Objective
In the previous lesson we introduced the concept of application development with SAP BTP. We now dive deeper into this concept by exploring the various runtime environments and programming models that SAP BTP provides.
This lesson contains the following topics:
Before discussing the different runtime environments we first ask a simple question: "Exactly what problem are we trying to solve?". Organizations face three challenges in regards to application development:
Runtime environments and programming models are the solution to this problem. The choice of which to use is one of the most important decisions to make when developing and deploying applications. Regarding SAP BTP there are three to choose from:
Cloud Foundry has established itself as a "go to" runtime environment for developers. This is due to several of its inherent features:
For a more in depth discussion of developing Cloud Foundry applications please see: Developing Applications on SAP BTP, Cloud Foundry runtime
In some use cases it is necessary to make use of containers when an application is deployed. Containers are a way to run an application by bundling up and packaging the application and its dependencies such that they run in a virtualized environment. Kubernetes adds container management (i.e., creating, scaling, failover) to the equation. Kyma takes the next step by adding what Kubernetes doesn't namely features such as monitoring, logging, event consumption, authentication, logging, tracing, monitoring and alerting just to name a few.
For a more in depth discussion of developing Kyma applications please see: Developing Applications in SAP BTP, Kyma Runtime
For use cases based on ABAP, SAP BTP has an ABAP Environment that can be utilized. A full fledged ABAP environment that runs in a PaaS environment it can be used to run everything from simple side-by-side extensions to custom built multitenancy-enabled SaaS applications. Some of the features of this environment are:
For a more in depth discussion of developing ABAP applications please see: Learning the Basics of ABAP Programming on SAP BTP
The good news is that three environments are available for organizations to choose from when deploying applications. The tricky part as always is "which should I choose"? While each customer and use case is unique (and should therefore always be evaluated on its own merits) there are some general factors we can list to help with making this decision:
Consider Cloud Foundry when the use case calls for:
Consider Kyma for use cases involving:
Consider ABAP to
Having looked at the different runtime environments available we now turn our attention to programming models. There are two to choose from:
CAP is a framework of languages, libraries, and tools for building enterprise-grade cloud applications. It guides developers along a golden path of proven best practices, which are served out of the box by generic providers cloud-natively, thereby relieving application developers from tedious recurring tasks. Ultimately CAP gives developers a way to create full stack applications quickly and easily.
One of the features of CAP is its focus on domain. By domain we mean the focus is on "what" is wanted and the "how" what is wanted is implemented is left up to the framework. The focus on domain is manifested by using Core Data Services (CDS). Using CDS developers can design data models, service definitions, queries, and expressions. CAP is the appropriate choice when deploying to either the Cloud Foundry or Kyma environments and as such provides a uniform programming model for the different languages supported by those environments (i.e., JAVA, JavaScript, Python, etc.).
For more information on CAP please see: Getting started with SAP Cloud Application Programming Model
Using RAP ABAP developers can create SAP HANA optimized OData services and Web APIs that can be used across any and all transactional, analytical and integration scenarios. Similar as to CAP, RAP also focuses on domain. Using CDS developers can model objects such as data definitions, business objects, service definitions and service bindings. RAP is the appropriate choice when deploying to the ABAP Environment on SAP BTP.
For more information on RAP please see: Getting Started with Creating an SAP Fiori Elements App Based on an OData V4 RAP Service
As a practical matter the choice of runtime environment dictates the programming model and vice versa. Thus if a use case calls for a specific runtime environment (i.e., Kyma or ABAP) then the choice of programming model is made automatically as a result. If any runtime environment is suitable then the decision can be made based on the programming model best suited. As mentioned earlier each use case stands on its own and must be evaluate independently. In many instances both programming models are suitable so resist the temptation to "overthink" it. One of the most important factors to consider is the developer skillset necessary based on programming model chosen. To wit:
CAP:
RAP:
A common way that the programming model is referred to sometimes is the "backend" of a full stack application. The backend part of the application design is not something that the end user typically sees. We now turn our attention to the part that the end user does see (the frontend). SAP Fiori is a design language and user experience (UX) paradigm that serves as a ideal solution for the frontend. SAP Fiori UIs will simplify and streamline user interactions with applications, making it intuitive, user-friendly, and visually appealing. SAP Fiori is built on modern web technologies (HTML, CSS, JavaScript) and can be accessed through a web browser on various devices, including desktop computers, tablets, and smartphones.
For a more in depth introduction to SAP Fiori please see: Learning the Basics of SAP Fiori
Think of the following three components as a complete mobile ecosystem:
What it is: A cloud platform service running on SAP BTP. It is a mobile application development platform. It is not an app that end-users install; it's a tool for developers and administrators.
Purpose & Key Features:
Analogy: SAP Mobile Services is the engine room and control tower for an enterprise's mobile strategy. It provides all the essential plumbing, security, and management capabilities needed to run robust mobile applications, but it's invisible to the final business user.
What it is: A native mobile app for iOS and Android that acts as a central, personalized entry point.
Purpose & Key Features:
Analogy: SAP Mobile Start is the personalized digital front door to a users workplace. Instead of searching for different apps or websites, they can open this one app to see their urgent tasks, launch the applications they need, and stay informed.
What it is: A framework and content type for creating and displaying simple, context-aware "micro-apps." These cards are presented in a wallet-style user interface.
Purpose & Key Features:
Analogy: SAP Mobile Cards are like a digital wallet for a users relevant business information. Each card is a small, easy-to-read summary of one specific item, allowing users to quickly check details and take action, much like pulling out a specific credit card or ID from a real wallet.
The MDK is a metadata-driven development framework. This means developers won't write traditional UI code; instead, they will define their app's pages, controls, and logic in a descriptive format (metadata), which the MDK client then renders as a native application.
Key Characteristics:
Target Audience:
Best For:
This is a toolkit for professional iOS developers to build native enterprise apps that adhere to Apple's design principles while incorporating SAP's Fiori design language for enterprise use.
Key Characteristics:
Target Audience:
Best For:
This is the Android equivalent of the iOS SDK, providing a complete set of tools for professional Android developers to create native enterprise apps.
Key Characteristics:
Target Audience:
Best For:
In summary, SAP BTP runtime environments and programming models along with tools such as SAP Build provides everything needed to build, deploy, and manage modern cloud applications and extensions.