Function Point (FP) Based Measures

Function  Point  (FP)  Based  Measures,  

Internal Logical Files

It is a user identifiable group of logically related data or control information that resides entirely within the application boundary. The primary intent of an ILF is to hold data maintained through one or more elementary processes of the application being counted.

External Interface Files

It is a user identifiable group of logically related data or control information that is used by the application for reference purposes only. The data resides entirely outside the application boundary and is maintained in an ILF by another application. An EIF has the inherent meaning that it is externally maintained, an interface has to be developed to get the data from the file.

There are three types of transaction functions.

• External Inputs
• External Outputs
• External Inquiries

Transaction functions are made up of the processes that are exchanged between the user, the external applications and the application being measured.

External Inputs

External Inputs (EI) - is an elementary process in which data crosses the boundary from outside to inside. This data is coming external to the application. The data may come from a data input screen or another application.It is a transaction function in which Data goes “into” the application from outside the boundary to inside. This data is coming external to the application.

• Data may come from a data input screen or another application.
• An EI is how an application gets information.
• Data can be either control information or business information.
• Data may be used to maintain one or more Internal Logical Files.
• If the data is control information, it does not have to update an Internal Logical File. 

External Outputs

It is a transaction function in which data comes “out” of the system. Additionally, an EO may update an ILF. The data creates reports or output files sent to other applications.

External Inquiries

It is a transaction function with both input and output components that result in data retrieval.

Advantages:

• Size oriented metrics
• Language dependent
• Understood by the non technical user
• To estimate cost and resources required for software development 

Disadvantages:

• Manually Counting Process
• Difficult to Understand
• Requires Experience