Everything in CAP / Node.js
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Domain: Protocols & APIs
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Node.js: Answers in Node.js
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Group by: Capability
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Error handlingSAP and community
Effective Axios Error Logging for Robust SAP IntegrationsEffective Axios Error Logging for Robust SAP IntegrationsTwo logged failures printed side by side, and the point is made by looking at them: one tells you what went wrong and one does not. Axios buries the useful part of an HTTP error, and this is what to unwrap before logging it from a CAP service.Sahil2508, published 2025-08-31
Messaging System for Transferring Error, Warning, and Information Messages from OData V4 Services to HTTP Client ApplicationsMessaging System for Transferring Error, Warning, and Information Messages from OData V4 Services to HTTP Client ApplicationsGetting a message out of a CAP service and onto a Fiori elements object page in a draft scenario — errors, warnings and information, each of which the UI treats differently. Co-written with one of the people on the OData side, and it spends its length on the message container rather than on the handler that fills it.arley-triana-morin, published 2022-08-11
Messaging System for Transferring Error, Warning, and Information Messages from OData V4 Services to HTTP Client Applications
OData changed in @cap-js-community/odata-v2-adapter 1.10.0, 2023-04-05. Affects A recipe, Runnable code.
GraphQLSAP only
CAP: GraphQL as new protocolCAP: GraphQL as new protocolWritten days after @cap-js/graphql appeared, by somebody who went looking for it — an introduction to GraphQL alongside what the adapter actually does to a CAP service. The first outside account of the capability, and still one of very few.jhodel18, published 2023-03-18
CAP: GraphQL as new protocol
@cap-js/graphql has been through 11 major lines since this was published, most recently 0.12 (2025-05), 0.13 (2025-07), 0.14 (2025-10). Affects Runnable code.
ODataSAP and community
#BTP #SAPCAP: Quirky Nuggets (N03-N04)#BTP #SAPCAP: Quirky Nuggets (N03-N04)Two unrelated findings in one post, which is the format of the series: the OData operators tried against a CAP service — with a schema of deliberately awkward types to try them on — and undeploying database artifacts, which is the half people hit in anger. Numbered N03 and N04 of a run that continues either side.Ajit_K_Panda, published 2023-06-05
#BTP #SAPCAP: Quirky Nuggets (N03-N04)
Deployment changed in @sap/cds-dk 8.9.0, 2025-03-31. Affects A recipe, Runnable code.
Adding Immutable Blockchain Proofs to SAP With CAP - Cardano and OData V4Adding Immutable Blockchain Proofs to SAP With CAP - Cardano and OData V4The write-up behind ODATANO, by its author: how a public blockchain gets reachable from CAP as an ordinary OData V4 service rather than through a bespoke client. The premise it starts from is worth the read on its own — SAP systems are trusted but mutable, which is what an immutable anchor is for — and Cardano is chosen for peer-reviewed research and formal methods rather than for popularity. Written as an experiment with feedback invited, not as a recommendation.maxalexweber, published 2026-05-15
Consume Remote Services in a Full-Stack CAP ApplicationConsume Remote Services in a Full-Stack CAP ApplicationExtending the Developer's Guide application with a remote S/4HANA service — connectivity, importing the Business Partner API, and running against it. SAP publishes this as four separate paths: mock server or real S/4HANA Cloud, times Cloud Foundry or Kyma. One entry covers all four, because the difference between them is which backend and which runtime, not what you learn.SAP
Create a Business Service using CDS, Node.js, SQLite and a OData serviceCreate a Business Service using CDS, Node.js, SQLite and a OData serviceThe stack at its smallest — CDS, Node, SQLite, an OData service — worked through at length. Nothing cloud in it, which is the point: it is the shape of a CAP service before any of the platform arrives.raybanton, published 2021-07-12
Create a Business Service using CDS, Node.js, SQLite and a OData service
Database connectors has changed twice since this was published, most recently in @sap/cds 10.1.0, 2026-09-07. Affects A recipe, Runnable code.
Custom Functions in OData V4 – SAP Cloud Application Programming ModelCustom Functions in OData V4 – SAP Cloud Application Programming ModelFunctions rather than actions, and the distinction is where it starts: a function must return data and must never change any, so it is the read-only half of custom operations. Then how to declare and implement one on a CAP service.Roopa_N, published 2021-04-28
Custom Functions in OData V4 – SAP Cloud Application Programming Model
OData changed in @cap-js-community/odata-v2-adapter 1.10.0, 2023-04-05. Affects A recipe.
Extend SAP SuccessFactors on SAP BTP with the SAP Cloud Application Programming ModelExtend SAP SuccessFactors on SAP BTP with the SAP Cloud Application Programming ModelTwelve tutorials, about two hours, building a side-by-side extension of SuccessFactors on BTP. The spine is remote services: importing the SuccessFactors OData service definitions into a CAP model, then treating them as entities the extension reads and writes through, rather than as an API called from a handler. Indexed as one entry because the parts only make sense in order.SAP
How to add OData v2 adapter proxy to your CAP projectHow to add OData v2 adapter proxy to your CAP projectThe problem is stated in one line — a UI5 application that only speaks OData v2 in front of a CAP service that speaks v4 — and the answer is a proxy in the middle rather than a rewrite of either end. Written while v4 support in the UI5 stack was still patchy, which is the whole reason the adapter exists.published 2020-06-30
How to add OData v2 adapter proxy to your CAP project
OData changed in @cap-js-community/odata-v2-adapter 1.10.0, 2023-04-05. Affects Runnable code.
Messaging System for Transferring Error, Warning, and Information Messages from OData V4 Services to HTTP Client ApplicationsMessaging System for Transferring Error, Warning, and Information Messages from OData V4 Services to HTTP Client ApplicationsGetting a message out of a CAP service and onto a Fiori elements object page in a draft scenario — errors, warnings and information, each of which the UI treats differently. Co-written with one of the people on the OData side, and it spends its length on the message container rather than on the handler that fills it.arley-triana-morin, published 2022-08-11
Messaging System for Transferring Error, Warning, and Information Messages from OData V4 Services to HTTP Client Applications
OData changed in @cap-js-community/odata-v2-adapter 1.10.0, 2023-04-05. Affects A recipe, Runnable code.
SAP Cloud Application Programming Model: Deep Insert (4) Consume Remote ServiceSAP Cloud Application Programming Model: Deep Insert (4) Consume Remote ServiceFourth in a long series on deep insert, and the one where the target stops being local. Twenty thousand characters, project files linked, and the earlier parts on UUIDs and multi-level structures are prerequisites the author names.CarlosRoggan, published 2019-07-24
SAP Cloud Application Programming Model: Deep Insert (4) Consume Remote Service
Destinations changed in @sap-cloud-sdk/connectivity 4.0.0, 2025-03-04. Affects A recipe, Runnable code.
SAP Cloud Application Programming Model: Deep Insert (5) Consume Remote Service with SAP Cloud SDKSAP Cloud Application Programming Model: Deep Insert (5) Consume Remote Service with SAP Cloud SDKThe same thing again through SAP Cloud SDK, published as a deliberate comparison with the part before it — the author says outright that it does what the previous post did, differently. Reading both is how you see what the SDK is actually doing for you.CarlosRoggan, published 2019-07-26
SAP Cloud Application Programming Model: Deep Insert (5) Consume Remote Service with SAP Cloud SDK
Destinations changed in @sap-cloud-sdk/connectivity 4.0.0, 2025-03-04. Affects Runnable code.
The Complete Guide to Calling Actions in UI5 with Custom CodeThe Complete Guide to Calling Actions in UI5 with Custom CodeWritten because the documentation is thin and the samples sparse, and openly as a note to the author's future self — hand-coding an action call has become a rare task for anyone mostly working in Fiori elements, which is exactly why it is hard to look up when it comes round. Comes with a CAP sample project, so the service half is there too.published 2025-07-21
The End2End Journey: Advocates Service – CAP Service, OData V2/4 & REST in One single ProjectThe End2End Journey: Advocates Service – CAP Service, OData V2/4 & REST in One single ProjectOne CAP service exposing OData V2, OData V4 and REST at the same time, which is unusual enough to be worth the read on its own. Part of an end-to-end series, deployed on Cloud Foundry against HANA Cloud, so the protocol question sits inside a whole application rather than a snippet.KRiedelsheimer, published 2021-05-06
The End2End Journey: Advocates Service – CAP Service, OData V2/4 & REST in One single Project
OData changed in @cap-js-community/odata-v2-adapter 1.10.0, 2023-04-05. Affects A recipe, Runnable code.
OpenAPISAP and community
Adding a Swagger UI to Your SAP Cloud Application Programming Model / Node.js ServiceAdding a Swagger UI to Your SAP Cloud Application Programming Model / Node.js ServiceThe problem stated from the other side of the wire: a CAP and HANA backend consumed by frontend developers with no SAP background, who said in the first meeting that they could not work from what the service offered. A browsable API page is the answer, and this is the post the Swagger UI plugin indexed here exists to serve.published 2020-01-23
Adding a Swagger UI to Your SAP Cloud Application Programming Model / Node.js Service
cds-swagger-ui-express has been through 11 major lines since this was published, most recently 0.9 (2024-07), 0.10 (2024-10), 0.11 (2026-02). Affects Runnable code.
Invoke OpenAPI-documented APIs remotely with SAP Cloud Application Programming ModelInvoke OpenAPI-documented APIs remotely with SAP Cloud Application Programming ModelThe other direction: consuming an API described by an OpenAPI document from CAP, rather than publishing one. Worth pairing with the plugin entries here, which all serve the outbound half.wittro, published 2022-08-30
Invoke OpenAPI-documented APIs remotely with SAP Cloud Application Programming Model
Destinations changed in @sap-cloud-sdk/connectivity 4.0.0, 2025-03-04. Affects Runnable code.
Serve your application over MCPSAP and community
Add MCP capabilities to a CAP serviceAdd MCP capabilities to a CAP serviceA fifteen-minute walkthrough of turning a plain CAP service into an MCP server: annotate the service with @mcp, install @cap-js/mcp, and it is served alongside OData at /mcp/<path>. The part worth reading it for is what happens next — cds watch writes the endpoint into the local agent's own configuration file, so OpenCode or Claude Code can call the service without anyone editing JSON by hand. It is built on the tiny-sample facet, so there is nothing to prepare, and it shows the protocol traffic rather than only the result. Written while the adapter was in beta, and it says so.published 2026-08-13
Agentic CAP: Build MCP servers and enterprise AI agentsAgentic CAP: Build MCP servers and enterprise AI agentsCAP applications become AI agents over the Model Context Protocol and the Agent2Agent protocol, which is the serve your application over MCP concern, and SAP AI Core is the LLM integration through which AI is embedded in a CAP app, with recommendations from the SAP-RPT-1 model as the abstract's example. The abstract names the two protocols and the one model and does not say which packages carry them. A two-hour TechEd 2026 session in a hands-on room (Tuesday 27 October, Berlin), presented by Daniel Hutzel, Daniel Schlachter, Marc Huber and Sami Lechner, written here from SAP's abstract; the recording is not yet published.
CAP Node.js Expert Session #6 - The MCP AdapterCAP Node.js Expert Session #6 - The MCP AdapterDaniel Schlachter and DJ Adams add @cap-js/mcp to a bookshop service, inspect its describe, query and action tools, and query the catalogue through an AI agent. The session distinguishes this runtime adapter from the development-time MCP server and demonstrates automatic registration of the running service with a local agent. The recording describes the adapter as beta in July 2026, with read-only queries and writes through unbound actions.
Examine the details of the Model Context Protocol on startupExamine the details of the Model Context Protocol on startupWhat the MCP adapter actually does when a CAP server boots, watched rather than described — the companion to the tutorial that switches it on.
Model Context Protocol Adapter — CAP guideModel Context Protocol Adapter — CAP guideDocuments @cap-js/mcp and com.sap.cds:cds-adapter-mcp, service annotations, generated describe/query/call tools and local client setup. The guide records Java doc-comment configuration, unbound-action-based data changes, incomplete XSUAA PKCE support and the adapter’s governance boundaries.
Natural Language Queries for SAP CAP via MCP: The LLM Translates, CDS ExecutesNatural Language Queries for SAP CAP via MCP: The LLM Translates, CDS ExecutesThe division of labour is the argument, and it is in the subtitle: the model turns English into a CDS query and CDS runs it, so nothing generates SQL and nothing hallucinates a join. Schema annotations do the resolving. Long, with the package, the repository and the MCP registry entry all linked.Shahid, published 2026-06-25
The Easiest Way to Expose a CAP Node.js Project as an MCP ServerThe Easiest Way to Expose a CAP Node.js Project as an MCP ServerFrom cds init to a running MCP server in a handful of steps, ending at the MCP Inspector so the result is something you can see rather than something you have to trust. The claim it makes for the plugin is the absence of work: no REST wiring by hand, the CAP application exposed as a server because the package is installed. A walkthrough rather than an argument — the reasoning about what should be exposed lives elsewhere.Jacky Liu, published 2026-07-03
WebSocketCommunity only
CAP WebSocketsCAP WebSocketsThe early one, from 2021, before an adapter existed to make it ordinary. Read for what the problem looked like when it had to be solved by hand.vvdries, published 2021-01-26
Real-Time Architecture in SAP CAP: Mastering Asynchronous Jobs, Gateways with WebSocketsReal-Time Architecture in SAP CAP: Mastering Asynchronous Jobs, Gateways with WebSocketsThe other half of the author's own industrial-data post: mass ingestion is only useful if the screen keeps up, so background jobs push progress to the UI over WebSockets instead of the user reloading. Written from a mission-critical case rather than a demo.rgadirov, published 2026-03-12
Real-Time Architecture in SAP CAP: Mastering Asynchronous Jobs, Gateways with WebSockets
Async processing changed in @sap/cds 10.0, 2026-07-02. Affects A recipe.
Streaming LLM Output with CAP and WebSocketsStreaming LLM Output with CAP and WebSocketsTokens arriving from the AI SDK's orchestration module, forwarded to the browser as they come rather than after the model finishes. Covers all four pieces — enabling WebSocket support in CAP, a service with actions and events, the streaming itself, and a frontend on the native WebSocket API — which is what makes it the clearest case for why a CAP service would want a socket at all.RobinP, published 2025-11-18
Streaming LLM Output with CAP and WebSockets
LLM integration changed in @cap-js/ai 1.0.0, 2026-04-28. Affects A recipe, Runnable code.