A Technical View on the Solid Ecosystem

Solid: a decentralized Web ecosystem

• Decouples data from application

• Personal data pods → control

• Collection of open Web standards

Solid combines several Web standards

• Linked Data Platform

  Reading and Writing over HTTP

• WebID-OIDC

  Authentication

• Web Access Control

  Authorization

• Linked Data Notifications

  Sending and receiving notifications

Reading and writing over HTTP

Linked Data Platform (LDP)

• Pods can store RDF and non-RDF files

  JSON-LD, Turtle, HTML+RDFa, ...
  Binary data, raw text, ...

• Read and write via HTTP methods and content-negotiation

  GET, POST, PUT, PATCH, DELETE
  PATCH: SPARQL update queries

• Directories represented by LDP Basic Containers

  Enables Linked-Data-based directory content discovery

Users are in control of their own identity

WebID-OpenID Connect (WebID-OIDC)

• WebID: a dereferenceable RDF Web resource

  https://rubensworks.solid.community/profile/card#me
  Profile contains basic information: name, image, ...

• Identity provider authenticates WebID

  WebID points to an identity provider server (!= pod server)
  → Different identity providers exist

Logging in to a Solid app

Select an identity provider

Logging in to a Solid app

Logging in at the selected identity provider

Fine-grained access control to data

Web Access Control (WAC)

• Each file has a corresponding Access Control List (ACL) file

  Describes who (WebID) has access to the resource, and the modes of access.

• Different modes of access

  Read, write, append, control

WAC: https://alice.inrupt.net/file1.acl

@prefix  acl:    .

<#authorization1>
    a             acl:Authorization;
    acl:agent     <https://alice.inrupt.net/profile/card#me>;
    acl:accessTo  <https://alice.inrupt.net/file1>;
    acl:mode      acl:Read, 
                  acl:Write, 
                  acl:Control.
        

• file1.acl defines access for file1.
• Alice has Read, Write and Control rights.

Sending notifications across pods

Linked Data Notifications (LDN)

• Senders can send notifications to the inbox of consumers

  For apps that require interaction between different users

Other standards

• WebSockets

  API for real-time resource notifications

• WebID-TLS

  Authentication using TLS certificates

Tools and services for Solid

• Node Solid Server

  File-system-based Solid server in JavaScript

• Solid Auth Client

  Library to perform authenticated requests to Solid pods

• Solid React SDK

  Components for developing Solid apps in React

• inrupt.net Node Solid Server instance

  A free pod service

Summary

• Solid aims to re-decentralize the Web

  Decouples data from applications

• Solid is not a tool, but an ecosystem

  A collection of open Web standards (LDP, WebID-OIDC, WAC, LDN, ...)

• Tools and libraries implement these standards

  Node Solid Server, Solid React SDK, ...

Backup Slides

Solid server API is relatively simple

→ Client-side Solid apps must be smart

• Hypermedia-based apps

  Discover files in containers, links to relevant files, ...
  Reusable libraries exist: SPARQL, GraphQL, ...

• Queries as abstraction layer

  Allows apps to be query-driven
  Reusable client-side query engines handle complexities
  SPARQL, GraphQL, LDflex, ...

Node Solid Server hosts file-based pods

Open source: https://github.com/solid/node-solid-server

• Reference implementation of Solid

  Implements LDP, WAC, WebID-OIDC, ... specifications

• Single-user or many-user mode

  Host a personal data pod, or service for hosting many data pods

• Optionally hosts WebIDs

  For people without a WebID, a new WebID can be created next to your pod

Auth Client for authenticated requests

Open source: https://github.com/solid/solid-auth-client

• JavaScript library for logging into Solid apps

  Implements the WebID-OIDC protocol for clients

• solid.auth.fetch enables authenticated HTTP(S) requests

  solid.auth.fetch has the same interface as fetch

• if (!await solid.auth.currentSession())
    await solid.auth.popupLogin({ popupUri });
  await fetch('https://timbl.com/timbl/Public/friends.ttl');

Solid React SDK for developing Solid apps

SDK overview: https://github.com/inrupt/solid-react-sdk

• Solid React Application Generator

  Generates a basic Solid app with basic files and dependencies

• Solid React Components Library

  Reusable React components for Solid applications
  login forms, private routes, uploaders, ShEx forms
  GraphQL-based components

• Under active development

  WIP: I18N, user preferences, Linked Data Notifications, data discovery, ...

inrupt.net for easily creating a Solid pod

• Public Node Solid Server instance

  Everyone can register for a pod and WebID

• Storage quota of 25MB

  To avoid abuse of this public service