3. Semi-structured Data (JSON & XML)

Question 1

What is structured data? Given an example

Answer 1

Data with high degree of organization, conforming to a data model which defines what the fields of data are and how they will be stored.
An example of this is data in a relational database, where data is managed using SQL

Question 2

What is semi structured data? Give an example

Answer 2

Form of structured data which does not conform to a formal structure such as with relational databases, but does contain tags and/or markers to enforce hierarchies of records and fields within data.
An example of this is using JSON, which allows transfer of data between programs using parsers such as javax

Question 3

What is unstructured data? Give and example

Answer 3

Data that does not conform to any formal structure or data model, or is not organized in a pre-defined manner.
An example of this is gathering bulk text online, or media such as images and streamed data

Question 4

Describe the main features of JSON (3)

Answer 4

• JavaScript Object Notation is a standard data-interchange format derived from JavaScript
• It is text based so is language dependent, so can be used with any programming language.
• It is so popular because it’s easy for humans to read and write, but is also easy for machines to parse and generate

Question 5

Describe the main features of XML (3)

Answer 5

• eXtensible Markup Language is standard, flexible text format derived from SGML
• It was originally designed to meet the challenges of large-scale electronic publishing
• Used to exchange a wide variety of data on the web

Question 6

How would XML be ‘well-formed’ (3)

Answer 6

• It contains only properly encoded legal Unicode characters
• The begin, end and empty-element tags that delimit elements are all correctly nested
• There is a single root element that contains all other elements

Question 7

What is a Streaming API? (3)

Answer 7

• Provides input and output streams that recognise basic syntax
• Provides methods to read/write next tag or object from document
• Good for query and modify tasks, and processing large objects

Question 8

What is a Object Model (In-memory) API? (3)

Answer 8

• Provides in-memory representation of whole XML document or JSON object
• Provides methods to read/write whole thing
• Good for load and unload tasks, particularly for smaller objects