Added samples overview

reviewed/services.js

@@ -0,0 +1,32 @@
+const cds = require ('@sap/cds')
+
+module.exports = cds.service.impl (async()=>{
+
+    // connect to requires services
+    const ReviewsService = await cds.connect.to ('sap.capire.reviews.ReviewsService')
+    const CatalogService = await cds.connect.to ('CatalogService')
+    const db = await cds.connect.to ('db')
+
+    // import model definitions from connected services to work with subsequently
+    const { Books } = db.entities
+    const { Reviews } = ReviewsService.entities
+
+    // delegate requests to read reviews to ReviewsService
+    CatalogService.impl (srv => {
+        srv.on ('READ', 'Books/reviews', (req) => {
+            const [ subject ] = req.params
+            const tx = ReviewsService.transaction (req)
+            return tx.run (SELECT.from (Reviews) .where ({subject}))
+        })
+    })
+
+    // react on event messages from reviews service
+    ReviewsService.on ('reviewed', (msg) => {
+        console.debug ('> received:', msg.event, msg.data)
+        const { subject, rating } = msg.data
+        const tx = db // TODO: db.transaction (msg)
+        return tx.run (UPDATE (Books, subject) .with ({rating}))
+        // return tx.update (Books, subject) .with ({rating})
+    })
+
+})