The document discusses different approaches to managing shared data and business logic across multiple systems in an enterprise architecture. It describes the master-copy principle where a single master system owns the data and replicates changes to copies. It also covers master-master replication where changes can be made to copies with conflicts resolved. Finally, it discusses managing shared business logic through libraries, proxies, and an enterprise service bus.

1. Enterprise Architecture
Master-Copy Principle
Peter Norrhall

2. Information and business logic in
System A several systems System B
Information
Business Logic
System C

3. SOA Silos

4. Master per domain/functionality in
the different systems

5. Master-copy replication

6. Master-copy replication
Copy Master

7. Publish-subscribe
Copy
Master

8. Common information
System A System B
System C

9. Common information
E-Commerce ERP
CRM

10. Master-master replication of common
information
E-Commerce ERP
ESB
CRM

11. Business logic

12. Shared Libraries
System A System B
jar
System C
COM

13. Business logic
One System To Rule Them All
Copy Master
Copy

14. Business logic
Master
Copy
Copy Master

15. Replication of declarative business
logic
Master
Copy
Copy Master

16. Proxy against cemented business logic
System A System B
System C

17. Enterprise Service Bus
System A System B
ESB
System C