Comment by TheAceOfHearts | Hacker News Reader

Comment by TheAceOfHearts | Hacker News Reader

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Try leading with an explanation of why developers should care about JSON-LD. Its value is not obvious to me.

According to the Wikipedia article [0] this is used by Google Knowledge Graph, but there's no other examples. Are there open source RDF processors? What are they used for?

Previously I've used json-schema for documenting, validating, and testing a REST API. The tooling wasn't very good, but it worked alright. As I understand it, JSON-LD wouldn't help at all with this.

The fact that JSON-LD is a W3C standard while json-schema isn't doesn't constitute an argument against it. Standards regularly show up and die without ever gaining adoption. Maybe instead of a vacuous remark on JSON-LD offering more than json-schema with respect to linked data you could actually muster some concrete example which highlight these alleged benefits?

I'm not an expert on this subject, but isn't it worrying that third-party links can change or go down without notice? Ideally if I'm hosting a context I'll want to replicate my whole dependency graph and provide a mirror in order to reduce dependencies on external systems. However, just because I want to host my own mirror doesn't mean I want it to be treated as a different kind of entity. It seems like something such as content-addressable storage [1] could be relevant here.

[0] https://en.wikipedia.org/wiki/JSON-LD

[1] https://en.wikipedia.org/wiki/Content-addressable_storage

The main benefit in my eyes is data integration. If you have multiple systems with data, and you want to merge the data together into a unified whole for some reason then RDF/JSON-LD make it easy and mostly automatic.

For example: 1. How do you distinguish IDs from one system with those of another? RDF solves this. 2. How do you distinguish property names across systems? RDF solves this. 3. What if a entity originates in system A which you don’t control but you want to add a property to it in your system? RDF solves this.

JSON-LD is simply one way to serialize RDF data that makes look like what you would typically expect from an API that returns JSON. I.e. it’s developer friendly

In addition to the above, RDF is also an extraordinarily flexible/schemaless data model if you store your data as triples rather than as documents. There is definitely a steep learning curve to linked data, and I’ve had a hard time explaining it’s value over the years, but I think it’s worth the time to learn, understand, and leverage.

All of these benefits exist before you get into things like ontologies, which allows you to add additional value on top of what I outlined above.

Outstanding explanation. I would like to emphasize one point:

> If you have multiple systems with data, and you want to merge the data together into a unified whole for some reason

This isn’t just about “big data” or “data warehousing” or such OLAPy concerns. It’s really about the bread and butter of modern information systems.

“Get some ID from service A, use it to query service B.” Does that sound familiar? That’s data integration for you. That’s what RDF / Linked Data is about.

ActivityPub [1], (Mastodon [2]), also use JSON-LD.

1 - https://www.w3.org/TR/activitypub

2 - https://joinmastodon.org

Here: https://json-ld.org/

JSON-LD is JSON for Linking Data.

When you're passing semantic web data around or maybe storing it temporarily in a text file (rather than in a triple-store) one of the formats you can use is JSON-LD. So that covers when you use it; the next question is why you use it over one of the other interchange or at rest formats. And generally the answer to that is that you're using Javascript as your language and you hate XML :)

Anyway, less facetiously here is the blurb from the website!

“Linked Data empowers people that publish and use information on the Web. It is a way to create a network of standards-based, machine-readable data across Web sites. It allows an application to start at one piece of Linked Data, and follow embedded links to other pieces of Linked Data that are hosted on different sites across the Web.”

“JSON-LD is a lightweight Linked Data format. It is easy for humans to read and write. It is based on the already successful JSON format and provides a way to help JSON data interoperate at Web-scale. JSON-LD is an ideal data format for programming environments, REST Web services, and unstructured databases such as CouchDB and MongoDB.”

> why developers should care about JSON-LD. Its value is not obvious to me.

This is at a lower level of abstraction, but... I care simply because it's Google's preferred encoding for web publishers to communicate metadata to them:

https://developers.google.com/search/docs/guides/intro-struc...

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