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Workers Durable Objects Beta: A New Approach to Stateful Serverless

by ispivey on 9/28/20, 1:02 PM with 91 comments

by _ahs0 on 9/28/20, 1:23 PM
Demo chat application from the article using Durable Objects:
- https://edge-chat-demo.cloudflareworkers.com
- A Public Room (to joint test):
hackernews
- Source: https://github.com/cloudflare/workers-chat-demo
Insanely awesome feature add (much needed for truly “serverless” application development). The power to scale here without insane infrastructure headache is amazing.
One day some kid is totally going to build a single-person billion dollar company from his mom’s basement.
by catern on 9/28/20, 3:38 PM
Wow, very cool! I didn't see the string "mobile code" in this press release, but that's essentially what this is, right? Automatically moving objects to be near the computation that needs it, is a long-standing dream. It's awesome to see that Cloudflare is giving it a try! Plus, the persistence is clever - I'm guessing that makes the semantics of mobility much easier to deal with.
I love the migration to nearby edge nodes, but here's a question to any Cloudflare employees around: Have you given any thought to automatically migrating Durable Objects to end user devices?
That has security implications of course, so if you've dismissed the idea previously because the security issues are too hard to surface to the developer, that's reasonable.
by jacques_chester on 9/28/20, 4:14 PM
> I'm going to be honest: naming this product was hard, because it's not quite like any other cloud technology that is widely-used today.
On a superficial skim it looks like a tuple space; they were heavily researched in the 80s and 90s. JavaSpaces emerged in the late 90s but never took off.
Scala folks are keen on Actor models (Lightbend have been using the term "Stateful Serverless" for a while now), as are Erlang and Elixir folks.
I guess the key here is "widely-used".
Edit: this sounds even more arrogant than I intended. Sorry. I just feel bad for tuple space researchers (including my Honours supervisor). They laboured mightily in the 80s and 90s and their reward was to be largely ignored by industry.
by jopsen on 9/28/20, 10:10 PM
What is the size limits for a durable object?
The read/write limit per second?
That usually the first things I want to know about my cloud primitives...
(Credits for at-least being clear about consistency which is always my very first question)
by toddh on 9/28/20, 3:15 PM
Interesting, i didn't see how security works? Is there backpressure on message senders? Any ordering guarantees? Are messages queued so activated objects can reconstruct state? Can passivation warmth be controlled? Can objects support multiple threads? Can objects move? Failover?
by ramchip on 9/28/20, 3:04 PM
> I'm going to be honest: naming this product was hard, because it's not quite like any other cloud technology that is widely-used today.
Perhaps I'm missing something important, but isn't this quite similar to Orleans grains and other distributed actors?
by cxr on 9/28/20, 4:10 PM
Some wanky theory about computing and the design of programs follows. (Not out of scope considering the philosophical underpinnings of this product and the "edge", etc.)
The chat demo says:
> With the introduction of modules, we're experimenting with allowing text/data blobs to be uploaded and exposed as synthetic modules. We uploaded `chat.html` as a module of type `application/octet-stream`, i.e. just a byte blob. So when we import it as `HTML` here, we get the HTML content as an `ArrayBuffer`[...]
```
    import HTML from "chat.html";
```
I've thought a lot about this for the work that I've been doing. From an ergonomics standpoint, it's really attractive, and the only other viable alternatives are (a) dynamically reading the asset, or (b) settling on using some wrapper pattern so the original asset can be represented in the host language, e.g.:
```
    export const IMAGE_DATA =
      "iVBORw0KGgoAAAANSUhEUgAAAD8AAAA/..." +
      "..."

    export const HTML = `
      
    `;
```
... which is much less attractive than the "import" way.
Ultimately I ended up going with something closer to the latter, and there wasn't even any reluctance about it on my part by the time I made the decision—I was pretty enthusiastic after having an insight verging on a minor epiphany.
I'd been conflicted around the same time also about representing "aliens" (cf Bracha) from other languages and integrating with them. I slapped my head after realizing that the entire reason for my uneasiness about the latter "data islands" approach was because I wasn't truly embracing objects and that these two problems (foreign integration and foreign representation) were very closely related. Usually you don't actually want `HTML`, for example, and focusing on it is missing the forest for the trees. I.e., forget whatever you were planning with your intention to leave it to the caller/importer to define procedures for operating on this inert data. Make it a class that can be instantiated as an object that knows things about itself (e.g. the mimetype) and that you can send messages to, because that's what your program really wants it to be, anyway. Once you're at that point, the "wrapper" approach is much more palatable, because it's really not even a wrapper anymore.
by pier25 on 9/28/20, 3:57 PM
If I'm getting this right, it's essentially immediately consistent distributed state for workers. They could have called it simply "Workers State" :)
Now in all seriousness, this is super impressive. Congrats to the CF team!
by agotterer on 9/29/20, 3:37 AM
Is it possible to query across objects? Like if you wanted to find every object instance which had “string” written to it?
Can the data store only store alphanumeric or can you write blobs? Could a chat app store uploads inside the object?
by luord on 9/29/20, 2:14 AM
Now this is one of the times I wish I had at least one idea for an application, because this is the kind of thing I'd like to try out.
Oh, well, I'll wait until it's an open beta or generally available.
by phn on 9/28/20, 1:52 PM
I cannot find any word on pricing, is it included in the regular workers $5/mo plan?
by visarga on 9/28/20, 2:29 PM
How would you debug and upgrade your durable objects?
by asdev on 9/28/20, 5:13 PM
are updates to durable objects guaranteed to be exactly once?if an update is sent but the connection between client and object are dropped, how is that handled?
by vyrotek on 9/28/20, 3:36 PM
Is this similar to Azure Durable Functions?
https://docs.microsoft.com/en-us/azure/azure-functions/durab...
From what I understand these features are a nice way to implement a serverless Actor Model. I was surprised to see no reference to it on the CloudFlare page.
by dividuum on 9/28/20, 2:29 PM
Is there only a single instance of the example Counter object globally and as there are no additional await'ed calls between the get and put operations, the atomicity is guaranteed? Is the object then prevented from getting instantiated on any other worker?
Can this result in a deadlock if I access DurableClass(1), then delayed DurableClass(2) in one worker and DurableClass(2) and delayed DurableClass(1) in another worker?
by ilaksh on 9/29/20, 1:18 AM
All hail the Cloudflare Gods! They are benevolent gods, say I!
And today they have given into us a new, powerful bounty of storage with a delicious API!
by kovek on 9/29/20, 2:41 AM
This is awesome, and I'm so excited to read through the chat.mjs code. I might consider trying this out for a project. It means I need to use cloudflare? I wonder if in the future, this could become more standard, and one could do something similar on their own infrastructure (maybe such a solution already exists, open sourced somewhere?)
by skybrian on 9/28/20, 4:06 PM
I’m wondering what sort of durability guarantees there are in case of an outage? It seems like replicating durable storage would add latency?
Is there going to be Jepsen testing for this?
by gavinray on 9/28/20, 2:59 PM
Really interesting, seems like it has some unique abilities.
Signed up for beta invite -- does anyone happen to know whether all interested parties are admitted?
by akritrime on 9/28/20, 3:58 PM
One thing I am not sure, maybe I missed something in the blog but will there be always one instance of this object or can there be multiple?
by proppy on 9/29/20, 12:18 AM
what's the maximum qps that a single durable object can handle?
by asim on 9/28/20, 9:37 PM
Is this not sharding?