Function Point Analysis for GUI applications

Function Point Analysis for GUI applications

 

When Alan Albrecht introduced Function Points sizing method to the world, most of the applications/ projects were data rich applications or MIS applications. In those days, first generation languages such as COBOL, Fortran etc. were in use. But when next generation languages were introduced, critics started slamming FP methodology citing its inability to size GUI, scientific, and complex applications. However, later it was proved by various practitioners that, Albrecht’s FP can be leveraged for sizing the entire spectrum of applications including GUI, and complex applications.

In this document, I will try to explain some of the rules for GUI functions using IFPUG FP. GUI is an on-line display and processing of graphical data presentation. 

Following rules can be applied.

1.    Menu bar – File

a.    Open – EO/EQ

b.    File Save/ Save as/ Edit/ Update/ Create/ Delete – EIs

c.    File Print – EO/EQ

2.    Help – EQ

3.    Selection of an item from the pick list is usually a DET on an EI or input side of an EQ/ EO and not a separate function

4.    Mutually exclusive choices on the same screen may count as unique EQ

5.    Command button may specify add/ delete or change actions. A button like “Ok” may invoke several types of transactions. Each command button would be counted as a data element for the action it invokes

6.    Dropdown or pick list can be considered as EQ if coming from an ILF/ EIF

7.    Informational and warning messages other than error or confirmation messages are considered as EQs/ EOs

8.    Functions which permit selection of one choice out of multiple choices such as radio button/s, one DET should be considered on the EI or EO/EQ

9.    If multiple selections can be accepted just like check boxes, then count each independent selection as a DET

10. Implied queries must be counted as EQs

11. Logon screens that facilitate entry to the application are counted as EQ

12. Pictures on the screen (if not hard coded) can be considered as DETs

13. A sound byte can also be considered as a DET

Do not count

1.    File – New option

2.    Exit

3.    Extract files/ view files as ILFs

4.    Separate EO/ EQ when same results are output to paper and screen

5.    Refresh/ Cancel

6.    Maximize/ minimize/ Zoom – Functions provided by OS

7.    Scroll bars, “Next”/ “Previous” buttons and other navigation devices/ functions

8.    Drop down list which displays data not maintained/ hard coded data

9.    Multiple screens as separate EOs/ EQs

10. Resorting or rearrangement of data as separate EO or EQ

11. Common print options as they are provided by the environment

12. Hyperlinks on webpages