Cost9b 1 Living with Function Points Bernstein and Lubashevsky Text pp

Cost9b 2 Function Point Analysis How to count function points

Cost9b 3 Function Points u Attempting to measure “functionality” u widely used in business applications

Cost9b 4 Program Features u outputs u inquiries u inputs u files u external interfaces

Cost9b 5 Pressman, Soft Eng, 5th Ed u Outputs –“Each user output that provides application- oriented information to the user is counted. In this context output refers to reports, screens, error messages, and so on. Individual data items within a report are not counted separately”

Cost9b 6 Pressman, Soft Eng, 5th Ed u Inputs –“Each user input that provides distinct application-oriented data to the software is counted. Inputs should be distinguished from inquiries, which are counted separately” u Inquiries –“An inquiry is defined as an on-line input that results in the generation of some immediate software response in the form of an on-line output. Each distinct inquiry is counted.”

Cost9b 7 Pressman, Soft Eng, 5th Ed u Files –“Each logical master file (I.e. a logical grouping of data that may be one part of a large database or a separate file), is counted” u External interfaces –“All machine readable interfaces (e.g. data files on tape or disk) that are used to transmit information to another system are counted.”

Cost9b 8 Dreger, FPA, 1989 u “A function point is defined as one end-user business function” u “business functions made available to the user are identified” u “outputs are items of business information processed by the computer for the end user”

Cost9b 9 Dreger, FPA, 1989 u Inquiries “are direct inquiries into a data base or master file that look for specific data, use simple keys, require immediate response and perform no update functions” u “Inputs are items of business data sent by the user to the computer for processing and to add, change, or delete something.” u “Files are data stored for an application, as logically viewed by the user”

Cost9b 10 Dreger, FPA, 1989 u Outputs –“count each of the outputs leaving the context diagram ‘area under study’ at the lowest (greatest detail) level of the logical … data flow diagram system” –count separately if different format or different processing u Dreger says detail lines and total lines are different, ifpug says no

Cost9b 11 Dreger, FPA, 1989 u Inputs –“count each unique user data or control input that enters the application boundary and also updates (adds to, changes, or deletes from) a logical internal file, data set, table or independent data item.” –“count as one input each uniquely formatted or processed portion...”

Cost9b 12 Dreger, FPA, 1989 u Files –“count each major logical group of user data or control information” u Interfaces –“count as one interface each major logical.. file or other logical group of user-approved data or control information within the application boundary that is set to, shared with, or received from another application.”

Cost9b 13 Weights for features u simple average complex u outputs u inquiries u inputs u files u interfaces

Cost9b 14 Questions u Does the system require reliable backup and recovery? u Are data communications required? u Are there distributed processing functions? u Is performance critical? u Will the system run in an existing, heavily utilized operational environment?

Cost9b 15 Questions u Does the system require on-line data entry? u Does the on-line data entry require the input transaction to be built over multiple screens or operations? u Are the master files updated on-line? u Are the inputs, outputs, files, or inquiries complex? u Is the internal processing complex?

Cost9b 16 Questions u Is the code designed to be reusable? u Are conversion and installation included in the design? u Is the system designed for multiple installations in different organizations? u Is the application designed to facilitate change and ease of use by the user?

Cost9b 17 Adjusted Function Points u FP = FP unadjusted * ( * (sum of ratings ) )

Cost9b 18 AT&T and FPA u “5. The measurements must be repeatable and independent of the observer” u “The prediction accuracy proved to be better than twice of traditional SLOC”