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Maintaining InfoSources (External
System) 
You can also assign an external system to an InfoSource. The data would then be loaded from this system into the BI system, using staging BAPIs. There are a number of extraction tools from third-party providers that you can use to load data from an external system, or you can use the DB Connect tool provided by BI. For an extraction tool, you can maintain a destination, which is given when you load data from the BI system. The extraction tool loads the data from the external system and transforms it into the relevant BI format.
When you load transaction data from an external system, you must make sure that the transfer structure is formed in exactly the same way as the data structure of the extraction tool.
When you load master data from an external system, you must make sure that the data structure of the extraction tool corresponds exactly to the transfer structure suggested by the BI system.
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1. Defining the source system from which you want to load data
Choose Source System Tree ® Root (Source System) ® Context menu (Right Mouse Button) ® Create.
For an external system, choose: External system, Data and Metadata Transfer Using Staging BAPIs.
Enter a name and a description, and maintain the RFC destination for your extraction tool.
2. Defining the InfoSource for which you want to load data
Maintaining the InfoSource and subsequent processes are identical to when you load data from a flat file. Choose a procedure according to data type:
¡ Uploading Transaction Data from Flat Files
¡ Loading master data from flat files directly or flexibly
¡ Uploading Hierarchies from Flat Files