Name the three general approaches to data integration and the core idea of each.

Answer

Consolidation (ETL) physically copies data into a central warehouse; federation (EII) provides a virtual real-time unified view without moving the data; propagation (EAI/replication) duplicates data in near-real time as updates occur.

Consolidation suits historical/complex-query needs; federation suits always-current or copy-forbidden data; propagation suits near-real-time requirements. Large environments often combine all three.