IoT Domain Sub model– Functional Model

Definition

It defines the main functionality and their interactions.
It is based on following three principles or concepts:
- Abstract:
  - It is not tied to any technology, application domain or implementation.
  - It does not explain different functional components that make up different functional groups.
- Define Functional Groups and their interactions.
- Functional View:
  - It defines runtime functional components of the system, that covers following aspects:
    - Responsibilities of functional components.
    - Default functions of functional components.
    - Main interfaces of functional components.
    - Primary interactions of functional components.

Functional Model defines two types of functional groups:

1. Longitudinal Functionality Group:

Functionalities are limited to that specific group only and are not required by any other functional groups. These functional groups are spread lengthwise in overall model and their interaction is also manly two way longitudinal.

Below are the 7 longitudinal Functional Groups:

Application
Service Organization
IoT Process Management
Virtual Entity
IoT Service
Communication
Device

2. Transversal Functionality Group:

Functionalities are required to be implemented almost in all functional groups, therefore these are spread across all functional groups. Example: Security and Management

Below are the 2 transversal Functional Groups:

Security
Management

Brief explanation of above mentioned functional groups:

1. IoT Process Management Functional Groups:

It provides necessary functional aspects to integrate the specific concept of IoT system with business process. This helps enterprises to make sure IoT Sub-System adhering the common & new industry standards and best practices like BPMN 2.0 (Business Process Model and Notation). So that an isolated and proprietary “IoT” solution is not required to establish.
As the reliability and accountability of sensor data providing information of virtual entity along with processing capabilities of devices are major aspects of business process, IoT process management helps to hide the IoT specific implementation at lower level to enable smooth integration.
While practical realization is done then bu sines process policies covering permissions, prohibitions and obligation aspects; are required to address in IoT Process management.
IoT Process Management FG are dependent on Service Organization FG for the execution of business process by finding, binding and invoking specific services.

2. Service Organization Functional Groups:

It acts as communication hub among other Functional groups because its primary responsibility to composing (combining multiple basic services to get response of a request) and orchestrating services at various abstraction level so that requests coming from IoT Process Management FG or external application can link to right services as well also link with associated entities by utilizing Virtual Entity FG & IoT Service FG.
It also acts as brokerage of services so that Services can subscribe to other services available in system.

3. Virtual Entity Functional Groups:

It contains following functionalities :

1. It has functions for interacting with IoT System having multiple Virtual entities.

2. It also has functionalities for discovering and looking up services that provide information about Virtual Entities.

3. It also has functionalities to managing the static association & dynamic association of moving and non moving Physical entities(virtual entities).

4. IoT Service Functional Groups:

It contains functionalities to discover, look-up and name resolution of IoT Services.

5. Communication Functional Groups:

It contains various communication schemes based on technologies and also provides interfaces to interact with IoT Services FG.
These functional groups consider following aspects related to communication:

Data Representation
End to End path information
Addressing issues
Network Management
Device Specific features
Protocol Translation
Context Passing functionalities

6. Management Functional Groups:

It contains all functionalities that are required to govern any IoT System. It covers below four high level goals:

1. Cost Reduction: It should covers maximum use cases or users to avoid creation of different solutions for different use cases. It also covers the capturing of data to know the current cost.

2. Attending unexpected usage issues: It covers the knowledge of system state and strategies to address along with mitigation of unforeseen situations like: link failure, queue overload, devices are not working, introduction of error into system and emergency situation like stopping a train or moving complete system into energy saving mode.

3. Fault handling:

It covers to address the unpredictability of future failures that includes below goals:

Prediction of failures
Detection of existing failures
Reduction of effects of failures
Repair

4. Flexibility:

It covers to address the changes in requirements so no new system is required to prepare when user requirements change.
It also includes management of membership, ownership, their administration, defining rules & rights and accompanying information of the given entity to the IoT system.

7. Security:

It covers security and privacy of IoT system that includes:

Initial registration of client into system securely to make sure only legitimate clients are allowed to login into system.

Keeping user information protected and anonymous while accessing resources or services.
Legitimate interaction occurs between peers that are statically authorized or trusted to interact with each other.
Secure and data integrity protections.

IoT Domain Sub model– Information Model

Definition

It defines the structure of all information of Virtual Entities only at conceptual level and not at concrete level. In other words, it covers all aspects of adding information in the data. Here, structure covers attributes, relations and services that helps to know what, who, where, and when.
The detailed representation of information is not covered in this model.

This model covers following details (elements & their association) and of modelling of virtual entities:

1. Virtual Entity has attributes with name and its type.

Each virtual entity has a unique id or type i.e human, a car, or a temperature sensor.

A virtual entity can have zero to many attributes.

2. Attribute can have one or more values.

Each attribute has a name, a type (semantics) and one to many values.

3. Value has meta information(Meta data)

Value can further also have more values and each value has zero or many meta data. A virtual container keeps grouping of a value and associated zero or many meta data.

4. Meta Data might help to define other information like:

Time stamp (what time information is defined)
Location (Location where measurement took place
Quality (Quality of measurement) etc.

Meta data can itself have additional meta data i.e unit

5. Association between Virtual entity and Service description for specific attributes. Service allows to read attribute value or set the value based on changes in physical entity.

6. Services description describes services and associated interface. It also contains resource description that covers functionality of resource those are exposed by service.

7. Resource Description describes a resource and also contains description of device on which resource is hosted.

IoT Domain Model–A brief Introduction

Definition

A model that is a base of any reference model, that creates a model for any specific domain and in this case , it is an IoT domain.

Below are the work scope of this model:

Define abstraction and not including real implementation
Define Responsibilities
Define relationship

Following are Sub-models of the IoT Domain model:

IoT Information Model
IoT Functional Model
IoT Communication Model
IoT Trust, Security and Privacy model

IOT Domain Model contains following entities:

User
Physical Entity
Virtual entity
Augmented Entity
Devices
Resource
Service

Description of Domain Model Entities

Devices

In the IOT Domain model, devices are technical artifacts that behave as interfaces between the digital (Virtual Entity) and physical (Physical Entity) world. Therefore, devices must have capabilities (like storage, computation & communication) to operate in the digital as well as physical world. Also resources available in devices also play a very critical role in overall operation.

Device Capabilities:

Communication related capabilities are covered under Communication Model that is a sub-model of the Domain model. It covers:
- Type of data exchange (like identifier, identifier + data, sensor data or commands) is supported by device.
- Support communication topology (like network, peer to peer etc.). It affects energy consumption, data collection frequency, and the amount of data transmitted. Location of Resources (on-device or on network) are also impacted based on communication capabilities.
- It also affects the Security features.
Computation Capabilities of devices have huge impacts on security features, and power resources.
Storage capabilities of devices are also impacted as it determines firmware or software running on devices.

Resource

Resources are software components that provide special functionality. Please note that hardware are not considered as resources.

Example: Actuation, Storage Resources, processing information or services on cloud/network etc.

Here, Actuation allows to get information and also changes in digital or physical entities.

Resources are of two types:

On-Device resources like sensor data retrieval or actuator to control the digital or physical world, storage with limited capacity.
Network Resources like services on cloud to perform large data processing like data aggregation, computation or storage in cloud.

Services

IoT Services are technical services that define standard interfaces and hide complexity of accessing a variety of heterogeneous Resources.

Following services are classified based on their level of abstractions:

1. Resource level Services: These services are for on device resources or network resources to provide functionality and also handles following quality aspects:

Dependability
Security
Resilience(availability)
Scalability & Timeliness

2. Virtual Entity level services:

These services can be associated with a single or multiple virtual entity that gives access to attributes to read and update the values.

3. Integrated Services:

These services are composition of Resource level and Virtual entity level services.

Physical Entities

Physical entity can be a living being or any other item like car, store, logistic items, electronics appliances etc.

In IoT domain model, physical entities are identified by two ways:

1. Primary Identification: Based on natural features of entity like camera having sensor

2. Secondary Identification: Tags or labels based identification, like RFID tags or barcodes

Note: For virtual and augmented entity, please refer “IoT Reference Model – Domain Model Entities” article

IoT Reference Model – Domain Model Entities

To illustrate and build a reference domain model for a very generic scenario of any IOT solution; below table describes all the entities that are required to define by solution architect:

Entity In Domain Model	Description
User	– A human being or a service or an application or a software agent. – Different types of users and associated roles are not included in the IOT Domain Model.
Physical Entity	Physical entity can be a living being or any other item like car, store, logistic items, electronics appliances etc.
Virtual entity	– The digital representation of a physical entity is called virtual entity or digital artifacts. – The same physical entity can be associated with several virtual entities. – Virtual Entity has two basic properties: 1. This is the digital representation of a physical entity. 2. This is the synchronized representation of properties/aspects of physical entities. A. Digital Representation: – Each virtual entity has a very unique id. – Virtual Entities can be classified into two types: 1. Active Digital Artifacts (ADA): Any running software, agents or services that access other Resources or Services. 2. Passive Digital Artifacts (PDA): Passive software like database entries. B. Synchronized Representation: It means that digital parameters of virtual entities represent characteristics of physical entities. Therefore, change of either entity (virtual/physical) will affect the other. Example: Manual locking the door will change the property/parameter of home automation software (virtual entity). Similarly, triggering the event to lock the door in home automation software will also triggered electric lock of door (physical entity).
Augmented Entity	– Composition of one virtual entity and associated physical entity. – Actually, it enables every object to become part of the digital process. – It is also regarded as a “thing” in the Internet of Things.
Devices	Basically, it is either an extension of virtual entities or extension of physical entities. Here, extension means generating a paired couple of virtual and physical entities. It means a device that bridges both virtual and physical entities. To build such devices, we have to provide or add capabilities like monitoring, sensing, actuation, computation, storage and processing. – In IOT Domain, there are 3 types of such devices: 1. Sensors 2. Tags 3. Actuators
Resource	– These are the software components that enable virtual entities to interact with physical entities. – There are two types of resources identified: 1. On-Device Resources: Resources deployed on physical devices like executable for accessing, processing and storing information, or controlling actuators. 2. Network Resources: Resources deployed on a network like back end or cloud. – Virtual entities can also be associated with Resources to enable interaction with associated physical entities.
Service	– In case of heterogeneous resources, a service is required to provide open and standard interfaces so that interaction with resources & devices associated with Physical entities can be achieved. – A virtual entity can be associated with one service or multiple services. – Multiple instances of a service are also possible in the model.

Table 1.0

Note: Here, Interaction can be done by calling services that either retrieve information or act on a physical entity to meet the goal of the user.

Interaction can be done between:

Human User and Physical entities.
As well as between Active Digital Artifact and Physical entity.