Function Points FAQs


Batch Functions and Release 4.2

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ISSUE

Should batch functions, which do not have any DETs that come from outside the application boundary, be counted as elementary processes?

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GENERAL DISCUSSION

Under Release 4.1 (and in 4.2) the definition of an External Input has been changed to:

"An elementary process, that processes data or control information that comes from outside the application’s boundary. The primary intent of an EI is to maintain one or more ILFs and/or to alter the behaviour of the system."

This definition implies that if there are no DETs, which come from outside the application boundary, there is no EI to be counted.

Many batch functions that satisfy the definition of an elementary process do not satisfy the 4.1 definition of an External Input. Such functions are often triggered by the system clock, which is considered to be internal to the application boundary. Alternatively it is possible to have ‘cascading’ batch functions, where the completion of one processing event triggers the next until the entire batch run is completed. In both these cases, the primary intent of the function is to maintain one or more ILFs, however there are no DETs which cross the application boundary. The elementary process is triggered internally, DETs are maintained, a business function is completed but no DETs have crossed the boundary.

An additional issue relates to the complexity of batch functions. Even if a control trigger does physically cross the boundary, if there is only one such trigger (<4 DETs) AVERAGE is the highest complexity rating that can be awarded to the function, regardless of how many DETs are maintained or files are referenced.

Internally triggered output and enquiry functions do not cause a problem as their primary intent is to present information to the user outside the application boundary.

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RESOLUTION

Where a batch function satisfies the definition for an Elementary Process, and its primary intent is to maintain one or more ILFs, this function is counted as an External Input with one DET, regardless of whether any DETs enter or exit the application boundary, or not.

Alternative Resolutions for Awarding Transactional Complexity:

In determining the complexity of the batch EI, two alternatives are possible:

  1. Where the number of DETs entering or exiting the application boundary is <5 the highest complexity rating that can be awarded is AVERAGE
  2. FP Analysts to revert to IFPUG 4.0 guidelines and count the DETs maintained as a result of the EI process. this will allow a complexity rating of HIGH to be awarded to certain batch functions.

A DET is a unique user recognisable, non-recursive field maintained on an Internal Logical File by the External Input"

Organisations should select one of the above alternatives.

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