First push

bookshop/db/schema.cds

@@ -1,7 +1,8 @@
-using { Currency, managed, sap } from '@sap/cds/common';
+using { Currency, managed, sap, extensible } from '@sap/cds/common';
 namespace sap.capire.bookshop;
 
-entity Books : managed {
+@Extensibility.Any.Enabled : true
+entity Books : managed, extensible {
   key ID : Integer;
   title  : localized String(111);
   descr  : localized String(1111);
@@ -11,15 +12,26 @@ entity Books : managed {
   price  : Decimal;
   currency : Currency;
   image : LargeBinary @Core.MediaType : 'image/png';
+  authorName: String;
 }
 
-entity Authors : managed {
+@Extensibility : {
+  Fields.Enabled      : true,
+  Relations.Enabled   : false,
+  Annotations.Enabled : true,
+  Logic.Enabled : true,
+  Logic.constraints: true,
+  Logic.calculations: true,
+  Logic.Handler : [create, update, delete, read]
+}
+entity Authors : managed, extensible {
   key ID : Integer;
   name   : String(111);
   dateOfBirth  : Date;
   dateOfDeath  : Date;
   placeOfBirth : String;
   placeOfDeath : String;
+  virtual age: Integer;
   books  : Association to many Books on books.author = $self;
 }
 

bookshop/handlers/AdminService.Authors.CREATE.js

@@ -1,13 +1,13 @@
 async function run() {
-  debugger
+  //debugger
-  while (true) {}
+  //while (true) {}
-  process.exit()
+  //process.exit()
   //1.substring()
   let res = await cds.read(SELECT.one`title`.from(`Books`).where(`ID=201`))
   let { title } = res
   const data = req.data
-  data.modifiedBy = "Custom Event handler read changed this!";
+  data.modifiedBy = "Custom Event handler read changed this!"
-  data.placeOfDeath = ' --- Somewhere over ' + title + ' --- create in Sandbox'
+  data.placeOfDeath = " --- Somewhere over " + title + " --- create in Sandbox"
   return data
 }
 output = run()

bookshop/handlers/AdminService.Authors.READ.js

@@ -0,0 +1,5 @@
+const result_ = Array.isArray(result) ? result : [result]
+for (const row of result_) {
+  row.modifiedBy += " --- read in sandbox"
+  row.age = 27
+}

bookshop/handlers/AdminService.Books.CREATE.js

@@ -0,0 +1,9 @@
+
+async function run() {
+  const {stock, price, author_ID} = req.data
+  if (stock<0) return req.reject('409', 'Stock must not be negative')
+  if (price<0) return req.reject('409', 'Price must not be negative')
+  let {name} = await SELECT.one`name`.from(`Authors`).where({ID: author_ID})
+  req.data.authorName=name
+}
+output = run()

bookshop/handlers/AdminService.Books.READ.js

@@ -0,0 +1,6 @@
+const result_ = Array.isArray(result) ? result : [result];
+for (const row of result_) {
+  if (row.stock > 50) {
+    row.title += " ---Order now for a 10% discount!";
+  }
+}

bookshop/package.json

@@ -12,7 +12,8 @@
   "dependencies": {
     "@sap/cds": ">=5.9",
     "express": "^4.17.1",
-    "passport": ">=0.4.1"
+    "passport": ">=0.4.1",
+    "vm2": ">=3.9.9"
   },
   "scripts": {
     "genres": "cds serve test/genres.cds",
@@ -22,8 +23,11 @@
   "cds": {
     "requires": {
       "db": {
-        "kind": "sql"
+        "kind": "sqlite",
+        "credentials": {
+          "database": "sqlite.db"
+        }
       }
     }
   }
-}
+}

bookshop/srv/admin-service.cds

@@ -1,5 +1,13 @@
-using { sap.capire.bookshop as my } from '../db/schema';
+using {sap.capire.bookshop as my} from '../db/schema';
-service AdminService @(requires:'admin') {
+
-  entity Books as projection on my.Books;
+service AdminService // @(requires : 'admin')
+{
+  entity Books   as projection on my.Books;
   entity Authors as projection on my.Authors;
+  action renameAuthor(author : Authors:ID, newName : String);
+
+  event newBook : {
+    book : Books:ID;
+    name : Books:title
+  };
 }

bookshop/srv/admin-service.js

@@ -1,77 +1,144 @@
-const cds = require("@sap/cds");
+const cds = require("@sap/cds")
-const { VM, VMScript } = require("vm2");
+const cds_sandbox = require("sap/cds/sandbox")
-const fs = require("fs");
+const { VM, VMScript } = require("vm2")
-const path = require("path");
+const fs = require("fs")
+const path = require("path")
+const { nextTick } = require("process")
 
 class AdminService extends cds.ApplicationService {
   init() {
-    const { Books, Authors } = cds.entities("sap.capire.bookshop");
-
     this.after("READ", async (result, req) => {
-      const code = getCode(req, "READ");
+      if (!(result === undefined || result == null)) {
-      if (code) {
+        const code = getCode(req.target.name, "READ")
-        await executeCode(code, req, result);
+        if (code) {
+          await executeCode(code, req, result)
+        }
       }
-    });
+    })
-
-    this.after("READ", "ListOfBooks", (each) => {
-      if (each.stock > 111) each.title += ` -- 11% discount!`;
-    });
 
     this.before("CREATE", async (req) => {
-      const code = getCode(req, "CREATE");
+      const code = getCode(req.target.name, "CREATE")
       if (code) {
-        await executeCode(code, req);
+        await executeCode(code, req)
-        //console.log(req.data)
       }
-    });
+    })
 
-    //this.before("NEW", "Authors", genid);
+    this.before("UPDATE", async (req) => {
-    //this.before("NEW", "Books", genid);
+      const code = getCode(req.target.name, "CREATE")
-    return super.init();
+      if (code) {
+        await executeCode(code, req)
+      }
+    })
+
+    this.on("*", async (req, next) => {
+      if (!(req.target === undefined || req.target == null)) return next()
+      //ToDo: check whether action or event is part of an extension
+      if (req.constructor.name === "EventMessage") {
+        const code = getCode(req.event, "ON")
+        if (code) {
+          await executeCode(code, req)
+        }
+      } else if (req.constructor.name === "ODataRequest") {
+        var output = {}
+        const code = getCode(this.name + "." + req.event, "ON")
+        if (code) {
+          await executeCode(code, req, {}, output)
+          return output
+        }
+      }
+    })
+
+    //ToDo: Prefix for Service not in event emitter
+    this.before("CREATE", "Authors", async (req) => {
+      let Author = req.data
+      await this.emit("createdAuthor", { Author })
+
+    })
+ 
+    return super.init()
   }
 }
 
-function getCode(req, operation) {
+var counter = 1;
-  const filename = req.target.name + "." + operation + ".js";
+
-  const file = path.join(__dirname, "..", "handlers", filename);
+function newLabel() {return "VM2 - req: " + counter++}
+
+function getCode(name, operation) {
+  const filename = name + "." + operation + ".js"
+  const file = path.join(__dirname, "..", "handlers", filename)
   try {
-    const code = fs.readFileSync(file, "utf8");
+    const code = fs.readFileSync(file, "utf8")
-    return code;
+    return code
   } catch (error) {
-    return "";
+    return ""
   }
 }
 
 function scanCode(code) {
   //ESLINT
 }
+/*
+Base assumption: event handlers will always use publicly available application API's (services)
+Inbound data for validations
+  - this could be a document --> req.target plus expand on related data
+  - event facade could have an explicit publishing of specific services or documents (e.g. remote services)
+  - CQN Protocol adapter for subsequent reads --> req.data plus application service calls
+  - what is the CDS subset to put in?
+    - req.data + target-rec (proxy, unloaded)
+    - ORM type lazy loading (dereferenced)
+    - application developer could actually provide custom proxies for specific functions
+    - performance impact of multiple accesses to object graph and multiple DB roundtrips
+    - can static code checking or developer annotations influence what is loaded into a graph?
+    - alternative: Stripped-down SELECT limited to req.target and ID
+      - application service only
+      - access rights of user respected
+  - What about to-many relationships? For compositions essential, for associations to be questioned
+  - Application Service Reads
+  - outbound data for changes
+  - call remote services
+    - register new remote services dynamically
+    - CAP provides an API on remote services - connect doesn't need to be done by extension developer
+    - alternative: declarative remote services plumbing with CDS service facade
+      - model looks like static internal services, remote calls done transparently behind the scenes
 
-async function executeCode(code, req, result) {
+  -Emit Events
-  let output = {};
+    
-  console.time("vm2");
+  - choreography of extension points
+    - deep inserts vs. fine grained operations
+    - input validation may be suited for fine grained operations
+    - today not in scope for performance reasons
+    - two different use case: Insert new page to book vs. update order-header with items-constraints in place
+  - reject request, return errors and warnings - suitable for UI, too
+
+*/
+async function executeCode(code, req, result, output) {
+  const label=newLabel()
+  console.time(label)
   const vm = new VM({
     console: "inherit",
-    timeout: 1000,
+    timeout: 500,
     allowAsync: true,
     sandbox: { req, result, output, cds, SELECT, INSERT, UPDATE, CREATE, JSON },
-  });
+  })
-  
+
   try {
     await vm.run(code)
+    return output
   } catch (error) {
-    req.reject('409','Error in VM')
     console.log(error)
+    req.reject("409", "Error in VM")
+  }
+  finally {
+    console.timeEnd(label)
   }
   // console.log(req.data)
-  console.timeEnd("vm2");
 }
 /** Generate primary keys for target entity in request */
 async function genid(req) {
   const { ID } = await cds
     .tx(req)
-    .run(SELECT.one.from(req.target).columns("max(ID) as ID"));
+    .run(SELECT.one.from(req.target).columns("max(ID) as ID"))
-  req.data.ID = ID - (ID % 100) + 100 + 1;
+  req.data.ID = ID - (ID % 100) + 100 + 1
 }
 
-module.exports = { AdminService };
+module.exports = { AdminService }

bookshop/test/requests.http

@@ -1,10 +1,46 @@
 @server = http://localhost:4004
 @me = Authorization: Basic {{$processEnv USER}}:
+@id = 1113
+
+
+### ------------------------------------------------------------------------
+# Fetch Authors
+GET {{server}}/admin/Authors
+
+### ------------------------------------------------------------------------
+# Fetch one Author
+GET {{server}}/admin/Authors({{id}})
+
+### ------------------------------------------------------------------------
+# Create Author
+POST {{server}}/admin/Authors
+Content-Type: application/json;IEEE754Compatible=true
+
+{
+  "ID": {{id}},
+  "name": "Nick",
+  "placeOfBirth": "Somewhere",
+  "placeOfDeath": "over the Rainbox",
+  "dateOfBirth" : "1975-05-27"
+}
+
+### ------------------------------------------------------------------------
+# rename author via unbound action
+POST {{server}}/admin/renameAuthor
+Content-Type: application/json
+{{me}}
+
+{ "author":{{id}}, "newName":"Super Nick" }
 
 
 ### ------------------------------------------------------------------------
 # Get service info
-GET {{server}}/browse
+GET {{server}}/admin
+{{me}}
+
+### ------------------------------------------------------------------------
+# Get $metadata document
+GET {{server}}/admin/$metadata
 {{me}}
 
 
@@ -23,21 +59,8 @@ GET {{server}}/browse/ListOfBooks?
 {{me}}
 
 
-### ------------------------------------------------------------------------
-# Fetch Authors as admin
-GET {{server}}/admin/Authors(307)
 
-### ------------------------------------------------------------------------
-# Create Author
-POST {{server}}/admin/Authors
-Content-Type: application/json;IEEE754Compatible=true
 
-{
-  "ID": 317,
-  "name": "Vitaly",
-  "placeOfDeath": "",
-  "placeOfBirth": ""
-}
 
 ### ------------------------------------------------------------------------
 # Fetch Books as admin
@@ -50,12 +73,12 @@ Content-Type: application/json;IEEE754Compatible=true
 Authorization: Basic alice:
 
 {
-  "ID": 13,
+  "ID": 16,
-  "title": "Deh3",
+  "title": "Deh4",
   "descr": "The Everyman's Library Pocket Poets hardcover series is popular for its compact size and reasonable price which does not compromise content. Poems: Bronte contains poems that demonstrate a sensibility elemental in its force with an imaginative discipline and flexibility of the highest order. Also included are an Editor's Note and an index of first lines.",
   "author": { "ID": 101 },
   "genre": { "ID": 12 },
-  "stock": 100,
+  "stock": -100,
   "price": "12.05",
   "currency": { "code": "USD" }
 }