Function Points FAQs
Positioning the Application Boundary
The positioning of an Application Boundary can be subjective. What factors should be considered when determining the position of Application Boundaries for applications?
The application boundary indicates the border between the software being measured and the user.(Reference 1)
The boundary is the conceptual interface between the software under study and its users. Where the users are, any person or any thing (including any software application), that communicates or interacts with the software'. (Reference 2)
Defining the boundary is an essential step in functional measurement. It is important in Function Point counting because of its role in identifying the transactions, which pass through it, and therefore can be potentially included in the 'scope' of the count. The positioning of the boundary between the software under investigation and other software applications may be subjective and consequently functional sizing may be subjective.
The positioning of application boundaries directly impacts the size of an organisation'sapplication portfolio. Multiple application boundaries between system suites introduce multiple "interfacing" transactions and shared files. This creates a potential for the same logical business function to be counted multiple times.
For FPA purposes most organisation'sApplication Boundaries are determined by:
The above guidelines apply regardless of whether the application functionality is distributed across multiple platforms and processors, or resides on a single platform/processor. Within the one 'application', boundaries are not drawn between platforms/processors.
The Function Point Administrator resolves application boundary issues, raised by FP Analysts. The Administrator is the final arbitrator in defining Application Boundaries for counts. It is recommended that function point FP Analysts provide an application boundary diagram as part of their count documentation.
Incorrect placement of the application boundary may change the emphasis of the count from a logical perspective, which is the underlying principle of FPA, to a more physical perspective. The main consequences of this are:
1. Refer IFPUG Counting Practices Manual, Release 4.1, January 1999
2. Refer ISO/IEC Standard - Definition of Functional Size Measurement (DIS 14143)