There are several basic architectural approaches to reference and Master Data integration. Each Master Data subject area will likely have its own system of record. For example, the human resource system usually serves as the system of record for employee data. A CRM system might serve as the system of record for customer data, while an ERP system might serve as the system of record for financial and product data.

The data sharing hub architecture model shown in this figure represents a hub-and-spoke architecture for Master Data. The Master Data hub can handle interactions with spoke items such as source systems, business applications, and data stores while minimizing the number of integration points. A local data hub can extend and scale the Master Data hub. (See Chapter 8.)

Each of the three basic approaches to implementing a Master Data hub environment has pros and cons:

• A Registry is an index that points to Master Data in the various systems of record. The systems of record manage Master Data local to their applications. Access to Master Data comes from the master index. A registry is relatively easy to implement because it requires few changes in the systems of record. But often, complex queries are required to assemble Master Data from multiple systems. Moreover, multiple business rules need to be implemented to address semantic differences across systems in multiple places.

• In a Transaction Hub, applications interface with the hub to access and update Master Data. The Master Data exists within the Transaction Hub and not within any other applications. The Transaction Hub is the system of record for Master Data. Transaction Hubs enable better governance and provide a consistent source of Master Data. However, it is costly to remove the functionality to update Master Data from existing systems of record. Business rules are implemented in a single system: the Hub.

• A Consolidated approach is a hybrid of Registry and Transaction Hub. The systems of record manage Master Data local to their applications. Master Data is consolidated within a common repository and made available from a data-sharing hub, the system of reference for Master Data. This eliminates the need to access directly from the systems of record. The Consolidated approach provides an enterprise view with limited impact on systems of record. However, it entails replication of data and there will be latency between the hub and the systems of record.