Sap cap advanced

Advanced CAP — Multitenancy, Kyma & Enterprise Patterns

Related Skills

• sap-hana-cloud — HANA Cloud as CAP persistence layer
• sap-kyma-runtime — Deploying CAP on Kyma/Kubernetes
• sap-security-authorization — XSUAA/IAS integration with CAP
• sap-event-mesh — CAP messaging with Event Mesh

Quick Start

Advanced CAP project setup:

# Create CAP project with advanced features
cds init my-project --add hana,xsuaa,multitenancy,approuter,helm

# Add individual features
cds add hana           # HANA Cloud persistence
cds add xsuaa          # Authentication
cds add multitenancy   # SaaS multitenancy
cds add extensibility  # Tenant extensions
cds add helm           # Kyma/K8s deployment
cds add mtx            # MTX sidecar for tenant management
cds add messaging      # Event Mesh integration
cds add toggles        # Feature toggles

Core Concepts

CAP Multitenancy Architecture

                    ┌─────────────────────────┐
                    │    SaaS Application      │
                    │  (CAP + MTX Sidecar)     │
                    └──────────┬──────────────┘
                               │
              ┌────────────────┼────────────────┐
              ▼                ▼                 ▼
     ┌──────────────┐ ┌──────────────┐ ┌──────────────┐
     │ HDI Tenant A │ │ HDI Tenant B │ │ HDI Tenant C │
     │ (Schema A)   │ │ (Schema B)   │ │ (Schema C)   │
     └──────────────┘ └──────────────┘ └──────────────┘
              │                │                 │
              └────────────────┼─────────────────┘
                               ▼
                    ┌──────────────────┐
                    │  HANA Cloud DB    │
                    └──────────────────┘

CAP Deployment Targets

Target	Command	Artifacts
Cloud Foundry	cds build --for cf	mta.yaml → cf deploy
Kyma/K8s	cds build --for kyma	Helm chart → helm upgrade
Hybrid (local+cloud DB)	cds bind + cds watch	Local app + remote HANA

CDS Advanced Modeling Features

Feature	Use Case
Aspects	Reusable field sets (managed, temporal, cuid)
Compositions	Document structures (header→items)
Associations	Cross-entity navigation
Projections	Service-level views (rename, exclude, redirect)
Temporal data	Bitemporal tables (valid-from/to, system time)
Localized data	Multi-language texts (auto-generated _texts table)
Extensibility	Tenant-specific model extensions

Common Patterns

Pattern 1: Multitenancy Setup

// package.json — MTX configuration
{
  "cds": {
    "requires": {
      "multitenancy": true,
      "extensibility": true,
      "toggles": true,
      "[production]": {
        "db": { "kind": "hana", "deploy-format": "hdbtable" },
        "auth": { "kind": "xsuaa" }
      }
    },
    "mtx": {
      "element-prefix": ["Z_", "z_"],
      "namespace-blocklist": ["com.sap.", "sap."],
      "extension-allowlist": [
        { "for": ["my.bookshop.Books"], "new-fields": 5 },
        { "for": ["my.bookshop.Authors"], "new-fields": 3 }
      ]
    }
  }
}

// srv/tenant-provisioning.js — Custom tenant lifecycle
const cds = require('@sap/cds');

module.exports = class TenantProvisioning extends cds.ApplicationService {
  async init() {
    this.on('CREATE', 'tenant', async (req, next) => {
      const { subscribedTenantId, subscribedSubdomain } = req.data;
      console.log(`Provisioning tenant: ${subscribedTenantId}`);

      // Standard HDI container creation
      await next();

      // Custom post-provisioning (seed data, config)
      await this.seedTenantData(subscribedTenantId);
    });

    this.on('DELETE', 'tenant', async (req, next) => {
      const { subscribedTenantId } = req.data;
      console.log(`Deprovisioning tenant: ${subscribedTenantId}`);

      // Custom cleanup before HDI container deletion
      await this.archiveTenantData(subscribedTenantId);
      await next();
    });

    await super.init();
  }

  async seedTenantData(tenantId) {
    const db = await cds.connect.to('db');
    const { Configurations } = db.entities('my.app');
    await db.run(INSERT.into(Configurations).entries([
      { key: 'CURRENCY', value: 'EUR' },
      { key: 'LANGUAGE', value: 'EN' }
    ]));
  }
};

Pattern 2: CAP + Kyma Helm Deployment

# chart/values.yaml
global:
  domain: my-cluster.kyma.ondemand.com
  imagePullSecret:
    name: docker-registry-secret

srv:
  image:
    repository: my-registry.io/my-app-srv
    tag: latest
  bindings:
    db:
      serviceInstanceName: hana-hdi
    auth:
      serviceInstanceName: xsuaa-instance
  resources:
    limits:
      memory: 512Mi
      cpu: 500m
    requests:
      memory: 256Mi
      cpu: 100m

hana-deployer:
  image:
    repository: my-registry.io/my-app-hana-deployer
    tag: latest
  bindings:
    hana:
      serviceInstanceName: hana-hdi

html5-apps-deployer:
  image:
    repository: my-registry.io/my-app-html5-deployer
    tag: latest

# Build and deploy to Kyma
cds build --for kyma
docker build -t my-registry.io/my-app-srv:latest -f gen/srv/Dockerfile .
docker push my-registry.io/my-app-srv:latest
helm upgrade --install my-app ./chart \
  --namespace my-namespace \
  --set-file xsuaa.jsonParameters=xs-security.json

Pattern 3: Remote Service Integration (Mashup)

// srv/external/API_BUSINESS_PARTNER.cds (imported)
// cds import API_BUSINESS_PARTNER --from <edmx-url>

using { API_BUSINESS_PARTNER as bupa } from './external/API_BUSINESS_PARTNER';

// srv/mashup-service.cds — Combine local + remote
service MashupService {
  // Local entity
  entity Orders as projection on my.Orders {
    *, customer: redirected to Customers
  };

  // Remote entity (federated from S/4HANA)
  @readonly entity Customers as projection on bupa.A_BusinessPartner {
    key BusinessPartner as ID,
    BusinessPartnerFullName as name,
    to_BusinessPartnerAddress as addresses
  };
}

// srv/mashup-service.js — Remote service handler
const cds = require('@sap/cds');

module.exports = class MashupService extends cds.ApplicationService {
  async init() {
    const bupa = await cds.connect.to('API_BUSINESS_PARTNER');

    // Delegate reads to remote service
    this.on('READ', 'Customers', (req) => bupa.run(req.query));

    // Enrich local orders with remote customer data
    this.after('READ', 'Orders', async (orders) => {
      const customerIds = [...new Set(orders.map(o => o.customer_ID))];
      if (customerIds.length === 0) return;

      const customers = await bupa.run(
        SELECT.from('A_BusinessPartner')
          .where({ BusinessPartner: { in: customerIds } })
          .columns('BusinessPartner', 'BusinessPartnerFullName')
      );

      const customerMap = new Map(customers.map(c => [c.BusinessPartner, c]));
      for (const order of orders) {
        order.customerName = customerMap.get(order.customer_ID)?.BusinessPartnerFullName;
      }
    });

    await super.init();
  }
};

Pattern 4: Advanced Authorization

// srv/admin-service.cds
@requires: 'authenticated-user'
service AdminService {

  @restrict: [
    { grant: 'READ',   to: 'Viewer' },
    { grant: 'WRITE',  to: 'Editor' },
    { grant: '*',      to: 'Admin' }
  ]
  entity Products as projection on my.Products;

  // Instance-based auth (row-level)
  @restrict: [
    { grant: 'READ',  to: 'SalesRep', where: 'region = $user.region' },
    { grant: '*',     to: 'SalesManager' }
  ]
  entity SalesOrders as projection on my.SalesOrders;
}

// xs-security.json
{
  "xsappname": "my-app",
  "tenant-mode": "shared",
  "scopes": [
    { "name": "$XSAPPNAME.Viewer", "description": "Read access" },
    { "name": "$XSAPPNAME.Editor", "description": "Write access" },
    { "name": "$XSAPPNAME.Admin",  "description": "Full access" }
  ],
  "role-templates": [
    {
      "name": "Viewer",
      "scope-references": ["$XSAPPNAME.Viewer"],
      "attribute-references": [{ "name": "region" }]
    },
    {
      "name": "Editor",
      "scope-references": ["$XSAPPNAME.Viewer", "$XSAPPNAME.Editor"],
      "attribute-references": [{ "name": "region" }]
    },
    {
      "name": "Admin",
      "scope-references": ["$XSAPPNAME.Admin"]
    }
  ]
}

Pattern 5: CAP with HANA Native Artifacts

// db/schema.cds — Use HANA-specific features
using { managed, cuid } from '@sap/cds/common';

@cds.persistence.journal  // Enable temporal tables
entity AuditLog : cuid, managed {
  action    : String(50);
  entity    : String(100);
  oldValue  : LargeString;
  newValue  : LargeString;
}

// Use HANA calculation view
@cds.persistence.exists  // Don't generate table, it exists in HANA
entity SalesDashboard {
  key region    : String(10);
  totalRevenue  : Decimal(15,2);
  orderCount    : Integer;
  avgOrderValue : Decimal(15,2);
}

// db/src/CV_SALES_DASHBOARD.hdbcalculationview
// (Graphical calculation view created in BAS)
// Referenced by @cds.persistence.exists entity above

-- db/src/SP_COMPLEX_CALC.hdbprocedure
PROCEDURE "SP_COMPLEX_CALC" (
  IN iv_year INTEGER,
  OUT et_result TABLE (region NVARCHAR(10), revenue DECIMAL(15,2))
)
LANGUAGE SQLSCRIPT
SQL SECURITY INVOKER
READS SQL DATA
AS
BEGIN
  et_result = SELECT region, SUM(amount) AS revenue
              FROM "MY_APP_ORDERS"
              WHERE YEAR("createdAt") = :iv_year
              GROUP BY region;
END;

Pattern 6: CAP Feature Toggles

// srv/feature-service.js
const cds = require('@sap/cds');
const toggles = require('@sap/cds-mtx/toggles');

module.exports = class FeatureService extends cds.ApplicationService {
  async init() {
    this.before('CREATE', 'Orders', async (req) => {
      // Check if new pricing engine is enabled for this tenant
      if (await toggles.isEnabled('new-pricing-engine', req.tenant)) {
        req.data.price = await this.calculateNewPrice(req.data);
      } else {
        req.data.price = await this.calculateLegacyPrice(req.data);
      }
    });

    await super.init();
  }
};

Error Catalog

Error	Message	Root Cause	Fix
TENANT_NOT_FOUND	No HDI container for tenant	Tenant not provisioned	Run tenant subscription; check MTX sidecar logs
CDS_COMPILE_ERROR	Model compilation failed	Invalid CDS syntax or circular dependency	Run cds compile --to sql locally to debug
XSUAA: Forbidden	JWT scope mismatch	Missing role assignment	Assign role collection to user in BTP cockpit
Remote service: 401	Destination auth failed	Expired OAuth token or wrong destination config	Check BTP destination; regenerate credentials
HDI deploy: 409	Container already exists	Duplicate tenant provisioning	Check MTX sidecar idempotency; clean up orphans
Helm: ImagePullBackOff	Cannot pull container image	Wrong registry or missing secret	Verify image exists; check imagePullSecret
cds bind: Service not found	Binding resolution failed	Service key missing or wrong name	Run cf service-key <instance> <key> to verify
HANA: Column store error	Schema deployment failed	Incompatible schema evolution	Check .hdbmigrationtable for migration steps

Performance Tips

1. Batch remote calls — Use $batch for multiple remote service requests; CAP auto-batches with cds.ql
2. Projection pushdown — Use columns() in queries; CAP pushes column selection to HANA
3. Expand wisely — $expand with deep nesting causes N+1; prefer flat queries with client-side assembly
4. Connection pooling — CAP pools HANA connections by default; tune pool.max for high-concurrency
5. MTX sidecar — Deploy MTX as separate microservice for tenant operations (don't block main app)
6. Streaming — Use $top/$skip pagination for large result sets; CAP supports @odata.maxpagesize
7. HANA artifacts — For complex analytics, use calculation views (@cds.persistence.exists) over CDS views

Validation Workflow

Before deploying a CAP project, validate structure and configuration:

bash scripts/validate-cap-project.sh .

Deploy checklist:

• CDS models compile (cds build)
• Tests pass (npm test)
• Auth annotations present on all services
• mta.yaml or Helm chart configured for target platform
• No hardcoded credentials in code

Gotchas

• MTX sidecar version: Must match @sap/cds version exactly; mismatch causes tenant operations to fail
• Kyma vs CF bindings: Kyma uses service bindings as Kubernetes secrets; CF uses VCAP_SERVICES
• Remote service quotas: BTP destination connections have concurrency limits; implement circuit breaker
• Schema evolution: HDI doesn't support all schema changes (e.g., narrowing column types); plan migrations
• cds build output: --for cf generates mta.yaml; --for kyma generates Helm chart — different structures
• Feature toggles: Require @sap/cds-mtx package and MTX sidecar; not available in single-tenant mode

MCP Server Integration

For AI-assisted CAP development, add to your .mcp.json:

{
  "mcpServers": {
    "cap-mcp": {
      "command": "npx", "args": ["-y", "@cap-js/mcp-server"]
    },
    "fiori-mcp": {
      "command": "npx", "args": ["-y", "@sap-ux/fiori-mcp-server"]
    }
  }
}

• CAP MCP (official): CDS model search + CAP documentation search
• Fiori MCP (official): Fiori elements app generation, annotation editing