Everything in CAP / Java
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Java: Answers in Java
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Tenant extensibilityUnmapped
Custom Business Logic Extensibility in CAP (CDS-Oyster)Custom Business Logic Extensibility in CAP (CDS-Oyster)A Devtoberfest 2026 session walking @sap/cds-oyster — at version 0.55, with 1.0 stated for Q4 — end to end on a multitenant xtravels, from the application developer's side and the extension developer's side. The application developer adds a submit-for-review action to the status flow and opens exactly one surface for custom code: a separate extension service marked as extensible code, holding a no-op validate action and two read-only helper entities, which the host application calls before the status change; nothing else is extensible, because the annotation defaults to false. The extension developer works in a project whose base model came from cds pull, with test data, a server.js and types from @cap-js/cds-typer added so the UI and code completion work, debugs the handler locally and pushes it as an @sap/cds-mtxs extension, after which the next request rejects a travel over the policy limit without a restart — the code having been stored as an annotation in the tenant's model and run in a Rust WebAssembly sandbox with no database connection, whose queries go back to the CAP runtime as CQL strings, which is tenant extensibility extended from fields to logic.published 2026-10-09
