I have deeply mixed feelings about #ActivityPub's adoption of JSON-LD, as someone who's spent way too long dealing with it while building #Fedify.
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@hongminhee take this part with a grain of salt because my benchmarks for it are with dotNetRdf which is the slowest C# implementation i know of (hence my replacement library), but JSON-LD is slower than RSA validation, which is one of the pain points around authorized fetch scalability
wetdry.world/@kopper/114678924693500011@kopper @hongminhee I'm glad I'm not the only one who noticed this.
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@hongminhee take this part with a grain of salt because my benchmarks for it are with dotNetRdf which is the slowest C# implementation i know of (hence my replacement library), but JSON-LD is slower than RSA validation, which is one of the pain points around authorized fetch scalability
wetdry.world/@kopper/114678924693500011@hongminhee if i can give one piece of advice to devs who want to process JSON-LD: dont bother compacting. you already know the schema you output (or you're just passing through what the user gives and it doesn't matter to you), serialize directly to the compacted representation, and only run expansion on incoming data
expansion is the cheapest JSON-LD operation (since all other operations depend on it and run it internally anyhow), and this will get you all the compatibility benefits of JSON-LD with little downsides (beyond more annoying deserialization code, as you have to map the expanded representation to your internal structure which will likely be modeled after the compacted one) -
@julian I don't know as much as I'd like about AT Lexicons. That is, not so much how they work, but what the grand idea is? I don't even understand if Bluesky imagines them being mixed and matched JSON-LD style. I think not?
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@silverpill @mariusor @hongminhee Fetching from the origin _is_ signature verification. It's just done by the TLS implementation rather than by the ActivityPub implementation.
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@hongminhee@hollo.social I'll give you my take on this... which is that my understanding of JSON-LD is that with JSON-LD you can have two disparate apps using the same property, like
thread, and avoid namespace collision because one is actuallyhttps://example.org/ns/threadand the other's reallyhttps://foobar.com/ns/thread.Great.
I posit that this is a premature optimization, and one that fails because of inadequate adoption. There are likely documented cases of implementations using the same property, and those concern the actual ActivityStreams vocabulary, and the solution to that is to communicate and work together so that you don't step on each others' toes.
I personally feel that it is a technical solution to a problem that can be completely handled by simply talking to one another... but we're coders, we're famously anti-social yes? mmmmm...
Manu, maker of JSON-LD who also helped with the AP Confs, made this nice video https://www.youtube.com/watch?v=vioCbTo3C-4
JSON-LD is a normative reference to ActivityPub. The context of AP is only 1 line, maybe 4 if you support the official extensions. It does not make anything much larger.
It is for example important if you want to consume the federated wikipedia, wikidata, European Broadcasting Union or these Public Broadcasters https://www.publicmediaalliance.org/public-broadcasters-create-public-spaces-incubator/ but also to know that e.g. mobilizon uses schema.org for addresses.
I give you an example, if you include
"mz": "https://joinmobilizon.org/ns#", "wd": "https://www.wikidata.org/wiki/Special:EntityData/",
"wdt": "https://www.wikidata.org/prop/direct/"in your context, then you know about mobilizon extension but also the whole common knowledge of the world …
I like that, now you can support the whole vocabulary of wikipedia and wikidata which is just JSON-LD.
You get it in all the languages of the world including the properties name.
No problem, if others don't support it, but sad for users. -
Manu, maker of JSON-LD who also helped with the AP Confs, made this nice video https://www.youtube.com/watch?v=vioCbTo3C-4
JSON-LD is a normative reference to ActivityPub. The context of AP is only 1 line, maybe 4 if you support the official extensions. It does not make anything much larger.
It is for example important if you want to consume the federated wikipedia, wikidata, European Broadcasting Union or these Public Broadcasters https://www.publicmediaalliance.org/public-broadcasters-create-public-spaces-incubator/ but also to know that e.g. mobilizon uses schema.org for addresses.
I give you an example, if you include
"mz": "https://joinmobilizon.org/ns#", "wd": "https://www.wikidata.org/wiki/Special:EntityData/",
"wdt": "https://www.wikidata.org/prop/direct/"in your context, then you know about mobilizon extension but also the whole common knowledge of the world …
I like that, now you can support the whole vocabulary of wikipedia and wikidata which is just JSON-LD.
You get it in all the languages of the world including the properties name.
No problem, if others don't support it, but sad for users.PS, I am using the official JSON-LD processor of Manu and contributors, if support in any language is lacking, we just speak to the JSON-LD Group (glad about the 2 webintents coming together now as well ) …
Cause we are social … -
@hongminhee if i can give one piece of advice to devs who want to process JSON-LD: dont bother compacting. you already know the schema you output (or you're just passing through what the user gives and it doesn't matter to you), serialize directly to the compacted representation, and only run expansion on incoming data
expansion is the cheapest JSON-LD operation (since all other operations depend on it and run it internally anyhow), and this will get you all the compatibility benefits of JSON-LD with little downsides (beyond more annoying deserialization code, as you have to map the expanded representation to your internal structure which will likely be modeled after the compacted one)@kopper@not-brain.d.on-t.work @hongminhee@hollo.social expansion is actually really annoying because the resulting JSON has annoyingly similar keys to lookup in a hashmap, wasting cache lines, and CPU time
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reposting so @julian sees this
"I noticed that your inbox endpoint returns 404s (my activities are delivered to personal inbox, not shared)." says @silverpill
@liaizon@social.wake.st actually, oddly, I did receive @silverpill@mitra.social's response, so it seems to be I can access some replies from Mitra, but not all.
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@kopper@not-brain.d.on-t.work @hongminhee@hollo.social expansion is actually really annoying because the resulting JSON has annoyingly similar keys to lookup in a hashmap, wasting cache lines, and CPU time
@natty @hongminhee i would imagine a Good hash algorithm wouldn't care about the similarity of the keys, no? -
@hongminhee take this part with a grain of salt because my benchmarks for it are with dotNetRdf which is the slowest C# implementation i know of (hence my replacement library), but JSON-LD is slower than RSA validation, which is one of the pain points around authorized fetch scalability
wetdry.world/@kopper/114678924693500011@hongminhee i put this in a quote but people reading the thread may also be interested: json-ld compaction does not really save that much bandwidth over having all the namespaces explicitly written in property names if you're gzipping (and you are gzipping, right? this is json. make sure your nginx gzip_types includes ld+json and activity+json)
RE: not-brain.d.on-t.work/notes/aihftmbjpxdyb9k7 -
@evan@cosocial.ca I don't remember exactly, but I think I came across it while doing research before developing Fedify. I probably didn't use it because the TypeScript type definitions were missing. In the end, I ended up making something similar in Fedify anyway.
@hongminhee that's great!
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@hongminhee from the point of view of someone who is "maintaining" a JSON-LD processing fedi software and has implemented their own JSON-LD processing library (which is, to my knowledge, the fastest in it's programming language), JSON-LD is pure overhead. there is nothing it allows for that can't be done with
1. making fields which take multiple values explicit
2. always using namespaces and letting HTTP compression take care of minimizing the transfer
without JSON-LD, fedi software could use zero-ish-copy deserialization for a majority of their objects (when strings aren't escaped) through tools like serde_json and Cow<str>, or System.Text.Json.JsonDocument. JSON-LD processing effectively mandates a JSON node DOM (in the algorithms standardized, you may be able to get rid of it with Clever Programming)
additionally, due to JSON-LD 1.1 features like @type:@json, you can not even fetch contexts ahead of time of running JSON DOM transformations, meaning all JSON-LD code has to be async (in the languages which has the concept), potentially losing out on significant optimizations that can't be done in coroutines due to various reasons (e.g. C# async methods can't have ref structs, Rust async functions usually require thread safety due to tokio's prevalence, even if they're ran in a single-threaded runtime)
this is after context processing introducing network dependency to the deserialization of data, wasting time and data on non-server cases (e.g. activitypub C2S). sure you can cache individual contexts, but then the context can change underneath you, desynchronizing your cached context and, in the worst case, opening you up to security vulnerabilities
json-ld is not my favorite part of this protocolhm, we really need to differentiate between users responsibility and dev responsibility.
Not sure if Hong saw the draft about the AP kv thing, it supports either JSON-LD fields _or_ as:attachment / as:context …
wtf do I want to say.user story:
We are working on 2 major and 3 projects fulltime which is
- federation of wikibase / wikidata
- federation of Public Broadcasters https://www.publicmediaalliance.org/public-broadcasters-create-public-spaces-incubator/
and these https://codeberg.org/Menschys/fedi-codebaseLet's say we want to federate a Country, then all the knowledge is sent in `attachment` with the fully qualified qikidata url in `context` [as:context - not @context ! - this is so confusing :)]
For example the according entries from the PressFreedomIndex `collection` (co-founder of freelens here
But anyway, the idea about having
"wd": "https://www.wikidata.org/wiki/Special:EntityData/",
"wdt": "https://www.wikidata.org/prop/direct/" in the `@context` was that any user can consume and federate wikibase
incl.
🧵 1/2 -
hm, we really need to differentiate between users responsibility and dev responsibility.
Not sure if Hong saw the draft about the AP kv thing, it supports either JSON-LD fields _or_ as:attachment / as:context …
wtf do I want to say.user story:
We are working on 2 major and 3 projects fulltime which is
- federation of wikibase / wikidata
- federation of Public Broadcasters https://www.publicmediaalliance.org/public-broadcasters-create-public-spaces-incubator/
and these https://codeberg.org/Menschys/fedi-codebaseLet's say we want to federate a Country, then all the knowledge is sent in `attachment` with the fully qualified qikidata url in `context` [as:context - not @context ! - this is so confusing :)]
For example the according entries from the PressFreedomIndex `collection` (co-founder of freelens hereBut anyway, the idea about having
"wd": "https://www.wikidata.org/wiki/Special:EntityData/",
"wdt": "https://www.wikidata.org/prop/direct/" in the `@context` was that any user can consume and federate wikibase
incl.
🧵 1/2incl.
- the properties in all the languages of the world
- the knowledge of the world in all the languages
- the wikidata relations and qualified statements including the nameMap etc. and all the urls to all wikiprojects incl. their languages and knowledgeHow else could I say to other softwares if they want all users qualified data, use wikidata vocabulary?
wikipedia, wikidata, EBU, Public Broadcasters, taxi data is _all_ JSON-LD … -
incl.
- the properties in all the languages of the world
- the knowledge of the world in all the languages
- the wikidata relations and qualified statements including the nameMap etc. and all the urls to all wikiprojects incl. their languages and knowledgeHow else could I say to other softwares if they want all users qualified data, use wikidata vocabulary?
wikipedia, wikidata, EBU, Public Broadcasters, taxi data is _all_ JSON-LD …@sl007 @hongminhee @julian i feel like you're falling into a trap i've seen a lot around AP spaces: just because the data can be contorted to represent something does not mean software will interpret it as such.
any software who wants to support wikidata statements and relations will have to go out of their way to implement that manually with or without json-ld in the mix, and interoperability between those software will have to specify how that works. and in your specification you can indeed make it so Simply Linking to the wikidata json-ld (which i don't believe it provides out of the box, it does for xml, turtle, and n-triples, if we're talking about rdf. if not, their bespoke json format is just as authoritative) can work (but i'd say using the Qxxx and Pxx IDs and letting the software figure out how to access it would be better!)
if you have the dream of making an as:Note and having it's as:attributedTo be the wikidata entity for alan turing... sorry, nobody other than maybe your own software will even attempt interpreting that -
@sl007 @hongminhee @julian i feel like you're falling into a trap i've seen a lot around AP spaces: just because the data can be contorted to represent something does not mean software will interpret it as such.
any software who wants to support wikidata statements and relations will have to go out of their way to implement that manually with or without json-ld in the mix, and interoperability between those software will have to specify how that works. and in your specification you can indeed make it so Simply Linking to the wikidata json-ld (which i don't believe it provides out of the box, it does for xml, turtle, and n-triples, if we're talking about rdf. if not, their bespoke json format is just as authoritative) can work (but i'd say using the Qxxx and Pxx IDs and letting the software figure out how to access it would be better!)
if you have the dream of making an as:Note and having it's as:attributedTo be the wikidata entity for alan turing... sorry, nobody other than maybe your own software will even attempt interpreting that@hongminhee @sl007 @julian attempting to support this kind of "data contortion" (i made this up and prolly isnt the right way to describe this) would rapidly balloon the scope of every fedi software ever. i don't believe anyone would want to develop for such ecosystem
a similar example i saw was someone attempting to explain how you can partially inline an as:object you as:Like'd in order to specify you only liked that past version of it and if it changed your like shouldn't count. without describing this exact scenario i don't believe any software, json-ld capable or not, would interpret that Like as such. same thing with the long-form text FEP which attempts to support non-activitypub authors -
@sl007 @hongminhee @julian i feel like you're falling into a trap i've seen a lot around AP spaces: just because the data can be contorted to represent something does not mean software will interpret it as such.
any software who wants to support wikidata statements and relations will have to go out of their way to implement that manually with or without json-ld in the mix, and interoperability between those software will have to specify how that works. and in your specification you can indeed make it so Simply Linking to the wikidata json-ld (which i don't believe it provides out of the box, it does for xml, turtle, and n-triples, if we're talking about rdf. if not, their bespoke json format is just as authoritative) can work (but i'd say using the Qxxx and Pxx IDs and letting the software figure out how to access it would be better!)
if you have the dream of making an as:Note and having it's as:attributedTo be the wikidata entity for alan turing... sorry, nobody other than maybe your own software will even attempt interpreting thatah, no - that is a misunderstanding!
Anyone can feel free to represent the texts only and the user at least "knows" it.
But the thing for Public Broadcasters means 47mio. users in DE alone and given the unified codebase for the 5 projects _these_ softwares will interpret it.
It does JSON-LD you could just check by asking for any JSON-LD e.g. Q1055 (Hamburg) - it is content-negotiation.
The taxiteam software is funded by the German yellow cabs - the official ones (!) the codename is FCKUBR
and I have no doubt about adoption fortunately.Maybe we can work out better examples …
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@hongminhee @sl007 @julian attempting to support this kind of "data contortion" (i made this up and prolly isnt the right way to describe this) would rapidly balloon the scope of every fedi software ever. i don't believe anyone would want to develop for such ecosystem
a similar example i saw was someone attempting to explain how you can partially inline an as:object you as:Like'd in order to specify you only liked that past version of it and if it changed your like shouldn't count. without describing this exact scenario i don't believe any software, json-ld capable or not, would interpret that Like as such. same thing with the long-form text FEP which attempts to support non-activitypub authorsit is just damned simple, your as: Client can do so much by asking wikidata, OSM, federated geocoding and not our system. When you use a property for the first time, the client can cache its names in the languages of the user etc.
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it is just damned simple, your as: Client can do so much by asking wikidata, OSM, federated geocoding and not our system. When you use a property for the first time, the client can cache its names in the languages of the user etc.
@sl007 @hongminhee @julian i genuinely can't see where json-ld is relevant here. if your client wants to support wikidata and OSM then it can do that with or without json-ld being involved. you are going to have to document how this integration works anyhow if you want anyone else to do so -
@hongminhee @sl007 @julian attempting to support this kind of "data contortion" (i made this up and prolly isnt the right way to describe this) would rapidly balloon the scope of every fedi software ever. i don't believe anyone would want to develop for such ecosystem
a similar example i saw was someone attempting to explain how you can partially inline an as:object you as:Like'd in order to specify you only liked that past version of it and if it changed your like shouldn't count. without describing this exact scenario i don't believe any software, json-ld capable or not, would interpret that Like as such. same thing with the long-form text FEP which attempts to support non-activitypub authorsjust btw, we had many W3C Social CG meetings about the importance and how to use the as:context property - not the JSON-LD @context and we all agreed.
About 30-40 devs attended.
Between 2016 and 2024 I attended basically any meeting. I felt that using wikidata urls in as:context was nice for anyone. -
@sl007 @hongminhee @julian i genuinely can't see where json-ld is relevant here. if your client wants to support wikidata and OSM then it can do that with or without json-ld being involved. you are going to have to document how this integration works anyhow if you want anyone else to do so
if I see wd: in lets say 3 of 12 AP software, I know tha I can give the user wikibase support.
