If you have worked with SAP applications, you have probably heard this:
"OData V4 is better than V2."
That is true. But only if you understand why.
This blog explains the difference without assuming deep technical knowledge, and helps you understand what actually changes when moving from OData V2 to V4.
First: This Is Not Just a Version Change
OData V4 is not a small upgrade of OData V2.
Think of it like this:
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OData V2: Flexible, forgiving, easy to start with
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OData V4: Structured, strict, designed for modern apps
Because of this, apps written for V2 often do not behave correctly with V4 unless they are adapted.
1. How Data Is Read (UI Perspective)
OData V2 – Simple but Loose
In V2-based apps:
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Data was often fetched using simple paths
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The framework tried to "figure things out"
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Even imperfect bindings often worked
OData V4 – Explicit and Structured
In V4:
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Data is always accessed through a context
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A context simply means:
"Which exact record am I currently working with?"
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The app must be clear and precise
Why this matters:
V4 avoids guessing. Clear instructions lead to predictable behavior.
2. Actions and Functions
What are Actions and Functions?
In simple terms, backend operations like:
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Approve
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Reject
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Recalculate
OData V2
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UI directly triggered backend logic
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Easy, but often tightly coupled to screens
OData V4
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Actions belong to business objects
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UI only triggers them
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Execution and lifecycle are controlled by the framework
This fits perfectly with RAP, where behavior is part of the business object.
3. Error Handling and Timing
OData V2
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Callback-based
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Errors could be missed or ignored
OData V4
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Everything is asynchronous
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The app waits for the backend
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Errors are handled in a predictable way
In simple words:
V4 makes failures visible instead of hiding them.
4. Metadata and UI Behavior
What is Metadata file?
A Metadata file defines Fields, Keys, Relationships, UI behavior.
OData V2
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Metadata could be incomplete
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UI tried to compensate
OData V4
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Metadata must be correct
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UI behavior is fully driven by it
This is why Fiori Elements works so well with OData V4.
5. Batch Processing ($batch)
What is Batch Processing?
Batch processing means:
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Sending multiple requests together
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Instead of many small network calls
OData V2
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Batch handling was optional
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Often complex to configure
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Easy to misconfigure or avoid altogether
OData V4
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Batch processing is a core design principle
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Optimized for performance by default
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The framework handles most of the complexity
Why this matters:
V4 apps make fewer network calls, which directly improves performance.
6. Filtering and Searching
OData V2
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Filtering worked mostly at the top level
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Searching within related or child data was limited
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Complex queries often required custom logic
OData V4
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Supports much richer filtering
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Allows searching and filtering across relationships
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Better suited for real-world business scenarios
Example in simple terms:
V4 can ask questions like:
"Give me all orders where any item has quantity greater than 10"
This was difficult or impossible in V2.
7. Why RAP and OData V4 Work So Well Together
RAP (ABAP RESTful Application Programming Model) and OData V4 have evolved together in SAP's development ecosystem.
The Evolution:
RAP's V2 API started in 2016 and was later enhanced to leverage RAP technology.
The V4 API, launched in 2021, was built on a more mature RAP framework from the start.
This means V4 was able to take advantage of established RAP patterns and capabilities.
Why They Align So Well:
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Draft handling: V4's draft mechanism fits naturally with RAP's managed approach
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Actions and validations: Business object behaviors in RAP align cleanly with V4's action model
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UI behavior: V4's strict metadata requirements match RAP's annotation-driven approach
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Performance: Both are optimized for modern application patterns
Using RAP with V2 often feels like adapting modern concepts to work within older constraints, while V4 leverages RAP's full capabilities from the ground up.
8. Smart Controls vs Modern UI
OData V2 Era
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SmartTable
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SmartFilterBar
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Runtime-heavy interpretation
OData V4 Era
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Fiori Elements
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Annotation-driven UI
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Predictable behavior
This is a major reason apps break when switching to V4 without redesign.
9. Integration Note
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OData V2 is still widely used in integrations
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Many tools were originally built around it
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V4 can be used, but often needs more explicit handling
So yes, V2 is still very relevant in integration-heavy landscapes.
Final Summary
Use OData V2 when:
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You maintain older UI5 apps
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You rely on Smart Controls
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You want stable, known behavior
Use OData V4 when:
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You build new applications
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You use RAP
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You use Fiori Elements
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You want better performance and cleaner architecture
OData V2 helps SAP scale quickly.
OData V4 helps SAP build correctly.
