Update technology_overview.md

Author: oblomov-dev

docs/advanced/technical/technology_overview.md

@@ -1,6 +1,32 @@
-## Technology Overview
+# Technology Comparison: abap2UI5 vs RAP, UI5 Freestyle, Web Dynpro, ITS Mobile
 
-### abap2UI5: Over-the-Wire for SAP (2023+)
+This page compares **abap2UI5** with other common SAP UI technologies to help understand its architectural position and when to use it.
+
+While many SAP applications rely on client-side Single Page Applications (SPAs) or traditional Server-Side Rendering (SSR), abap2UI5 follows a pragmatic **Over-the-Wire** approach. It bridges the gap between simplicity and flexibility by shifting UI control back to the ABAP backend — without sacrificing the power of UI5 on the frontend.
+
+The following table highlights key differences between:
+- **abap2UI5** (Over-the-Wire)
+- **RAP / Fiori Elements** (Backend-driven SPA)
+- **UI5 Freestyle** (Custom SPA)
+- **Web Dynpro (ABAP)** (SSR)
+- **ITS Mobile** (Legacy SSR for mobile devices)
+
+### Comparison Table
+
+| Feature | abap2UI5 | RAP (Fiori Elements) | UI5 Freestyle | Web Dynpro (ABAP) | ITS Mobile |
+|----------|----------|---------------------|---------------|------------------|------------|
+| **UI Definition** | ABAP Class (XML View & JSON ViewModel) | CDS Annotations | JavaScript + XML Views | Dynpro / Floorplan Components | Dynpro (SAP GUI Screens) |
+| **Data Flow** | View + ViewModel via JSON (Over-the-Wire) | OData V4: Metadata & Data | OData / Custom APIs | Server-side (Context Nodes) | Server-side (Dynpro → HTML) |
+| **UI Rendering** | UI5 Shell renders dynamic View from backend definitions | UI5 Fiori Elements renders UI in Browser (SPA) | UI5 Framework renders UI in Browser (SPA) | Server-side Rendering (SSR) | Server-side Rendering (SSR) |
+| **Frontend Code** | Static generic UI5 Shell | UI5 Fiori Elements SPA Runtime | Custom UI5 App (SPA) | Generated HTML/JS from ABAP runtime | Generated HTML from ITS Service |
+| **Developer Focus** | 100% ABAP (no JS needed) | 100% ABAP (no JS needed) | ABAP + JavaScript development | ABAP development | ABAP Dynpro development |
+| **Architecture** | Over-the-Wire | Backend-driven SPA | Custom SPA | Server-Side Rendering (SSR) | Server-Side Rendering (SSR) |
+| **Complexity (Frontend)** | Very Low | Medium (predefined SPA runtime) | High (full frontend stack) | Low (no client-side rendering logic) | Very Low (HTML rendering of GUI screens) |
+| **Typical Use Cases** | CRUD-heavy apps, forms, dashboards | Standard apps with CDS-based annotations | Custom UIs, interactive dashboards | Classic SAP transactional apps | Legacy mobile apps (scanner, warehouse) |
+
+### Technology Overview
+
+#### abap2UI5: Over-the-Wire
 abap2UI5 applies the Over-the-Wire principle to SAP UI5 apps. The backend (ABAP) defines UI5 XML Views and ViewModels, which are sent to the browser. A generic, static UI5 app dynamically renders this content.
 
 - **Frontend stays generic & static**
@@ -9,35 +35,34 @@ abap2UI5 applies the Over-the-Wire principle to SAP UI5 apps. The backend (ABAP)
 - Inspired by modern Over-the-Wire frameworks like Hotwire, Livewire
 - Addresses SAP's "Clean Core" approach by keeping custom code backend-driven
 
-### RAP / Fiori Elements: Backend-driven SPA (2019+)
+#### RAP / Fiori Elements: Backend-driven SPA (2019+)
 The **RESTful Application Programming Model (RAP)** standardizes how SAP applications expose data and services via OData V4. **Fiori Elements** apps use these services to render UIs client-side in the browser.
 
 - Developers define CDS Annotations in ABAP
 - UI is built dynamically by the UI5 Fiori Elements runtime (SPA)
 - Suitable for standard apps with CRUD patterns
 - Reduces custom UI development, but still SPA complexity (OData Metadata handling, UI5 runtime)
 
-### UI5 Freestyle: Custom SPA (2010+)
+#### UI5 Freestyle: Custom SPA (2010+)
 UI5 Freestyle apps offer full control over the frontend. Developers build custom UI5 applications using JavaScript, XML Views, and UI5 Controls.
 
 - Allows highly customized, interactive UIs
 - Full SPA architecture in the browser
 - Requires frontend expertise (JavaScript, UI5 skills)
 - More flexible, but also more complex in development & maintenance
 
-### Web Dynpro ABAP: Server-Side Rendering (2003+)
+#### Web Dynpro ABAP: Server-Side Rendering (2003+)
 Web Dynpro ABAP is SAP's traditional web UI framework. It renders HTML on the server and sends complete pages to the browser for each interaction.
 
 - Component-based UI framework fully implemented in ABAP
 - Classic Server-Side Rendering paradigm (SSR)
 - Suitable for transactional SAP applications
 - Limited flexibility for modern UI patterns, but robust and widely used
 
-### ITS Mobile: Legacy SSR for Mobile Devices (2000+)
+#### ITS Mobile: Legacy SSR for Mobile Devices (2000+)
 **Internet Transaction Server (ITS) Mobile** converts classical SAP Dynpro (SAP GUI) screens into HTML pages for mobile browsers.
 
 - Simplifies legacy app mobilization (e.g., warehouse scanners)
 - Pure server-side HTML rendering (SSR)
 - Very basic UI, optimized for keyboard-based navigation
 - Still relevant for niche use cases with rugged devices
-