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The Sign-Off Table

Lesson 4 of 5

Integration patterns

9 min

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A technology says how bytes travel. A pattern says how systems are arranged. Three patterns cover most SAP landscapes: point-to-point, mediated (hub-and-spoke) and event-driven. Recognizing the pattern tells you who depends on whom, where to test, and what breaks when one system changes.

Point-to-point

In a point-to-point pattern, each sender connects directly to each receiver. It is quick to build for the first few interfaces: the shop-floor system in Detroit calls a BAPI in SAP directly. The problem is growth. With many systems, every new connection adds another custom link, and nobody has a single view of the traffic. A change to one system can break links that nobody remembers exist.

Mediated (hub-and-spoke)

In a mediated pattern, systems connect to a central platform, which transforms and routes messages. SAP Process Orchestration and SAP Integration Suite are mediators. The benefits are central monitoring, reusable mappings and one place to change routing. The cost is that the hub becomes critical: when it is down, everything waits, and every change to it needs testing across many interfaces.

Four systems need six direct links point-to-point, but only four links to a hub, which then carries every message.
The Sign-Off Table · thesignofftable.com/academy/sap-int-101

Event-driven

In an event-driven pattern, a system publishes an event, such as "sales order created", to a broker. Any system that is interested subscribes. The publisher does not know or care who listens. This decouples systems well: Contoso can add a new subscriber, for example a fleet analytics service, without touching SAP S/4HANA. Events are usually thin notifications; a subscriber that needs the full order calls an API to fetch it.

An event is a thin notification: the subscriber learns that order changed, then fetches the details it needs through an API.
The Sign-Off Table · thesignofftable.com/academy/sap-int-101
PatternShapeStrengthWeaknessTest focus
Point-to-pointDirect link per pair of systemsSimple and fast for a few interfacesGrows into a tangle; no central viewEach link separately; hidden dependencies
MediatedAll links through a hubCentral monitoring, mapping and routingHub is a single critical componentMappings, routing rules, hub capacity
Event-drivenPublish to a broker; subscribers reactLoose coupling; easy to add consumersHarder to trace end to end; ordering and duplicatesEvent delivery, subscriber behavior, replay
Three integration patterns and what each one means for testing.
The Sign-Off Table · thesignofftable.com/academy/sap-int-101
Point-to-pointFew systems, little change: a direct link is acceptable
Event-drivenFew producers, need to react quickly as things happen
Mediated batch and messagesMany systems exchanging business documents on a schedule or in queues
Mediated plus eventsMany systems and real-time needs: a hub for documents, a broker for notifications
A rough guide to choosing a pattern. Most landscapes mix all three.
The Sign-Off Table · thesignofftable.com/academy/sap-int-101

Patterns by use case

SAP's Integration Solution Advisory Methodology (ISA-M) describes integration in terms of integration styles, such as process integration and data integration, refined into use case patterns. For the process integration style, SAP Learning lists patterns including A2A (application-to-application), B2B (business-to-business), B2G (business-to-government) and master data integration. These names help teams talk about the business purpose of an interface before arguing about technology.

Use case patternContoso exampleTypical technology
A2ASAP S/4HANA to the warehouse and shop-floor systemsIDoc, RFC, OData through the platform
B2BOrders from Great Lakes Fleet Services; POs to Lakeside ComponentsEDI translated to IDocs via the platform
B2GElectronic tax filings to authorities, relevant for the planned Mexican acquisitionCountry-specific SAP solutions and APIs
Master data integrationProduct data replicated to the e-commerce catalogIDoc or APIs, increasingly events

ISA-M process integration use case patterns with Contoso examples.

What would you do?

An architect proposes connecting a new fleet analytics service directly to the SAP S/4HANA database tables to read delivery data. What is the best response?

Key points
  • Point-to-point is simple at first and tangled at scale.
  • Mediated integration centralizes mapping, routing and monitoring, but makes the hub critical.
  • Event-driven integration decouples publishers from subscribers; trace and duplicate handling need care.
  • ISA-M names use case patterns such as A2A, B2B, B2G and master data integration.

Check your understanding · not graded

Lesson check

  1. 1. What is the main weakness of point-to-point integration as a landscape grows?

  2. 2. In an event-driven pattern, what does the publisher know about its subscribers?

  3. 3. Orders from Great Lakes Fleet Services over EDI are which ISA-M use case pattern?