Motoko, a programming language for building directly on the internet
stackoverflow.blog
stackoverflow.blog
> Actors are a great model for concurrent programming because they automatically prevent race conditions (thanks to atomicity and encapsulated state) and deadlocks (because execution never blocks)
This isn't really true afaik. You can still have logical race conditions if you don't synchronize messages (but they won't be architectural races), and you can still have deadlocks if two actors wait on messages from each other at the same time.
I feel like people often treat race conditions and deadlocks as small, computer-architecture ideas when really they're quite broad concepts. You may be able to prevent them automatically at certain scales, like say a single uint64, but when you try to treat two uint64s as a single uint128 then suddenly race conditions are possible again, despite the guarantees your language has made on the smaller scale.
When a certain amount of state is encapsulated within a single actor (or a single message for that matter) you can act on all of it sorta transactionally since no other actor has access.
This is probably more power/control than some programers have had in other languages or paradigms.
Your full program state dosn't retain this property once it spans actors but what can ya do.
Actor model with explicit synchronicity and access scoping:
actor Counter {
var value = 0;
public func inc() : async Nat {
value += 1;
return value;
};
}
type Tree<T> = {
#leaf : T;
#branch : {left : Tree<T>; right : Tree<T>};
};
func iterTree<T>(tree : Tree<T>, f : T -> ()) {
switch (tree) {
case (#leaf(x)) { f(x) };
case (#branch{left; right}) {
iterTree<T>(left, f);
iterTree<T>(right, f);
};
}
}
Not to my taste personally.
Think I will enjoy trying this once its available
My guess is that storage persistence is the Godzilla of all leaky abstractions. There are huge tradeoffs in regards to consistency, durability, random access, performance, and cost. In addition, there are huge issues with lock-in. If I can save my data to sqlite or postgress or even S3, I know that I will be able to migrate the data to other languages and systems pretty easily. But if all my data is in a abstract "Internet Computer persistence pod", that is a huge issue.
You can’t have users’ personal data lingering in a soup of opaque cloud continuations for months. There needs to be a way to strongly commit deletions and audit that the data is gone. And once you build that on top of the “Internet Computer”, my guess is that it will look disappointingly like a very slow ordinary database.
Imagine you're building an app that lets users of a music streaming service see how much time they spent listening to particular genres of music.
The way you would do this with REST, SOAP or similar could roughly be:
1. Retrieve the user's whole listen history.
2. For each track, send a request to get the track info, which includes album and duration.
3. For each album, retrieve the album info, which contains the genre.
4. Tabulate the returned data.
That's thousands of requests, and a lot of network bandwidth wasted.
GraphQL is a bit better, you only receive what you need, and you send just one request, but you still get a whole lot of track objects, which need to go through the network and be processed on your side.
With my proposed approach, you would send a piece of wasm code, a bit similar to a Lambda function, which would run on the streaming service's API cloud.
Such a function could use fine-grained API calls to retrieve what it needs. It would be executing on the service's network, so round trips would be either short or nonexistent. After tabulating the data, it would send back a simple JSON with the genres and time spent.
This approach would allow developers to extend any service in ways the original developers have never imagined. We could also re-think the way backends and frontends communicate, giving frontend devs a way to do even more, without changing the back end.
This feature hasn't yet made it into a stable Windows release, but it's available in Insider builds, and the high-level client libraries and accompanying tests are on GitHub here:
https://github.com/microsoft/microsoft-ui-uiautomation
Disclaimer: Remote Operations is still a work in progress. There's no public documentation yet aside from the README in the GitHub repo, and the client libraries aren't yet packaged for easy consumption. Moreover, this is not an official Microsoft announcement; I'm just bringing it up on this thread because it's relevant and I'm proud of this feature that I helped develop.
As an aside, how do you get to the bytecodeyou use? Do you write quazi-assembly by hand? Did you develop your own compiler? For what language?
Will other, non-microsoft assistive technologies, like NVDA for example, be able to use it?
As for how the bytecode is built, the GitHub repository I linked has a library with a WinRT API for building the bytecode at run time, by calling methods that correspond to the individual opcodes. It's an object-oriented API, so there's a class for each type of operand. And for control flow blocks (e.g. if-else and while loops), the method takes a WinRT delegate (basically a lambda) that builds the body of the block. You can see how it works in the functional tests; stay tuned for actual sample code.
If only such structured query language data bases existed, I bet they would get a lot of use.
(No but really: how is what you’re describing meaningfully different from SQL, especially with the restrictions you’d want to put on the code in practice?)
I also find the idea of arbitrary code execution on a remote host to build a derivative service to be a quite naive point-of-view. Even if you can validate that the code isn't going to pwn you - a mighty stretch - how can one justify being a recipient of free compute cycles on someone else's infra? It's not quite realistic to me
But I do think this is a problem our industry will have to solve eventually. The volume of data we have to move between servers in order to ask questions is exploding. We move petabytes of image data between filesystems in order to train machine learning models. If the problems in this thread can be solved (admittedly a big if), moving the code to the data would be fundamentally better.
Such a thing could become the de-facto API, if Rest or GraphQL were needed, they could even be implemented on top of it.
Yes there is - that program would need to be extremely hardened (even against DDOS style attacks - run a ton of memory-consuming cycle-hogs on a service's platform), integrated with tracking & billing, and open-source (or itself charging).
I just don't see the incentive for someone building this, and then I doubly don't see the incentive for a corp running this. Why take on this huge extra burden of infra to help derivative services? It's not going to make you money.
Be aware that's exactly what you are doing when you go to any modern site. You let a remote server execute arbitrary code on your computer, trusting it's not going to pwn you. Sure, there were tons of loopholes in the first few years of JS, but now browsers and operating systems are so secure that it's mostly a non-issue. Web assembly is a sandboxing-first technology, so I don't think it's an impossible or even a particularly hard issue to solve.
>how can one justify being a recipient of free compute cycles on someone else's infra? It's not quite realistic to me
Well, there are API call limits, or something equivalent to them. Maybe computing credits in this instance. Calculating how much computing resources you're using is something that i.e. AWS Lambda does already, no reason why an open-source runtime couldn't do so either. The fact it wouldn't be native code, executed directly by the CPU, but Wasm executed by a VM, makes things even simpler.
Right, which is the point - it took an absolutely behemoth effort backed by megacorps to get us to this point. These applications are public-facing because that's the key way for the corps to make money - content delivery.
Why would anyone put this same effort into building more complicated internal services enabling derivative services to extract value from their platform?
> Calculating how much computing resources you're using is something that i.e. AWS Lambda does already
Yes, exactly - another megacorp built a service that makes them huge amounts of money, and now they sell access to it. This code is certainly not publicly accessible
So, again, help me bridge this gap - what possible reason would Spotify (to further GP's example) build such a platform for? This means that Spotify needs to maintain massively more infrastructure in order to help others extract value from their platform.
It just doesn't check out. Is it objectively a more efficient method of computation? Yes. Is it also completely misaligned with corporate incentives in the modern day? In my opinion, yes.
SQL isn't everything, though. Be aware that such APIs, for security reasons, wouldn't allow you to modify some of the data in arbitrary ways, but require you to use special functions instead. Think of being able to query the number of upvotes, call an upvote function, without being able to just change the upvote count.
Maybe a mix of wasm (as an imperative platform) combined with a structured query API? Maybe a programming language with something like Elixir's Ecto or C#'s LINQ? Not plain SQL, but an imperative language with the power of relational queries?
The “communicate with code, not messages” in your first comment strikes me the same way: code is data, and data is code, and Wasm does nothing to change that. Nothing about making an interface more expressive guarantees one is making it better, and overspecification of user intent can make it much harder for the system to optimize execution.
Even if we really do want imperativity: your upvote example, even including the security aspects, is easily handled using stored procedure support that’s been available in SQL dbs for decades. It is not unfair to describe that support, and its variants (eg postgres lets you use python) as “not plain SQL, but an imperative language with the power of relational queries”.
Can this approach handle everything? No; it would be madness to try and build e.g. huge neural network models in SQL + some stored procedures. But it handles a lot, including your two examples, and handles them more compactly than a general purpose language would, and exists.
Mind you, I’m not saying your general concept isn’t great. It is great, it is a great step. It’s just that distributed programming already took it, back in the 70s.
You can move code to the data, or the data to the code.
Sometimes you want to work with big data banks that you have no hope of ever storing. Your listening history is small enough to fit on your phone. Amazon's whole product directory, with reviews and indexes for quick data retrieval, is not.
If you want to run compute over big data, you replicate the database with a server you own and run compute on a copy of the data. Realistically that is what Amazon would have to do for you either way - they'd be running replicas you could compute over. And those replicas need to say in sync via db replication.
Secure competition over anonymized datasets is useful for security reasons, not efficiency reasons IMHO.
select s.genre,
sum(s.duration) as total_duration
from listen_history h
inner join songs s on s.song_id = h.song_id
where h.user_id = 12345
group by s.genre ; DROP TABLE songs
It is worth noting, though, that many RDBMS allow for "read only" permission groups, so the risk of malicious DELETES/UPDATES isn't a huge problem in practice. Rather, it's the unbounded queries that could make your severs spin forever that truly represent the problem domain.
The query (or code, if you will) is separate from your data, meaning the aspects of the data a query depends on can’t change without breaking the query. You can have versioned apis and keep the old apis around, or have a query compatibility rewrite layer, etc. but obviously these kinds of things have serious complications/limitations.
That approach is useful only in proportion to how broad, granular, and flexible the API is that you provide for the code/query to access. That sounds good, but such an API is a lot of work to create and a lot more work to maintain. An API is like a promise. If you make big promises, it will take a lot of effort to keep them.
Also, realistically you have to limit arbitrary code sent in from untrusted sources that runs on your server. Even completely non-malicious users will write inefficient code or have inadvertent infinite loops that will eat up your compute budget if you don’t have controls in place.
So...
It’s very often better to add a “listeningStatsByGenre” endpoint if that seems to be what your users want.
And this is where I went from "good faith reading" to actually not believing the article. Every general language that has made this claim has had holes - and those holes are usually patchable, but to claim a language with almost no adoption is leak proof is foolhardy at best. Just because you haven't discovered how your particular abstraction is broken doesn't mean it isn't.
> A sound type system means you can never get into a state where an expression evaluates to a value that doesn't match the expression's static type.
It's not actually that hard to make a provably sound type system. The claim can only strain belief if it includes some type-level feature that makes this difficult.
Of course, it should also be proved. e.g. Java's type system is not sound even though there is no good design reason while it shouldn't be (to be fair - it only happens in cases so intricately twisted that nobody will ever stumble on them by accident).
Maybe someone will provide the same developer niceness in a traditional cloud way. The only people who would prefer DFINITY at that point are people who really care about decentralization (which is fewer than the marketing hype suggests imo.)
* Can you expand on Orthogonal Persistence -- is this a "per actor" persistence, or from the references to blockchain is it some sort of shared state between actors?
* How does the internet look/feel/work different once this exists?
1. Compared to other forms of DECENTRALIZED compute, IC + Motoko shines in making web apps with User experience comparable to centralized providers (AWS, GCP, Azure). Example: You can build simple react web social network and expect quick reads (in milliseconds) and writes (1-3 seconds). Note I did not say "blocks" or "finalization." I deliberately trying not to have a leaky abstraction from the POV of the app developer.
Compared to CENTRALIZED compute, you can create "open internet services" like an open version of TikTok where the control of the app and its features can be be done by (in simple terms) voting. Example: https://www.youtube.com/watch?v=_MkRszZw7hU
More broadly, one of the things that is surprising (it was to me when I joined, and it still is), how much of the cloud stack that developers or compute providers create is not necessary when you have protocol-based compute. As a developer, some things like firewalls, databases, seem less important in enforcing the security and scalability of my apps. I realize as I type this can sound a bit naive AND esoteric... and I think the only way to really show this is by action and folks just playing with it. Few words will really convey this as much as people playing with it directly, I get that.
2. Our compute model are "canisters" which (if you are familiar with actor model) are actors that contain both their code and their state. Actors communicate by sending messages to each other (as actor model implies). Example: I could create a twitter canister. Orthogonal persistance means its state can grow without me spinning up DBs or worrying about replication and consistency.
https://sdk.dfinity.org/docs/language-guide/motoko.html#_ort...
3. Oh boy thats a big question... I don't think I can do better than our founder Dom: https://www.youtube.com/watch?v=dALucsAgAwE
Was that a helpful set of answers?
This sounds very convenient until one fine day you decide add a new feature, so you need to change your code, but the new code has different variables and there may not be any sensible way to "port" the data.
Because that's not probably what it happens...
It's an idea that has been tried on and off for decades and is obviously very appealing but tends to have lots of interesting problems when it has been used for a while - often when you want to access your data outside the context of your application.
So in this sense it could be a bit like creating migrations to your database. Maybe on ”cloud scale” you just would like to migrate the data when it is used.
Edit: Few more details in this document: https://sdk.dfinity.org/docs/language-guide/actors-async.htm...
Good question. It is not public yet. We have started opening more in summer 2020 (this post is an example) as things start to line up. Some of the folks in the Languages do give talks Motoko and Wasm... and expect us to open up further.
I do not expect that answer will truly sate your curiosity, and I am very humbled you are even interested to read the code and go deep. That means a lot, thank you.
But I suppose it’s probably actually the kind of article the AI engines digest in order to be able to generate similar ones.
Idk web assembly yet though, scanning to figure out how this could be useful for an amateur web-dev.
This seems to be just like Ethereum without the blockchain. What does "building directly on the internet" even mean? What do I ever need distributed, cryptographic consensus for? The use-case escapes me completely, this even seems more useless than Ethereum, where I can see at least some applications thanks to the blockchain. But that thing without the blockchain just doesn't make any sense. But hey, it got WASM, so must be cool.
educate yourself and try again.
i work with bchains since 2013 and ethereum is a major driver for a lot of innovation and real life applications. i've built an energy trading platform on top of it that allows local business to localize their energy management. its deployed and working, granted , in a small poc here in Adam. but still.
also what do you think powers 99% of all altcoins?
Generally the use case for decentralized systems is if you want to disintermediate an existing middle-man who has proven untrustworthy, expensive, or problematic in some way. Or, you want to enable a group of parties to coordinate their activities in ways not previously possible without a (currently non-existing) trusted intermediary. The middle-man function is automated and federated. That’s it.
Any business model dependent on a middle-man is potentially a business model for decentralized systems, if the economics, risks and feature requirements compare favorably. Bitcoin addressed arguably the most impactful one - money - but there may be others.
>this even seems more useless than Ethereum, where I can see at least some applications thanks to the blockchain.
DFINITY is a “blockchain” in the general meaning of the word, aka a public decentralized computing platform with a native currency and attendent economic incentives. It may use other data structures under the hood than most current blockchains, but the use cases are mostly the same as Ethereum.