Everything in CAP / Java
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Java: Answers in Java
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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
Don't "let it crash", is this the new CAP guideline?Don't "let it crash", is this the new CAP guideline?Dinu traces a change in error handling in CAP's Node.js runtime: @sap/cds@8.2.0 adds a cds.server.shutdown_on_uncaught_errors config flag, defaulting to true, but invoking an operation with an undefined variable no longer takes the server down, with or without the flag, where the same code crashed it on cds@6 and cds@7, and the author notes the old behaviour was already missing in cds@8.1. It still crashes with features.odata_new_adapter turned off to use the old OData parser, so it is the new OData adapter, like the REST adapter before it, that answers an uncaught error with a 500 instead of taking the process down.Dinu, published 2024-09-06
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.
SAP Cloud Application Programming Model（CAP）：カスタムロジックの実装 – Part 2SAP Cloud Application Programming Model（CAP）：カスタムロジックの実装 – Part 2A walkthrough of implementing custom logic in a CAP Node.js service for the capire bookshop sample, registering before, on and after handlers around the generated CRUD service for its Books and Orders entities. The before handler validates an incoming order's amount and runs a transactional CQN UPDATE to decrement stock, raising a 400 or 409 through req.error when the amount is invalid or no rows match; an after handler on READ appends a discount note to overstocked books.rasai, published 2021-01-01
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 CAP function and action with Unstructured/Dynamic Type Input/OutputSAP CAP function and action with Unstructured/Dynamic Type Input/OutputA CAP action or function can take or return an unstructured type: annotate the service @protocol: 'rest', declare the parameter or return value as @open type object {}, and a handler shapes the payload however a given request needs, shown here with a bound action and a function that returns a different structure per input. The text states plainly that OData V4 and GraphQL services require a fixed structure for action and function parameters, so the dynamic type works only over CAP's REST protocol.published 2022-12-08
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
SAP GraphQL in CAPm (node.js)SAP GraphQL in CAPm (node.js)Adding the GraphQL protocol adapter to a CAP project when it was new — an entity, some data, the feature switched on, and a check that it answers. Short, and it is the earliest account here of CAP speaking something other than OData.enric101, published 2021-11-29
Metadata publishingSAP only
CAP, CDS, CDL, CSN and jq - finding associationsCAP, CDS, CDL, CSN and jq - finding associationsHow associations are actually represented once CDL is compiled into CSN, worked out by parsing the machine-readable form with jq. Useful less as a recipe than as a way in: anything that wants to reason about a CDS model without the compiler has to read CSN, and this is what that looks like from the outside.published 2024-04-16
Develop a full stack Business application with SAP Cloud Application Programming ModelDevelop a full stack Business application with SAP Cloud Application Programming ModelBuilds a full-stack CAP application in SAP Web IDE Full Stack's now-retired 'SAP Cloud Platform Business Application' template: a data-model.cds entity with its own service definition, then Fiori annotations on the generated OData. Building the project compiles that model into Catalog.xml and csn.json, the EDMX and CSN that metadata publishing says every exposed service gets. The entity and service definitions it writes by hand are the basic shape data modelling covers, though the webIDE and MTA tooling staged around them is gone.former_member584731, published 2018-11-29
Importing an external data model using CDS Graphical Modeler for Visual Studio CodeImporting an external data model using CDS Graphical Modeler for Visual Studio CodeWalks through the CDS Graphical Modeler for Visual Studio Code: creating a "Customers" entity, importing an external OData model from an edmx file into the CDS model, and drawing a managed association from the new entity to an entity from the imported namespace. The import happens through the modeler's GUI rather than the cds import command, and the imported edmx becomes a CDS file the modeler can open directly.Xiao-fei_Song, published 2022-05-09
Importing external edmx files to your CAP project using the CDS Graphical ModelerImporting external edmx files to your CAP project using the CDS Graphical ModelerAn EDMX downloaded from the API hub — API_BUSINESS_PARTNER in the example — imported into the CDS model and its entities exposed as projections, done through the graphical modeller rather than cds import. Barely a page long.Xiao-fei_Song, published 2021-05-19
Introducing the Cloud Application Programming Model (CAP)Introducing the Cloud Application Programming Model (CAP)SAP's own general-availability announcement for CAP, laid out as a Golden Path: a data model and service defined in CDS gets a generated service provider that serves metadata publishing and CRUD requests, fills in primary keys and audit data, and writes trace and audit logs without application code. The same CDS model carries annotations that translate to OData vocabularies and generate a Fiori elements app skeleton, which is how Fiori annotations work in CAP.Daniel7, published 2018-06-05
SAP Cloud Platform Backend service: Tutorial [12]: CDS : local: buildSAP Cloud Platform Backend service: Tutorial [12]: CDS : local: buildCompiling a CDS model locally with the cds command-line tool, installed from @sap/cds via SAP's own npm registry, before uploading it to SAP Cloud Platform Backend service: cds compile converts the model to CSN by default, --to edmx or --to edm produces the OData V2 or V4 metadata document, and --to hana or --to sql produces the database-specific definition files. It shows the local build catching an error the CDS editor's own validation misses — an entity with no key, valid CSN but invalid OData — before the same model reaches the server's compiler.CarlosRoggan, published 2019-04-15
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.
Calling bound / unbound CAP actions from Fiori elements application.Calling bound / unbound CAP actions from Fiori elements application.invokeAction from the Fiori elements Edit flow API, with the difference between bound and unbound actions spelled out first because the call shape differs. Under three thousand characters and it answers exactly one question.vidhyasagarmule, published 2024-09-07
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.
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
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 CAP - Create the CAP ServiceExtend SAP SuccessFactors on SAP BTP with CAP - Create the CAP ServiceWalks through writing a service definition in SAP Business Application Studio that projects entities from an existing CDS model: one entity gets @odata.draft.enabled because Fiori Elements only shows CRUD actions on a draft-enabled entity, and a read-only projection of an already-imported SuccessFactors OData entity fails with the generic handlers because the call is delegated to the remote service, so a custom handler is needed. Running cds watch then serves the entities, drafts and $metadata at the declared service path.published 2022-03-23
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.
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
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.
Resolving date serialization issues when using an external OData v2 service with CAPResolving date serialization issues when using an external OData v2 service with CAPDates coming out of an external OData v2 service in a shape CAP does not expect, and what to do about it. A narrow bug report with a fix, and the kind of thing that costs an afternoon if nobody has written it down.pieterjanssens, published 2020-07-09
SAP BTP SDK for iOS & CAP with OData V4 supportSAP BTP SDK for iOS & CAP with OData V4 supportThe iOS SDK gaining OData V4, which until then made connecting a native app to a CAP service awkward — CAP defaults to v4 and the SDK did not speak it. Short, and it marks the date that stopped being a problem.KRiedelsheimer, published 2021-04-21
SAP CAP Adapter to expose OData as custom REST ServiceSAP CAP Adapter to expose OData as custom REST ServiceWalks through consuming an external OData V2 service in a CAP project — cds import converts the Northwind service's EDMX into a CSN and cds.connect.to wires up the remote proxy — then re-exposing it as plain REST with the @protocol:'rest' annotation instead of OData's own envelope. Shows two ways to reshape the response, renaming and dropping fields in a CDS projection or rewriting the returned objects in a custom service handler, and remaps ?pageSize and ?offset onto OData's $top and $skip in that same handler.Former Member, published 2021-09-15
SAP CAP function and action with Unstructured/Dynamic Type Input/OutputSAP CAP function and action with Unstructured/Dynamic Type Input/OutputA CAP action or function can take or return an unstructured type: annotate the service @protocol: 'rest', declare the parameter or return value as @open type object {}, and a handler shapes the payload however a given request needs, shown here with a bound action and a function that returns a different structure per input. The text states plainly that OData V4 and GraphQL services require a fixed structure for action and function parameters, so the dynamic type works only over CAP's REST protocol.published 2022-12-08
SAP CAP(Cloud Application Programming)开发框架概述SAP CAP(Cloud Application Programming)开发框架概述A Chinese-language walkthrough of CAP built mainly from CAPire's own "About CAP" page: CDS entities, associations, compositions and aspects for data modelling, with an extend Books with @restrict: [{ grant:'WRITE', to:'admin' }] aspect as its authorization example; CQL and CQN queries shown against both a local service and OData's $select/$expand; and the service-and-event model — this.on, this.emit, srv.on — that carries CAP's async processing. It closes with the author's own setup: installing @sap/cds-dk, scaffolding a bookshop project with cds init, and running it with cds watch against local SQLite, mocked authentication and file-based messaging standing in for HANA Cloud, IAS and Kafka.ArthurYang, published 2024-01-07
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.
SAP Cloud Platform Backend service: Tutorial [11]: CDS : magic: key: generationSAP Cloud Platform Backend service: Tutorial [11]: CDS : magic: key: generationExplains CDS's UUID key type: giving a key property UUID gets its value generated automatically instead of a hand-picked unused number, as data modelling lets an element's type do, at the cost of a 36-character value unfit for a user-facing display. It then works out how that generated value is addressed in a single-entity read URL — bare brackets in OData V4 against the guid'...' literal V2 requires — citing the OData specification for the difference.CarlosRoggan, published 2019-03-15
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.
OpenAPIUnmapped
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.
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
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.
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
Swagger UI | SAP BTP Extension Generators | Hands-on Video TutorialsSwagger UI | SAP BTP Extension Generators | Hands-on Video TutorialsA blog post wrapped around a video playlist from the SAP HANA Academy — Swagger UI for CDS, added to the BTP extension generator series. The written half is an ingredients list and a table of contents; the substance is in the recordings.dvankempen, published 2021-07-09
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
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
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