Whether to go for EAI or ETL

Factors for consideration in the decision include:
1. Costs of run-time processing and development.
2. Proprietary nature of source or target systems. A situation where the source system can only be accessed via screen scrapping because the file layouts and key structures are part of package and source is not available. In such cases neither ETL nor EAI will work and a solution might have to be developed on case to case basis.
3. The state of data and load-time window available to migrate data from source to target and vice versa which needs real-time movement of data.
4. Complexity and mapping of source and target systems by data elements and data quality in each system.
5. Skills of staff relative to EAI and ETL tools.