UnifiedPush: A decentralized, open-source push notification protocol
f-droid.org
f-droid.org
UnifiedPush has been a thing for a while, see the official website: https://unifiedpush.org/
With this blog post, we† tried to clarify a few names. Feel free to point out things that are still unclear, the documentation is pretty much a WIP.
UnifiedPush aims at replacing the push notifications mechanism provided by Google services with something independent, that anyone can self-host or any OS can provide without compatibility issues. It does require small adjustments server-side and client-side for applications assuming Google services.
There is also a Matrix room at #unifiedpush:matrix.org and a Mastodon account at https://fosstodon.org/@unifiedpush
Note: we'll be monitoring this topic for a while, you don't have to reply to this thread.
† karmanyaahm and S1m are main authors
I think the consensus was that we wanted to wait for UnifiedPush to be more mature before approaching them, but it's probably about time. S1m made an interesting implementation for the (compatible) Signal fork Molly: https://github.com/mollyim/mollyim-android/pull/152
The implementation is quite interesting: it adds a linked device that does not receive encryption keys, but sends push notifications to the client.
A police unit parked outside a guy’s house and confirmed it was him in the real time chatroom, by cutting his internet and seeing him drop off.
If you want real anonymity on the Internet, never use push notifications. Always “pick up your mail” periodically from random endpoints on the Web.
You can accumulate encrypted messages at random urls instead
Note that a similar thing happens with any two-way conversation; if an immediate reply is expected and there's no reply, it's not a conversation anymore. (For more possible reasons, though.)
Disappearances can't have good error messages if you want plausible deniability. This will make any UI much less user-friendly.
Have many servers who just accumulate encrypted packets and then only the host knows how to reassemble them in order and decrypt.
Could probably be somewhat realtime if executed correctly.
*You send PGP encrypted messages via Mixmaster Remailers (via Tor) and preferably use a hashed subject (hsub) so that the intended receiver(s) can filter out their messages.
https://lists.gnupg.org/pipermail/gnupg-users/2019-March/061...
I guess I'm going off of too few details probably, but this doesn't seem like a very sound strategy to me. It's certainly not impossible that the real criminal lost internet around the same time as some suspect's was cut by the police. I know I've shown up as online to other people for up to several minutes after losing internet in real-time situations (e.g. games). I suppose police just need "reasonably likely" to take action though, not definite reasons.
The AAAA record was temporarily removed to try to mitigate.
Shouldn't Happy eyeballs fall back to IPv4 when IPv6 is broken?
Someone told us IPv6 was broken after we submitted here, as they use an IPv6-only network, apparently. I just posted that up there in case that was the actual issue encountered by the commenter. We're not sure why it broke yet, but we'll fix it when there's less traffic.
OS makers could install a default UnifiedPush distributor though.
Lastly, the Embedded FCM UnifiedPush library (to be embeded into a client app) handles UnifiedPush over FCM (Google-provided push notifications), so that a server only has to handle the UnifiedPush API (with a rewrite proxy for UP->FCM).
What's the actual likely hood that the average end user is going to install a random service?
For now, UnifiedPush is targeted towards De-Googlers, self-hosters and FOSS enthusiasts, not average users.
Which implies the use case people are seeing is phone apps. Unless people are building one off apps for themselves, you've got end users in the mix.
I don't see how this can be positions as much outside of phone apps, as txt messages or emails would be easier and more universal. Being that they're probably going to be supported here.
To note, i haven't see anyone talking about this being replacement for the part of webpush that handles registration for notifications or whatnot, but as a whole separate channel/technology. Not 'install this to avoid using google/apple for webpush' but 'use this in your app, and have your users install the service'.
So yeah, the app has to support it, but the user can choose then.
That's pretty much it. Because there isn't really any possible alternative except something that looks like this.
GCM/APNS/ETC do not fit those requirements, so it needs to be something new.
At least, if they feel big enough to gain initial traction...
Huawei is pushing their own thing, alternative to Firebase[1]; Amazon as well[2].
There's a dozen services that provide cloud-based services to send push notifications to various services. I think the incentive to gain subscription revenue was greater than the opportunity to make these partially redundant.
I'm not sure why it took so long for something like UnifiedPush to appear. It took a fair bit of debugging, but ultimately, it was mostly up to one dedicated individual (S1m) with Android experience.
Before UnifiedPush, there was OpenPush[3], but it never materialized.
[1]: https://developer.huawei.com/consumer/en/hms/huawei-pushkit
[2]: https://docs.aws.amazon.com/sns/latest/dg/sns-mobile-applica...
Doesn’t Apple and Google on the OS level only allow push notifications to come from its own services? Like, they look for the signature to be compatible with https certificate etc. Otherwise the phone could have a ton of push notifications incoming from anywhere on the Internet. The APN service for instance would only route notifications to a phone if it came from a registered website. How do you get around this?
As far as I know, even for VOIP permissions, iOS only wakes your code up if ITS APNS SERVICE sends the notification. How are you able to install a long-lived application in the background on iOS?
Similarly, the phone radio is listening for calls from the nearby cell towers in the network, not from absolutely any tower. I guess a Stingray can impersonate one, but they would probably need to fake the attestation, right?
The reason to use the google services is mostly touted as for battery savings, I believe.
Thus, it makes total sense to have one mechanism for push messages for the entire device. It's great to have degoogled alternatives here.
This is now impossible with background execution restraints set in Oreo. The OS clusters requests for background execution and does them with the same wake. Apps can only wake the device every 15 minutes at most (and requests to wake are not guaranteed).
Signature spoofing is similarly "impossible" there's no rule saying this stuff can't be changed by distributions that care about it. You already have to install a custom OS to get rid of gapps to begin with so aside from the maintenance burden for changes that will never get upstreamed this is really a nonissue.
Not true since Android Oreo. Long running background Service execution (without a foreground notification) has been dead for a while. Most of the useful system-wide config change updates (implicit Broadcasts) got killed as well. Basically, only Google (or GCM/Firebase Messaging) gets to do timely push notifications. You can try to roll your own MQTT server, but there’s a good chance the OS will kill your Service, in which case you would have to poll every 15 minutes with JobScheduler/WorkManager, with no guarantee that background task would even get run every 15 min.
Wake up one thing,
Check one place,
If (message) wake up correct app
Plus the real time push works differently… like a phonecall comes in and your phone rings thay same second
Wouldn't microG be enough for that?
If UnifiedPush were to gain enough traction (say it would be adopted on FireOS, HuaweiOS and whatever platform don't use Google services), those apps would likely start to support it directly.
Another possible avenue is to add UnifiedPush support to push libraries used by these apps both server and client-side. Multiple libraries (Google FCM included, I linked at least two others from Amazon and Huawei in another comment here) abstract push notifications away so the developer gets a single server to talk to, and a unified API across iOS, Android, Web, etc. If these libraries started supporting UnifiedPush, adoption could increase a lot, without involving any developer effort for these proprietary apps.
And a special thanks for not forcing us to use a slack channel!
Hopefully other OS projects will follow.
Good health and all the best for 2023!
Is this just for mobile (android only?) developers, or is it for any push notifications e.g. browser.
Could I use this with PHP or JavaScript for example?
It would be nice to have a solution for delivering pushes internally, and also hold open a best-effort connection to a remote server that allows some notifications through.
The last solution I considered was running a Matrix homeserver on the ship with some local channels, and another instance on shore, and using federation to connect them when the uplink is available. Monitoring systems could send their alerts as DMs or to a shared channel.
Then for the notifications, Apple has its Local Push Connectivity API you might be able to use to send notifications within the ship network. I'm not sure if this UnifiedPush would solve the problem on Android. Either way, though, it seems like a lot of engineering effort just for a chatroom.
[1] https://matrix.to/#/!vwmBiTqilorqNCbGab:matrix.org/$hJpXxhVR...
ntfy is also a distributor for UnifiedPush, so you're not entirely off topic here. Hehe.
Disclaimer: I am the maintainer of ntfy.
https://developer.apple.com/documentation/networkextension/l...
https://github.com/gotify/android
The problem is that there is no iOS app. You could use the browser there but maybe ntfy would be a better fit (Android + iOS.)
... email?
Lastly, Secure Scuttlebutt was actually designed on a boat for sporadic internet connection and local connections, as well as sneakernet, so that would work too, but I don't think it's designed for IM. Perfect for blogs or facebook-like stuff though.
Have a member of the crew go onshore up to a Wi-Fi AP, it will act as an async data transfer for everyone. You can also exhange data with other travellers, including passing boats.
Interestingly, there are a few Matrix p2p experiments. I wish apple opened their Airdrop feature as that would make proximity networking easier, though that should be achievable with Wi-Fi NAN+P2P.
Among my acquaintances, I can count Apple users on a single hand (<1% of the people I know), which severly limits the usefulness of the network.
There's OWL [1] which looks promising on Linux. I hope Android devices can get something soon. I'm still a bit confused by how Linux drives Wi-Fi radio, and what is and isn't implementable in software: could older Android devices gain support for NAN and OWL through a software update? What about old computers with old Wi-Fi cards?
I first got aware of Wi-Fi NAN by chatting with neilalexander on #yggdrasil:matrix.org :)
It looks promising for advertising capabilities to nearby hosts, allowing to negotiate p2p connections.
[1]: https://owlink.org/
Similar to how Apples push notification service works already (APN: https://en.wikipedia.org/wiki/Apple_Push_Notification_servic...)
It looks like the submission side of UnifiedPush could indeed have been Web Push-compatible but isn’t, though.
Exactly. It was discussed a bit early on whether to mandate encryption, but simplicity was chosen instead.
Adjusting the server protocol to make it compatible with WebPush is also being discussed: https://github.com/UnifiedPush/wishlist/issues/15
That would be useful for supporting Telegram, for instance. I don't really see it becoming mandatory, however.
Actually, the web push standard strongly recommends that you use RFC 8030 for this, but it does allow browsers to substitute other protocols as long as their semantics are the same https://datatracker.ietf.org/doc/html/rfc8030. I believe Mozilla and Edge both use HTTP Push, I'm not sure what Google uses on Desktop Chrome but I could see it going either way. Safari probably uses APNS.
I'm personally using UnifiedPush HTTP endpoints as-if they were Web Push, and it just works. I handle decryption manually on the receiving end.
However, we don't use the WebPush API between the push server and distributor since there is a lot of scope for innovation in that space (for example Google's FCM uses a custom XMPP based protocol).
[1] One example, https://github.com/UnifiedPush/dart-webpush-encryption
If you are sending a small amount of data it is likely a tiny overhead for some notable benefits.
1. If all data is encrypted then no data stands out for being encrypted.
2. It provides integrity which may prevent push servers from changing message to be invalid or triggering parsing bugs in applications.
3. If only encrypted messages are supported it is impossible for uses which do need encryption to forget to turn it on or accidentally turn it off.
For many apps the benefit here is indeed tiny, but so is the cost. So I think it is best to not support unencrypted messages altogether.
As a small project, ease of adoption has been our most important goal. However, as we work towards better WebPush compatibility [2], I personally absolutely want to promote RFC8291 encryption and make it easy to implement for developers using UnifiedPush, hopefully making it the norm.
[1] https://volkerkrause.eu/2022/11/12/kde-unifiedpush-push-noti...
As soon as you need encryption in at least one place in your software, it's going to happen.
I agree encryption should be the default choice though. Maybe we can introduce it in a future protocol revision? Client side, I expect most people use libraries, making this easy. Server side? Not so much.
The main goal was to get it adopted as widely as possible though, and encryption certainly seemed like something that would slow the effort.
While I understand that some developers may think of security as wasteful, having unencrypted data be the default relies on every developer to spend much more time considering the possible threat models and how . Case in point here is Matrix—the IDs they send aren't random at all, they actually send full room IDs and event IDs for each message, so you'd be able to build up someone's entire social graph just from reading their unencrypted push notification data and looking up room IDs on the Matrix server in question or even correlating room IDs across different Element installs. This also hurts users, since they're not in a position to inspect the source code and understand how or whether they need to trust their "push provider" with whatever data the app developers might have chosen to regard as "less sensitive"—WebPush's encryption-by-default design removes trust from the equation entirely and prevents of these sorts of "passive surveillance" attacks (except those based on timing or message length)
> You can then decrypt these notifications in the app
This pushes all of the complexity of supporting encryption onto the app developer, instead of having it be provided by the platform where it can be centrally audited and securely managed.
> However, we don't use the WebPush API between the push server and distributor since there is a lot of scope for innovation in that space (for example Google's FCM uses a custom XMPP based protocol).
Why not do this innovation in an open standards body like the IESG where other stakeholders can give feedback and review? The web push standard does allow for Push Servers to use other custom wire protocols besides the default RFC8030, but having open and standards-based discussion of the possible performance improvements would "lift all boats" in terms of being able to provide low-power devices with timely push notifications
Will this service allow the same thing FCM does, including waking up the device? I'm looking at both iOS and Android devices, I see there's Flutter available but not iOS necessarily in the docs [1]. Related question, will the Flutter version also work for iOS devices? I know FCM (and its Flutter SDK) works for both, as well as web.
How would iOS native only apps on Swift do push notifications, surely Apple has their own service and everyone doesn't use Firebase?
[0] https://developer.apple.com/documentation/usernotifications/...
[1] https://firebase.flutter.dev/docs/messaging/apple-integratio...
The issue is highlighted in this article [1].
[1] https://www.sixthtone.com/news/1011308/the-real-story-behind...
Disclaimer: I am the maintainer of ntfy.
System-level integration into Android ROMs would eliminate the need for those things.
[1] https://docs.ntfy.sh/faq/?h=battery#how-much-battery-does-th...
At least I replaced the one from my Matrix client with the UnifiedPush-enabled ntfy. Hopefully it'll replace Signal too at some point. KDE Connect? Why not. K-9 mail? I hope, but that would require JMAP or IMAP adjustments.
One option would be to install the distributor as a system app.
I'm planning to use WebSub and/or RSS, but on the look out for others. Any pointers?
See also... The See also section in that article :)
You say it would be server to server, but are both publicly reachable?
> You say it would be server to server, but are both publicly reachable?
So yes, the user would have to run a public server. But only for practical reasons, otherwise how can you push.
Webmention isn't quite it, we're notifying about our own API Resources.
Websub (FKA PubSubHubub) does. It just doesn't seem to be widely adopted for some reason.
Using WebSub or UnifiedPush would technically very similar but you need a way for the client to pass you the subscription information. WebSub has a standard discovery process to manage this.
Also since Google is blocked in China, Firebase Cloud Messaging doesn't work there. Android has something like a 75% market share in that market. Some vendors have their own offerings (e.g. Xiaomi MiPush, Huawei PushKit) etc, I could buy that a popular centralised solution would be more attractive than doing N integrations.
The vision is that you only need to implement support for 1 integration: UnifiedPush, possibly by embedding one of the libraries that manage it and fallbacks. You automatically gain support for compatible alternatives.
There's a variety of reasons why people can't or don't want to rely on Google services. Before UnifiedPush, one would have to "hardcode" an alternative, or more commonly implement a persistent connection within the app.
This also has some potential for more efficient push implementation: for instance, if you have access to an SMS gateway, you could use that to push notification without enabling data connection.
The specification also makes it easier to support third-party operating systems and clients.
So this is welcome, but it requires application support. And if apps on your phone use both GCM and UnifiedPush you still end up with multiple providers. But at least I think I can trust UnifiedPush to be light on my battery.
It's possible. There is nothing ready right now.
[1] https://github.com/UnifiedPush/wishlist/issues/18
[2] https://github.com/Telegram-FOSS-Team/Telegram-FOSS/issues/5...
So it's a hypothetical problem IMHO. There are very few cases or phones i see these days where people complain about battery: https://docs.ntfy.sh/faq/#how-much-battery-does-the-android-...
But this at least gives FOSS a chance to compete on battery life without FCM fallback like some do.
Most likely FOSS will never get full parity, Android might be gone and replaced long before then, but the ability to make an app that's F-droid legal is still a big deal.
Carrying two phones seems like a lot of stress, I generally like to minimize the number of objects in my life as much as I can.
There's definitely room for adoption within the freedesktop.org umbrella for the Linux part, once this part is a bit more mature.
Moreover, when something is sent to that URL, it gets forwarded to the application, which then interprets it before displaying a notification (for most apps).
By spam, I think you meant someone sending messages to random people's notification area. No, this is highly unlikely.
The use-case would be new mail notifications; it wouldn't be too hard to do, and would be quite useful, as I typically have multiple e-mail accounts.
You could however build a UnifiedPush-compliant SMTP-based or IMAP-based distributor.
This is a limitation with Android and not a fundamental network/OS limitation. As long as your protocol allows for long enough keep alive latency you can periodically wake up for a short period and allow apps to service their connections (which is what I'd imagine this does anyway just with a singular app.) This works on Linux if you don't have the extra Android crap getting in the way.
It's kind of a bummer to see bad OS architecture feed into over-complicated protocol/application design.
EDIT: I guess I wasn't clear here. In my experiments I had the background wake up service wake the device up once and applications had just that singular window for all of them to service their connections. The problem with Android is instead applications either keep the phone from suspending entirely or (apparently) have some API allowing them to register their own periodic wake up that isn't shared.
EDIT2: I also want to be clear that this isn't a criticism of NTFY. The developers behind it deserve congratulations for solving a serious problem with FOSS Android apps. My complaint is that the poor architecture and unescisary inflexibility of Android made this such a complex problem in the first place.
I think the OS could synchronize them if keep alive packets are sent at the TCP level, but that would be hard to do at a higher level.
Letting a single program handle persistent connections leaves a lot more potential for energy efficiency optimizations.
Overall, the thought was that wakeups are expensive, wakeups that involve the network are particularly expensive, so might as well run them all at once (they tend not to be CPU bound - often much of the wakeup handler is spent waiting for the network to connect and send a packet or an ack to arrive back).
This turned out to be a very very bad idea. All it takes is some app to have a 'wake up exactly on the hour', and now all other app callbacks will also run exactly on the hour. End result: Mobile networks get 10 million phones all waking up within a few milliseconds of one another, and everyone wanting to connect, and the whole mobile network fails because it was never designed to have 10 million phones all trying to connect within a few milliseconds.
That idea was scrapped.
That network and the server get them from many users spread out evenly is only a benefit.
Unfortunately there are lots of bits of hardware in mobile networks that fake acks - ie. TCP level acks will be received very quickly to indicate the mobile network has accepted the data, and will deliver it at some future time out to the internet.
The problem is they still send acks even if the remote end is no longer responsive.
So you can't reliably use TCP acks to know if a connection is still alive. You need to send actual data and have the application respond.
In fact, I choose not to believe it. Is there some document discussing this kind of functionality?
For this to work, you need apps to somehow conform to a standard timing and respond to a signal that says "hey, the OS is awake for you to do network things". Now each developer needs to implement some special code that understands the situation. After a while, all the devs start using libSleepyNetwork because getting those details right is hard. The libSleepyNetwork people realize that they can use a system daemon to further coalesce work for greater efficiency (one event loop is better than N event loops), so now all the consumer program C APIs are now backed by IPCs to the daemon.
This is exactly what's already happened on Android, except libSleepyNetwork is implemented by either Google, or these people. I don't think it's bad OS design at all. It's chasing efficiency via abstraction that encapsulates some complex coordination.
The protocol does not specify how the distributor and push server communicate or keep a connection going. It's up to them to define an energy efficient way to do that. For ntfy [1], a single WebSocket or JSON stream connection is used to deliver messages to the device. This is very energy efficient and consumes <1% of battery on most phones.
As for regular wakeups (for polling), Android does not allow periodic work to be done more frequently than every 15 minutes, which is obviously not frequent enough to be useful.
> It's kind of a bummer to see bad OS architecture feed into over-complicated protocol/application design.
This is somewhat true. The restrictive Android eco-system is what led to the creation of UnifiedPush, but it's far from complicated IMHO
Disclaimer: I am the maintainer of ntfy [1], one of the UnifiedPush distributors.
[1] https://ntfy.sh
Also, you cannot specify the exact time when it's supposed to run, so it's likely they will just run at the same time.
Your app is only woken up by the OS if FCM receives a notification for you. For e.g. Xiaomi will not wake you up even if you get a notification, unless you're on a white list (the much glorified Xiaomi whitelist). When Android is put in power saving mode, the FCM manager optimized this even further.
- why is web development such a big thing
- why is app development a thing at all
From the HN guidelines [1]:
> Be kind. Don't be snarky. Have curious conversation; don't cross-examine. Please don't fulminate. Please don't sneer, including at the rest of the community. Edit out swipes.
> One key feature of UnifiedPush is that the communication between the push server and the distributor is not specified. This means that a variety of technologies can be employed, such as WebSockets, Server-Sent Events, *XMPP*, raw TCP, or even SMS, whatever works best for the user.
That part is what specify UnifiedPush. It does not specify the communication between the push server and the distributor.
I just read the specification you linked. If I understand it right, it just specifies what we call a "Push gateway" in our last diagram in the "under the hood" section.
As in, it specifies how multiple servers can connect to a single (XMPP-speaking) push server. This is also evident from the excerpt I'm quoting:
>XMPP Push works between the user's XMPP server and two push notification services in tandem:
> The user's XMPP server publishes notifications to the XMPP Push Service of each of the user's client applications.
> The XMPP Push Service (as defined here) for a client application then delivers the notification to a third-party notification delivery service.
> The third-party (and potentially proprietary or platform-dependent) push service delivers the notification from the client application's backend service to the user's device.
As I said, we did it as far back as 2016: a watered-down XMPP client (a "distributor", as you call it) was used to deliver push notifications to a few different apps on devices that didn't have GCM (as it was called then).
> Please make an effort to come across as less antagonizing in the future.
Someone has to antagonize people who ignore prior art.
I almost used my sentence myself. The overlap is almost zero.
> All it needs to reach the final 1% is to send a message with an agreed payload format to a client.
This is the part we're interested in. We standardize this part and make it modular. The core issue is that multiple "client"s that do not interact with each other traditionally each implement their own payload format and background connection. Which drains battery. We propose a mechanism to delegate that to a third-party that can then multiplex those messages. That's all.
It's not a lot of work per se, but coming up with a modular API is not that trivial either, and we have to spread the word so that it can be used by multiple projects.
Lastly, you seem pretty focused on XMPP clients. Unfortunately (or maybe fortunately), not every app uses XMPP. On my phone, apps that could theoretically use UnifiedPush are: NextCloud, Etar Calendar, DavX5 caldav synchronization, K-9 mail, Element & others Matrix clients, HomeAssistant, FindMy & other device locators, covid tracker, Carnet notes application, Fennec (Firefox), KDE Connect, Mobilizon, Peertube Client, UnCiv, and various others, including chat apps and weather apps. XMPP would bring very little to those, especially as they just need that "1%" functionality you quoted.
There is some overlap indeed, as there is a server-server API. However, 99% of the spec you linked is completely useless or overkill for our use-case. We just accept POST requests to an endpoint and forward them to the app running on a user's device.
> As I said, we did it as far back as 2016: a watered-down XMPP client (a "distributor", as you call it) was used to deliver push notifications to a few different apps on devices that didn't have GCM (as it was called then).
That's pretty good indeed; was the specification open so that other apps could join in? Do you mind sharing a link? You can just implement the UnifiedPush specification in that distributor, make sure the server-side part accepts requests in the format specified, and you have a UnifiedPush-compliant application that other apps can use.
I've been looking for such a specification for a while, there's been some talks around the topic for years, including OpenPush [1], but nothing concrete or public that I know of. The link you shared in your previous comment does not address the "distributor" part.
> Someone has to antagonize people who ignore prior art.
Well, please at least try to understand the thing you're criticizing before, that's the bare minimum.
App doesn't need to 'use' XMPP to use push notifications. For developers, it is essentially identical to using FCM. XMPP part here simply offers a very effective way to decentralize the service, as federation server-to-server part in XMPP is wonderful, and top XMPP servers like ejabberd have great performance.
> Well, please at least try to understand the thing you're criticizing before, that's the bare minimum.
My company has created this very thing for a customer years ago, so I think I pretty much do understand what you are creating.
It wasn't open, yet, the effort to make it open would be pretty small. We could probably release it, but I don't see the real need for it, as it is a likely dead end: making apps run in the background on Android was what we did for years, and the writing is on the wall. Background running becomes more and more difficult with each new version of Android, even on pure Android phones. Biggest manufacturers, however, like Samsung, Huawei, Xiaomi simply kill off background processes without mercy. So it is more than likely we won't be able to run 'dispatcher' apps on Android, just like we can't on iOS, and we'll have to rely solely on push notification service which is built into the phone OS. If there is a fight worth fighting, it is the one to force phone OS developers to open this part of an OS to allow using custom push notifications services.
> It wasn't open
Then, I'm sorry, but even if the design was miles ahead of what is being proposed here, it might as well not have existed.
> If there is a fight worth fighting, it is the one to force phone OS developers to open this part of an OS to allow using custom push notifications services.
Well, we're proposing an API for it, and we will certainly push alternative OSes such as LineageOS, /e/ and others to adopt it; we hope it gets picked up by bigger fish, but we can't exactly pressure them into doing it, besides demonstrating that it works, documenting it and raising awareness, which is what we're doing here.