Density.md

Density

The goal is to talk about density of information in data format like XML, JSON, YAML, HTML, CSV

Node Density

The node density is the number of node that we can create with any given amount of bytes

XML Node Density: max 40%

For example, the maximum node density is reached via this simple pattern

a<b/>

which makes 5 bytes long and generates 2 nodes:

• a text node with the string "a"
• a element with the name "b"

So in the end

<r>(a<b/>)+</r>

is the densiest XML available in node density: 40%.

JSON Node Density: max 50%

For example, the maximum node density is reached via this pattern

[1,1, ... ,1]

which provides 1 node (number_value) for each 2 bytes: "," and "1".

So in the end

{"A":[1,1, ... ,1]}

is the densiest JSON available in node density: 50%.

Event Density

The event density is the number of event that we can create with any given amount of bytes. Their is a direct relationship with Node density:

• Node density <= Event density (always)

It comes from the fact that every node that is always a leaf (attribute, processing-instruction) generates 1 events, while node that can contains other node always generate 2 events (start_element, end_element)

XML Event Density: max 60%

For example, the maximum event density is reached via this simple pattern

a<b/>

which makes 5 bytes long and generates 3 events:

• a text event with the string "a"
• a start_element event with the name "b"
• a end_element event with the name "b"

So in the end

<r>(a<b/>)+</r>

is the densiest XML available in event density: 60%

JSON Event Density: max 99,99%

Zero depth: max 66,67%

For example, the maximum node density is reached via this pattern

[{},{}, ... ,{}]

which provides 2 events (start_object and end_object) for each 3 bytes: "," and "{" and "}".

So in the end

{"A":[{},{}, ... ,{}]}

is the densiest JSON available in Event density without depth: 66,67%.

Increasing depth: max 99,99%

For example, the maximum node density is reached via this pattern

[[[.....[[......]].....]]]

which provides 2 events (start_array and end_array) for each 2 bytes: "[" and "]".

So in the end

{"A":[[[.....[[......]].....]]]}

is the densiest JSON available in Event density with depth: 99,99%.