Data Exchange Formats

Data Exchange

• 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)

Comma-separated Values (CSV)

• A CSV file is used to represent tabular data

• The proposed specification:

  1. is plain text using a character set such as ASCII, Unicode, etc.

  2. consists of records (typically one record per line,

  3. with the records divided into fields separated by delimiters (typically a single reserved character, such as a comma),

  4. 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.

JavaScript Object Notation (JSON)

• 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

• 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

JSON Data Types

• 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