Roy's CCNA Notes

Day 60 - JSON, XML, & YAML

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Jeremy’s IT Lab lecture video:

Day 60 - JSON, XML, & YAML

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JSON, XML, & YAML Info

Data serialization is the process of converting data into a standardized format/structure that can be stored (in a file) or transmitted (over a network) and reconstructed later (by a different application).

  • This allows the data to be communicated between applications in a way both applications can understand.
  • Data serialization languages allow us to represent variables with text.
Example of Data Serialization

Data Serialization Languages

There are three different data serialization languages you need to know for the CCNA, being:

  1. JSON
  2. XML
  3. YAML

1. JSON

JavaScript Object Notation (JSON) is an open standard file format and data interchange format that uses human-readable text to store and transmit data objects.

  • It was derived from JavaScript, but it is language-independent and many modern programming languages are able to generate and read JSON data.

JSON Properties

  • JSON is very human-readable
  • REST APIs often use JSON.
  • Whitespace is insignificant
  • JSON can represent four ‘primitive’ data types
    1. String
      • A string is a text value. It is surrounded by double quotes ” ”.
      • Examples: ( “Hello.” | “five” | “5” | “true” | “null” )
    2. Number
      • A number is a numeric value. It is not surrounded by quotes.
      • Examples: ( 5 | 100 )
    3. Boolean
      • A boolean is a data type that has only two possible values. It is not surrounded by quotes.
      • ( true | false )
    4. Null
      • A null value represents the intentional absence of any object value. It is not surrounded by quotes.
      • ( null )
  • JSON also has two ‘structured’ data types:
    1. Object
      • Sometimes called a dictionary
      • An object is an unordered list of key-value pairs (variables)
      • The key is a string.
      • The value is any valid JSON data type (string, number, boolean, null, object, array).
      • The key and value are enclosed with curly brackets ( { } )
      • The key and value are separated by a colon ( : )
      • If there are multiple key-value pairs, each pair is separated by a comma ( , )
      • Objects within objects are called ‘nested objects’.
    2. Array
      • Values are enclosed with square brackets ( [ ] )
      • An array is a series of values separated by commas ( , )
      • The values can be any type of data type.
      • The values don’t have to be the same data type.
JSON Object Example (1)
JSON Object Example (2)
JSON Object Example (3)
JSON Array Example (4)

2. XML

Extensible Markup Language (XML) was developed as markup language, but is now used a general data serialization language.

XML Properties

  • XML is generally less human-readable than JSON.
  • REST APIs often use XML.
  • Whitespace is insignificant.
  • XML is represented as key-value pairs.
  • It is presented as <key>value</key>.
XML Example (1)

3. YAML

Yet Another Markup Language (YAML) is also used a data serialization language.

  • YAML is used by the network automation tool Ansible.

YAML Properties

  • YAML is the most human-readable language.
  • Whitespace is significant (unlike JSON and XML). That means that indentation is very important.
  • YAML files start with ---.
  • - is used to indicate a list.
  • Keys and values are represented as key:value
YAML Example (1)

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