Everything in CAP / Java
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Domain: Protocols & APIs
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Java: Answers in Java
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Domain Protocols & APIsSource capireSource SAP CommunitySource SAP Developer CenterPublished 2025Published 2023Clear all
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Error handlingSAP only
Beginners Guide to Advanced Event MeshBeginners Guide to Advanced Event MeshA scenario-by-scenario walkthrough of Advanced Event Mesh, run through Cloud Integration iFlows: publishing and consuming queue messages, dead message queue setup with retry counts and acknowledgment modes, direct messages, durable topic endpoints and selectors, time-to-live, REST Delivery Points, replay by replication group message ID, parallel consumers with partition keys, and the request-reply pattern. Each scenario is built and verified step by step against a Solace trial account standing in for AEM.PriyankaChak, published 2025-07-24
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
GraphQLUnmapped
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.
SAP CAPv7 - Node.js Highlights and ExperiencesSAP CAPv7 - Node.js Highlights and ExperiencesAn account of upgrading a 100+ table CAP Node.js project from v6 to v7, working through breaking changes in @sap/cds 7: event handlers now always receive an array, service paths move under /odata/v4/... unless serve_on_root is set, and cds-serve replaces cds run. It goes deepest on the GraphQL plugin, @cap-js/graphql: the /graphql endpoint it serves, Composition results wrapped in a nodes connection, and offset-based pagination reached through OData's top and skip rather than GraphQL's own limit and offset.published 2023-08-03
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.
Create CDS Views and expose through OData service in CAPMCreate CDS Views and expose through OData service in CAPMViews defined in CDS and then exposed, which is the whole of what a small CAP service is. Written step by step from cds init onward in Business Application Studio.VenkateshMundru, published 2025-08-11
How to Perform Initial Loads from S/4HANA to Advanced Event Mesh with Odata PollHow to Perform Initial Loads from S/4HANA to Advanced Event Mesh with Odata PollWalks through building a Cloud Integration flow that polls the S/4HANA Business Partner OData API on a timer, splits the response into individual records, and publishes each as an event to Advanced Event Mesh through its adapter, with the topic set dynamically from a grouping property. Selects fields and expands associations with $select/$expand against an EDMX from the API Business Hub, and works around the OData V2 adapter's lack of JSON support by falling back to the HTTP adapter with an XML-to-JSON converter. Flags the trade-off: the pattern needs no backend change beyond activating the API, but the polled payload has to stay aligned with whatever event format the ERP pushes on change.AlexPfeil, published 2025-04-04
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
OpenAPIUnmapped
Edge Integration Cell : Design, deploy and manage APIsEdge Integration Cell : Design, deploy and manage APIsWalks through creating an API artifact in API Management on the customer-managed Edge Integration Cell runtime, including the option to generate the artifact by importing an OpenAPI specification rather than from a URL or by hand. It then attaches an Authentication policy and a Quota step capped at four calls per minute, deploys, and shows both the resulting 401 and the quota-breach error in the Monitor logs. The author frames it as the first of a series on Edge Integration Cell's policies.published 2023-11-15
Part 2 – Empowering SAP BTP CAP Services through Open API Spec and Annotations for Effective Communication, Collaboration and GovernancePart 2 – Empowering SAP BTP CAP Services through Open API Spec and Annotations for Effective Communication, Collaboration and GovernanceWalks through generating an OpenAPI specification for a Node.js CAP service: installing cds-swagger-ui-express, bootstrapping it in server.js, a sample CDS data model with associations and compositions, and the YUML diagram and endpoint details the Open API Preview renders in Business Application Studio. Also shows gating the Swagger UI behind a user-defined environment variable so it is served in development and QA subaccounts but excluded from the production deployment on Cloud Foundry. Second of a three-part series; the first covers the concepts and the third goes deeper into annotations.mohit_bansal3, published 2023-05-24
Pagination and streamingSAP only
[Part – 2] Enrich CAP based Services with Behaviors using Annotations[Part – 2] Enrich CAP based Services with Behaviors using AnnotationsThe second half of a two-part walkthrough of CAP's behavioral annotations, following on from access control and input validation in the first part. This post works through @cds.autoexpose, @cds.api.ignore, @cds.persistence.exists/skip, @cds.on.insert/@cds.on.update and the @odata.Type/@odata.singleton mapping overrides, all shaping how a CDS model is projected into a service, which is data modelling. Alongside these it covers @cds.query.limit for default and maximum page sizes (pagination and streaming), @odata.etag with exclusive and shared locks for optimistic concurrency (concurrency control), and @cds.search for scoping $search to chosen elements (search), each with a CDS code example.published 2023-01-29
WebSocketUnmapped
A Practical Real-Time CTI Widget for SAP Sales Cloud V2A Practical Real-Time CTI Widget for SAP Sales Cloud V2A small CAP backend, a WebSocket channel and a UI5 widget in an iframe — enough to get telephony events into Sales Cloud without any custom backend inside the CRM. The smallness is the design.gizemsoylutr, published 2025-11-28
Communicate from a Java Application to ABAP via WebSocket RFC using JCo - Migration GuideCommunicate from a Java Application to ABAP via WebSocket RFC using JCo - Migration GuideWalks a JCo setup from classic CPIC-based RFC to WebSocket RFC: swap the application- or message-server logon properties for jco.client.wshost and jco.client.wsport, and implement DestinationDataProvider's getSSLContext (and, for mTLS, getClientCertificate) since the new connection runs over TLS. It covers building the PKI trust on both sides — a local PKCS12 keystore for the Java side, STRUST's SSL-Server Standard certificate exported and imported for mutual trust on the ABAP side — and notes that on BTP, JCo paired with the Destination service already implements this via the Connectivity service, so the custom SSLContext work can be skipped there.simon_luser, published 2025-01-21
SAP Event Mesh: S4 HANA On-Prem and SAP CI(BTP IS) through WebSocket and WebhooksSAP Event Mesh: S4 HANA On-Prem and SAP CI(BTP IS) through WebSocket and WebhooksA step-by-step walkthrough of wiring Event Mesh to publish and consume events between an on-premise S/4HANA system and Cloud Integration, contrasting persistent queues (one subscriber, kept until consumed) against unpersisted topics, and WebSocket's AMQP transport against webhook delivery for the same queue. Two tested findings support it: a queue consumer running in continuous consumption mode receives a message ahead of a webhook on the same topic, and a message stays queued and is retried (almost 8770 times in under a minute, in the author's test) until the consumer processes it successfully.FarooqAhmed, published 2023-10-03
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.