S/4HANA Extensibility: Customization, Modifications, Custom Code ...

S/4HANA Extensibility – 1511 On-Premise Extensibility Features for Key Users

SAP HANA Cloud Platform Developer Center

HCP SAP HANA Cloud Platform is the default opportunity to extend SaaS applications like S/4HANA CE (Cloud Edition) or Business Network applications like Ariba, Fieldglass and Concur, but why would I use HCP for S/4HANA on premise, or Suite on HANA or Suite on AnyDB extensions?

1. Innovate - Anytime - Anywhere
In traditional on premise deployments, customers were able to deploy innovations once or maybe twice a year to a productive ERP system using release windows. This required RICEF's, change requests, transports and extensive testing across the 5 +1 system landscape (Production support environment: (DEV, QA, PRD), Release environment: (DEV, QA) + SBX).
With PaaS capabilities in HCP, customers and partners can deploy agile software development -DevOps - processes in a side car in the cloud next to the highly restrictive governed ERP on-premise production instance for Suite on AnyDB, Suite on HANA and S/4HANA) or non-modifiable SaaS deployments in areas like for example:

• User Experience - Fiori, always start your Fiori journey in HCP
  • Fiori CE Cloud Edition Web IDE
    • HCP enables ONE UX across all on-premise, cloud and Business Network applications
  • Cloud Portal
• Integration - HCI connects S/4HANA with
  • SAP SaaS applications as C4C, SuccessFactors, S/4HANA CE
  • Business Network as Ariba, Fieldglass, Concur
  • Business Application Services in HCP as Hybris - Yaas
  • Custom apps in HCP 
  • 'other" apps outside HCP such as Salesforce
  • API management
• Collaboration
  • Jam
  • Mobile App development
  • Security for mobile devices and apps
  • Mobile Documents
• Analytics
  • Agile HANA data marts in HCP
  • C4A
  • Predictive Services in HCP as KXCEN/Infinite Insight
  • Unstructured data storage
• Digital (IoT Services)
  • Connect to sensor data Remote Device Management
    • Inside HCP
    • via SDA to outside HCP via SDA
  • API to consume IoT services
  • Remote data sync services

2. Streamline your HANA DB migration and S/4HANA on-premise or cloud conversion projects
As part of to any migration and conversion project, every custom code development/modification needs to be analyzed if still required and if yes, optimized for HANA db processing (SoH and S/4) and S/4HANA data model simplification. HCP offers the opportunity to streamline the future SoH and S/4HANA deployment by moving the required enhancements outside the highly restricted ERP governance process into the cloud-based PaaS environment of HCP.
Means: The SAP S/4HANA on-premise core system remains “clean” and can be quickly and easily updated when new innovations are added quarterly. (quote: S/4HANA FAQ)

Picture from the Open SAP course: Implementation of SAP S/4HANA

What are the S/4HANA capabilities to support customer and partner extensions, customization and modifications?

In general with S/4HANA, SAP suggests to differentiate between in-app (in S/4HANA) and side-by-side (ex-app in HCP) extensions. This SAP white paper provides insights and guidance:

"Extensibility covers a broad spectrum of topics that allows customers and partners to adapt standard business software to their business needs. It ranges from business configuration; layout adaptation of user interface (UI), forms, and reports; custom fields and logic; integration; and custom terminology and translation to customer-specific applications. Extensibility in theSAP® S/4HANA can be categorized into two main parts: side-by-side extensibility through SAP HANA® Cloud Platform, and in-app extensibility through built-in capabilities"

Obviously the focus for the cloud edition is on ex-app extensibility to maximize SaaS capabilities, whereas for the on premise edition SAP continues to offer all traditional modification, custom coding (z-nnn) and customization capabilities as well.

SAP LT or SLT and HCI are used to connect between on premise, cloud edition and HCP and HEC.

For more background and different view points, please see also these discussions/pages

Will HCP HANA Cloud Platform be mandatory to customize S/4HANA? in S/4HANA - SAP Business Suite 4 SAP HANA overview

Overview of SAP S/4HANA Cloud options

Mastering SAP Technologies 2015 Melbourne and especially the corresponding comment section (over 100 comments and counting), where for example Bjoern Goerke;provides additional information.