What is JSON? Practical basic knowledge

5. What is the relation between JSON and Java? 

JSON’s definition originates from a subset of the JavaScript language definition of the ECMA-262 standard. However, the fact that JSON has this origin, and the name “Java Script Object Notation” does not mean that JSON is limited for the use in JavaScript. JSON is completely independent and not tied to the JavaScript language. There are many built-in functions in JavaScript for working with JSON, which makes it particularly easy to use JSON in JavaScript. In many other languages, however, corresponding frameworks are also available. When in doubt, the simple text format of JSON can be read and processed in any programming language. 

6. Which areas of application and practical benefits are there? 

Due to its simplified structure and encoding in the Unicode character set, JSON is the ideal format for exchanging data between systems. And this without having to consider operating systems, computer architectures or programming languages. 

Data is stored in JSON format and transmitted as a data packet to the target system via any channels (http, file, TCP/IP, database, etc.). Due to the structure and the integrated descriptive elements, it is very straightforward to evaluate the data again by the target system. Since the data will exchange as a closed packet/document, it is very suitable for asynchronous processes. JSON is most used in web environments but is establishing itself more and more in various application areas. 

7. How does JSON work in the industry? 

The JSON format is becoming more common in the industrial environment. An important factor is the increasingly close integration of machines and field level devices with web-based technologies. Due to field devices and software systems with REST interfaces (What is REST?) and integration of sensors and devices via MQTT, JSON is already widely used. The current use of NoSQL and the growing trend towards machine learning and artificial intelligence make JSON indispensable as a simple but flexible data format. 

8. Devices and services 

Services that provide information via the REST interface return their data frequently as JSON. An example is the weather service OpenWeatherMap. As an example, this call returns the current weather in London as JSON: https://openweathermap.org/ 

For a detailed example, visit our how-to article on connecting OpenWeatherMap. 

JSON devices are generally data sources that send their data via MQTT and are part of the IoT. 

9. JSON and XML

XML (Extensible Markup Language) is a description language. The description of data is similar in its core to JSON. The description with Tags in XML results in higher workload. Not only can data be described by Tags, but also by Attributes (e.g.: TEXT). As a result, when data is exchanged, the Sender and Receiver must have very explicit information about the agreed structure. 

In contrast, the structure in JSON is flexible and completely understandable by the Receiver in any case and convertible into objects without any prior structure agreement. 

Therefore, XML is suitable for clearly defined data interfaces and JSON for flexible data exchange. 

10. JSON and MQTT

The MQTT protocol is a simple and lightweight transport protocol for data exchange. It is frequently used by devices and services that have to deal with limited bandwidth and computing capacity. The data format of MQTT is not specified. However, the data payload is frequently formatted as a JSON document since it is ideal for this use case. Due to this reason, there are many MQTT connection partners that publish their data in the form of JSON. 

11. JSON and NoSQL

Document-based databases using the NoSQL concept are a well-known use case for JSON. These databases accept JSON documents for storage and return them for queries. Due to the flexible structure of JSON, it is possible to pass any JSON documents into a document-oriented NoSQL database. Queries in these databases can access all fields and objects in the documents without prior schema definition and therefore return the documents with matching criteria in queries. There is no need for a schema definition as with the traditional SQL. An example of a database like this is the MongoDB database. The OPC Router features a Plug-in to send data to MongoDB databases. 

11. JSON example

A slightly more complex example is explained in the production order with multiple components. The production order is described by some base fields and an Array which contains the components. Each component is described as a separate object with its own description fields. 

{
"Order number": 4711,
"Quantity": 15000.0,
"Item": "Product A",
"Planned date": "6/4/2020",
"Release": true,
"Components":[
{
"Name": "Component A",
"Material number": 292345,
"Quantity": 345,123,
"Storage areas": [ 3, 6, 23 ] }, {
"Name": "Component B",
"Material number": 908431,
"Quantity": 12034,123,
"Storage areas": [ 1, 2, 9 ] },
{
"Name": "Component C",
"Material number": 928398,
"Quantity": 2623.2,
"Storage locations": [ 10 ] },
] }