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Progressive JSON

• animanoir 1y ago
  [dead]
• behnamoh 1y ago
  I think the pydantic library has something similar that involves validating streaming JSON from large language models.
• polyomino 1y ago
  We encountered this problem when converting audio only LLM applications to visual + audio. The visuals would increase latency by a lot since they need to be parsed completely before displaying, whereas you can just play audio token by token and wait for the LLM to generate the next one while audio is playing.
• nixpulvis 1y ago
  I've always liked the idea of putting latency requirements in to API specifications. Maybe that could help delimit what is and is not automatically inlined as the author proposes.
  • xtajv 1y ago
    Choose APIs that offer SLAs. <3 It's not about being picky. It's about communicating needs, and setting boundaries that are designed to satisfy those needs without overwhelming anybody's system to the point of saturation and degraded performance.
    • nixpulvis 1y ago
      Right, but what if some of that SLA information actually directed the code itself. In the context of this blog post, what if the SLA was <100ms for an initial response, with some mandatory fields, but then any additional information which happens to be loaded within that 100ms automatically is included. With anything outside the 100ms is automatically sent in a followup message?
• uncomplete 1y ago
  jsonl is json objects separated by endline characters. Used in Bedrock batch processing.
  • markerz 1y ago
    ndjson is extremely similar, Splunk uses it for exporting logs as json
    • lucb1e 1y ago
      From a quick lookup, aren't "newline-delimited json" and "json lines" identical? Different name for the same thing?
      • Izkata 1y ago
        Came up at work a few weeks ago when a co-worker used "ndjson" which I'd never heard of before, but I knew "jsonl" which he'd never heard of before: As far as I could tell with some searching, they are basically the same thing and have two different names because they came from two different places. "ndjson" was a full-on spec, while "jsonl" was more informal - kind of like an enterprise vs open source, that converged on the same idea. From wikipedia, "ndjson" used to include single-line comments with "//" and needed custom parsers for it, but the spec no longer includes it. So now they are the same.
      • yencabulator 1y ago
        ndjson has an actual spec (however bitrotted), everything else in that space makes rookie mistakes like not specifying that a newline is a required message terminator -- consider receiving "13\n42", is that truncated or not? https://github.com/ndjson/ndjson.github.io/issues/1#issuecomment-109935996 https://github.com/ndjson/ndjson.github.io/issues/1#issuecom... None of the above is actually good enough to build on, so a thousand little slightly-different ad hoc protocols bloom. For example, is empty line a keepalive or an error? (This might be perfectly fine. They're trivial to program, not like you need a library.)
• xelxebar 1y ago
  Very cool point, and it applies to any tree data in general. I like to represent tree data with parent, type, and data vectors along with a string table, so everything else is just small integers. Sending the string table and type info as upfront headers, we can follow with a stream of parent and data vector chunks, batched N nodes at a time. Tye depth- or breadth-first streaming becomes a choice of ordering on the vectors. I'm gonna have to play around with this! Might be a general way to get snappier load time UX on network bound applications.
  • x-complexity 1y ago
    ... It might be a pursuit worth making a small library for.
    • deleted 1y ago
      [deleted]
  • thethimble 1y ago
    You can even alternate between sending table and node chunks! This will effectively allow you to reveal the tree in any order including revealing children before parents as well as representing arbitrary graphs! Could lead to some interesting applications.
    • xelxebar 1y ago
      Good point! The parent vector rep is what allows arbitrary node order, but chunking the table data off chunks of node IDs is brilliant idea. Cheers!
  • dmkolobov 1y ago
    If you send the tree in preorder traversal order with known depth, you can send the tree without node ids or parent ids! You can just send the level for each node and recover the tree structure with a stack.
    • xelxebar 1y ago
• aljow 1y ago
  If it has to be mangled to such an extent to do this, then it seems reasonable to assume JSON is the wrong format for the task. Better to rethink it from scratch instead of trying to put a square peg in a round hog.
  • deleted 1y ago
    [deleted]
  • danabramov 1y ago
    I'm being a bit coy about it but the article aims to describe key ideas in the RSC wire protocol, which is an implementation detail of React and isn't actually beholden to JSON itself. JSON is just a nice starting point to motivate it. However, I think reusing JSON for object notation kind of makes sense (and allows native JSON.parse calls for large objects).
• KronisLV 1y ago
  I feel like in an ideal world, this would start in the DB: your query referencing objects and in what order to return them (so not just a bunch of wide rows, nor multiple separate queries) and as the data arrives, the back end could then pass it on to the client.
  • powgpu 1y ago
    Many db has done that, 4d.com is one that comes to mind. It is kinda like socket.io + PostgreSQL + node/ruby/php (middleware layer) all in one. In db there is also concept of cursor, etc. Seems like it is never about merit of technological design. As some CS professor put it, tech is more about fashion than tech now days. IMHO that is true, and often also comes down to the technological context surrounding the industry at the time, and now days if the code is open sourced/FOSS.
  • pigbearpig 1y ago
    That’s not going to make the front page of HN though.
• Velorivox 1y ago
  99.9999%* of apps don't need anything nearly as 'fancy' as this, if resolving breadth-first is critical they can just make multiple calls (which can have very little overhead depending on how you do it). * I made it up - and by extension, the status quo is 'correct'.
  • echelon 1y ago
    We technically didn't need more than 640K either. Having progressive or partial reads would dramatically speed up applications, especially as we move into an era of WASM on the frontend. A proper binary encoded format like protobuf with support for partial reads and well defined streaming behavior for sub message payloads would be incredible. It puts more work on the engineer, but the improvement to UX could be massive.
    • pigbearpig 1y ago
      Sure, if you’re the 0.00001% that need that. It’s going to be over engineering for most cases. There are so many simpler and easier to support things that can be done before trying this sort of thing. Following the example, why is all the data in one giant request? Is the DB query efficient? Is the DB sized correctly? How about some caching? All boring, but if rather support and train someone on boring stuff.
      • deleted 1y ago
        [deleted]
    • willywanker 1y ago
      >We technically didn't need more than 640K either. That old chestnut again - this was true for MSDOS PCs in 1981 when the quote was said. It was still true 10 years later for whatever version of DOS was current then. People keep bringing it up as though Bill Gates said 'no one will need > 640k for all time to come'.
  • danabramov 1y ago
    To be clear, I wouldn't suggest someone to implement this manually in their app. I'm just describing at the high level how the RSC wire protocol works, but narratively I wrapped it in a "from the first principles" invention because it's more fun to read. I don't necessarily try to sell you on using RSC either but I think it's handy to understand how some tools are designed, and sometimes people take ideas from different tools and remix them.
• jimmcslim 1y ago
  I understand the GraphQL has fallen out of favour somewhat, but wasn’t it intended to solve for this?
  • delichon 1y ago
    For serialization GraphQL uses ... JSON. GraphQL could use Progressive JSON to serialize subscriptions.
    • Spivak 1y ago
      I think the point is that GraphQL solves the problem, a client only actually needing a subset of the data, by allowing the client to request only those fields.
  • owebmaster 1y ago
    It can't fall out of favor if it was never really in favor to begin with. GraphQL was a quite brief hype then a big technical debt.
    • tunesmith 1y ago
      So if not graphql, then what's the latest "in-favor" thinking to solve the problem of underfetching and overfetching? Especially in an environment with multiple kinds of frontends?
    • cluckindan 1y ago
      What do you mean by technical debt here?
      • owebmaster 1y ago
        Everywhere I worked with GraphQL it was always a pain for the backend team to keep the graphql server updated and also a pain to use in the frontend, simple REST apis or JSON-RPC are much better.
• roxolotl 1y ago
  This feels very similar to JSON API links[0]. This is a great way to implement handling resolving those links on the frontend though. 0: https://jsonapi.org/format/#document-links https://jsonapi.org/format/#document-links
  • mdaniel 1y ago
    In the recent Web 2.0 2.0 submission <https://news.ycombinator.com/item?id=44073785 https://news.ycombinator.com/item?id=44073785> there was some HATEOAS poo-poo-ing, but maybe this is the delivery mechanism which makes that concept easier to swallow, 'cause JSON
• ChrisMarshallNY 1y ago
  This would be good. I got really, really sick of XML, but one thing that XML parsers have always been good at, is realtime decoding of XML streams. It is infuriating, waiting for a big-ass JSON file to completely download, before proceeding. Also JSON parsers can be memory hogs (but not all of them).
  • hsbauauvhabzb 1y ago
    Json is just a packing format that does have that limitation. If you control the source and the destination, could you possibly use a format that supports streaming better like Protobuf?
    • ChrisMarshallNY 1y ago
      Yes, but that also interferes with portability. I’ve written a lot of APIs. I generally start with CSV, convert that to XML, then convert that to JSON. CSV is extremely limited, and there’s a lot of stuff that can only be expressed in XML or JSON, but starting with CSV usually enforces a “stream-friendly” structure.
    • sopooneo 1y ago
      I've heard two side the the Protobuf/streaming idea. On my first introduction, it seemed you could. But later reading leads me to believe it is only almost streamable: https://belkadan.com/blog/2023/12/Protobuf-Is-Almost-Streamable/ https://belkadan.com/blog/2023/12/Protobuf-Is-Almost-Streama.... * I do acknowledge you qualified the question with "better".
    • zzo38computer 1y ago
      I had invented a variant of DER called DSER (Distinguished Streaming Encoding Rules), which is not compatible with DER (nor with BER) but is intended for when streaming is needed. The type and value are encoded the same as DER, but the length is different: - If it is constructed, the length is omitted, and a single byte with value 0x00 terminates the construction. - If it is primitive, the value is split into segments of lengths not exceeding 255, and each segment is preceded by a single byte 1 to 255 indicating the length of that segment (in bytes); it is then terminated by a single byte with value 0x00. When it is in canonical form, the length of segments other than the last segment must be 255. Protobuf seems to not do this unless you use the deprecated "Groups" feature, and this is only as an alternative of submessages, not for strings. In my opinion, Protobuf also seems to have many other limits and other problems, that DER (and DSER) seems to do better anyways.
• okasaki 1y ago
  Reinventing pagination ?page=3&size=100
• 3cats-in-a-coat 1y ago
  I'll try to explain why this is a solution looking for a problem. Yes, breadth-first is always an option, but JSON is a heterogenous structured data source, so assuming that breadth-first will help the app start rendering faster is often a poor assumption. The app will need a subset of the JSON, but it's not simply the depth-first or breadth-first first chunk of the data set. So for this reason what we do is include URLs in JSON or other API continuation identifiers, to let the caller choose where in the data tree/graph they want to dig in further, and then the "progressiveness" comes from simply spreading your fetch operation over multiple requests. Also often times JSON is deserialized to objects so depth-frst or breadth-first doesn't matter, as the object needs to be "whole" before you can use it. Hence again: multiple requests, smaller objects. In general when you fetch JSON from a server, you don't want it to be so big that you need to EVEN CONSIDER progressive loading. HTML needs progressive loading because a web page can be, historically especially, rather monolithic and large. But that's because a page is (...was) static. Thus you load it as a big lump and you can even cache it as such, and reuse it. It can't intelligently adapt to the user and their needs. But JSON, and by extension the JavaScript loading it, can adapt. So use THAT, and do not over-fetch data. Read only what you need. Also, JSON is often not cacheable as the data source state is always in flux. One more reason not to load a whole lot in big lumps. Now, I have a similar encoding with references, which results in a breadth-first encoding. Almost by accident. I do it for another reason and that is structural sharing, as my data is shaped like a DAG not like a tree, so I need references to encode that. But even though I have breadth-first encoding, I never needed to progressively decode the DAG as this problem should be solved in the API layer, where you can request exactly what you need (or close to it) when you need it.
  • danabramov 1y ago
    >The app will need a subset of the JSON, but it's not simply the depth-first or breadth-first first chunk of the data set. Right. Closer to the end of the article I slightly pivot to talk about RSC. In RSC, the data is the UI, so the outermost data literally corresponds to the outermost UI. That's what makes it work. It's encoded like progressive JSON but conceptually it's more like HTML. Except you can also have your own "tags" on the client that can receive object attributes.
• its-summertime 1y ago
  why send the footer above the comments? Maybe its not a footer then but a sidebar? Should be treated as a sidebar then? Besides this could all kinda be solved by still using plain streaming json and sending .comments last?
  • danabramov 1y ago
    Part of the point I'm making is that an out-of-order format is more efficient because we can send stuff as it's ready (so footer can go as soon as it's ready). It'll still "slot in" the right place in the UI. What this lets us do, compared to traditional top-down streaming, is to progressively reveal inner parts of the UI as more stuff loads.
• goranmoomin 1y ago
  Seems like some people here are taking this post literally, as in the author (Dan Abramov) is proposing a format called Progressive JSON — it is not. This is more of a post on explaining the idea of React Server Components where they represent component trees as javascript objects, and then stream them on the wire with a format similar to the blog post (with similar features, though AFAIK it’s bundler/framework specific). This allows React to have holes (that represent loading states) on the tree to display fallback states on first load, and then only display the loaded component tree afterwards when the server actually can provide the data (which means you can display the fallback spinner and the skeleton much faster, with more fine grained loading). (This comment is probably wrong in various ways if you get pedantic, but I think I got the main idea right.)
  • danabramov 1y ago
    Yup! To be fair, I also don't mind if people take the described ideas and do something else with them. I wanted to describe RSC's take on data serialization without it seeming too React-specific because the ideas are actually more general. I'd love if more ideas I saw in RSC made it to other technologies.
    • tough 1y ago
      hi dan! really interesting post. do you think a new data serialization format built around easier generation/parseability and that also happened to be streamable because its line based like jsonld could be useful for some?
      • danabramov 1y ago
        I don’t know! I think it depends on whether you’re running into any of these problems and have levers to fix them. RSC was specifically designed for that so I was trying to explain its design choices. If you’re building a serializer then I think it’s worth thinking about the format’s characteristics.
        • 1y ago
• bob1029 1y ago
  > We can try to improve this by implementing a streaming JSON parser. In .NET land, Utf8JsonReader is essentially this idea. You can parse up until you have everything you need and then bail on the stream. https://learn.microsoft.com/en-us/dotnet/standard/serialization/system-text-json/use-utf8jsonreader https://learn.microsoft.com/en-us/dotnet/standard/serializat...
• yen223 1y ago
  I've never really thought about how all the common ways we serialise trees in text (JSON, s-expressions, even things like tables of content, etc), serialise them depth-first. I suppose it's because doing it breadth-first means you need to come up with a way to reference items that will arrive many lines later, whereas you don't have that need with depth-first serialisation.
  • NoahZuniga 1y ago
    Also it makes memory allocation easier
• turtlebits 1y ago
  Progressive JPEG make sense, because it's a media file and by nature is large. Text/HTML on the other hand, not so much. Seems like a self-inflicted solution where JS bundles are giant and now we're creating more complexity by streaming it.
  • danabramov 1y ago
    Things can be slow not because they're large but because they take latency to produce or to receive. The latency can be on the server side (some things genuinely take long to query, and might be not possible or easy to cache). Some latency may just be due to the user having poor network conditions. In both cases, there's benefits to progressively revealing content as it becomes available (with intentional loading stages) instead of always waiting for the entire thing.
    • whilenot-dev 1y ago
      Agree with everything you're saying here, but to be fair I think the analogy with Progressive JPEG doesn't sit quite right with your concept. What you're describing sounds more like "semantic-aware streaming" - it's as if a Progressive JPEG would be semantically aware of its blob and load any objects that are in focus first before going after data for things that are out of focus. I think that's a very contemporary problem and worth pursuing, but I also somehow won't see that happening in real-time (with the priority to reduce latency) without necessary metadata.
      • danabramov 1y ago
        It’s not an exact analogy but streaming outside-in (with gradually more and more concrete visual loading states) rather than top-down feels similar to a progressive image to me.
        • whilenot-dev 1y ago
          It's data (JPEG/JSON) VS software (HTML/CSS/JS)... you can choose to look at HTML/CSS/JS as just some chunks of data, or you can look at it as a serialized program that wants to be executed with optimal performance. Your blog post makes it seem like your focus is on the latter (and it's just quite typical for react applications to fetch their content dynamically via JSON), and that's where your analogy to the progressive mode of JPEGs falls a bit flat and "streaming outside-in" doesn't seem like all you want. Progressively loaded JPEGs just apply some type of "selective refinement" to chunks of data, and for Progressive selective refinement to work it's necessary to "specify the location and size of the region of one or more components prior to the scan"[0][1]. If you don't know what size to allocate, then it's quite difficult(?) to optimize the execution. This doesn't seem like the kind of discussion you'd like to have. Performance aware web developers are working with semantic awareness of their content in order to make tweaks to the sites loading time. YouTube might prefer videos (or ads) to be loaded before any comments, news sites might prioritize text over any other media, and a good dashboard might prioritize data visualizations before header and sidebar etc. The position of the nodes in any structured tree tells you very little about the preferred loading priority, wouldn't you agree? [0] https://jpeg.org/jpeg/workplan.html https://jpeg.org/jpeg/workplan.html [1] https://www.itu.int/ITU-T/recommendations/rec.aspx?id=3381 https://www.itu.int/ITU-T/recommendations/rec.aspx?id=3381 (see D.2 in the PDF) EDIT: Btw thanks for your invaluable contributions to react (and redux back then)!
• efitz 1y ago
  What if we like, I don’t know, you know, separate data from formatting?
• jarym 1y ago
  This appears conceptually similar to something like line-delimited JSON with JSON Patch[1]. Personally I prefer that sort of approach - parsing a line of JSON at a time and incrementally updating state feels easier to reason and work with (at least in my mind) [1] https://en.wikipedia.org/wiki/JSON_Patch https://en.wikipedia.org/wiki/JSON_Patch
• slt2021 1y ago
  if you ever feel the need to send progressive JSON - just zip it and don't bother solving fake problem at the wrong abstraction layer
  • aloha2436 1y ago
    The article doesn't advocate sending it progressively to make it smaller on the wire. The motivating example is one where some of the data (e.g. posts) is available before the rest of the data in the response (e.g. comments). Rather than: - Sending a request for posts, then a request for comments, resulting in multiple round trips (a.k.a. a "waterfall"), or, - Sending a request for posts and comments, but having to wait until the commends have loaded to get the posts, ...you can instead get posts and comments available as soon as they're ready, by progressively loading information. The message, though, is that this is something a full-stack web framework should handle for you, hence the revelation at the end of the article about it being a lesson in the motivation behind React's Server Components.
• harrall 1y ago
  I don’t think progressive loading is innovative. What is innovative trying to build a framework that does it for you. Progressive loading is easy, but figuring out which items to progressively load and in which order without asking the developer/user to do much extra config is hard.
  • hobs 1y ago
    That's because its basically cache invalidation.
  • motorest 1y ago
    > Progressive loading is easy, but figuring out which items to progressively load and in which order without asking the developer/user to do much extra config is hard. Do developers even control the order in which stuff is loaded? Tha depends on factors beyond a developer's control, such as the user's network speed, the origin server's response speed, which resources are already cached, how much data each request fetches for user A or user B, etc.
  • danabramov 1y ago
    Right, which is why I describe a framework that does it for you (RSC) at the end of the article. The article itself is meant as an explanation of how RSC works under the hood.
• yawaramin 1y ago
  > I’d like to challenge more tools to adopt progressive streaming of data. It's a solved problem. Use HTTP/2 and keep the connection open. You now have effectively a stream. Get the top-level response: { header: "/posts/1/header", post: "/posts/1/body", footer: "/posts/1/footer" } Now reuse the same connection to request the nested data, which can all have more nested links in them, and so on.
  • aloha2436 1y ago
    > Now reuse the same connection to request the nested data, which can all have more nested links in them, and so on. This still involves multiple round-trips though. The approach laid out in the article lets you request exactly the data you need up-front and the server streams it in as it becomes available, e.g. cached data first, then data from the DB, then data from other services, etc.
    • yawaramin 1y ago
      When you have an HTTP/2 connection already open a 'round-trip' is not really a gigantic concern performance-wise. And it gives the client application complete control and ver what nested parts it wants to get and in what order. Remember that the article said it's up to the server what order to stream the parts? That might not necessarily be a good idea on the client side though. It would probably be better for the client to decide what it wants and when. Eg, it can request the header and footer, then swap in a skeleton facade in the main content area, then load the body and swap it in when loaded.
      • jlokier 1y ago
        Round trips for parallel requests work fine over HTTP/2. (As long as there aren't vast numbers of tiny requests, for example every cell in a spreadsheet). However, sequentially-dependent requests are about as slow with HTTP/2 as HTTP/1.1. For example, if your client side, after loading the page, requests data to fill a form component, and then that data indicates a map location, so your client side requests a map image with pins, and then the pin data has a link to site-of-interest bubble content, and you will be automatically expanding the nearest one, so your client side requests requests the bubble content, and the bubble data has a link to an image, so the client requests the image... Then over HTTP/2 you can either have 1 x round trip time (server knows the request hierarchy all the way up to the page it sends with SSR) or 5 x round trip time (client side only). When round trip times are on the order of 1 second or more (as they often are for me on mobile), >1s versus >5s is a very noticable difference in user experience. With lower latency links of 100ms per RTT, the UX difference between 100ms and 500ms is not a problem but it does feel different. If you're on <10ms RTT, then 5 sequential round trips are hardly noticable, thought it depends more on client-side processing time affecting back-to-back delays.
• aperturecjs 1y ago
  I previously wrote a prototype of streaming a JSON tree this way: https://github.com/rgraphql/rgraphql https://github.com/rgraphql/rgraphql But it was too graphql-coupled and didn't really take off, even for my own projects. But it might be worth revisiting this kind of protocol again someday, it can tag locations within a JSON response and send updates to specific fields (streaming changes).
• Aeolun 1y ago
  I think the problem with this is that it makes a very simple thing a lot harder. I don’t want to try and debug a JSON stream that can fail at any point. I just want to send a block of text (which I generate in 2ms anyway) and call it a day.
  • jlokier 1y ago
    2ms to generate, 1 second for basic text to appear and 20 more seconds to receive the whole page on my phone in the centre of town, due to poor service. Compared with waiting on a blank page for ages, sometimes it's nice to see text content if it's useful, and to be able to click navigation links early. It's much better than pages which look like they have finished loading but important buttons and drop-downs are broken without any visible indication because there's JS still loading in the background. I'm also not fond of pages where you can select options and enter data, and then a few seconds after you've entered data, all the fields reset as background loading completes. All the above are things I've experienced in the last week.
• hyfgfh 1y ago
  The thing I have seem in performance is people trying to shave ms loading a page, while they fetch several mbs and do complex operations in the FE, when in the reality writing a BFF, improving the architecture and leaner APIs would be a more productive solution. We tried to do that with GraphQL, http2,... And arguably failed. Until we can properly evolve web standards we won't be able to fix the main issue. Novel frameworks won't do it either
  • kristianp 1y ago
    What's a BFF in this context? Writing an AI best friend isn't all that rare these days...
    • continuational 1y ago
      BFF (pun intended?) in this context means "backend for frontend". The idea is that every frontend has a dedicated backend with exactly the api that that frontend needs.
      • zelphirkalt 1y ago
        It is a terrible idea organizationally. It puts backend devs at the whims of often hype train and CV driven development of frontend devs. What often happens is, that complexity is moved from the frontend to the backend. But that complexity is not necessarily implicit, but often self inflicted accidental complexity by choices in frontend. The backend API should facilitate getting the required data to render pages and perform required operations to interact with that data. Everything else is optimization that one may or may not need.
  • xiphias2 1y ago
    At least this post explains why when I load a Facebook page the only thing that really matters (the content) is what loads last
    • globalise83 1y ago
• jatins 1y ago
  I have seen Dan's "2 computers" talk and read some of his recent posts trying to explore RSC and their benefits. Dan is one of the best explainers in React ecosystem but IMO if one has to work this hard to sell/explain a tech there's 2 possibilities 1/ there is no real need of tech 2/ it's a flawed abstraction #2 seems somewhat true because most frontend devs I know still don't "get" RSC. Vercel has been aggressively pushing this on users and most of the adoption of RSC is due to Nextjs emerging as the default React framework. Even among Nextjs users most devs don't really seem to understand the boundaries of server components and are cargo culting That coupled with fact that React wouldn't even merge the PR that mentions Vite as a way to create React apps makes me wonder if the whole push for RSC is for really meant for users/devs or just as a way for vendors to push their hosting platforms. If you could just ship an SPA from S3 fronted with a CDN clearly that's not great for Vercels and Netflifys of the world. In hindsight Vercel just hiring a lot of OG React team members was a way to control the future of React and not just a talent play
  • kenanfyi 1y ago
    I find your analysis very good and agree on why companies like Vercel are pushing hard on RSC.
    • foo42 1y ago
      [flagged]
      • tomhow 1y ago
        Please don't do this here. If a comment seems unfit for HN, please flag it and email us at hn@ycombinator.com so we can have a look.
      • kenanfyi 1y ago
        Sorry, what? Is it just my phrasing or my rant on VC-backed entities pushing things to gain advantage?
  • Garlef 1y ago
• tills13 1y ago
  Holy the pomp in this thread. It would perhaps help for some people here to have the context that this isn't some random person on the internet but Dan Abromov -- probably one of the most influential figures in building React (if not one of the creators, iirc)
  • kolme 1y ago
    He got famous because of "redux" and "hot module reload" and then he got hired by Meta and started working on react. This was before the hook era.
  • yard2010 1y ago
    Dan is hands down THE best captain to steer this ship - he manages to push react forward even though it changed a lot (and faced many growth pains and challenges) in the last few years. He is doing it in his own special way - he is kind, thoughtful, patient and visionary. He is the best kind of master teacher there is - although he has many many years of experience, he understands exactly what newbies don't understand. That's inspiring. Read a few of his many comments in any React issue and see what I mean. We are truly gifted. Dan you are my idol!
  • timeflex 1y ago
    You're free to say thank you but acting like everyone else here should is weird. There are a lot of good points.
• sriku 1y ago
  Would a stream where each entry is a list of kv-pairs work just as well? The parser is then expected to apply the kv pairs to the single json object as it is receiving them. The key would describe a json path in the tree - like 'a.b[3].c'.
• dejj 1y ago
  Reminds me of Aftertext, which uses backward references to apply markup to earlier parts of the data. Think about how this could be done recursively, and how scoping could work to avoid spaghetti markup. Aftertext: https://breckyunits.com/aftertext.html https://breckyunits.com/aftertext.html
• philippta 1y ago
  This sounds suspiciously similar to CSV.
• anonzzzies 1y ago
  So is there a library / npm to do this? Even his not good cases example; just making partial JSON to parse all the time. I don't care if it's just the top and missing things, as long as it always parses as legal json.
• tarasglek 1y ago
  People put so much effort into streaming Json parsing whereas we have a format called Yaml which takes up less characters on the wire and happens to work incrementally out of the box meaning that you can reparse the stream as it's coming in without having to actually do any incremental parsing
  • motorest 1y ago
    > People put so much effort into streaming Json parsing whereas we have a format called (...) There are many formats out there. If payload size is a concern, everyone is far better off enabling HTTP response compression instead of onboarding a flavor-of-the-month language.
  • croes 1y ago
    YAML is more complex and harder to parse
  • rk06 1y ago
    Yaml makes json appear user friendly by comparison. Last thing one want in a wire format is white space sensitivity and ambiguous syntax. Besides, if you are really transferring that much json data, there are ways to achieve it that solves the issues
  • filoeleven 1y ago
    If we're talking about niche data protocols, edn is hard to beat. Real dates and timestamps and comments, namespaced symbols, tagged elements, oh my! https://github.com/edn-format/edn https://github.com/edn-format/edn
• Existenceblinks 1y ago
  It's useless as data is not just some graphic semantic, they have relation, business rules on top, not ready to interact with if not all are ready, loaded.
  • danabramov 1y ago
    It’s definitely not useless. You’re right that it requires the interpreting layer to be able to handle missing info. The use case at the end of the article is streaming UI. UI, unlike arbitrary data, is actually self-describing — and we have meaningful semantics for incomplete UI (show the closest loading state placeholder). That’s what makes it work, as the article explains in the last section.
    • Existenceblinks 1y ago
      Thanks Dan. Yes, I agreed on the ui part, it seems to work in most cases. Some html tags have relation like `<datalist>` or `[popover]` attribute, but if we make all kind of relations trivial then it's benefit for sure.
      • danabramov 1y ago
        Yea, and also to clarify by "UI", I don't necessarily mean HTML — it could be your own React components and their props. In idiomatic React, you generally don't have these kinds of "global" relations between things anyway. (They could appear inside components but then presumably they'd be bound by matching IDs.)
• metalrain 1y ago
  It feels like this idea needs Cap'n'Proto style request inlining so client can choose what parts to stream instead of getting everything asynchronously. https://capnproto.org/ https://capnproto.org/
• inglor 1y ago
  I am not sure the wheel can be rediscovered many more times but definitely check out Kris's work from around 2010-2012 around q-connection and streaming/rpc of chunks of data. Promises themselves have roots in this and there are better formats for this. Check our mark miller's E stuff and thesis - this stuff goes all the way back to the 80s.
  • inglor 1y ago
    @dang - I hit "reply" once (I am sure of that) and I see my (identical) comment twice in the UI. Not sure what sort of logging/tracing/instrumentation you have in place - I am not delete'ing this so you have a chance to investigate but if that's not useful by all means feel free to do so.
• inglor 1y ago
  I am not sure the wheel can be rediscovered many more times but definitely check out Kris's work from around 2010-2012 around q-connection and streaming/rpc of chunks of data. Promises themselves have roots in this and there are better formats for this. Check our mark miller's E stuff and thesis - this stuff goes all the way back to the 80s.
  • inglor 1y ago
    Not to disrespect Dan here, each discovery is impressive on its own but I wish we had a better way to preserve this sort of knowledge.
    • vanderZwan 1y ago
      > I wish we had a better way to preserve this sort of knowledge. It's called "being part of the curriculum" and apparently the general insights involved aren't, so far.
• camgunz 1y ago
  I don't mean to be dismissive, but haven't we solved this by using different endpoints? There's so many virtues: you avoid head of line blocking; you can implement better filtering (eg "sort comments by most popular"); you can do live updates; you can iterate on the performance of individual objects (caching, etc). --- I broadly see this as the fallout of using a document system as an application platform. Everything wants to treat a page like a doc, but applications don't usually work that way, so lots of code and infra gets built to massage the one into the other.
  • danabramov 1y ago
    Sort of! I have two (admittedly long) articles on this topic, comparing how the code tends to evolve with separate endpoints and what the downsides are: - https://overreacted.io/one-roundtrip-per-navigation/ https://overreacted.io/one-roundtrip-per-navigation/ - https://overreacted.io/jsx-over-the-wire/ https://overreacted.io/jsx-over-the-wire/ The tldr is that endpoints are not very fluid — they kind of become a "public" API contract between two sides. As they proliferate and your code gets more modular, it's easy to hurt performance because it's easy to introduce server/client waterfalls at each endpoint. Coalescing the decisions on the server as a single pass solves that problem and also makes the boundaries much more fluid.
    • camgunz 1y ago
      Oh I see. Maybe a way to restate this is "how do I communicate the costs of data to the client", that is the cost of returning top-level user data is let's just say 1; the cost of returning the last 10 comments is 2, and the cost of returning older comments is 2000. Because otherwise pushing that set of decisions back to the server doesn't exactly solve it, it just means you now actually can make that decision server side, even though you're still waiting a long time on comment 11 no matter what. Re your "JSX Over The Wire" post, I think we've gone totally around the bend. A piece of code that takes 0 or more responses from a data backend and returns some kind of HTML is a web service. Like, that's CGI, that's PHP, that's Rails, Node, Django, whatever. If the argument here is "the browser should have some kind of state tracking/reactivity built in, and until that day we have a shim like jQuery or the old school thin React or the new school htmx" then OK, but this is so, so much engineering to elide `onclick` et al. --- I kind of worry that we've spent way, way too much time in these weeds. There's millions and millions of lines of React out there, and certainly the majority of it is "stitch the responses of these N API calls together into a view/document, maybe poll them for updates from time to time", to the degree that AI just does it now. If it's so predictable that a couple of video cards can do it in a few seconds, why have we spent gazillions of engineering years polishing this?
• techpression 1y ago
  Reading this makes me even happier I decided on Phoenix LiveView a while back. React has become a behemoth requiring vendor specific hosting (if you want the bells and whistles) and even a compiler to overcome all the legacy. Most of the time nobody needs this, make sure your database indexes are correct and don’t use some under powered serverless runtime to execute your code and you’ll handle more load than most people realize. If you’re Facebook scale you have unique problems, most of us doesn’t.
  • gavinray 1y ago
    > React has become a behemoth requiring vendor specific hosting This is one of the silliest things I've read in a while. React is sub-3kB minified + gzip'ed [0], and the grand majority of React apps I've deployed are served as static assets from a fileserver. My blog runs off of Github Pages, for instance. People will always find a way to invent problems for themselves, but this is a silly example. [0] https://bundlephobia.com/package/react@19.1.0 https://bundlephobia.com/package/react@19.1.0
    • owebmaster 1y ago
      > This is one of the silliest things I've read in a while. You know that the author of this post is the creator of React and that he's been pushing for RSC/Vercel relentlessly, right? btw reactdom is ~30kb gzipped so React minimal bundle is around 35kb
      • whilenot-dev 1y ago
        Dan Abramov isn't "the creator of React", he just became an evangelist for react ever since he got to the team at Facebook through his work on redux. He is pushing for RSC (as that's where react's future seems to be), but what makes you think he's pushing for Vercel?
      • gavinray 1y ago
        If you really want to bikeshed over size, you can use Preact which is a genuine 3kB full drop-in for React.
• PetahNZ 1y ago
  Reminds me of Oboe.js https://oboejs.com/ https://oboejs.com/
• atombender 1y ago
  You could stream incrementally like this without explicitly demarcating the "holes". You can simply send the unfinished JSON (with empty arrays as the holes), then compute the next iteration and send a delta, then compute the next and send a delta, and so on. A good delta format is Mendoza [1] (full disclosure: I work at Sanity where we developed this), which has Go and JS/TypeScript [2] implementations. It expresses diffs and patches as very compact operations. Another way is to use binary digging. For example, zstd has some nifty built-in support for diffing where you can use the previous version as a dictionary and then produce a diff that can be applied to that version, although we found Mendoza to often be as small as zstd. This approach also requires treating the JSON as bytes and keeping the previous binary snapshot in memory for the next delta, whereas a Mendoza patch can be applied to a JavaScript value, so you only need the deserialized data. This scheme would force you to compare the new version for what's changed rather than plug in exactly what's changed, but I believe React already needs to do that? Also, I suppose the Mendoza applier could be extended to return a list of keys that were affected by a patch application. [1] https://github.com/sanity-io/mendoza https://github.com/sanity-io/mendoza [2] https://github.com/sanity-io/mendoza-js https://github.com/sanity-io/mendoza-js
  • __mattya 1y ago
    They want to know where the holes are so that they can show a loading state.
    • atombender 1y ago
      You don't need templating ($1 etc.) for that as long as you can describe the holes somehow, which can be done out-of-band. If we imagine a streaming protocol of key/value pairs that are either snapshots or deltas: event: snapshot data: {"topPost":[], "user": {"comments": []}} pending: topPosts,user.comments event: delta data: [17,{"comments":[{"body":"hello world"}]},"user"] pending: topPosts
  • andrewingram 1y ago
    For the use case of streaming data for UI, I don’t think empty arrays and nulls are sufficient information. At any moment during the stream, you need the ability to tell what data is pending. If pending arrays are just returned as empty arrays, how do I know if it’s empty because it’s actually empty, or empty because it’s pending? GraphQL’s streaming payloads try to get the best of both worlds, at any point in time you have a valid payload according the GraphQL schema - so it’s possible to render some valid UI, but it also communicates what paths contain pending data, and then subsequent payloads act as patches (though not as sophisticated as Mendoza’s).
• pjungwir 1y ago
  Does this scheme give a way to progressively load slices of an array? What I want is something like this: ["foo", "bar", "$1"] And then we can consume this by resolving the Promise for $1 and splatting it into the array (sort of). The Promise might resolve to this: ["baz", "gar", "$2"] And so on. And then a higher level is just iterating the array, and doesn't have to think about the promise. Like a Python generator or Ruby enumerator. I see that Javascript does have async generators, so I guess you'd be using that. The "sort of" is that you can stream the array contents without literally splatting. The caller doesn't have to reify the whole array, but they could. EDIT: To this not-really-a-proposal I propose adding a new spread syntax, ["foo", "bar", "...$1"]. Then your progressive JSON layer can just deal with it. That would be awesome.
  • danabramov 1y ago
    From what I understand of the RSC protocol which the post is based on (might be wrong since I haven't looked closely at this part), this is supported: https://github.com/facebook/react/pull/28847 https://github.com/facebook/react/pull/28847. >The format is a leading row that indicates which type of stream it is. Then a new row with the same ID is emitted for every chunk. Followed by either an error or close row.
• izger 1y ago
  Interesting idea. Another way to implement the same without breaking json protocol framing is just sent {progressive: "true"} {a:"value"} {b:"value b"} {c: {d}c:"value b"} .. {progressive: "false"} and have { progressive: "false", a:"value", b:"value b", .. } on top of that add some flavor of message_id, message_no (some other on your taste) and you will have a protocol to consistently update multiple objects at a time.
• jerf 1y ago
  There are at least two other alternatives I'd reach for before this. Probably the simplest one is to refactor the JSON to not be one large object. A lot of "one large objects" have the form {"something": "some small data", "something_else": "some other small data", results: [vast quantities of identically-structured objects]}. In this case you can refactor this to use JSON lines. You send the "small data" header bits as a single object. Ideally this incorporates a count of how many other objects are coming, if you can know that. Then you send each of the vast quantity of identically-structed objects as one-line each. Each of them may have to be parsed in one shot but many times each individual one is below the size of a single packet, at which point streamed parsing is of dubious helpfulness anyhow. This can also be applied recursively if the objects are then themselves large, though that starts to break the simplicity of the scheme down. The other thing you can consider is guaranteeing order of attributes going out. JSON attributes are unordered, and it's important to understand that when no guarantees are made you don't have them, but nothing stops you from specifying an API in which you, the server, guarantee that the keys will be in some order useful for progressive parsing. (I would always shy away from specifying incoming parameter order from clients, though.) In the case of the above, you can guarantee that the big array of results comes at the end, so a progressive parser can be used and you will guarantee that all the "header"-type values come out before the "body". Of course, in the case of a truly large pile of structured data, this won't work. I'm not pitching this as The Solution To All Problems. It's just a couple of tools you can use to solve what is probably the most common case of very large JSON documents. And both of these are a lot simpler than any promise-based approach.
• defraudbah 1y ago
  nah, I got enough with TCP
• 65 1y ago
  Here's a random, crazy idea: What if instead of streaming JSON, we streamed CSV line by line? That'd theoretically make it way easier to figure out what byte to stream from and then parse the CSV data into something usable... like a Javascript object.
• geokon 1y ago
  This is outside my realm of experience, isn't this kind part of the utility of a triple-store? Isn't that the canonical way to flatten trees data to a streamable sequence? I think you'd also need to have some priority mechanism for which order to send your triple store entries (so you get the same "breadth first" effect) .. and correctly handle missing entries.. but that's the data structure that comes to mind to build off of
• jongjong 1y ago
  This is an interesting idea. I solved this problem in a different way by loading each resource/JSON individually, using foreign keys to link them on the front end. This can add latency/delays with deeply nested child resources but it was not a problem for any of the use cases I came across (pages/screens rarely display parent/child resources connected by more than 3 hops; and if they do, they almost never need them to be loaded all at once). But anyway this is a different custom framework which follows the principle of resource atomicity and a totally different direction than GraphQL approach which follows the principle of aggregating all the data into a big nested JSON. The big JSON approach is convenient but it's not optimized for this kind of lazy loading flexibility. IMO, resource atomicity is a superior philosophy. Field-level atomicity is a great way to avoid conflicts when supporting real-time updates. Unfortunately nobody has shown any interest or is even aware of its existence as an alternative. We are yet to figure out that maybe the real issue with REST is that it's not granular enough (should be field granularity, not whole resource)... Everyone knows HTTP has heavy header overheads, hence you can't load fields individually (there would be too many heavy HTTP requests)... This is not a limitation for WebSockets however... But still, people are clutching onto HTTP; a transfer protocol originally designed for hypertext content, as their data transport.
• rictic 1y ago
  If you've got some client side code and want to parse and render JSON progressively, try out jsonriver: https://github.com/rictic/jsonriver https://github.com/rictic/jsonriver Very simple API, takes a stream of string chunks and returns a stream of increasingly complete values. Helpful for parsing large JSON, and JSON being emitted by LLMs. Extensively tested and performance optimized. Guaranteed that the final value emitted is identical to passing the entire string through JSON.parse.
  • jumploops 1y ago
    What’s the benefit of `jsonriver` over one of the myriad of “best effort” parsers[0][1][2] in a try/catch loop while streaming? [0]https://github.com/beenotung/best-effort-json-parser https://github.com/beenotung/best-effort-json-parser [1]https://github.com/unjs/destr https://github.com/unjs/destr [2]https://www.npmjs.com/package/json-parse-even-better-errors https://www.npmjs.com/package/json-parse-even-better-errors
    • rictic 1y ago
      Good question. jsonriver is well optimized, exhaustively tested (tens of thousands of test cases), and provides a number of potentially useful invariants[0] about its parsing. jsonriver's performance comes primarily from simplicity, and doing as little work per character as we can. Repeatedly reparsing from scratch on the other hand gets expensive quick, your parse time is quadratic in the length of the string to parse. [0] https://github.com/rictic/jsonriver?tab=readme-ov-file#invariants https://github.com/rictic/jsonriver?tab=readme-ov-file#invar...
      • jumploops 1y ago
        I've been looking for a better solution for awhile now (if you couldn't tell), and will definitely try out jsonriver for our use-case. Thanks!
• jto1218 1y ago
  typically if we need to lazy load parts of the data model we make multiple calls to the backend for those pieces. And our redux state has indicators for loading/loaded so we can show placeholders. Is the idea that that kind of setup is inefficient?
• fdoifdois 1y ago
  [flagged]
• nesarkvechnep 1y ago
  In my opinion, REST, proper, hypertext driven, solves the same problems. When you have small, interlinked, cacheable resources, the client decides how many relations to follow.
• yencabulator 1y ago
  SvelteKit has something like this to facilitate loading data where some of the values are Promises. I don't think the format is documented for external consumption, but it basically does this: placeholders for values where the JSON value at that point is still loading, replaced by streaming the results as they complete. https://svelte.dev/docs/kit/load#Streaming-with-promises https://svelte.dev/docs/kit/load#Streaming-with-promises
• bilater 1y ago
  This is something I've been thinking about ever since I saw BAML. Progressive streaming for JSON should absolutely be a first class thing in Javascript-land. I wonder if Gemini Diffusion (and that class of models) really popularize this concept as the tokens streamed in won't be from top to bottom. Then we can have a skeleton response that checks these chunks, updates those value and sends them to the UI.
• aaronvg 1y ago
  You might also find Semantic Streaming interesting. It's t he same concept but applied to llm token streaming. It's used in BAML (the ai framework). https://www.boundaryml.com/blog/semantic-streaming https://www.boundaryml.com/blog/semantic-streaming I'm one of the developers of BAML.
• creatonez 1y ago
  This HN thread is fascinating. A third of the commenters here only read 1/3 of the article, another third read 2/3 of the article, and another third actually read the whole article. It's almost like the people in this thread linearly loaded the article and stopped at random points. Please, don't be the next clueless fool with a "what about X" or "this is completely useless" response that is irrelevant to the point of the article and doesn't bother to cover the use case being proposed here.
• EugeneOZ 1y ago
  Just don't resurrect HATEOAS monster, please.
• 1vuio0pswjnm7 1y ago
  "Because the format is JSON, you're not going to have a valid object tree until the last byte loads. You have to wait for the entire thing to load, then call JSON.parse, and then process it. I have a filter I wrote that just reformats JSON into line-delimited text that can be processed immediately by line-oriented UNIX utilities. No waiting. "The client can't do anything with JSON until the server sends the last byte." "Would you call [JSON] good engineering?" I would not call it "engineering". I would call it design. IMO, djb's netstrings^1 is better design. It inspired similar designs such as bencode.^2 1. https://cr.yp.to/proto/netstrings.txt https://cr.yp.to/proto/netstrings.txt (1997) 2. https://wiki.theory.org/BitTorrentSpecification https://wiki.theory.org/BitTorrentSpecification (2001) "And yet [JSON's] the status quo-that's how 99.9999%^* of apps send and process JSON." Perhaps "good" does not necessarily correlate with status quo and popularity. Also, it is worth considering that JSON was created for certain popular www browsers. It could piggyback on the popularity of that software.
• alganet 1y ago
  This breaks JSON. Now we need a different JSON that escapes the $ sign, and it is incompatible with other JSON parsers. Also, not a single note about error handling? There is already a common practice around streaming JSON content. One JSON document per line. This also breaks JSON (removal of newline whitespace), but the resulting documents are backwards compatible (a JSON parser can read them). Here's a simpler protocol: Upon connecting, the first line sent by the server is a JavaScript function that accepts 2 nullable parameters (a, b) followed by two new lines. All the remaining lines are complete JSON documents, one per line. The consuming end should read the JavaScript function followed by two new lines and execute it once passing a=null, b=null. If that succeeds, it stores the return value and moves to the next line. Upon reading a complete JSON, it executes the function passing a=previousReturn, b=newDocument. Do this for every line consumed. The server can indicate the end of a stream by sending an extra new line after a document. It can reuse the socket (send another function, indicating new streamed content). Any line that is not a JavaScript function, JSON document or empty is considered an error. When one is found by the consuming end, it should read at most 1024 bytes from the server socket and close the connection. -- TL;DR just send one JSON per line and agree on a reduce function between the producer and consumer of objects.
• usrbinbash 1y ago
  Or here is a different approach: We acknowledge that streaming data is not a problem that JSON was intended, or designed, to solve, and ... not do that. If an application has a usecase that necessitates sending truly gigantic JSON objects across the wire, to the point where such a scheme seems like a good idea, the much better question to ask is "why is my application sending ginormeous JSON objects again?" And the answer is usually this: Fat clients using bloated libraries and ignoring REST, trying to shoehorn JSON into a "one size fits all" solution, sending first data, then data + metadata, then data + metadata + metadata describing the interface, because finally we came full circle and re-invented a really really bad version of REST that requires several MB of minified JS for the browser to use. Again, the solution is not to change JSON, the solution is to not do the thing that causes the problem. Most pages don't need a giant SPA framework.
• K0IN 1y ago
  For me this seems over complicated, or am i missing something? Any benefits using this over jsonl + json patch?
• tacone 1y ago
  I don't really like the use of comments to mark variables, an ad-hoc syntax would be probably a better idea.
• sillyboi 1y ago
  Honestly, this approach feels like it adds a lot of unnecessary complexity. It introduces a custom serialization structure that can easily lead to subtle UI bugs and a nightmare of component state tracking. The author seems to be solving two issues at once: large payloads and stream-structured delivery. But the latter only really arises because of the former. For small to medium JSON responses, this won't improve performance meaningfully. It’s hard to imagine this being faster or more reliable than simply redesigning the backend to separate out the heavy parts (like article bodies or large comment trees) and fetch them independently. Or better yet, just use a proper streaming response (like chunked HTTP or GraphQL @defer/@stream). In practice, trying to progressively hydrate JSON this way may solve a niche problem while creating broader engineering headaches.
• rabiescow 1y ago
  I think the main issue with this goes against the fundamental vore principles of a json object has no internal order. If it was an ordered object it would be very different and maybe feasible. But you would have to change the complete standard if JSON. It makes no sense speaking of an object without order as if it has order in terms of "header" etc...
• jsnelgro 1y ago
  I feel like this is a great practical example showcasing the value of static types and designing your data model up front. If you know the structure of the object, you can put in placeholders while the real thing loads in. Then you get to choose how it loads in. Ideally you can stream the patches via serialized actions. This is basically Redux/Elm in a nutshell where the action objects can come from events sent via SSE/websockets/polling/etc. Reducing a change log is about as stateless, functional, and elegant as it gets. I love these sorts of designs but reality seems to complicate them in unexpected ways unfortunately. Still worth striving for though!
• OrangeMusic 1y ago
  GraphQL has a defer mode that looks like this. You receive the fast pieces first, and the slower pieces of the json come later, with the path to where they should be attached to.
• methods21 1y ago
  Bring back XML or a better format than both, or at least a DTD for JSON.