Choosing the Right Architecture for SAP-Centric Commerce
If your organization relies on SAP ERP and wants to extend it with eCommerce capabilities, one key decision is architectural: How should eCommerce integrate with SAP?
There are two primary approaches:
Outside-In: Using a standalone eCommerce platform that integrates with SAP
Inside-Out: Building eCommerce functionality directly within SAP
Each method has its strengths. Understanding how they differ is critical for long-term scalability, cost, and simplicity.
The Outside-In Approach
This is the traditional model used by popular platforms like Magento, Hybris, or Shopify.
These systems are designed to operate independently with their own internal databases for products, pricing, and orders.
To connect with SAP, they use external middleware or custom integration solutions to sync product data, pricing, inventory, and transactions.
Integration is often handled by third parties using custom-built connectors.
Because the eCommerce functionality lives outside of SAP, this is known as the Outside-In model. In this setup, customers, orders, and other transactions are pushed into SAP after being processed by the external system.
The Inside-Out Approach
Solutions like WECO eCommerce take a different route.
The eCommerce application is developed within SAP itself (primarily in ABAP).
It runs directly inside ECC or S/4HANA and leverages native SAP business logic, master data, and customizations.
The user interface is built with modern web technologies like HTML5 and JavaScript, but the back end is entirely SAP-native.
Because it extends SAP from the inside, this model is known as Inside-Out.
Pros and Cons
Feature | Inside-Out | Outside-In |
|---|---|---|
Architecture | Embedded in SAP | External platform |
Real-time ERP Data | ✅ Native access | ❌ Needs syncing |
Maintenance | Lower, SAP-driven | Higher, third-party sync |
Flexibility (UI/UX) | Moderate | High |
Best for | SAP-centric, mid-sized firms | Distributed, B2C-style operations |
Hosting Needs | Minimal | Dedicated infrastructure |
When to Use Inside-Out
You are a small to mid-sized company with SAP at the center of your operations
You want to minimize middleware and external hosting
Your internal SAP team can manage the solution
You want real-time pricing, inventory, and order logic
You have existing user exits or custom pricing logic in SAP
Inside-Out solutions often rely on SAP's native order simulation (e.g. VA01) for checkout. This ensures that all business logic used by internal teams is automatically applied to online transactions too.
When to Use Outside-In
You are a large enterprise with distributed systems (e.g. CPQ, payment gateways, CRM)
You require rapid web design changes, driven by marketing
You can allocate resources for data syncing and infrastructure
You need best-of-breed tools across multiple platforms
Outside-In systems offer more front-end freedom, making them ideal for companies where speed of UX changes is a priority.
Final Thoughts
Both architectures are valid and powerful in the right context. The best approach depends on your business priorities, existing infrastructure, and internal resources.
At WECO Software, our Inside-Out solution is built for SAP-first organizations looking to streamline eCommerce without reinventing their backend processes.
Want to Learn More?
Explore our Blog or contact us to discover how WECO helps simplify eCommerce for SAP-centric organizations.
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