AirTag emulator could send out battery level and bilge pump data any time someone sailed by, without the need for a dedicated modem. Might have to try this out!

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I recall a mechanism like this used to deliver email in rural India. There were basically email “kiosks” which would let you receive and send mail for a fee and would store these messages locally until a truck with the company’s transponder stopped at the village, at which point it would send the data to the truck which would upload the data to the Internet when it reached the city. Obviously obviated by mobile data.

In 2006, I did a summer internship at NASA implementing the Bundle protocol [1]. It assumes intermittent connectivity and/or large delays between transfers. For example, you have intermittent line-of-sight between Mars and a tracking station on earth or line-of-sight between a rover and an orbiter on the far side of Mars that will at some point in the future relay the data onto Earth. I can't find it in the RFC, but using it to provide internet to rural villages was definitely discussed.

[1] https://datatracker.ietf.org/doc/html/rfc5050

Do you know if there are open reference implementations of this protocol?

I haven’t looked since I worked on it. I think it kind of fell into the dustbin of history...

The process of delivering the internet by trucks is quite laughable, yet SMTP is the perfect protocol for that: Mail can hop from server to server until it finds the right one, as opposed to now where SMTP hosts like Gmail only accepts mail sent from or to a Gmail account.

Back when computers were connected only intermittently, UUCP was the means of doing this.

https://en.wikipedia.org/wiki/UUCP

I had a professor that made us answer questions about the bandwidth, latency, and reliability of a stationwagon loaded with hard drives. I never imagined I'd see a practical example of that principal at work.

Cloud providers like AWS will do data import/export via racks of drives in a shipping crate, if you have that much data. [1] (Or just a few drives in the mail if you're not moving petabytes.)

On the other end of the enterpriseyness scale, but still an actual real-world use, there's SD cards attached to homing pigeons [2], in addition to numerous stunts or pranks ala RFC1149.

[1] https://aws.amazon.com/snowball/#Snowball_Data_Transfer

[2] https://www.denverpost.com/2007/06/22/homing-pigeons-get-dow...

Physical transportation of storage has always been a thing. Of course, over time, internet speeds increasing means it only makes since for larger amounts of storage. https://aws.amazon.com/snowmobile/

Can you explain what you mean about gmail?

Classically SMTP let you "relay" mail that neither originated or is destined for the specific server. Gmail, and most modern SMTP servers, only permit mail from or to a Gmail address/their primary domain.

Edit: added clarification that all SMTP servers do not only permit Gmail addresses...

Is this sarcasm? As the gmail part is completely false.

Relaying used to be a thing, before spammers and unwillingness to deal with it at the source (boot infected devices, originating AS / IX, .. ) resulted in a choice between a game of whack-a-mole or only accepting gmail¹.

These days, relaying has to be setup on the specific relay server, the originating address needs to permit it (DNS SPF/DKIM/DMARC/whatever), and the relay server will still have a reputational problem with deliverability to unrelated servers, which is problematic even for direct mail, unless you are gmail¹.

¹ usually gmail + varying number of big players

Ah I was a little unclear. Edited. I meant that free-for-all relaying is a thing of the past.

Sneaker UUnet?

Yeah another use case is broadcasting air quality metrics for consumption by the Health app, to start capturing exposure to various air environments you spend a lot of time in (office being primary example). I talk about this air quality broadcast a bit toward the end of my piece on repositioning HomePod around air quality - https://nickpunt.com/blog/apples-next-homepod-should-monitor...

Health doesn't track air quality, but HomeKit does, and I believe it already has a mesh protocol (Thread) though I don't know how it works.

Unfortunately Health doesn't yet store air quality, but I spelled out how air quality scores might be designed in the article. To the user it would be something akin to Fitness apps three rings but for different aspects of air quality: Safe, Fresh, and Comfortable. Within each would be specific air quality metrics (pm2.5, pm10, co, co2, vocs, temp/humidity, etc), which would sum up into three different scores for the three aspects. These would drive recommendations to the user.

I don't have an opinion on what protocol would work best, just that it needs to be localized pretty well to match up with the localization of air quality. My hunch is UWB is a better fit for that.

Could this be made into a cool emergency short messaging service during natural disasters or emergencies where connectivity may be unreliable or unavailable? Wonder how much “AirTags” payload one phone will proxy/buffer? And if/how well it works offline between phones?

By the way, you can get Bluetooth telemetry sensors that connect to your phone and upload the data via cell phone.

It might be easier than any of the stuff you described above.

That’s not what they want to do. If a phone has to be present near your sensor, either you have to be near the sensor or have two phones.

This way you can be away from the sensor and also only have one phone.

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