Data exchange is the process of transforming structured data from one format to another to facilitate data sharing between programs
A data exchange language is a language that is capable of expressing general purpose data
We will look at two data exchange languages that are commonly used to share data sets:
Comma Separated Values (CSV)
JavaScript Object Notation (JSON)
A CSV file is used to represent tabular data
The proposed specification:
is plain text using a character set such as ASCII, Unicode, etc.
consists of records (typically one record per line,
with the records divided into fields separated by delimiters (typically a single reserved character, such as a comma),
where every record has the same sequence of fields.
Within these general constraints, many variations are used, that is, there is no standard CSV format.
JSON is designed to be a lightweight data exchange language
JSON is data is plain text
The file extension for JSON files is .json
The MIME type for JSON text is application/json
JSON syntax is similar to the syntax of defining literal objects in JavaScript:
Data is in name/value pairs of the form "name":value
Data is separated by commas
Curly braces hold objects
Square braces hold arrays
Number: a signed decimal number
String: a sequence of zero or more unicode characters delimited by by double quotes
Boolean: a value of true or false
Array: an ordered list of zero or more values separated by commas and delimited by square brackets
Object: an unordered collection of name/value pairs where pairs are separated by commas and delimited by curly braces
Null: the empty value indicated by the word null