new messaging

bookshop/package.json

@@ -4,7 +4,7 @@
   "description": "A simple self-contained bookshop service.",
   "dependencies": {
     "@capire/common": "../common",
-    "@sap/cds": ">=3.33.1",
+    "@sap/cds": "^4",
     "express": "^4.17.1"
   },
   "scripts": {

fiori/package.json

@@ -5,7 +5,7 @@
     "@capire/bookshop": "../bookshop",
     "@capire/orders": "../orders",
     "@capire/common": "../common",
-    "@sap/cds": ">=3.33.1",
+    "@sap/cds": "^4",
     "express": "^4.17.1"
   },
   "scripts": {

reviewed/package.json

@@ -4,7 +4,7 @@
   "dependencies": {
     "@capire/bookshop": "../bookshop",
     "@capire/reviews": "../reviews",
-    "@sap/cds": "^3.33.1",
+    "@sap/cds": "^4",
     "express": "^4.17.1"
   },
   "cds": {

reviewed/server.js

@@ -11,6 +11,7 @@ cds.once('served', async ({CatalogService}) => {
     // reflect entity definitions used below...
     const { Books } = cds.entities('sap.capire.bookshop')
     const { Reviews } = cds.entities('ReviewsService')
+    const messaging = await cds.connect.to('messaging')
 
     // prepend the following handler so it overrides the default handler
     CatalogService.prepend (srv => srv.on ('READ', 'Books/reviews', (req) => {
@@ -19,9 +20,7 @@ cds.once('served', async ({CatalogService}) => {
         return SELECT(columns).from(Reviews).limit(limit).where({subject:String(id)})
     }))
 
-    // subscribe to events emitted by ReviewsService
-    const ReviewsService = await cds.connect.to ('ReviewsService')
-    ReviewsService.on ('reviewed', (msg) => {
+    messaging.on ('review/reviewed', (msg) => {
         console.debug ('> received:', msg.event, msg.data)
         const { subject, rating } = msg.data
         return UPDATE(Books,subject).with({rating})

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

test/messaging.test.js

@@ -1,10 +1,14 @@
 const cwd = process.cwd(); process.chdir (__dirname) //> only for internal CI/CD@SAP
 const cds = require ('./cds'), {expect} = cds.test
 const _model = '@capire/reviews'
+let messaging
 
 
 describe('Messaging', ()=>{
 
+    beforeAll(async () => {
+        messaging = await cds.connect.to('messaging')
+    })
     after(()=> process.chdir(cwd))
 
     it ('should bootstrap sqlite in-memory db', async()=>{
@@ -20,11 +24,11 @@ describe('Messaging', ()=>{
 
     let N=0, received=[], M=0
     it ('should add messaging event handlers', ()=>{
-        srv.on('reviewed', (msg,next)=> { received.push(msg); return next() })
+        messaging.on('review/reviewed', (msg,next)=> { received.push(msg); return next() })
     })
 
     it ('should add more messaging event handlers', ()=>{
-        srv.on('reviewed', (_,next)=> { ++M; return next() })
+        messaging.on('review/reviewed', (_,next)=> { ++M; return next() })
     })
 
     it ('should add review', async ()=>{