IoT Concepts and Applications Lecture 7.pdf
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Lecture 7 IoT System Architecture Part I By: Dr. Hajar Esmaeil As-Suhbani IT, 4th Level Outline IoT Architecture Physical Design of IoT Logical Design of IoT IoT Enabling Technologi...
Lecture 7 IoT System Architecture Part I By: Dr. Hajar Esmaeil As-Suhbani IT, 4th Level Outline IoT Architecture Physical Design of IoT Logical Design of IoT IoT Enabling Technologies IoT Levels IoT layers and Protocol Stack 2 IoT Architecture The term IoT architecture refers to the framework which defines how various IoT elements (e.g., devices, networks, sensors, applications) interact within an IoT environment. Typically, IoT architecture consists of several layers and components which perform a variety of functions from physical devices, and data acquisition systems, to network devices communicating IoT data to data processing applications, and IoT data storage. 3 IoT Four Layers Architecture Figure 1 Four layer IoT Architecture 4 …IoT three Layers Architecture perception Layer: Includes objects to be detected (from physical moving objects, such as humans, cars, ) or factors to be observed ( temperature, or humidity). Includes sensors, other hardware such as; embedded systems, RFID tags and readers and others. The network layer: It is responsible for processing the received data from the Perception Layer. It is in charge of transmitting data to the application layer through various network technologies, such as wireless/wired networks and Local Area Networks (LAN). The main media for transmission include 3G, 4G, 5G, WiFi, Bluetooth, Zigbee, infrared technology, and so on. Huge quantities of data will be carried by the network. 5 …IoT three Layers Architecture Middleware Layer: Crucial to provide a middleware to store and process this massive amount of data. Application Layer: It is the layer at the top of the architecture and is responsible for delivery of various applications to different users in IoT. It realizes the use of smart objects by a set of functions to users to meet defined requirements. The applications can be from different industry segments such as: manufacturing, logistics, retail, environment, public safety, healthcare, food and drug etc. 6 Physical and Logical Designs of IOT IoT is the physical devices that are connected to a network. These physical devices are called node devices. These are embedded with sensors, software, and other technologies to exchange data with other devices and systems over the Internet. With IoT, digital systems can record, monitor, and adjust each interaction between connected things. Hence now we can connect everyday objects like kitchen appliances, cars, thermostats, etc to the internet via embedded devices. This makes communication streamlined between people, processes, and things. To understand IoT properly we need to understand the Logical and Physical Designs of IOT. 7 Physical Design of IoT The Physical design of IoT deals with the individual devices connected to the IoT network and the protocols used to create a functional IoT environment. Each IoT device can perform tasks of remote sensing, actuating, monitoring, etc., due to the IoT network they are connected to. These can also transmit information through different types of wireless or wired connections. They can generate data, which is used to perform analysis and perform operations for improving the system. 8 Physical Design of IoT: Node Devices (Things) Things in IoT refers to IoT devices, which have unique identities. Node devices (things) are used to build a connection, process data, and provide interfaces, and storage, in an IoT system. They generate data that can be analyzed by the IoT system and program to perform operations and improve the system. Connectivity: Devices like USB hosts and ETHERNET provides connectivity between the devices and the server. Processor: Processors like CPU and other units process the data. This is used to improve the decision quality of an IoT system. Audio/Video Interfaces: System interfaces like HDMI and RCA devices record audio and videos. Input/Output interface: Devices like UART, SPI, CAN, etc give input and output signals to sensors and actuators. Storage Interfaces: IoT devices like SD, MMC, and SDIO generate data. Storage interfaces store those data. Controlling of activity: Devices like DDR and GPU control the activity of an IoT system. 9 Figure1 Generic block Diagram for IoT Devices 10 Physical Design of IoT: IoT Protocols A protocol is a set of rules that governs the communication between two or more devices. A protocol defines the rules and synchronization of communication and possible error recovery methods. IoT protcols help to establish Communication between IoT Device (Node Device) and Cloud based Server over the Internet. It help to sent commands to IoT Device and received data from an IoT device over the Internet. 11 Figure2 IoT Protocols with respect to TCP/IP protocol stack 12 Physical Design of IoT: IoT Protocols: Link Layer Protocols The link layer is responsible for establishing and terminating links between the nodes. The packets or datagrams travel through these links. The link layer also defines the format of packet that is to be communicated across the link and is responsible for physical addressing. The link layer also handles error detection, retransmission, flow control and access of the link. 13 Table 1 Summary of link layer protocols 14 Physical Design of IoT: IoT Protocols: Network Layer Protocols The main role of the network layer is transfer the packet from sender to receiving host. The network layer also handles routing, which involves selecting the next node and forwarding the packets across the communication path. The network layer is also responsible for logical addressing (like IP address) and for congestion control which prevents the network from being overloaded with traffic. Different protocols at network layer are: IPv4 (32-bit addresses): This is a protocol address that is a numerical label assigned to each device connected to the network. IPv6 (128-bit addresses): It is a successor of IPv4 that uses 128 bits for an IP address. It is developed to deal with long-anticipated problems. 6LoWPAN: IPv6 over Low power Wireless Personal Area Network. 15 Physical Design of IoT: IoT Protocols: Transport Layer Protocols The main role of transport layer is providing end-to-end communication between the applications running on hosts. The transport layer provides a logical communication channel through which the end applications can communicate with each other. The transport layer is implemented on the end hosts. It is not present in the routers. The transport layer is also responsible for the reliable delivery of the message across the end nodes, flow control and multiplexing and demultiplexing of the channels at end nodes. Different protocols at transport layer are: TCP (Transmission Control Protocol): It is a connection-oriented protocol. UDP (User Datagram Protocol): It is a connectionless protocol. 16 Physical Design of IoT: IoT Protocols: Application Layer Protocols The application layer is where the users of an IoT application interact with the IoT application/system. The application layer allows the users to interact with the IoT sensors and access other services provided by the communication network. The application layer provides services like authentication, naming, message formatting, email, etc, to the users. Different protocols at transport layer are: HTTP (HyperText Transfer Protocol): Uses TCP, Stateless, Request-Response Model. It is a protocol that presents in an application layer for transmitting media documents. It is used to communicate between web browsers and servers. It makes a request to a server and then waits till it receives a response and in between the request server does not keep any data between the two requests. 17 Physical Design of IoT: IoT Protocols: … Application Layer Protocols CoAP (Constrained Application Protocol): Uses UDP, Request-Response Model. XMPP (Extensible Messaging and Presence Protocol): Real-time communication, For sending XML data. MQTT (Message Queue Telemetry Transport): It is a machine-to-machine connectivity protocol that was designed as a publish/subscribe messaging transport. It is used for remote locations where a small code footprint is required. No security. Used with low power devices. AMQP (Advanced Message Queuing Protocol): Supports both point-to-point and publisher-subscriber models. High performance and secure protocol. Uses TCP. 18 Physical Design of IoT: IoT Protocols: … Application Layer Protocols WebSocket: Full-duplex connection over a single socket connection. This protocol enables two-way communication between a client and a host that can be run on an untrusted code in a controlled environment. This protocol is commonly used by web browsers. Uses TCP. DDS (Data Distribution Service): Middleware standard, Reliable than MQTT. Follows publish-subscribe model. Uses UDP. 19 Logical Design of IoT It is the actual design of the IoT system. It illustrates the assembling and configuration of the components i.e. computers, sensors, and actuators. The logical design of internet of things includes: IoT Functional Blocks IoT Communication Models IoT Communication APIs 20 Logical Design of IoT: IoT Functional Blocks Different functional blocks in an IoT system or application are device, communication, services, application, management, and security. The functional blocks of IoT systems provide sensing, identification, actuation, management, and communication capabilities to the IoT ecosystem. The Functional blocks of IoT are: Device: Devices provide sensing, actuation, monitoring, and control functions to the IoT ecosystem. Communication: Manages communication for the IoT system. Services: Services perform the functions of device monitoring, device control, data publishing, and device discovery. Management: Gives functions to govern the IoT system. Security: Provides security to the IoT system. It performs authentication, authorization, message and content integrity, and data security functions. Application: An interface where the users can control and monitor various aspects of the IoT system. It allows the users to view the system status and analyze the processed data. 21 Figure 3 IoT Functional Blocks 22 Logical Design of IoT: IoT Communication Models The communication models of IoT are used for communicating between the system and the server. Internet of things supports different communication models between the entities in an IoT system. These communication models are: Request-Response Model Publish-Subscribe Model Push-Pull Model Exclusive Pair Model 23 Logical Design of IoT: IoT Communication Models: Request-Response Model In this communication model, the client (IoT device) sends requests to the server and the server responds to their requests. After receiving a request, the server decides how to respond by fetching the data, retrieving resource representation, preparing the response, and then sending the response to the client. This model is stateless because the data between requests is not retained, therefore each request is handled independently. The request-response protocol between a client and a server is HTTP. 24 Figure 4 Request-Response Model 25 Logical Design of IoT: IoT Communication Models: Publisher-Subscriber Model This model is made up of three entities: 1. Publisher: It is the source of data that sends the data to the topic. 2. Consumers: They subscribe to the topics. The consumers consume the data published by the publishers. A consumer is generally the IoT application through which the users interact. 3. Brokers:They accept data from publishers and send it to the consumers. The publisher always publishes messages at a pre-defined interval. The sensors in IoT can be thought of as publishers. The publishers publish data as topics. The broker is an entity that maintains different topics to which consumers subscribe. The broker is generally a server. The published messages of publishers are maintained by the broker. A consumer can subscribe to one or more topics maintained by a broker. 26 Figure 5 Publisher-Subscriber Model 27 Logical Design of IoT: IoT Communication Models: Push-Pull Model This model is made up of data publishers, data consumers, and data queues. 1. Publishers: They publish the message and push it into the queue. The sensors in IoT can be thought of as publishers of data. 2. Queues: It helps in decoupling the messages between the producer and consumer. One or more queues store that data pushed by the publishers. 3. Consumers: They present on the other side and they pull the data out of the queue.The consumers pull the messages from the queues and consume the messages. A consumer is generally the IoT application through which the users interact. Unlike the publish-subscribe model, there is ordering of messages in push- pull model. 28 Figure 6 Push-Pull Model 29 Logical Design of IoT: IoT Communication Models: Exclusive Pair The main entities in an exclusive pair model are client and server. It is a bi-directional model that includes full-duplex communication between client and server. The client and server establish a full duplex connection for sending and receiving data. Before sending a request, the client establishes a connection with the server and then sends the request. The data requests can be one or more. The server receives these requests through the same connection and sends back responses. After the data transfer is complete, the connection between the client and server is terminated. Unlike publish-subscribe model, exclusive pair model is stateful. The client sends a request and the server keeps the record of all the connections. So, the server can automatically identify that the request is coming from a previous client or not. In this model, only WebSocket-based communication API is based. 30 Figure 7 Exclusive Pair 31 Logical Design of IoT: IoT Communication APIs An Application Programming Interface (API) provides an unified interface to access the server resources. An API is the one which connects the things together in the Internet of Things. APIs act as a point of interaction between the IoT devices and the Internet and/or other elements within the network. In IoT there two types of communication APIs: 1. REST-based communication APIs 2. WebSocket-based communication APIs 32 Logical Design of IoT: IoT Communication APIs: REST-based communication APIs In a REST-based communication, the client sends HTTP or HTTPS requests like GET, POST, PUT, DELETE, etc., to the server where the REST-based API will accept these requests, process them and send back responses. The responses sent back to the clients will be in Extensible Markup Language (XML) or JavaScript Object Notation (JSON) format. Example: Accuweather.com. Users can see the weather at a given location though accuweather’s weather application in their mobiles. This application uses a REST API provided by accuweather to access the weather details. When a user selects a location in the mobile app, the application sends a HTTP or HTTPS request. Accuweather’s server responds back with the weather details. 33 Figure 8 REST-based communication 34 Figure 9 Accuweather.com. 35 Logical Design of IoT: IoT Communication APIs: WebSocket-based Communication APIs WebSocket-based API creates full-duplex communication between clients and servers. It follows exclusive Web pair communication model. WebSocket-based communication is stateful. This Communication API does not require a new connection to be set up for each message to be sent between clients and servers. Once the connection is set up the messages can be sent and received continuously without any interruption. WebSocket APIs are suitable for IoT Applications with low latency or high throughput requirements. 36 Figure 9 WebSocket-based Communication 37 THANK YOU!
