SOAP

SOAP (Simple Object Access Protocol) is a formal, XML-based messaging protocol. It was designed to be platform-independent, letting systems exchange structured information over HTTP (or even SMTP).

• Default format:
  • SOAP uses XML by design. It’s an XML-based protocol.
  • The request and response envelopes are always in XML.
• Can SOAP use JSON?
  • Not really. The protocol itself defines an XML envelope structure.
  • Some systems might convert or wrap JSON inside XML or expose a JSON-like endpoint separately, but that’s non-standard and rare.

So: SOAP is generally XML-only.

OData

OData (Open Data Protocol) is a REST-based standard that goes beyond basic REST by adding rich query options ($filter, $expand, etc.). It supports both JSON and XML, depending on what the client asks for.

• Default formats:
  • OData (especially OData v4) is designed to be format-flexible.
  • It commonly supports:
    • JSON (most common nowadays, especially for web APIs/OData v4).
    • XML / AtomPub (more common in older OData or specific scenarios).
• The format is typically determined by the Accept HTTP header. For example:
  • Accept: application/json → get JSON
  • Accept: application/atom+xml → get Atom/XML

So: OData supports both JSON and XML.

Summary

SOAP: Strictly XML. No JSON without heavy workarounds.
OData: Fully supports both JSON and XML, modern clients default to JSON.

Protocol	Supports JSON?	Supports XML?	Typical output
SOAP	❌ (not directly)	✅	XML
OData	✅	✅	JSON (modern) or XML

What does this mean for Business Central developers?

• If you’re building integrations with new web or mobile apps, OData (JSON) is typically your best choice. It’s lightweight, modern, and easy for frontend frameworks or microservices to consume.
• If you’re integrating with older systems or existing SOAP-based infrastructure, you’ll continue to use SOAP (XML). Business Central makes this easy by exposing Codeunits and Pages as SOAP services.