Directions for openHAB 3

I don’t know if we should open a new thread now or not. But I have some real concerns about removing the compatibility layer without offering any way to continue to support 1.x bindings.

There are far too many 1.x bindings for which there isn’t a 2.x binding to replace them and sadly that will always be the case as there are some bindings that have lots of users that are basically abandoned and have no one to rewrite them as 2.x. The list of 1.x bindings that have a 2.x version in the works appears to have closed to a trickle and some very heavily used ones (e.g. Expire) do not have any replacement in the works as far as I know. But even obscure bindings like Insteon and Asterisk (which never actually got listed as officially supported in OH 2) have some number of users who will either be stuck on OH 2 forever or lose full support for their technologies.

For many 1.x bindings that have a maintainer those developers do not see the benefit or spending a lot of effort to rewrite the binding without adding any functionality. Apparently a consistent user experience is not sufficient enough benefit for these maintainers. :frowning: But many users would rather live with the inconsistency then to lose access entirely.

The loss of support for the 1.x bindings at this time will result in a significant loss of users and potentially maintainers as well, and all the acrimony and bad feelings that would go with that. It could take a long time to recover from this as a community, if we ever do.

So if we do remove the compat layer, we need to provide a path for users that still depend upon 1.x version bindings to continue to do so. Some ideas have been raised on the thread I linked above.

Ultimately I think we either need to come up with a way to make the OH 1.x bindings work on the new core with all the necessary REST end points and everything, or continue to use something like the compatibility layer.


We’ll said @rlkoshak really echos my feelings. Following the if it isn’t broke philosophy I can say. I use insteon and expire. Really as a user I care that it works more than new features.

For expire not sure things and auto discovery apply.

For insteon yes I suppose auto discovery/channel links could help but not sure what other features could be added.

So, my main agreement is that we need a solution that encompasses many of these bindings that I am sure exhibit the same conditions. I feel some of the reason the bindings appear abandoned is because they function great and need few added features. So it would be more or less work for the sake of work.

I do understand we need to balance this thought process with whether or not things do just need a general review and update every few years.


For expire specifically, I think it should just be a setting in the Item definition window in PaperUI, much like Groups currently are. Expire directly acts on the “state” of the Item, so it should just be a configuration setting for each item, rather than a dedicated binding.


So much this.


I absolutely agree and stated the same here a while ago. Imho, the expire1 binding should never have been introduced in the first place, I only learned about it when it was too late already.

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So if they work, they should have been added to the distro. This is hardly any work and people were asked since FIVE years many times to do so. If nobody felt willing to take this little effort over 5 years, this speaks a lot about their engagement and help for the project.

The loss of support for the 1.x bindings at this time will result in a significant loss of users and potentially maintainers as well

Keeping up complexity will PREVENT maintainers from joining/staying with the project, so it’s hard to tell, which side is more relevant in the long run. Fact is, in 5 years time nobody ever took care of the compat layer but me. It’ll be interesting to see, which developers will jump to the rescue the next time it breaks and I don’t fix it. Let’s try that out. I am not very confident, though. A funny experience were the last 2-3 weeks: While hundreds of people had opinions and spent a massive time on discussions, nobody seemed to care about the fact that we had no working snapshot distro and I was more or less the only one chasing bugs and regressions… Pretty frustrating, really. So whatever you discuss, please always consider the situation where I might not be available and others have to keep the project running - that’s why I focus so much to make it easy for others, because otherwise it could be an instant death.

Ultimately I think we either need to come up with a way to make the OH 1.x bindings work on the new core

I don’t agree that it has to be “on the new core”. I think @David_Graeff made a great suggestion about it: A feature to connect multiple openHAB instances would be cool for distributed setups (and to allow this was a design goal of the openHAB architecture 10 years ago already) - so if that would be easily possible, you can run a 2.x instance with all 1.x legacy stuff and connect it to a lean and modern 3.x instance to have everything working seemlessly as one setup. Makes imho a lot of sense and I think it’d be great if @David_Graeff would work extending the MQTT support that way.


I just happened to stumble on this topic because I happen to be watching a topic which was referenced here. I can imagine that there are many users who hardly ever visit this forum if at all. Is feedback from the user base ever actively sought? One gap I encounter is that between what users are doing and what developers/maintainers are doing.

It is true that it is the maintainers that provide the functionality in the product. But the fact that they have not maintained their code for a long period of time does not mean that users aren’t using it… and are depending on it.

For the case where a OH2 binding has been made available, I can see making the case that users are given the option to migrate. But I go back to what I said at the front - that would have to be a more direct communication. Otherwise a user will likely face the situation where what is to be a simple update ends up removing some functionality they depend on. Even though the typical openHAB user is probably more technically savvy than the average Joe, my gut tells me that they aren’t strict subscribers to ITIL practices when it comes to running their home computing environments.

But what of the OH1 functionality that has never been brought forward? In some cases it’s because it just works. If it ain’t broke… What options will users have then? Telling them to follow up with the maintainer to plead with them to update the code to the latest architecture is going to be difficult to say the least. And probably not very efficient in getting the desired result. Yes, OH needs to make changes for continued improvement. But backward compatibility is an issue. One that will very likely result in losing users. Will it be offset by new users coming on board? Or will users just make the decision that if they have to completely change their installation, they might as well make the jump to a different home automation solution altogether.

Finally, I know that there is a code of behavior when it comes to touching someone else’s code.

If someone is working on a new binding and drops it for months, it stays there because they are the owners… even if someone else might want to see the work to the finish line. Trying to get permission to do so sometimes goes on deaf ears.

The same for a working binding. It was put out there and now let’s say it’s been orphaned. Is there no way to transfer that to someone willing to maintain it even w/o being given explicit permission? Maybe the terms to contribute to OH should include a “dormant” clause?

I’m sure that this post sounds disjointed perhaps. It’s just comes from my stream of consciousness dump when I saw the theme of the topic - dropping backward compatibility. Don’t get me wrong, I truly appreciate what the OH developer community has done in creating a great tool. I just want to make sure that the voice of the user is given the opportunity to be heard. How can that happen more effectively?




There is. That’s the sole reason why every binding is in one openHab controlled repository. Everybody can at any time suggest changes. And if they improve the binding (performance wise, usability wise) the original author will usually not veto such a change, even if it fundamentally changes his binding.

I have already presented my first option of having two independent OH run-times running, connected by some means like MQTT to sync the two event-bus events.

Threat every OH version as a different product

How about making that even more obvious.

Threat every major OH version as a different product. No migration paths at all (those cost developer hours as stated above). So there are two products currently available OH1 and OH2. Those products might be able to interact with each other, or might as well not. Depending on the core developers of each product.

Binding API versioned

At the podium discussion on the smarthome day 2018, there was also the proposal to version parts of the API independently. So there would be a binding API at version 2.x, a REST API version 2.x and maybe a service API version 2.x. That way the core could develop independently as well and be at version 6.x. As long as it provides a binding API at version 2, all those bindings will still work.

This also means, that we don’t need to auto-sync the binding versions in openhab2-addons anymore. The major version must match the binding API version, and the minor and revision version can be determined by the binding developers themselves. Breaking changes in bindings are more obvious as well. And if a binding developer really require advanced functionality of a newer binding version, he would increase the major version of his binding. Making it incompatible to older core versions. But very well communicated.

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Is no response is treated as a “no veto”? Is the period to wait for a response defined?

But very well communicated - yes!

Threat every major OH version as a different product. No migration paths at all

That sounds really bad.
As a user I would feel completly f*cked.
When I was replying in all the discussions in the last month or so, my main concern was: make sure you have an upgrade path for your end-users.

I can understand we don’t want to force 2.4 users to upgrade the moment when we bring out 3.0 yet I do think we should offer upgrade paths.

those cost developer hours as stated above

Supporting 3 or more versions costs even more development hours.
Once there is a good upgrade path for a binding in 2.x, people no longer use the older 1.x binding.


That is true. But the concepts changed so radically that no upgrade path can be provided without a lot of development hours (migrations). You also need to differentiate what core developers we have. Personally I’m a pure OH2 developer. And as far as I know (please correct me if I’m wrong) Kai is the only OH1 developer left. And he stated something along the line of that he is not willing to do that in the future anymore.

So the “product” OH1 has no developers left. The question is actually: Can we find other solutions. For insteon there is the mqtt bridge for example. Anel would work with the Http+UDP binding. And so on.

This is where I actually disagree to some extent. There is benefit in consistency is setup and use of bindings. Even if OH 1.x bindings were to become first class citizens again, they will always be different with all the advantages and all the disadvantages of that.

So if someone were to take the Insteon binding and rewrite it as a 2.x version biding with exactly the same capabilities, it would still be an improvement from a usability perspective, particularly usability for new users. It’s not make work.

There is already an issue open on this. I don’t know where it ended up after the great merge.

It’s definitely an approach I can support. My concern is that there is some path for support, not that it necessarily has to remain on OH 3.

Yes but the forum is our only communication medium. Threads like this are actively seeking feedback from the user base.

The newly published Governance addresses this to some extent.

It’s a start at least.

No matter the outcome of this topic, this is a much requested feature so I hope it happens anyway. :wink:

I think going to that extreme would be disruptive, particularly if those older versions cease receiving bug fixes and security updates. If the answer is “well, when we stopped development of OH2 it still had this ugly memory leak that never got fixed, but if you need to use a binding no longer supported on OH3, your only choice is to continue to run that” it isn’t very satisfactory for the users. It means we are telling them that we don’t provide long term support for OH. Every two to three years you will lose functionality if you stick with OH.

I really like this idea for lots of reasons. But does this actually make the job of the OH maintainers easier? It certainly provides a way for users to know and understand what a binding is capable of and why it can’t work on a newer OH core (i.e. OH 3.1.23 supports only API versions 2.5 and above).

Ultimately, I think we are faced with a no-win situation. Any choice leads to harm to the community.

Option Consequence
Remove support for 1.x bindings entirely Loss of users and binding maintainers
Run multiple instances of OH If the older instance is not longer maintained eventually this will break
Keep the compatibility layer With only one developer who can or will maintain it this will eventually break
Make OH 1.x bindings first class citizens There is no volunteer to develop this so this path is essentially not an option unless and until someone volunteers

All viable paths lead to the OH 1.x bindings becoming unusable on the new instances of OH. When that happens there will be a loss of users, perhaps binding maintainers as well.

If we break the currently viable options down further we are faced with the following choices:

  • Do we choose when the 1.x bindings finally break or let it happen naturally?
  • Do we take on effort for longer term support to the older versions of OH for those who need to keep these 1.x bindings running or just leave them and hope it continues to work?

There are some things that we can do I think to mitigate the user’s long term ability to continue to run older OH instances using Docker or VMs and the like (one of the problems will be continuing to be able to obtain Java 1.8) but even that will be a challenge. I don’t think it will be reasonable to expect in five years that a user will easily be able to continue to run a Java program that depends on a long abandoned JRE. So even the “continue to run older versions of OH and federate” approach only serves to buy us a little bit of time.

It’s a tough situation.


Regarding the expire binding.
Could it be treated or converted to a profile:

[profile="expire", action="command", value="OFF", time="2h30m"]

I stated this already in another discussion, but as this is on the table here as well: Two instances of OH (one OH2, one OH3) on a single Raspberry Pi is probably not a good idea (only 1GB RAM). As this is a very popular platform, this should be considered…

Please don’t propose to run two Raspberries to resolve this: Double the rules programming and maintenance effort, double the energy costs.

Plus, this is simply ugly!


But in the other thread there were also considerations if the OH1-core which runs inside OH2 isn’t loaded it might have not much impact. And that OH3 and and a newer powerful pi might be ready at the same time.
I think this should be mentioned, too. The thread mentioned is this one.

If this is tested on a Pi and confirmed, fine… Up to now, this is unclear!

Thanks :slight_smile:

No no no. This is not how it would work. I want to make sure it is really clear how this would work. It’s important to understand this to properly understand what is proposed.


All your Rules, Persistence, Things, UIs, and everything else will live on the OH 3 instance. The ONLY thing that will live on the OH 2 instance are the OH 1.x bindings and the Items bound to them. Those Items will also be represented in the OH 3 instance somehow through the federation.

There is one place to develop Rules. There is one place to develop your UIs/sitemaps. The only thing that will exist in the OH 2 instance is the OH 1.x bindings, the compatibility layer and the federation of the event bus. That federation means that any updates/commands that come from OH 2 get reflected in the same Items in OH 3, and back.

The work/energy used by OH 2 is not duplicated. It is work that your current system has to do already anyway. There is just more RAM required because there will be some overhead in running two separate instances of OH. But it isn’t double the RAM either, because OH 3 will no longer be hosting almost a complete copy of OH 1.x inside it. We won’t know until OH 3 is built how well the two will live side be side on the same RPi. It may work great or it may not. It will largely depend on your specific configuration I suspect. But some users will have to prepare to have to run to RPis to retain support for OH 1.x bindings under OH 3 I suspect. Would you rather not have the ability to run OH 1.x bindings at all?

The work you have to do is only slightly increased as well. You will need to set up the federation and you will have to places to go to to configure bindings. But that is far from doubling your manual work.

With the MQTT 1.x binding, this sort of set is already possible. The MQTT 2 binding doesn’t have direct support for a setup like this, but it is possible to set it up this way. What is being proposed is to make this sort of federated OH configuration part of the core instead of part of the MQTT 1 binding or accomplished through the MQTT 2 binding and Rules.


@rlkoshak Thanks for the explanation. Maybe I was a bit unclear, but that concern you cited referred to the idea of employing two Raspberries for the two OH instances…

Doubling the maintenance - no. Maintenance overhead - yes. But ok, valid point, sort of.
But double energy cost? Come on! Throw your smarthomethings out of the windows very fast and don’t buy any of this stuff if you argue about 8 Euro energycost per year.

Agreed. Still ugly :wink: