ISOC: W3C Standards in the Internet Ecosystem

About this article:
►Purpose: to present a high-level overview and introduction of the W3C open standards as part of the Internet Ecosystem.
►Audience: to academics and technology researchers.
►Keywords: Internet Society (ISOC), Internet Ecosystem, Open Standards Everywhere (OSE), the World Wide Web Consortium (W3C), architecture, technology stack, the Web, Extensible Markup Language (XML), Web Services, Web of Things (WoT), Semantic Web, Linked Data, Knowledge Graphs.
►Structure:
— The Internet Ecosystem and Open Standards.
— The W3C Standards.
— The Web Architecture.
— The XML Standards Family.
— The Web of Services Technology Stack.
— The Web of Things Architecture.
— The Semantic Web Technology Stack.
— Conclusions.
►Note: (the richness of the content is found in all the links).

The Internet Ecosystem and Open Standards

Following its vision of “The Internet is for everyone”, the Internet Society (ISOC) promotes the evolution and growth of the global Internet. At its core, it supports and promotes the Internet’s development as a global technical infrastructure, based on an open, transparent, and collaborative model.

ISOC’s Internet Ecosystem diagram presents the Open Standards Development (OSD) as the main technical component and engineering-heavy-oriented axis. Under the OSD umbrella, technologists, engineers, architects, creatives, and organisations, help coordinate and implement open standards. Two notorious organisations that are essential to the OSD activities are:

• The Internet Engineering Task Force (IETF): a large, open, international community of network designers, operators, vendors, and researchers concerned with the evolution of the Internet architecture and the smooth operation of the Internet.
• The World Wide Web Consortium (W3C): an international consortium where Member organisations, a full-time staff, and the public, work together to develop World Wide Web (Web) standards.

In a nutshell — with a bit of abstraction — , whilst IETF standards, a.k.a Request for Comments (RFC), focus on the “Internet infrastructure and architecture” (computer network protocol technologies), the W3C standards focus on the “Internet suprastructure: an information space” (information processing technologies). Figure 1 shows where the W3C sits as part of the Standards Bodies in the ISOC’s Internet Ecosystem.

Fig. 1 The World Wide Web Consortium as part of the Standards Bodies in the Internet Ecosystem.

Currently, ISOC’s Open Standards Everywhere (OSE) initiative focuses mainly on Web server administration, emphasising the latest standards developed by IETF. The current OSE documentation repo on GitHub presents specific guidelines and recommendations for configuring Web servers, IPv6, DNSSEC, TLS, and HTTP/2.

Below, this article presents a high-level overview of the main open standards and technology stacks that the W3C has developed. The purpose is to complement the current ISOC’s OSE documentation repo on GitHub with a “panoramic view” of the W3C standards, which are an essential cornerstone in the Internet Ecosystem.

The W3C Standards

Led by the Web inventor, Sir Tim Berners-Lee, the W3C mission is to “lead the World Wide Web to its full potential” by developing protocols and guidelines that ensure the long-term growth of the Web, in order to further W3C’s vision of One Web. These protocols and guidelines are being developed following the Modern Standards Paradigm — Five Key Principles, known as the Open Standards Principles, which are also followed by ISOC and IETF.

The W3C develops and publishes the Web Standards as “Recommendations” that define an Open Web Platform (OWP) for application development. In a nutshell, they are technical specifications, protocols, and guidelines through a process designed to maximise consensus about the content, to ensure high technical and editorial quality.

Figure 2 presents a high-level depiction of the main W3C Standards ecosystem. The intention of the figure is not to be academically correct but to highlight the major technology stacks and architectures that the W3C has (and continues to) developed. And, of course, technology-wise there are some overlaps between the components.

Fig. 2 The W3C Standards Ecosystem

The Web Architecture

Web Architecture focuses on the foundation technologies and principles which sustain the Web (read Tim’s high-level overview here). Core design principles include simplicity, modularity, decentralisation, orthogonal specifications, extensibility, and tolerance.

The Architecture of the World Wide Web, Volume One defines the Web as an “information space in which the items of interest, referred to as resources, are identified by global identifiers”. The three architectural bases of the Web, along with the core concepts that introduce/use each of them, are:

• Identification: Uniform Resource Identifiers (URIs) and Internationalised Resource Identifiers (IRIs).
• Interaction: Web agents, protocols (HyperText Transfer Protocol — HTTP, XML-based protocols — see below), The Representational State Transfer (REST) architectural style, Architectural Principles of the Internet.
• (Meta) Formats: REST, MIME Types (part 1 and part 2), HyperText Markup Language (HTML), Cascading Style Sheets (CSS), Document Object Model (DOM), XML-based formats (see below), RDF (see below), JSON.

From the original conception of the Web in 1989, the Web technology ecosystem has exploded in complexity to address various aspects regarding modeling, exchanging, processing, and rendering information over this distributed hypertext space. To have a glimpse of this complexity, the following figure presents the place where HTML sits in the Web platform specification stack relative to other specs.

Fig. 3 HTML in the Web platform spec stack (Source: the HTML spec)

The XML Standards Family

The Extensible Markup Language (XML) provides a simple standardised way to serialise (text-based) information through a flexible markup vocabulary model for representing structured information, used for human-authored documents as well as for machine-to-machine data transfer. XML was developed as an application profile (or restricted form) of the Standard Generalized Markup Language (SGML), ISO 8879:1986, designed to ease the parser implementation and primarily for use on the Web. XML has become the defacto standard and lingua franca for document processing on the Web.

Fig. 4 The origins of XML (Source: Bachelor’s XML Thesis (Spanish))

The XML ecosystem has evolved to become a group of comprehensive technologies: the XML standards family. Some of these standards that comprise the core components of the group are:

1. XML 1.0, XML 1.1.
2. XML Namespaces (XMLNS): XMLNS 1.0, XMLNS 1.1.
3. xml:id and XML Base.
4. XML Information Set (XML Infoset).
5. XML Schema Definition Language (XSD): Part 0 — Primer, Part 1 — Structures, Part 2 — Datatypes.
6. Extensible Stylesheet Language (XSL): Associating Stylesheets with XML, XSL Transformations (XSLT), XSL Formatting Objects (XSL-FO).
7. XML Path Language (XPath) and XML Query Language (XQuery). XQuery and XPath have joint specs such as Data Model and Functions and Operators, which are also core to XSLT.
8. XML Linking (XLL): XML Linking Language (XLink), XML Pointer Language (XPointer) → XPointer is a working draft that was superseded by multiple Recommendations.

Fig. 5 Conceptual look of the core subset of the XML Standards Family (Source: Bachelor’s XML Thesis (Spanish))

Other important components are:

• XML Inclusions (XInclude).
• XML Fragment Interchange (Candidate Recommendation).
• XML Forms (XForms).
• XML Events.
• XML Pipeline Language (XProc) and XProc 2.0 — Working Group Note.

The Web of Services Technology Stack

Web of Services refers to message-based component automation and API (Application Programming Interface) design and deployment frequently found on the Web and in enterprise software. The W3C defined a Web Service as the following:

• “A software system designed to support interoperable machine-to-machine interaction over a network”.
• “It has an interface described in a machine-processable format (specifically WSDL)”.
• “Other systems interact with the Web service in a manner prescribed by its description using SOAP messages, typically conveyed using HTTP with an XML serialization in conjunction with other Web-related standards”.

The Web Services Architecture (WSA) document identifies and defines the functional components along with their relationships in four distinct models: message-oriented model, service-oriented model, resource-oriented model, and policy model.

The following figure presents the WSA’s illustration of the general process of engaging a Web service, which depicts the main concepts, components/agents, and data flow of the architecture.

Fig. 6 The General Process of Engaging a Web Service (Source: the WSA spec)

Based on the aforementioned concepts and models, the WSA proceeds to depict the technology families involved in a layered and interrelated structure as shown below.

Fig. 7 The Web Services Architecture Stack (Source: the WSA spec)

The Web of Services is based on the following critical technologies:

1. HTTP (from the Web Architecture view).
2. XML (from the XML Standards Family view): XML, XML Namespaces, XML Infoset, XML Schema.
3. Simple Object Access Protocol (SOAP): Part 0 — Primer, Part 1 — Messaging Framework, Part 2 — Adjuncts.
4. Web Services Description Language (WSDL): Part 0 — Primer, Part 1 — Core Language, Part 2 — Adjuncts.
5. Other sets of related technologies developed (along with) by other standardisation bodies such as the Organization for the Advancement of Structured Information Standards (OASIS) → the WS-* technology stack: WS-Addressing, WS-Interoperability — UDDI (Universal Description, Discovery, and Integration), WS-Inspection, WS-Enumeration, WS-Eventing, WS-Transfer, WS-ResourceTransfer, WS-MetadataExchange, WS-Security, WS-SecureConversation, WS-Federation, WS-Authorization, WS-Policy, WS-Trust, WS-Privacy, WS-Test, etc.

The Web of Things Architecture

The Web of Things (WoT) is intended to enable interoperability across IoT (Internet of Things) platforms and application domains. Overall, the goal of the WoT is to preserve and complement existing IoT standards and solutions. The WoT Architecture (WoTA) specification describes the abstract architecture and conceptual framework for the W3C Web of Things: main concepts (such as consumer, thing, thing description, property, action, event, and servient) and their relations/interactions in different perspectives and models.

Fig. 8 The Web of Things Architecture (Source: the WoT Architecture spec)

W3C WoT enables applications to interact with and orchestrate connected Things at Web scale. The WoT Building Blocks provide a way to implement systems that conform with WoTA. These blocks are:

1. WoT Thing Description (TD): a royalty-free, open information model with a JSON-based representation format for IoT.
2. WoT Binding Templates, a Working Group Note that describes how to enable a TD to be adapted to the specific protocol or data payload usage across different standards, through an additional descriptive vocabulary that is used in TD.
3. WoT Scripting API, a Working Group Note that describes an API representing the WoT Interface that allows scripts to discover, operate Things and to expose locally defined Things characterized by WoT Interactions specified by a script. A WoT Interface models network interactions as Properties, Actions, and Events.
4. WoT Security and Privacy Guidelines, a Working Group Note that provides general guidance on WoT security and privacy using a threat model. It provides guidelines for the secure implementation and configuration of Things.

The Semantic Web Technology Stack

In addition to the classic Web of documents (HTTP, URIs, HTML, etc.), the W3C is building a technology stack to support a Web of data, based on a semantic data model structured as a directed graph. The ultimate goal of the Web of data is to make Internet data machine-readable, that is, to enable computers to do more useful work and to develop systems that can support trusted interactions over the network. The term “Semantic Web” (SW) — a.k.a. Web 3.0 — refers to W3C’s vision (Fig. 9) of the Web of Linked Data.

Fig. 9 Tim Berners-Lee’s vision of the Semantic Web Architecture (Source: “Semantic Web — XML 2000”)

The SW technology stack (Fig. 10) enables to:

1. create data stores on the Web,
2. build vocabularies (or ontologies),
3. access/retrieve/query data,
4. write rules for handling and processing data,
5. discover new data relationships (inference).

Fig. 10 The Semantic Web technology stack (Source: “Semantic Web Architecture” [wiki][src])

Linked data are empowered by the SW technology stack:

1. Resource Description Framework (RDF): a framework for representing and linking information about resources in a direct graph form (core construct: a subject → predicate → object triple). The core RDF specs are the core concepts and abstract syntax and the precise semantics (formal model-theoric semantics). Some related technologies that allow embedding data in documents or make any data set available as RDF files are GRDDL and POWDER.
2. RDF Schemas (RDFS): allows standardised description of taxonomies and basic ontological constructs by defining the notion of classes and properties. It provides a data modeling vocabulary for RDF data by extending the basic RDF vocabulary.
3. OWL2 Web Ontology Language (OWL2): an ontology language for the SW with formally defined meaning derived from Description Logic that offers more advanced ontological constructs over RDFS. OWL2 ontologies provide classes, properties, individuals, annotations, data values, and restrictions, stored as SW documents. The OWL2 Documentation Roadmap presents the specs list of this standard. It includes 5 core specs (such as Structural Specification and Functional-Style Syntax, Direct Semantics, and RDF-Based Semantics), 4 specs (such as Profiles and XML Serialisation), and 4 documents for users.
4. SPARQL Protocol and RDF Query Language (SPARQL): a SQL-like language for RDF-triple matching (query) and retrieval (protocol). It can be used for querying OWL ontologies and RDF-based knowledge bases. A total of 11 W3C Recommendations defines this standard. The specifications define the query language, update constructs, service description, federated query, query results (in various formats), general retrieval protocol (operations), and the graph store HTTP protocol.
5. Rule Interchange Format (RIF): a rule language for the SW. RIF concepts and architecture is described in a set of 13 documents that include RIF Core Dialect, RIF Basic Logic Dialect, and RIF Framework for Logic Dialects. Another proposed rule language for the SW is SWRL: Semantic Web Rule Language.
6. Serialisation formats for RDF: (a) Turtle (Terse RDF Triple Language) and TriG (RDF Dataset Language); (b) JSON-LD (JSON based); (c) RDFa (for HTML embedding — Rich Structured Data Markup for Web Documents); (d) N-Triples and N-Quads (line-based exchange formats); (e) RDF/XML (XML based — the original syntax); (f) Notation3 (a superset of Turtle).
7. Simple Knowledge Organisation System (SKOS): designed for representation of thesauri, classification schemes, taxonomies, subject heading systems, or any other type of structured controlled vocabulary.
8. Languages for expressing customised mappings: R2RML (RDB to RDF Mapping Language) and RML (RDF Mapping Language — early draft).

Linked Data is the term used to qualify RDF when it’s used to publish and interlink data on the Web following the set of Link Data Principles. By having the huge amount of data on the Web available in a standard format under the Linked Data Principles, reachable, interrelated, and manageable by SW tools, we would make the Web of data a reality.

Most recently, the term Knowledge Graph (KG) has gained a lot of popularity and traction from both industry and academia. In general, a KG is a knowledge base that uses a graph-structured data model to integrate data from heterogeneous data sources. KGs stored interlinked descriptions of entities with free-form semantics. From the W3C perspective, KGs combine expressivity, interoperability, and standardisation based on the SW technology stack, providing a strong foundation for querying and analysis. Some academic resources regarding the topics of Linked Data, Semantic Web, and KGs are presented below:

• Bizer, C. The Web of Linked Data: A global public Dataspace on the Web. Webdb Keynote (2010).
• Allemang, D., Hendler, J., Fabien, G. Semantic Web for the Working Ontologist: Effective Modeling for Linked Data, RDFS, and OWL. Book (July 2020).
• Hogan, A, et. al. Knowledge Graphs. arXiv. (v5, January 2021).

Conclusions

This article presents a high-level overview and description of the main technologies and basic concepts of the Web, developed and endorsed by the W3C.

The W3C standards for the Web are a cornerstone in the Internet ecosystem. These technologies can be visualised as a superstructure on the top of the Internet infrastructure that extends the layered protocol stack with a comprehensive set of architectures for data modeling, retrieval, and processing in the distributed information space of the Web.

As Tim Berners-Lee depicted in his Level of Abstraction: Net, Web, Graph note, the global computing of shared resources is evolving in the following way:

1. Net: the Internet connects computers.
2. Web: the Web of documents.
3. Graph: the Web of things (and data).

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