Episode: 3015
Title: HPR3015: ActivityPub Conference 2019 - The Semantic Social Network
Source: https://hub.hackerpublicradio.org/ccdn.php?filename=/eps/hpr3015/hpr3015.mp3
Transcribed: 2025-10-24 15:10:31

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This is Hacker Public Radio Episode 3,015 for Friday 21 February 2020.
Today's show is entitled, Activity Pub Conference 2019, The Semantic Social Network,
and is part of the series' social media. It is hosted by Ahuka
and is about seven minutes long
and carries a clean flag. The summer is
Activity Pub Conference 2019, building a semantic social network.
This episode of HPR is brought to you by archive.org.
Support universal access to all knowledge
by heading over to archive.org forward slash donate.
Music
Hello, this is Ahuka.
Welcome to Hacker Public Radio and another exciting episode.
Continuing our look at the Activity Pub Conference 2019.
The talk I want to take a look at this time is by someone named
Puka Mustard. You can get a link to the video in the show notes.
His talk is called The Semantic Social Network.
Now, if you have been around the web for any length of time,
you may have heard the semantic web.
Something that the W3C has been talking about.
And when we talk about that, it's all about, you know,
how do you identify and deal with data in various ways.
So the idea of a semantic network is that various kinds of data are linked.
The model that this person uses has subjects linked to objects via predicates.
Okay. Well, yeah, nouns and verbs.
There can be multiple objects for any subject or multiple subjects for any object.
And any subject can be an object of any other subject.
Now, by linking, we can do interesting queries of data.
As an example, consider a search for vegetarian restaurants in Brussels.
Brussels could be the subject and take as an object restaurants.
And of course, there could be other objects for Brussels like museums.
And one object of that might be the Brussels Tram Museum.
Now, if everything is properly linked, you can do queries like,
are there any vegetarian restaurants near the Tram Museum in Brussels?
Now, so far, this is just basic search.
And when a single entity controls the data like Google, it's not too difficult to manage.
But what when it's a network of independent sites?
Now, you have to start thinking about how things will be named and labeled.
What if one site labels what we want as a restaurant?
And another says, it's a cafe.
To avoid problems, you need a naming convention.
Now, if you identify subjects and objects using URIs,
the ambiguity disappears since everyone has a single unique URI.
But then you need to add a name field to make it useful to humans.
Think about it. URIs are wonderful.
But in reality, what they are is something like
147.23.44.101.
And we don't work with stuff like that.
That's why we have name servers.
So, you know, how do you move back and forth between URIs
and something that people can deal with?
Now, a good place to begin is at schema.org, link in the show notes,
where you can find the data to start to essentially do XML on everything.
You know, looking there at restaurants, I see it includes the property,
serves cuisine, which is a text field.
You could use this to put in vegetarian as your text,
and that takes care of one thing.
Another field that's available there is one called area served,
which lets you identify where it is and so on.
It does not look like there is a direct link to nearby museums,
but if each museum was an object with a similar geographic identifier,
you can see how it would link things.
If you use URIs to name the properties, which you can do through schema.org,
you are pretty close to the resource description framework or RDF,
which is the W3C standard model for data interchange
and part of the semantic web project.
So, see how that all ties back in.
Now, where activity pub enters this picture is when you have an agreed structure
for identifying data.
As an example, suppose Alice and Bob are on two different servers.
Bob makes a post, and Alice likes it.
Then Clarissa on yet a third server sees that Alice liked Bob's post.
The idea of federated media is that you should be able to link to any remote content
in an understandable way.
Of course, this could go beyond activity pub,
since it's the agreed framework that matters.
And in essence, that is what the W3C is trying to establish
with the resource description framework, i.e. RDF, and the semantic web project.
But because activity pub is a shared protocol, it makes it very easy to get there.
That's why the speaker on this talk makes this definition.
The Fediverse is a distributed graph of interlinked content created by social interactions.
And that's a fascinating description.
And that's why he says this is, in fact, the semantic social network.
And that's why he says that interlinked content.
Now, this in turn means activity pub content can be seen as documents or as graphs.
A graph can be traversed and queried in interesting ways.
There's no limit to the kind of data that can be created in a crowdsourced manner.
Open data sets are publicly available.
As an example, see the five star open data plan from Tim Berners-Lee, W3C guy.
And there's a whole semantic web community with tools, research, standards.
Now, towards the end of this, there was some discussion about the use of JSON-LD.
And that's JavaScript object notation for linked data.
And from the discussion, I got the impression that somehow using JSON-LD is controversial.
I have to admit, I don't get what the dispute is about.
But if you know all about that and you want to do a show, by all means do so.
But right now, that's quite enough for me.
This is Huka for Hacker Public Radio, signing off and saying, support free software.
Bye-bye.
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