Building a decentralized Semantic Web

Ruben Verborgh, Ghent Universityimec

Linked Data in Architecture and Construction Week, Lisbon, Portugal,

Building a decentralized Semantic Web

Ruben Verborgh

Ghent University – imec

To computers,
the hard is easy
and the easy is hard.

paraphrased from Moravec’s Paradox

[Cover of Scientific American, May 2001]
©2001 Scientific American

Mom needs to see a specialist
and then has to have a series
of physical therapy sessions.
Biweekly or something.
I’m going to have my agent
set up the appointments.

Berners-Lee, Hendler, and Lassila
The Semantic Web, 2001

What is the easy?

What is the hard?

Are we tackling
the right problems?

Are we tackling
the problems right?

Building a decentralized Semantic Web

Building a decentralized Semantic Web

Despite our strong focus on identity,
we struggle to find our own.

Exactly how much semantics
is enough semantics?

A little semantics
goes a long way.

Jim Hendler

Exactly how much semantics
is too much semantics?

Ontologies are like underwear.

Everyone agrees they’re a good idea,
but few people like to reuse someone else’s.


Domain models are only as valuable as
the scope of the underlying consensus.

Core frameworks such as RDF and OWL
are perceived as complex by developers. fills the void for
a more pragmatic audience.

There is a mismatch between ontologies
in theory and in practice.

Building a decentralized Semantic Web

If semantics do no truly set us apart,
then maybe it is the Web.

“Web” is our main argument in
justifications for RDF’s complexity.

So why are we so afraid then
to take our work to the Web?

What is the external validity
of our controlled experiments?

Are we solving all the problems
we should be solving?

The Semantic Web research community
might have a habit of handwaving.

The Web is a good platform for data publication,
but a pretty bad platform for data consumption.

Frank van Harmelen

Building a decentralized Semantic Web

When looking for an identity
it helps to know who you are.

We are totally doing Big Data.
We are totally doing blockchain.
We are totally doing AI.

And I agree on that last point (just not necessarily ML).

The Semantic Web teenage years
have perhaps been a bit confusing.

Perhaps Linked Data is actually
more challenging than Big Data.

Big Data is finite,
no matter how big it gets.

Building a decentralized Semantic Web

The Web strives to be universal
through independence of many factors.

©2008 Lucélia Ribeiro

The Web brings freedom of expression
to everyone across the world.

©2012 Luke McKernan

People started their own blogs and sites,
sharing things on their own terms.

©2012 Gregor Fischer

A generation of social platforms
helped people interact and share.

The Web brings permissionless innovation
at a global scale.

©2012 SparkFun Electronics

Permissionless innovation has brought
unprecedented creativity to the world.

Building a decentralized Semantic Web

Like other systems at the time,
the Web was designed decentrally.

Its novelty was universality.

The first threat to universality
were the browser wars.

[Internet Explorer logo]

This battle was replaced by another:
the search engine wars.

[Google logo]

This battle was also replaced by another:
the platform wars.

[Facebook logo]

Building a decentralized Semantic Web

Our data has become centralized
in a handful of Web platforms.

Within the walled gardens of social media,
you have to move either data or people.

© David Simonds

The current massive centralization
hurts diversity, innovation, and choice.

Ironically, permissionless innovation
even allows platforms that prevent it.

The Facebook founder has no intention of
allowing anyone to build anything on his platform
that does not have his express approval.

Having profited mightily from the Web’s openness,
he has kicked away the ladder that elevated him
to his current eminence.

John Naughton, The Guardian
[photo of a ladder]
© Vinayak Shankar Rao

Building a decentralized Semantic Web

Solid aims to restore choice.

The Solid ecosystem enables people to pick the apps they need, while
storing their data wherever they want.

People control their data, and share it
with the apps and people they choose.

People choose where they store
every single piece of data they produce.

They can grant apps and people access
to very specific parts of their data.

Separating app and storage competition
drives permissionless innovation.

Building a decentralized Semantic Web

Solid is not a company or organisation.
Solid is not (just) software.

[the Solid logo]

The Solid server acts as a data pod
that stores and guards your data.

A typical data pod can contain
any data you create or need online.

Solid clients are browser or native apps
that read from or write to your data pod.

Any app you can envision,
you can build with Solid.

The Solid server and several apps exist
and are usable for developers.

Building a decentralized Semantic Web

Decentralized apps have many back-ends. Back-ends work with many apps.

Interoperability challenges in Solid
are solved through Linked Data in RDF.

With JSON-LD, every piece of data
can link to any other piece of data.

  "@context":  "",
  "id":        "#ruben-likes-ldac2019",
  "type":      "Like",
  "actor":     "",
  "object":    "",
  "published": "2019-04-25T08:00:00Z"

Data shapes and their semantics
enable layered compatibility.

  "@context":  "",
  "id":        "#ruben-likes-ldac2019",
  "type":      "Like",
  "actor":     "",
  "object":    "",
  "published": "2019-06-19T08:00:00Z"

Different source data
can be concatenated.

  "@context":  "",
  "@graph": [{
    "type":      "Like",
    "actor":     "",
    "object":    "",
    "published": "2019-06-19T08:00:00Z"
    "type":      "Like",
    "actor":     "",
    "object":    "",
    "published": "2019-06-19T08:05:00Z"

The developer experience is the most
crucial factor for Solid success.

Simple tasks should be simple,
complex tasks should be manageable.

People think RDF is a pain
because it is complicated.
The truth is even worse.

RDF is painfully simplistic,
but it allows you to work with real-world data
and problems that are horribly complicated.

Dan Brickley & Libby Miller

Building a decentralized Semantic Web

The best way to predict
the future is to invent it.

Alan Kay
[photo of Alan Kay]
©2008 jeanbaptisteparis

The best way to invent
the future is to predict it.

John Perry Barlow
[photo of John Perry Barlow]
©2007 Joi Ito

Building a decentralized Semantic Web