IOT -- interpreting the four tier architecture of the Internet of things

This paper is based on the four layers of the Internet of things framework Based on , Interpret the functions and main contents of each layer of architecture from the perspective of IOT product design , It aims to provide some help to IOT products or R & D personnel who are interested in IOT product design and implementation ideas .

Through the Internet , People can transfer and exchange information . The Internet of things ,IoT,Internet of Things, As the name suggests, things can also transmit and exchange information , The biggest difference between the interconnection of people and things is reflected in the difference between people and things .

People have five senses and skin to receive and collect data , After brain processing , Then form an idea , Finally, it is transmitted through the network , Achieve the purpose of communicating with others . Compared with people , Things lack information that needs to be communicated , That is, the object lacks a grasp for collecting data , And integrate information to form a brain with communication value .

Then information collection technology and embedded programs are particularly important in the field of Internet of things , Information collection technology has replaced human facial features and skin , Data collection .

The embedded program mainly replaces the final output information of the whole decision-making of the brain , The Internet of things has appeared in the market for a long time, but it has not produced considerable influence , So the public's attention to it is not very high .

But in the last ten years , Internet of things develops rapidly , This not only benefits from the support of national policies － stay 2010 In, it was listed as a national development strategy , It also benefits from the supporting technology of the Internet of things , Such as data acquisition technology 、 Microprocessor 、 communication module 、 Communication network 、 big data 、 The rapid development of Cloud Computing  .

The Internet of things once again entered the public view , And successfully achieved the attention and pursuit of the public , And is expected to set off the next wave . The IOT technology system can be divided into four layers ： Perception layer 、 The network layer 、 Platform layer and application layer . Each layer has different responsibilities , This kind of division of labor is similar to that of a specially assigned person , It can improve work quality and efficiency .

  chart 1： Four layer architecture of Internet of things

One 、 Perception layer

The main function of the perception layer is to collect the data of the physical world , It is the key bridge between the human world and the physical world .

There are two main sources of data in the perception layer ：

One is to actively collect generated information , Like sensors 、 Multimedia information collection 、GPS etc. , In this way, you need to actively record or interact with the target object to get the data , There is a process of collecting data , And high real-time information .

For example, in the field of intelligent drinking water, a flow sensor will be used , As long as users drink water , The flow sensor will immediately collect how much water you drink this time , There is a long-term process of interactive data collection .

The other is to accept external instructions and passively save information , Such as radio frequency identification （RFID）、IC Card identification technology 、 Bar code 、 QR code technology , This method usually saves the information in advance , Waiting to be read directly .

For example, the access control card used in some communities now is used IC Card identification technology , First enter the user information into the central processing system , Then the user swipes his card directly every time he enters the door .

Two 、 The network layer

The main function of the network layer is to transmit information , Transmit the data obtained by the sensing layer to the designated destination .

In the field of the Internet of things , Embedded program is equivalent to human brain , After information collection , The brain will issue instructions to the communication module to transmit this information to so and so , The network layer will involve what kind of communication network you choose and what kind of communication mechanism you use to transmit your information .

In the Internet of things “ network ” The word actually contains 2 Parts of ： Access network 、 Internet .

In the past, the Internet only opened up the information exchange between people , But there is no connection between people and things or between things , Because things themselves do not have networking capabilities .

Later, the technology of connecting objects to the network was developed , We call it device access network , Through this network, things can be connected with the Internet , Realize the information interaction between people and things and between things , It greatly increases the boundary of information exchange , It is more conducive to the adoption of big data 、 Cloud computing 、AI The application of advanced technologies such as intelligence will increase the richness of the physical and human world .

At present, there are mainly two ways of access network , One is wired network access , One is wireless network access .

chart 2： Internet of things network structure

Wired mainly includes Ethernet 、 serial communication （RS-232、RS485 etc. ） and USB etc. .

Wireless is also divided into short-range wireless 、 Short distance wireless and long distance wireless communication . Short range wireless communication mainly includes NFC、RFID 、IC etc. , Short distance wireless communication mainly includes Wifi、ZigBee、 Bluetooth, etc , Long distance wireless communication mainly includes GSM（2G、3G、4G、5G etc. ）、eMTS、Lora、NB-IoT etc. .

In the face of many ways to access the network , We need to consider the application scenario and the characteristics of the device itself to choose the appropriate access method , See the following table for the characteristics of various access networks .

Choose a suitable network , The physical bearing road equivalent to data transmission has been opened , Now it is necessary to determine what mechanism is used to transmit information , This involves communication protocols .

essentially , Communication protocol is a set of data transmission specifications , Just contact us in English 、 German 、 Chinese and other similar languages , It is formed by certain rules , Easy to communicate between things .

Internet of things device side resources are limited , For example, the processing capacity is poor 、 Small storage capacity 、 The network transmission volume is small 、 Network instability, etc , Obviously, there is a great difference between the resource environment provided by the Internet of things and the Internet on the device side .

So in order to better serve the Internet of things , Optimize the communication protocol of the Internet , Developed a widely used MQTT(Message Queuing Telemetry Transport) and CoAP（Constrained Application Protocal ） Two Internet of things communication protocols .

MQTT The protocol is based on TCP Agreed , It is certain that the receiver will receive the information sent by the device .MQTT The protocol can maintain a long connection , This enables real-time communication between the device and the cloud , So it is more suitable for real-time control of interactive scenes .

Because it's based on TCP Agreed , Its communication protocol is complex , If the device side needs to run a complex mechanism , You need to have certain requirements for performance , Like storage 、 Calculation 、 Network quality, etc .

CoAP The protocol is based on UDP Agreed , There are two data transmission mechanisms ： One is that the receiver must receive the data sent by the device , The other is whether the receiver receives , The device only sends 1 The data is over .

The device enters the sleep state after completing the data transmission , So low power consumption is CoAP The biggest feature of the agreement , It is also more suitable for the occasion of data collection , Such as copying electricity meters 、 Data of water meter .

Because it's based on UDP Agreed , The complexity of its communication protocol is simpler , Naturally, the performance requirements of the device end will be lower .

3、 ... and 、 Platform level

The Internet of things platform can provide devices with safe and reliable connection and communication capabilities , Connect mass devices down , Support data reporting to the cloud , Provide the cloud up API, The server calls the cloud API Send the instruction to the equipment end , Realize remote control .

The Internet of things platform mainly includes device access 、 Equipment management 、 security management 、 Message communication 、 Monitoring operation and maintenance and data application .

chart 3： Basic architecture of IOT management platform

Device access mainly refers to how the device end communicates with the Internet of things platform , Mainly in ：

Device side development ： Provide MQTT、CoAP、HTTP、HTTPS And other protocols SDK Development, etc. , Help different devices access easily

Equipment network access management ： Provide cellular based （2G、3G、4G、5G）、NB-IoT、LoRaWAN、WI-FI And other different network access schemes .

1. Equipment management

It mainly includes equipment creation 、 maintain 、 Data conversion 、 Data synchronization 、 Equipment distribution, etc , Specifically, ：

1） Object model management

Things in the Internet of things are entities of the physical world , If we want to develop a digital system , Then this entity must not be absent , This time will involve a problem ： How to turn offline entities into online entities ？

And this is the value of the object model . The popular explanation of the object model is to represent the objects of the physical world in the way of the digital world , Use the rules of the digital world to describe what this object is 、 What does it do , This is what we often hear about the function of products .

Internet of things platforms will provide a variety of ways to build things models , We can choose the appropriate model according to different needs .

2） Equipment life cycle management

It mainly involves creating devices 、 Device up and down 、 Ban ／ Enable 、 Delete device, etc . After the object model is established , It is equivalent to defining the master of the product , At this time, we can create a device under the product , The device will also have the functions of the product .

3） Data analysis

For devices with low configuration, limited resources or network traffic requirements , Not suitable for construction JSON Format to communicate with the Internet of things platform , At this time, the original data can be transmitted to the Internet of things platform , The IOT platform then converts the script rules according to the original data , Convert it to JSON Format .

4） Device shadow

The Internet of things is a very important link , If the device is not networked , Then the device end and the server end are in the state of communication interruption , Both parties cannot exchange information . In order to solve this normal dilemma , Build on the IOT platform for every device 1 Shadow , Its have 2 There are two main functions ：

1. The instructions of the server saved in the device shadow during the offline period of the device can be sent to the device for execution immediately when the device is online ;

2. When the device is online , If the data on the device side changes, it will be synchronized to the device in time , This can solve the problem that the server cannot request device data when the device is offline .

In other words, to some extent, the device shadow can make the device side and the server side maintain relatively timely interactive communication , At least, the server can get the relatively latest data from the device and tell the device which instructions to execute in a relatively timely manner .

5） Device topology

The IOT platform supports direct connection of devices , It also supports the device to be attached to the gateway , As a sub device of the gateway , Directly connected by gateway .

The scenarios of gateway direct connection mainly include those in which sub devices cannot be directly connected or topology relationship management is required , such as WI-FI gateway 、ZigBee gateway 、 And Bluetooth gateway . Device topology management can help manage sub devices 、 The topological relationship between the sub device and the gateway 、 Monitor and operate the sub equipment , At the same time, the server can send and receive messages directly to sub devices .

2. security management

Mainly from the two aspects of equipment security certification and communication security to ensure the security of Internet of things data transmission .

1） Equipment safety certification

Before the device is connected to the IOT platform , Authentication required , To ensure the safety of the equipment .

at present , The Internet of things platform supports the use of device keys 、ID² and X.509 Certificate and other methods for identity authentication , Here, only the device key is taken as an example to briefly explain the implementation of device identity authentication （ Generate 、 obtain 、 Use ）.

When creating a device on the Internet of things platform, a key will be issued to the device , There are many kinds of keys , For example, one machine and one secret 、 One type, one dense, etc , After the key is generated , Yes 2 There are two ways to put the key on the device ：

One is to burn the key in the device program in advance , The other is to request the device key from the Internet of things platform when the device is connected to the Internet for the first time , At this time, if the device has been registered, the corresponding key will be passed to the device . After the device has a key, it is equivalent to getting a pass , It can communicate normally with the Internet of things platform .

2） Communication security

It mainly refers to the safety management of data transmission , Support MQTT、HTTPS、CoAP Data transmission channel , Ensure the confidentiality and integrity of data , Support device authority management mechanism , Secure communication between the device and the cloud ; Support device level communication resources （Topic etc. ） Isolation , To prevent the equipment from exceeding the authority .

3. Message communication

It mainly includes sending data from the device to the Internet of things platform , The Internet of things platform transfers data to the server ／ Other cloud products , The remote control equipment on the server side 3 There are two ways of message transmission .

Equipment management mainly defines what equipment is , The main solution of message communication is the information transmission mechanism ： How to connect the device information configured on the Internet of things platform with the device end 、 Server side 、 Other cloud products . A very important concept involved in this mechanism is Topic, Through to Topic For information transmission .

1） be based on Topic The uplink and downlink communication of can send the data of the device end to the Internet of things platform or realize the remote control device of the service end

The device end communicates with the Internet of things platform MQTT agreement , The protocol is a topic based publish and subscribe mechanism , All information transmission is completed through the intermediary of theme .

The device can publish a topic or subscribe to a topic , The device release is actually the message mode for the device to send data , The device subscription is actually the message mode for the device to receive data , For IOT devices, reporting and receiving are two basic and important message interaction modes , How to define the theme ？

There are two ways to define a topic ： One is user-defined data mode , One is the standardized data model established by using the object model .

The definition of theme is based on product function , When the product function is determined , How to associate these functions with device communication is a very important problem .

At this time, we need to set the theme of the product . After selecting product features , You can set different topics as needed, such as reporting 、 receive 、 to update 、 Delete etc. . After defining the theme class at the product level , All devices under this product will have the characteristics of this topic , The device can use the topic for uplink and downlink communication .

2） Based on server subscription 、 Cloud products transfer the data of the Internet of things platform to the server ／ Transmission mode of other cloud products

The server can directly subscribe to various types of messages under the product ： The device reports messages 、 Notification of equipment status change 、 Equipment life cycle changes 、 Change of device topology relationship .

After configuring the server subscription , The Internet of things platform will forward the subscribed messages of all devices under the product to the server . Use the data flow function of the Internet of things platform , Can be Topic The data messages in are forwarded to other cloud products for storage or processing , This is the so-called cloud product circulation .

4. Monitoring operation and maintenance

It mainly involves equipment monitoring and operation and maintenance .

Monitoring diagnosis ： The number of online devices provided by the Internet of things platform 、 Number of uplink and downlink messages 、 Number of rule engine flow messages 、 Real time monitoring function of equipment network status and other index data ;

OTA upgrade ： If an application upgrade occurs after the device is released , You can use the OTA Upgrade and management services , Realize the work of remote upgrade program ;

Online debugging ： Online debugging is mainly used in the program development stage , First, after the development of the device end , You can use the online debugging function of the Internet of things platform , Send instructions from the console to the device end for function test ; Second, the Internet of things provides virtual device functions , For cloud application development and testing ;

The log service ： You can save the operation logs of the cloud or device for fault query , And the log data can be exported and stored for long-term storage . After opening log dump , Support querying and analyzing logs on the Internet of things console , And provide log reports 、 Report subscription 、 Alarm notification and other functions .

5. Data applications

Mainly related to data storage 、 Analysis and Application .

The data backup ： It can provide distribution and backup services for massive data ;

Data analysis ： It provides developers with device intelligence analysis , The full link covers the generation of equipment data 、 management （ Storage ）、 cleaning 、 Analysis and visualization ;

Data applications ： It can be combined with third parties or other cloud products to solve different problems, such as reporting data from thermohygrometers to nail group robots or building a large device monitoring screen through a big data platform .

Four 、 application layer

The application layer is the ultimate goal of the Internet of things , It mainly processes the data collected from the device , So as to provide intelligent services to different industries .

At present, the Internet of things involves many industries , Like electricity 、 logistics 、 Environmental protection 、 Agriculture 、 Industry 、 city management 、 Home life , But in essence, the types of IOT services adopted mainly include 4 class ：

Monitoring type , For example, logistics monitoring 、 Pollution monitoring, etc ;

Control type , Such as intelligent transportation 、 Smart home, etc ;

Scanning type , Such as mobile wallet 、 Freeway toll collection, etc ;

Query type , Such as remote meter reading 、 Intelligent retrieval, etc .

chart 4： Internet of things application layer structure

The application layer architecture mainly includes 3 Components ： Business processing , Database and client .

Internet of things business processing is more complex , Because it will involve the integration of massive data , This is a great challenge for terminal users in different industries , So at present, there are middleware specially provided in the market, such as cloud computing 、 data mining 、 Artificial intelligence 、 Information fusion can be used by industry , This has also stimulated the prosperity of the Internet of things application industry to a certain extent .

Databases are mainly used to store devices 、 user 、 Business and other relevant data . The application layer will contact the end users , So it will involve the development of the client , I won't go into details here .

The key technologies involved in the Internet of things mainly include Cloud Computing 、 data mining 、 Artificial intelligence , Here is a brief introduction ：

Cloud computing has powerful storage capabilities 、 processing capacity 、 Bandwidth and high cost performance , It can provide unified services for different Internet of things applications . Different technical service chambers will develop a complete set of cloud computing resources , It's like hydropower , Customers can pay on demand , How much do you need? , Just buy as much as you want ;

Data mining is from a large number of 、 Not completely 、 Noisy 、 Fuzzy and random practical application data , Dig out the hidden 、 Unknown 、 The process of data that has potential value for decision making . Data mining is mainly based on artificial intelligence 、 machine learning 、 pattern recognition 、 Statistics, etc , Highly automated statistics of data 、 analysis 、 comprehensive 、 Induction and reasoning , Reveal the relationship between things , Predict the future development trend , Provide decision-makers with decision-making basis ;

Artificial intelligence is to explore and study how to make various machines simulate certain thinking processes and intelligent behaviors of human beings （ Such as learning 、 Reasoning 、 Thinking etc. ）. Research in this field includes robots 、 Speech recognition 、 Image recognition 、 Natural language processing and expert system, etc . In the Internet of things , AI technology is mainly responsible for analyzing the information content carried by objects , So as to realize computer automatic processing .

One of the purposes of writing this article is to summarize my knowledge of products in the field of Internet of things , Another of the most important purposes is to establish an overall grasp of IOT product design and Implementation for those who are interested in IOT product design , You can understand the main contents of each component of the Internet of things and the corresponding key nodes .

Due to the limited level of personal knowledge , If some of the above points are wrong , Welcome to correct , Thank you very much ～

author ： quiet & Indifferent source ： Everyone is a product manager

Link to the original text ：IoT -- Interpret the four tier architecture of the Internet of things _ Blog of interconnected community -CSDN Blog