Textual Data Formats in API Communication

When APIs exchange information over networks, data must be serialized before transmission. Picture this process as packing a suitcase before a trip – you need to organize and compress your belongings to fit the limited space.

While programming languages offer built-in serialization methods (like Ruby’s Marshal or Python’s pickle), these come with drawbacks. They often tie APIs to specific languages and lack efficient version control. Moreover, they can be resource-intensive and produce bulky encoded data. That’s why developers frequently opt for standardized encoding formats such as XML, JSON, or Protobuf.

Let’s explore two popular text-based formats: XML and JSON.

XML

Extensible Markup Language (XML) is a subset of SGML, designed for web data exchange. It resembles HTML but allows custom tags, making it highly flexible. Here’s a taste of XML structure:

XML
<?xml version="1.0" encoding="UTF-8"?>

<recipe id="42" cuisine="Italian">

  <name>Spaghetti Carbonara</name>

  <ingredients>

    <item>Pasta</item>

    <item>Eggs</item>

    <item>Pancetta</item>

  </ingredients>

  <instructions>

    <step>Boil pasta</step>

    <step>Mix eggs and cheese</step>

    <step>Combine all ingredients</step>

  </instructions>

</recipe>

XML shines in scenarios requiring robust structure and extensive metadata. It’s widely used in:

  1. Secure B2B data exchange (e.g., SOAP protocols)
  2. Web automation (thanks to efficient search capabilities)
  3. Complex data storage in industries like wireless communication

However, XML has its limitations:

  • Verbose due to repetitive tags
  • Large file sizes
  • Lacks native support for number types and binary strings

JSON

JavaScript Object Notation (JSON) emerged as a simpler alternative to XML. It uses key-value pairs and supports four primitive types: strings, numbers, booleans, and null. Here’s our recipe in JSON:

JSON
{

  "id": 42,

  "cuisine": "Italian",

  "name": "Spaghetti Carbonara",

  "ingredients": ["Pasta", "Eggs", "Pancetta"],

  "instructions": [

    "Boil pasta",

    "Mix eggs and cheese",

    "Combine all ingredients"

  ]

}

JSON’s strengths include:

  • Language independence
  • Popularity in web and mobile applications
  • Compact size and faster parsing compared to XML
  • Lower network latency

However, JSON isn’t without flaws:

  • Lacks standardized ways to define common descriptions
  • No built-in distinction between integers and floats
  • Limited precision for large numbers
  • Inconsistent use of schema definitions

Choosing Your Format

When selecting between XML and JSON, consider these factors:

  1. Readability: Both are human-readable, but JSON is generally easier to parse visually.
  2. Latency: JSON typically offers lower latency due to its compact nature.
  3. Standardization: XML supports partial standardization through namespaces and schemas, while JSON lacks widespread standardized usage.
  4. Machine-friendliness: Neither format is particularly machine-friendly out of the box.
  5. Interoperability: XML excels in multi-domain use, while JSON is popular in JavaScript-based systems but adaptable to others.
  6. Flexibility: Both offer full compatibility for forward and backward changes.