new messaging

reviews/package.json

@@ -7,7 +7,7 @@
     "index.cds"
   ],
   "dependencies": {
-    "@sap/cds": ">=3.33.1",
+    "@sap/cds": "^4",
     "express": "^4.17.1"
   },
   "scripts": {

reviews/srv/reviews-service.cds

@@ -2,17 +2,10 @@ using { sap.capire.reviews as my } from '../db/schema';
 
 service ReviewsService {
 
-  // Sync API
   entity Reviews as projection on my.Reviews excluding { likes }
   action like (review: type of Reviews:ID);
   action unlike (review: type of Reviews:ID);
 
-  // Async API
-  event reviewed : {
-    subject: type of Reviews:subject;
-    rating: Decimal(2,1)
-  };
-
   // Input validation
   annotate Reviews with {
     subject  @mandatory;

reviews/srv/reviews-service.js

@@ -1,25 +1,24 @@
 const cds = require ('@sap/cds')
-module.exports = cds.service.impl (function(){
+module.exports = cds.service.impl (async function(){
 
   // Get the CSN definition for Reviews from the db schema for sub-sequent queries
   // ( Note: we explicitly specify the namespace to support embedded reuse )
   const { Reviews, Likes } = this.entities ('sap.capire.reviews')
+  const messaging = await cds.connect.to('messaging')
 
   this.before (['CREATE','UPDATE'], 'Reviews', req => {
     if (!req.data.rating) req.data.rating = Math.round(Math.random()*4)+1
   })
 
   // Emit an event to inform subscribers about new avg ratings for reviewed subjects
-  // ( Note: req.on.succeeded ensures we only do that if there's no error )
   this.after (['CREATE','UPDATE','DELETE'], 'Reviews', async(_,req) => {
     const {subject} = req.data
     const {rating} = await cds.transaction(req) .run (
       SELECT.one (['round(avg(rating),2) as rating']) .from (Reviews) .where ({subject})
     )
-    req.on ('succeeded', ()=>{
-      global.it || console.log ('< emitting:', 'reviewed', { subject, rating })
-      this.emit ('reviewed', { subject, rating })
-    })
+    const msgTx = messaging.tx(req)
+    global.it || console.log ('< emitting:', 'reviewed', { subject, rating })
+    msgTx.emit ('review/reviewed', { subject, rating })
   })
 
   // Increment counter for reviews considered helpful