COMP1531
4.1 - SDLC Development - Data Transfer
Standard Interfaces
In any field in engineering, we often have systems, components, and designs built by different parties for different purposes.
How do all of these systems connect together? Through standard interfaces
Standard Interfaces
Data Interchange Formats
When it comes to transferring data, we also need common interface(s) that people all send or store data in universal ways to be shared between applications or shared over networks.
Three main interchange formats we will talk about:
- JSON
- YAML
- XML
JSON
JavaScript Object Notation (JSON) - TFC 7159
A format made up of braces for dictionaries, square brackets for lists, where all non-numeric items must be wrapped in quotations. Very similar to python data structures.
JSON
Let's represent a structure that contains a list of locations, where each location has a suburb and postcode:
{
"locations": [
{
"suburb" : "Kensington",
"postcode" : 2033
},
{
"suburb" : "Mascot",
"postcode" : 2020
},
{
"suburb" : "Sydney CBD",
"postcode" : 2000
}
]
}Note:
- No trailing commas allowed
- Whitespace is ignored
JSON - Writing & Reading
Python has powerful built in libraries to write and read json.
This involves converting JSON between a python-readable data structure, and a text-based dump of JSON
json_it.py
unjson_it.py
YAML
YAML Ain't Markup Language (YAML) is a popular modern interchange format due it's ease of editing and concise nature. It's easy to convert between JSON and YAML online.
---
locations:
- suburb: Kensington
postcode: 2033
- suburb: Mascot
postcode: 2020
- suburb: Sydney CBD
postcode: 2000
Note:
- Like python, indentation matters
- A dash is used to begin a list item
- very common for configuration(s)
XML
eXtensible Markup Language (XML) is more of a legacy interchange format being used less and less
<?xml version="1.0" encoding="UTF-8"?>
<root>
<locations>
<element>
<postcode>2033</postcode>
<suburb>Kensington</suburb>
</element>
<element>
<postcode>2020</postcode>
<suburb>Mascot</suburb>
</element>
<element>
<postcode>2000</postcode>
<suburb>Sydney CBD</suburb>
</element>
</locations>
</root>
XML
Issues with XML include:
- More verbose (harder to read at a glance)
- More demanding to process/interpret
- More bytes required to store (due to open/closing tags)
While you will find very few modern applications choose to use XML as an interchange format, many legacy systems will still use XML as a means of storing data
COMP1531 21T1 - 4.1 - SDLC Development - Data Transfer
By haydensmith
