The ABAP RESTful Application Programming Model (RAP) provides a robust framework for building modern SAP applications. While previous discussions may have focused on data modeling and behavior, the true power of RAP shines when you learn how to expose your business logic & ABAP RAP Service provisioning to the outside world and consume it effectively.
This blog post, drawing insights from the “Business Service Provisioning & Consumption RAP Part 4” video, will guide you through the crucial second main task of creating a RAP application: Business Service Provisioning and Service Consumption.
The Core of RAP: Business Service Provisioning
Business Service Provisioning is the critical middle layer in RAP. It’s how you define which aspects of your Business Object can be made available to external consumers. This layered approach allows for remarkable flexibility, enabling you to create multiple, distinct business services from a single, foundational business object.
Let’s break down the three key steps in Business Service Provisioning:
1. Business Object Projection: Tailoring Your Business Object
The Business Object Projection is the initial and highly flexible layer where you make service-specific definitions. Its primary purpose is to project a subset of a base business object’s structure and behavior to create service-specific views. For instance, a single “Business Partner” base object can be projected into specialized “Customer” or “Vendor” views, each tailored to specific business needs.
This projection layer offers significant advantages:
- Service-Agnostic Base: Changes to your underlying base business object have minimal impact on the projected services, enhancing stability.
- UI-Specific Customization: You can define UI-specific elements, value helps, calculations, and default values for each unique projected view, catering precisely to front-end requirements.
- Alias Projection Views: Fields can have different, more relevant names in various projected views (e.g., “name_one” from the base could become “customer_name” in a customer projection and “vendor_name” in a vendor projection).
- Key Artifacts: This layer involves creating CDS projection views (to define the specific fields to be consumed) and projection behavior definitions (to define the specific behavior exposed for that projection).
2. Service Definition: Defining the Scope
Once your business object is projected, the Service Definition comes into play. This artifact defines the exact scope of CDS entities from your projection views that will be exposed.
Key characteristics of a Service Definition:
- Protocol-Agnostic: It is important to note that the Service Definition does not specify the communication protocol (like OData V2 or OData V4). It purely focuses on the data entities and their relationships.
- ABAP Repository Object: Like other core RAP artifacts, the Service Definition is managed as an ABAP repository object.
3. Service Binding: Protocols and Consumption Type
The final step in provisioning is the Service Binding. This is where you connect your protocol-agnostic Service Definition to a specific communication protocol and define how the service will be consumed.
The Service Binding:
- Binds to Protocol: It specifies the communication protocol, such as OData V2, OData V4, or even
Inafor analytics. - Defines Consumption: It explicitly states whether the service is intended to be consumed as a UI service (for front-end applications) or a Web API (for machine-to-machine communication).
- ABAP Repository Object: Like the Service Definition, it’s also an ABAP repository object.
Consuming Your ABAP RAP Services
Once your ABAP RAP service is provisioned and bound, it’s ready for consumption. There are two primary ways to consume these services:
1. UI Service for SAP Fiori Elements
- SAP Fiori Elements: If your service binding defines the service as a UI service, it’s perfectly set up to be consumed by SAP Fiori Elements applications. Fiori Elements leverages the rich metadata provided by your OData service to generate beautiful and functional UIs with minimal coding.
- Metadata Extension Files: To provide the necessary UI information for front-end rendering, you’ll often add metadata extension files at the projection layer.
- Direct Preview: A powerful feature within the service binding tool is the ability to directly preview a basic Fiori Elements application, allowing for rapid prototyping and validation.
2. Web API: For Diverse Consumers
- Non-UI Consumption: When your OData service is not meant for a direct front-end user interface, it functions as a Web API. This means it’s designed to provide data or enable operations for other systems or services.
- Any OData Access: Web APIs can be consumed by any client capable of accessing OData services, including other OData services themselves.
- Versioning and Deprecation: Importantly, Web APIs allow for proper versioning and deprecation strategies, ensuring long-term maintainability and controlled evolution of your integrations.
Conclusion: Empowering Your SAP Landscape with RAP Services
Understanding the layers of Business Service Provisioning and the two distinct modes of Service Consumption is crucial for unlocking the full potential of ABAP RAP. This framework empowers ABAP developers to design and deliver highly flexible, scalable, and adaptable OData services that drive modern SAP Fiori applications and seamless system integrations.
As you move from theory to practical ABAP development, applying these concepts will be key to building the next generation of enterprise-grade SAP solutions
Also read – Mastering ABAP RAP: Business Object Behavior & Runtime Implementation Explained