Implement eventing

suppliers/monkey-patch.js

@@ -1,5 +1,7 @@
 const deploy = require("@sap/cds/lib/deploy");
 
+// TODO: https://github.wdf.sap.corp/cdx/cds/pull/1949
+
 const DEBUG = (...args) => console.log(...args);
 
 deploy.exclude_external_entities_in = function (csn, _bound) {
@@ -12,8 +14,6 @@ deploy.exclude_external_entities_in = function (csn, _bound) {
     DEBUG && DEBUG("excluding external entities for", service, "...");
     const prefix = service + ".";
     for (let each in csn.definitions) {
-      const def = csn.definitions[each];
-      if (def["@cds.persistence.table"] === true) continue;
       if (each.startsWith(prefix)) {
         DEBUG && DEBUG("excluding external entity", each);
         _exclude(each);

suppliers/requests.http

@@ -20,7 +20,14 @@ Content-Type: application/json
     "supplier_ID": "PNG"
 }
 
+###
 
+PATCH {{bpServer}}/api-business-partner/A_BusinessPartner('PNG')
+Content-Type: application/json
+
+{
+    "BusinessPartnerFullName": "Penguin Books (Changed)"
+}
 
 ###
 

suppliers/srv/external/API_BUSINESS_PARTNER.js

@@ -1,11 +1,10 @@
 const cds = require('@sap/cds');
 
 module.exports = cds.service.impl(async function (srv) {
-  const messaging = await cds.connect.to('messaging')
   const { A_BusinessPartner } = this.entities;
 
   srv.after('UPDATE', A_BusinessPartner, data => {
     console.log(`>>> BusinessPartner updated ${data.BusinessPartner}`);
-    messaging.emit("BusinessPartners/Changed", { businessPartners: [ data.BusinessPartner ] });
+    srv.emit("A_BusinessPartner.Changed", { businessPartners: [ data.BusinessPartner ] });
   });
 });

suppliers/srv/mashup.cds

@@ -66,3 +66,11 @@ extend service AdminService with {
 extend projection CatalogService.ListOfBooks with {
   supplier
 }
+
+// Extend S4 service with not modelled event
+extend service S4 {
+  @topic: 'BusinessPartners/Changed'
+  event A_BusinessPartner.Changed {
+    BusinessPartners: array of S4.A_BusinessPartner:BusinessPartner;
+  }
+}

suppliers/srv/mashup.js

@@ -10,7 +10,6 @@ module.exports = async()=>{ // called by server.js
   const S4bupa = await cds.connect.to('API_BUSINESS_PARTNER')   //> external S4 service
   const admin = await cds.connect.to('AdminService')            //> local domain service
   const db = await cds.connect.to('db')                         //> our primary database
-  const messaging = await cds.connect.to('messaging');
 
   // Reflect CDS definition of the Suppliers entity
   const Suppliers  = db.entities["sap.capire.bookshop.Suppliers"];
@@ -41,7 +40,8 @@ module.exports = async()=>{ // called by server.js
   // Subscribe to changes in the S4 origin of Suppliers data
   // REVISIT: cds context is still from the UPDATE method when running in same programm, but should
   // be a separate
-  messaging.on ('BusinessPartners/Changed', async msg => { //> would be great if we had batch events from S/4
+  // https://github.wdf.sap.corp/cap/matters/projects/44#card-196556
+  S4bupa.on ('A_BusinessPartner.Changed', async msg => { //> would be great if we had batch events from S/4
     await new Promise( resolve => setTimeout( resolve, 1000 ));
     const tx = cds.db.tx(msg);
     let replicas = await tx.run(SELECT('ID').from (Suppliers) .where ('ID in', msg.data.businessPartners));
@@ -81,24 +81,24 @@ module.exports = async()=>{ // called by server.js
   }
 
 
+  // TODO: remove test code
   {
-    // one server: returns AdminSuppliers
+    // one server: returns AdminService.Suppliers
-    // two servers: returns A_BusinessPartner
+    // two servers: returns API_BUSINESS_PARTNER.A_BusinessPartner
     const tx = S4bupa.tx({});
     let result = await tx.run(SELECT('*').from ('AdminService.Suppliers') .where ('ID =', 'ACME'));
     tx.commit();
     console.log(result);
   }
 
+  // TODO: remove test code
   {
-    // one server: returns AdminSuppliers
+    // one server: returns AdminService.Suppliers
-    // two servers: returns AdminSuppliers
+    // two servers: returns AdminService.Suppliers
     const tx = db.tx({});
     let result = await db.run(SELECT('*').from ('AdminService.Suppliers') .where ('ID =', 'ACME'));
     tx.commit();
     console.log(result);
   }
 
-  //process.exit(0);
-
 }