Occasionally, there is a need to limit the usage of an iFlow to certain runtime users. The following NWDS screenshots specify the required changes that need to be applied to achieve this.
By default, any authorized user can send messages in the integration flow from the sender system. On adding users, you are specifying that only the added users can send messages from the sender system and thus, restricting other users.
http://help.sap.com/saphelp_nw73ehp1/helpdata/en/7e/f0af872e6e42fd9e176c53ca8510de/content.htm
Step 1: Allocate users to the Business System/Component.
Step 2: Add user to the iFlow by clicking on the Sending Business System/Component
Note: This feature is available in Integration Directory under integrated configuration > Assigned user. Please take care when assigning users to an iFlow configuration in Integration Directory as this will be lost when an iFlow is redeployed.