1. A system comprising: a processor; and one or more computer readable storage media accessible by the processor and storing computer instructions executable by the processor to implement an interface layer between one or more users and a master entity index (MEI) system employing a first data model, the interface layer receiving a query for the MEI system and interacting with the MEI system based on the query to provide desired information, the interface layer comprising a set of interfaces and business services, wherein each of the business services is defined according to a second different custom data model created by the one or more users with elements mapped to elements of the first data model, is associated with one of the interfaces, and comprises one or more operations, wherein each of the one or more operations is associated with a logical procedure that when executed interacts with the MEI system based on the query and in accordance with the first data model and provides the desired information according to the second data model from information from the MEI system in the first data model; wherein the logical procedure is defined by the one or more users via a set of graphical objects on a graphical interface representing functional operations for the logical procedure, and wherein the graphical interface enables the one or more users to select and arrange the graphical objects to graphically define operational logic flow of the logical procedure for providing the desired information according to the second data model; wherein the logical procedure invokes a service function of the MEI system to obtain outputs defined for a particular operation by the one or more users.