Overview and Walkthrough of the Application Programming Model with SAP Cloud Platform

SAP Cloud Platform
Application Programming Model
Daniel Hutzel
CNA221

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SAP TechEd
2018

Introduction
SAP
Web IDE
CDS
Service
SDKs
REST
OData
FioriHANA
Java EE,
Spring
Node.js
express
Eclipse
VSCode
CLI
The “Application Programming Model for SAP Cloud Platform” is a
framework of tools, languages and libraries by SAP and OSS to
efficiently and rapidly build enterprise services and applications in a
full-stack development approach.
It guides developers along a golden path of best practices, allowing
them to focus on their domain while relieving them from tedious
technical tasks.

Overview
We complement cloud-native technologies with…
 a CDS-based Services framework
with 1st-class support by and for…
 SAP Web IDE w/ tailored tools
 SAP Fiori
 SAP HANA
 S/4 Extension scenarios
Resulting in…
 A consistent end-to-end programming model for
enterprise services & applications
 Guidance and best practices leveraging proven
SAP technologies + Open Source software
WebIDE
Infrastructure
App UIs?
Domain Logic?
Domain Model?
localWebIDE+local
SAP Fiori + other
SAP HANA + other
Service SDKsCDS
CDS
planned:
CDS
PlatformServices

Setup
Develop TestRun
CI/CD
Operate
Data
Services
Consumers
Context and our focus
Databases
SAP HANA
API Management
Monitoring
Scaling
Profiling
Connectivity
Big Data
Identities
Authentication
CI/CD
Destinations
Provisioning
Caching
Frontends / UIs
Your Services
and Apps
by S/4 HANA Cloud SDK, …

Fictional task given
Extension on
Cloud PlatformAdd Reviews
Manage
Orders
Maintain
Catalog
Admins
Browse Books
anybody
Order Books
registered
includes…
login…
includes…
T/5 backend system
In cloud first… T/5 later
Reuse
Service

Capture Intent on Conceptual Level
Best Practices & Benefits…
using { Country, managed }
from '@sap/cds/common‘;
service ProductService {
entity Products : managed {
key ID : UUID;
title : localized String;
descr : localized String;
country : Country;
}
}
» What, not How. «

Minimizing Boilerplate
entity Products {
key ID : UUID;
country : Country;
createdAt : DateTime @cds.on.insert: $now;
createdBy : User @cds.on.insert: $user;
modifiedBy : User @cds.on.update: $user;
modifiedAt : DateTime @cds.on.update: $now;
localized : Association to Products_texts
on localized.lang = $user.locale
and localized.ID = ID;
texts : Association to many Products_texts
on texts.ID=ID;
}
entity Products_texts {
key lang : Language;
key ID : UUID;
title : String;
descr : String;
}
type User : String(111);
type CountryCode : String(3);
type Locale : String(5);
//...
type Country : Association to Countries;
type Language : Association to Languages;
entity Countries : CodeList{
key code: CountryCode;
}
entity Languages : CodeList{
key code: Locale;
}
abstract entity CodeList {
name : localized String;
}
annotate Country with @(
title:'{i18n>Country}',
Common.ValueList.entity: 'Languages'
);
annotate Language with @(
title:'{i18n>Language}',
Common.ValueList.entity: 'Countries'
);
annotate CodeList with @(
UI.Identification: [{
$Type: 'UI.DataField', Value: name
}],
);
}
using { Country, managed }
from '@sap/cds/common‘;
entity Products : managed {
key ID : UUID;
country : Country;
}
}

It’s not just about less to type…
It’s much more about:
 Conciseness and comprehensiveness
 Detecting flaws early
 Single points to fix
 Single points to optimize
 Refocusing on your domain
i.e. about improving overall quality,
robustness and adaptability.

Accelerate your Projects
» Run early «
» Grow as you go «
Getting Started
—————————————
o Setup your env (once)
o Start a Project
o Define Services  Run
Add UIs / Frontends
——————————————
o Switch to Web IDE, and…
o Add a Fiori app  Run
o Add Fiori markup  Run
Provide Services
——————————————
o Derive Data Models  Run
o Deploy to DBs  Run
o Add Initial Data  Run
o … 2b continued…
Close Feedback Loop
• Start with services top-down
• Spin-off parallel workstreams (→ frontend / backend)
• Using the Service Definitions as their contracts

Leverage proven Methods
» We eat your dog food «
… originate close
to use cases
… are pushed down
to data sources
for execution
Database
CDS-based
Runtimes
Data
Models
Service
Defs.
Fiori UIs
Fiori
Markup
OData
CQLas views on
Queries
• OData = REST + Querying
• SAP Fiori = flexible generic UIs
• CDS += View Building

RESTful ABAP
Common Programming Model
SAP Fiori / UI5
SAP HANA
SQL
OData, REST
ABAP
Frameworks
ABAP
Toolset
Core Data
Services
SAP Gateway
Extension
Services
Events
Models
Replication
Interoperability
Reuse of Skills
Cloud App Prog Model
SAP Fiori / UI5
SAP HANA / other
SQL
OData, REST
Java / Node
Frameworks
S/4 HANA
Cloud SDK
Core Data
Services
REST + OData libraries
» Our dog food @ SAP «

Openness & Flexibility
Cloud Foundry
Kubernetes
XSA
local
SAP Fiori Angular React Vue • • •
SAP HANA PostgreSQL sqlite • • •
SAP Web IDE
Eclipse
VSCode
• • •
Core
Node.js Java
Core Data Services
• We focus on the Core of Data-oriented Services
• We integrate recommended choices from periphery …
• But without lock-in!  still you decide what you use

Web IDE provides tailored tools for the
application programming model.
You can use Web IDE and/or local tools of
your choice and switch between both.
Common Project Layout & Build
• app
• srv
• db
Local Development
• Command-line Tools
• known IDEs / Editors
• w/ CDS Editors
• Local test runs
• Maven/npm-based
automation
• • •
SAP Web IDE Full-Stack
• Project Storyboard
• Project Explorer
• Database Explorer
• Graphical Modeling
• Service Discovery
• Fiori Dev Tools
• CDS Editors
• Drag & Drop

SAPWeb IDE Full-Stack tailored tools
 Project Storyboard
 Project Explorer
 Database Explorer
 CDS Editors
 Outline
 Drag & Drop
 Problems View
 Graphical Editors
 Service Discovery and
integration wizards (e.g. S/4)
 Fiori Development Toolset

Enterprise Qualities
Intrinsic Enterprise Features & Qualities
 Localized Metadata  e.g. labels
 Localized Data  text tables
o Temporal Data  valid from/to, time travel
 Authorization
 Audit Logging
 Project-level Extensibility ( providers)
o Tenant-level Extensibility ( clients)
o GDPR support
o Validation Framework
o Declarative Constraints
o TypeScript for implementors
o …

Cloud Qualities
Intrinsic Cloud Integration & Qualities
 Authentication / UAA
 JWT token handling
 Configuration (via VCAP services, …)
 Health checks
 Logging & Monitoring
 Tenant on/off boarding
 Tenant isolation
o Rate limiting
o Caching (via Hystrix, …)
o Messaging (via RapidMQ, …)
o Resilience (in S/4H CloudSDK)
o …
by S/4 HANA Cloud SDK

Entities & Views (from SQL)
Associations
Annotations
Aspects
Concise Queries
entity Books @(title:‘Bücher‘) {
key ID : UUID;
author : Association to Authors;
}
entity Authors {
key ID : UUID;
name : String;
books : Composition of many Books;
}
entity BooksList as select from Books {
ID, title, author.name as author
}
 Entity-Relationship Modeling
 Reflexive View Building  borrowed from SQL
CDS is about…

Associations
Annotations
Aspects
Concise Queries
// Pure, unpolluted Structure
define entity Foo { bar : String; }
// Fiori UI Markup
annotate Foo with @UI.Label:'Foo‘;
// Authorization Model
annotate Foo with @requires:‘admin‘;
// Customer-specific Extensions
extend entity Foo with {
car:{ wheels: Integer; }
}
 separate concerns into partial definitions
 avoids polluting your structure
 allows using different tools on same effective models
 in same or different files up to different projects
CDS is about…

SELECT from Employees {
name, addresses [kind='business’] .city.{
name, country.name
}
}
 Path Expressions w/ optional Infix Filters
 (Nested) Postfix Projections
 Permeable for native database features
SELECT e.name, city.name, country.name from Employees e
LEFT JOIN Addresses a on a.id = e.address_id and a.kind='business'
LEFT JOIN Cities city on city.id = addresses.city_id
LEFT JOIN Countries country on country.id = city.country_id
Associations
Annotations
Aspects
Concise Queries
CDS is about…

Associations
Annotations
Aspects
Concise Queries
service CatalogService {
entity Books as projection on my.Books;
entity Authors as projection on my.Authors;
entity Orders as projection on my.Orders {
*, book.title, book.author.name as author
} where createdBy = $user;
action cancel(order:UUID);
}
 data-centric: entities with intrinsic CRUD ops
 entities as views on underlying ones
 with seamless mapping to REST + OData
CDS is about…
Service Definitions

Associations
Annotations
Aspects
Concise Queries
 Core Schema Notation (CSN) as the core of all:
models are plain JavaScript/JSON objects
 minimal footprint, dynamic, no repositories
 fast innovation and delivery cycles
 zero lock-in to any database or stack
{ CSN }
CDS
YAML
OData
JSON, YAML
JPA
process
Open API
Code
SQL DDL
HANA DDL
JSON
CDS is about…
Litew8 reincarnation in Node.js
Service Definitions
let model = {Foo:{kind:'entity'}}

Adding Custom Logic…
cds.services
cds.ql

Implementing Services
Place a <service>.js file next to your <service>.cds file1 Add a Service Implementation Function2
Register your Event Handlers
.before → before generic ones
.on → instead of generic ones
.after → before results go out
3
+
Only for your real, domain-specific custom
logic, leaving the rest to the built-in generic
handlers
Note:
• all non-blocking, running in parallel
• all connection handling, transaction mgmt.,
etc. is taken care of by the fwk

Consuming Services
API Hub
cds importImport Service Definition
in case of external ones
1
Data Source
Database Data Model
Local Service
Service
Definition
External Service
Service
Definition
// query-style
SELECT.from (Foo) .where ({ID:111}) .then (foo => … )
let foo = await SELECT.from (Foo) .where ({ID:111})
// method call-style
ds.read(Foo) .where ({ID:111}) .then (foo => … )
// using declared custom operations
ds.getFoo (111) .then (foo => … )
Data Sources can be Databases, external Services or
local Services and are all consumed in the same way.
OData and cds.services support querying by default.
Connect to Data Source2
Read/Write Data3
const ds = await cds.connect.to ('SomeDataSource‘)
const { Foo } = ds.entities()

Service-level Mashups
CDS allows to easily mashup imported
definitions with local ones.
Views define which subset of data we are
interested in.
Imported
Service
Definition
API Hub
cds import
Import the Service Definition1
Local Service
Definitions
using ExternalService as ext from ‚./imported/service‘;
// served from local database
entity Books as projection on bookshop.Books;
entity Authors as projection on bookshop.Authors;
// served from external service
entity Orders as SELECT from ext.Orders {
}
const ext = await cds.connect.to ('ExternalService')
const { Orders } = ext.entities()
cds.serve ('CatalogService').with (function(){
this.on ('READ', 'Orders', ()=> SELECT.from (Orders) … )
})
Mashup into Local Service Definition:2
Call out to the external service in a custom handler:3

Service-level Replication
using ExternalService as ext from '@imported/service‘;
entity Books {…}
entity Authors {…}
// local replica entity filled from external service
entity Orders as SELECT from ext.Orders {
const { Orders } = cds.entities // local
cds.subscribe.to ('ExternalService‘) .with (ext => {
ext.on (['CREATED', 'UPDATED'], 'Orders‘, ({data:{IDs}}) => {
ext.read ('Orders') .where ('ID in', IDs) .foreach (
each => UPSERT(each).into (Orders)
)
})
})
Local Data
Model
Imported
Service
Definition
API Hub
cds import
Import the Service Definition1
Mashup into Local Data Model:2
Replicate actual data upon change events from the source:3
Cache data locally which is required in
frequent and close access.
Create tables with the views’ signature.

Open, Non-intrusive Design — you stay in control
We use established OSS de-facto standards
We add components focused on enterprise features
You stay in control, you choose what to use and when!
… e.g. in a custom server.js:
Node.js
express.js, …
cds.services
cds.ql, …
Java
Servlets, Spring
Service SDK
JDBC, JPA, cds.ql

Cloud Qualities
Services, not BObjects
Data Model
Service A Service B
Services are stateless API facades.
They contain all logic and validations and
frequently expose views on data.
Data Models define passive
objects, mostly normalized and
managed in databases

Single-purposed Services
Manage
Orders
Maintain
Catalog
Admins
expose entity Books @readonly;
expose entity Authors @readonly;
action order (book) @requires:$user;
}
service CustomersService @(requires:$user) {
expose entity Orders @(restrict:[
{grant:'READ,DELETE', where:'buyer=$user‘}
]);
}
service AdminService @(requires:‘admin‘) {
expose entity Books
expose entity Authors;
expose entity Orders;
}
 fosters focused and efficient implementations
 enables ‘late-cut µ services’
Browse Books
anybody
Order Books
registered
login
includes…

Cloud Qualities
Services, not BObjects
Querying, not ORM
ORMs provide…?
• Active objects manipulating internal state
• Abstraction, shielding me from SQL
• Portability across databases
• Eager/Lazy Loading
• Object Caches
• …?

Data Access with cds.ql
Managed Data Sources w/ CDS-based Reflection
Queries as 1st class objects
SQL-style usage
Object-style usage
Reflexive Querying w/ Late Materialization
Asynchronous, non-blocking execution
Managed Units of Work

Data
Services
Data
Models
Service
Defs.
Custom
Handlers
Fiori UIs
Fiori
Markup
OData
Stored
Procs
Breakouts
Summary — Core Programming Model
CDS
cds.services
cds.ql
We promote…
• Best Practices, not Anarchy!
• Openness, not Blackbox!
• Services, not Objects!
• Querying, not ORM!
• Capturing Intent
• Enterprise & Cloud Qualities

Cookbook — there’s more…
Getting Started
—————————————
o Setup your env (once)
o Start a Project
o Define Services  Run
Add UIs / Frontends
——————————————
o Switch to Web IDE, and…
o Add a Fiori app  Run
o Add Fiori markup  Run
Provide Services
——————————————
o Derive Data Models  Run
o Deploy to DBs  Run
o Add Initial Data  Run
o Add Custom Logic  Run
o Reading / Writing Data
o Add Authorization, I18n, …
Reuse & Modularize
—————————————
o Reuse @sap/cds/common
o Reuse other packages
o Modularize your app
Consume Services
—————————————
o Import ext. Service APIs
o Consume Services
o Service-level Mashups
o Service-level Replication
o Serve required Interfaces
Deploy
——————————
o Deploy to Cloud
o Serverless
o … for own use
o … as SaaS solution
Customize
——————————
o Verticalization
o Tenant-level
Customization✓
✓
✓
✓
✓

Status Quo / Outlook
o SAP Analytics Cloud integration
o Analytical List Page by Fiori
o Serverless deployment
o Reactive Java
o Enhanced GDPR support
o Validation Framework
o Declarative Constraints
o TypeScript for implementors
o …
 CDS-based Service and Data Model
 Service Providers in Node.js / Java
 1st class support for HANA DBaaS
 1st class support for Fiori Uis
 1st class support in Web IDE
 Local dev in VSCode, Eclipse, …
 Fastrack dev with node + sqlite db
 Intrinsic Enterprise Qualities, e.g…
 Localized Data + I18n
 Authorization
 Audit Logging
 GDPR support (basic)
 Service Consumption via S/4H SDK
 Service-level Mashups & Replication
 Project-level Extensibility
 Deployment to Cloud Foundry
o Basis for Serverless eBaaS
o 1st class support for PostgreSQL, …
o Fiori Draft support +
o OData v4
o Advanced support for Spring
o SaaS Tenant-level Extensibility
o More Tailored Tools Web IDE
o Temporal Data
o Events Consumption & Emitting
o Generic Service Consumption
o Generic support for Messaging
o Deploy to Kubernetes
 available o in progress o planned

Thank you!
Keren Rotenberg
Lead Product Manager
keren.rotenberg@sap.com
Daniel Hutzel
Chief Product Owner
daniel.hutzel@sap.com

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