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BTP CAP : Custom plugin to separate generic change log capture logic
Walks through building a custom [CAP](ecosystem:cap) plugin that centralises change-log capture: on cds.once('served') it collects entities annotated @audit, then hooks srv.before('UPDATE') to read the existing record, diff it field by field against the incoming payload, and record old/new values with the user and timestamp. It also documents a cds build failure packaging the plugin's own directory into gen/srv for MTA deployment, fixed by adding it as a copyfiles build-parameter step in mta.yaml.
Where it sits
Explains
Change trackingCAPChange trackingKeeping a readable history of what changed on a record, who changed it and when — as business history rather than database journalling.Plugin authoringCAPPlugin authoringWriting a package that extends a framework or runtime rather than an application that uses it — a reusable extension loaded by its host, and the question you arrive at once solving a problem twice makes you want to solve it once for everyone.
Source
reachable
Who is behind it
sreehari_vpillaiauthor
Properties
About this work
For change-tracking
Applies in
Group by10 of 10 pieces
Piece, what it offersStill applies
What's in Daniel Hutzel's brain?What's in Daniel Hutzel's brain?A Devtoberfest 2026 session in the building-apps track, in which Daniel Hutzel and DJ Adams work through what the CAP team is building for agents. A bookshop gets an MCP endpoint beside its OData one from a single annotation, with the plugin writing the coding agent's configuration itself; in the xt-travels sample five services that know nothing about each other are served over MCP and an agent does the orchestration the hand-built UI and its value helps used to do. Hutzel then annotates a service as an agent so the ReAct loop and the choice of model move into the CAP service, and finally drops MCP for a skill that teaches the agent CQL instead, which is where the edges to Serve your application over MCP, Agent tooling and Agent guidance come from. The mechanism under all of it, a plugin file in the package root and event handlers that can be added to any CAP service, is the edge to Plugin authoring.published 2026-10-02
DRY CAP – Making Sustainable Solutions Through PluginsDRY CAP – Making Sustainable Solutions Through PluginsA Devtoberfest 2026 building-apps session on packaging the things you would otherwise write twice, from in-house API clients and shared data models to validation logic, as a CAP plugin. The presenter builds one live: a cds-plugin.js next to package.json is what makes CAP notice the plugin at all, an index.cds carries a reusable user context and service that the consuming application projects into its own and protects there, and the plugin registers an Express middleware at a chosen step of the bootstrap to put user properties on the request. A feature-flagging plugin his team already uses closes it, and the whole walkthrough is the edge to Plugin authoring.SAP Developers, published 2026-10-02
CAP: The Road Ahead - Simplicity in an AI EraCAP: The Road Ahead - Simplicity in an AI EraDevtoberfest 2026 session CAP10, from the head of SAP's Cloud Application Programming Model: forty minutes of live building rather than slides, on the argument that the cheapest code in an AI project is code nobody has to generate. Claude Code builds an invoice-matching workspace from cds init onwards, and each step is one the framework answers rather than the agent: a 42-line domain model that @sap/cds serves as OData and Fiori elements with a status flow, data privacy and change-tracking annotations that produce audit log entries in the console and would reach the SAP Audit Log service once deployed, an imported S/4HANA supplier data product, and semantic matching from a local embedding model after @cap-js/ai is added. The last three steps are annotations: @mcp beside @odata turns the service into an MCP server that a second Claude session queries through @cap-js/mcp, an agent annotation adds the A2A protocol with an agent card and an audit log entry for the agent task, and a skill file gives the agent the matching policy.SAP Developers, published 2026-09-25
New and improved: Change Tracking pluginNew and improved: Change Tracking pluginThe 2.0 announcement, and unusually candid about why there is a 2.0 at all: the plugin already existed and was, in the author's words, plagued by many issues. What it records is every insert, update and delete with the user and the timestamp, aimed at root-cause analysis and at detecting changes nobody authorised. Generally available as of this post, having been hinted at as beta in the April release notes.published 2026-06-12
New and improved: Change Tracking plugin
cds 2, line ended. Affects A recipe, Runnable code.
Create your first CAP pluginCreate your first CAP pluginA step-by-step guide to the cds-plugin.js extension point: scaffold a package, add an index.cds for shared model artifacts, and test it locally against a throwaway CAP project before publishing to npm, with a separate section on building the same plugin in TypeScript and compiling it with tsc. Points to the author's own cds-plugin-handlers and ui5-cap-serverside-rendering-plugin as worked examples.published 2024-12-09
SAP AI Services - DOX - Gen AI with SAP CAP Plugin - Part 3SAP AI Services - DOX - Gen AI with SAP CAP Plugin - Part 3Building on Reusable components for CAP with cds-plugin by Daniel Schlachter, this part walks through a custom CAP plugin — a cds-plugin.js plus a lib_cap_dox.js helper — that authenticates against SAP's Document Information Extraction (DOX) service and calls its schema and job-status APIs to fill an entity from extracted document fields. It covers reading the service key from Cloud Foundry (cf service-key) for the OAuth token endpoint, and dynamically mapping DOX's header and line-item output onto CAP entity properties.sabarna17, published 2024-06-11
Open Sourcing CAP – how to learn more or get involvedOpen Sourcing CAP – how to learn more or get involvedA roundup of CAP's open-sourcing, begun at TechEd the year before, pointing to a webinar recording, a podcast episode and reCAP 2023 talks for background. Among the components it names are a feature toggle library giving Node.js CAP apps live-updatable toggles backed by Redis, a new pluggable database layer with SQLite and PostgreSQL implementations plus a generic SQL layer, and a change tracking component that builds a change history for data from CDS models.Fempel, published 2023-10-02
How to build reusable plugin components for CAP Java applicationsHow to build reusable plugin components for CAP Java applicationsA companion to Daniel Schlachter's Reusable components for CAP with cds-plugin, showing the same mechanism on CAP Java: a plugin ships as its own Maven artifact with an event handler and a CdsRuntimeConfiguration implementation, registered through the JDK's ServiceLoader rather than any CAP-specific wiring. The walkthrough builds a cds-emoji-plugin-java jar that decorates @emoji-annotated fields on read, installs it to the local Maven repository, and adds it as a runtime dependency to a cds init --add java bookshop application. It argues the plugin mechanism was not new to CAP Java, just previously undocumented.robinjayasinghe, published 2023-05-16
Reusable components for CAP with cds-pluginReusable components for CAP with cds-pluginThe post that taught the mechanism, and it teaches it by picking a requirement small enough to be absurd: every string a service returns should end in a random emoji. Working through that on the bookshop example leaves nothing to argue about except the plumbing, which is the point — what a cds-plugin is, where it hooks in, and why packaging it beats copying it into the next project. Vinícius Barrionuevo credits this post as the thing that gave him the idea for sap-cap-sdm-plugin, and it is hard to read the plugin ecosystem in this graph without it.published 2023-04-30
AI needs a foundation: A map of the plug-in ecosystem for CAPAI needs a foundation: A map of the plug-in ecosystem for CAPA map of the plug-ins for CAP (@sap/cds), official, community and independent, drawn across regions such as integration, performance and tooling, so that a team can see what exists to reuse and what it would have to build: the question plugin authoring answers from the other side. SAP's abstract places CAP at the centre of its AI strategy, with model context protocol support, and the map is offered as the foundation under that. A TechEd 2026 session (Tuesday 27 October, Community Theater, Berlin), presented by Mike Zaschka, written here from SAP's abstract; the recording is not yet published.
Details
Graph
Change trackingcapability, core and community
Plugin authoringcapability, core only
SAP Communitypublishing source
SAP Communitycap-tag
Source
Type
blog
Published on
Host
community.sap.com
Discovered via
First seen
History
- explains → applies_to on capability:change-tracking (cap)Door scope proposed from the title and summary, so a door page lists the piece only where it holds (docs/concepts/content-on-doors.md).
- Entered the atlasDiscovered via SAP Community · cap-tag.
For your agent
- Ref
content:btp-cap-custom-plugin-to-separate-generic-change-log-capture-logic- JSON
- /content/btp-cap-custom-plugin-to-separate-generic-change-log-capture-logic.json
- MCP
- Connecting an agent