ajson
abap2UI5 handles all frontend-backend communication with JSON. Initially, the framework used SAP's /UI2/CL_JSON, but that approach turned out to be problematic: key behavior varied across releases, documentation was sparse, and compatibility issues came up often.
The solution: ajson, a solid open-source JSON library that greatly improved abap2UI5's functionality.
Why ajson?
- Zero SAP API Dependencies — No reliance on release-specific SAP classes
- Broad Compatibility — Works smoothly from NW 7.02 to ABAP Cloud
- Developer-Friendly — Clear API with thorough documentation
- Active Maintenance — Responsive issue resolution and ongoing improvement
It is the framework's engine, not an API for your app
ajson is what serializes the model on every roundtrip and what reads the delta back — z2ui5_cl_ui5_srv_model is built on it, and so is _bind( json = abap_true ). That is where it belongs.
What ships under z2ui5_cl_ajson is a mirrored copy of an external project (src/00/01), not a contract abap2UI5 owns. It sits outside the released API, it is resynced from upstream automatically (see below), and a resync is free to change it. An app that calls it binds itself to whatever the mirror looks like today — which is why the abap2UI5 linter reports such a call as non-released-api, correctly.
Do not call it from app code
Nothing in an app class should name z2ui5_cl_ajson, z2ui5_cx_ajson_error, z2ui5_if_ajson_mapping or z2ui5_if_ajson_filter. There is no released JSON parser to use instead, and that is deliberate — see JSON is built and read by hand for what to write in both directions.
Nor is there a substitute to reach for: /ui2/cl_json is not released for ABAP Cloud and xco_cp_json is missing on 7.02 — the two reasons the framework vendored a library in the first place.
Automatic Updates
Every ajson update and bug fix flows into abap2UI5 automatically via GitHub Actions and the mirror-ajson repository. You always run the latest stable version — no manual steps needed.
That automation is the other half of the argument above: the copy in your system moves without anybody in this project reviewing the diff for app-facing impact, because nothing app-facing is supposed to depend on it.