60. JSON, XML, AND YAML

DATA SERIALIZATION

• 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 (ie: by a different application)

  • This allows the DATA to be communicated between applications in a way both APPLICATIONS understand.

• DATA SERIALIZATION languages allow us to represent variables with text

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JSON (JAVASCRIPT OBJECT NOTATION)

• JSON (JAVASCRIPT OBJECT NOTATION) **is an open standard FILE FORMAT and DATA INTERCHANGE FORMAT that uses human-readable text to store and transmit data objects

• It is standardized in RFC 8259 (https://datatracker.ietf.org/doc/html/rfc8259)

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

  • REST APIs often use JSON

• Whitespace is insignificant

• JSON can represent FOUR “primitive” DATA Types:

  • String
  • Number
  • Boolean
  • Null

• JSON also has TWO “structured” DATA Types:

  • Object
  • Array

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JSON PRIMITIVE DATA TYPES:

• A STRING is a text value. It is surrounded by double quotes “ “

  • “Hello”
  • “Five”
  • “5”

• A NUMBER is a numeric value. It is NOT surrounded by quotes

  • 5
  • 100

• A BOOLEAN is a DATA Type that has only TWO possible values, not surrounded by quotes

  • true
  • false

• A NULL value represents the intentional absence of any object value. It is not surrounded by quotes

  • null

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JSON STRUCTURED DATA TYPES:

• An OBJECT is an unordered list of key-value pairs (variables)
  • Sometimes called a DICTIONARY
  • OBJECTS are surrounded by curly brackets {}
  • The key is a STRING
  • The value is any valid JSON DATA Type (string, number, boolean, null, object, array)
  • The key and value are separated by a colon :
  • If there are multiple key-value pairs, each pair is separated by a comma

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• An ARRAY is a series of values separated by commas
  • Not key-value pairs
  • The values do NOT have to be the same DATA Type

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XML (EXTENSIBLE MARKUP LANGUAGE)

• XML (EXTENSIBLE MARKUP LANGUAGE) was developed as a MARKUP language, but is now used as a general data serialization language
  • Markup languages (ie: HTML) are used to format text (font, size, color, headings, etc)
  • XML is generally less human-readable than JSON
  • Whitespace is insignificant
  • Often used by REST APIs
  • <key> value </key> (similar to HTML)

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YAML (YAML AIN’T MARKUP LANGUAGE)

• YAML originally meant YET ANOTHER MARKUP LANGUAGE but to distinguish its purpose as a data-serialization language rather than a markup language, it was repurposed to YAML AINT MARKUP LANGUAGE
• YAML is used by the network automation tool ANSIBLE (covered later in the course)
• YAML is VERY Human-Readable
• Whitespace is significant (unlike JSON and XML)
  • Indentation is very important
• YAML files start with - - - (three dashes)
• • is used to indicate a list
• Keys and Values are represented as key : value

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COMPARISON BETWEEN JSON and YAML using the same DATA

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