Interoperability is the ability of computerized systems to readily connect, communicate, work with or use the components of another system. A distributed network enables applications to operate across different devices and platforms, creating ubiquity, i.e., it allows access to data and information across multiple applications without the need for a specialized machine. Users can access the Web using any basic internet functionality and connectivity device.

Interoperability

Web 3.0 provides a communicative channel for knowledge and information exchange, and once applications are developed, they will work independently on various devices. Such applications run on multiple types of computers,  microwaves,  mobile phones,  televisions, automobiles, etc. The web then becomes operational to varied electronic devices,

The current Internet-of-Things ecosystems install and operate appliances and applications in their platforms and clouds, but without good congruity with products from different brands. For instance, an Android smartwatch can't interact with an intelligent bulb without a requisite gated application availed by the same vendor. 

Standards are needed to allow horizontal and vertical communication,  operation,  and programming across devices and platforms, notwithstanding their model or manufacturer. 

Levels of Interoperability

Technological, syntactic, and semantic interoperability enables horizontal compatibility of technologies and platforms, while the vertical operation is achieved through organizational interoperability.

Technological Interoperability

Multimode radio instruments are the leading technology solution for harmonizing disparate devices that utilize varied networking and communication means. For example, a  smartphone operating with any cellular network can communicate with any other phone. Similarly, this is applicable in various  IoT ecosystems,  like smart homes. 

Home hubs, such as gateways and routers, apply multimode radios and support communication technologies like WiFi and Bluetooth. These hubs, in turn, act as linkages and provide the desired compatibility. Modern TVs and thermostats using WiFi, speakers that communicate with  Bluetooth, and switches and light bulbs that connect with  ZigBee can interact, providing the user with flexible and convenient ways to interoperate with innovative home ecosystems.  

Once the devices are connected, the software can establish another compatibility.

Syntactic Interoperability 

IoT vendors use standardized technologies and platforms to increase product acceptance. Regular solutions include messaging protocols such as CoAP,  XMPP,  AMQP,  MQTT, DDS, and Hy-LP. Venues include DPWS, UPnP, and OSGi.

These solutions offer only interdome compatibility. They have a narrow application focus and impose specific data formats and interfaces. Gateway proxies for the messaging protocols are enacted to achieve horizontal interoperability. Messages from one messaging protocol are converted to the compatible format of another.

Messages are passed through message brokers that implement the critical functionality of a  multiprotocol proxy,  translating messages from one protocol to another and managing the communication flow.

Each platform uses specific message protocols. Using a  multiprotocol, functionality is expanded, and interaction with devices that support different protocols is enabled. These methods provide inter-domain interoperability at the syntactic level. 

At this point, devices can communicate seamlessly but cannot understand each other. Therefore, additional procedures are required to expound the information in machine-interpretable format. 

Semantic Interoperability

Semantic technologies such as XML schemes, like the Resource Description Framework  (RDF),  RDF  Schema (RDFS),  and  Web  Ontology  Language  (OWL)  for ontologies, and the  Web  Services  Description  Language (WSDL)  for services, facilitate interoperability in web services are frequently adapted in the IoT domain.  

These technologies offer descriptions and representation of data and services, cluster things, and their abilities. Among the features, they deal with include the discovery of resources, semantic annotation, knowledge extraction, and access management. Knowledge extraction is done in a manner that is interoperable and machine-readable.

Organizational Interoperability 

The standard semantic information interpretation of the current ontology-based world comes in handy. Several systems may use desired or standardized ontologies and establish their semantics and interfaces. Direct interaction between these systems is not feasible. Semantic Information Brokers (SIBs) correlate the required information and enable the interoperability of plans with cross-domain interaction or different semantics.

More so, a generic and common Application Programming  Interface  (API)  is established between the different  IoT middleware platforms. The API and the related information models are determined, enhancing the supported standards of this community. The API eases the development of software services and applications for different platforms according to a well-defined architecture.

Thus, the cooperation of a SIB with a standard API allows complex service generation and value-added applications. Such APIs provide well-defined functionalities that can also implement interoperability on devices,  fog,  and cloud-level.  

The  main functionalities include: 

Author's Take

Monetization of IoT resources is an essential and fundamental ability that establishes business models and is crucial in initiating interoperability. Such technologies basically define Web 3.0. 

The manufacturer’s resources are advertised on the marketplace. Clients can discover the offered applications and gain access to them. Marketplaces could be established for specific application domains, e.g., e-health,  smart home,  etc., or there could be numerous marketplaces for a  single environment but set by different vendors.

As the developers conform to defined interfaces, the marketplaces enhance organizational interoperability. Modern IoT applications can use services from different manufacturers and implement horizontal interoperable solutions that also utilize the vertical interoperability levels, achieving seamless operation from the device end to the backend infrastructure.