In IFPUG, we measure the functional software user requirement size by the following, in units of “function points.”  For example, an application may have ”500 function points.”  In this presentation, all function points refer to IFPUG function points unless otherwise stated.

• External inputs.
• External outputs.
• External inquiries.
• Internal logical files.
• External interface files.

We use the IFPUG Counting Practices Manual (CPM) [IFPUG 2010] and ISO/IEC 20926:2009 Software and systems engineering – Software measurement – IFPUG functional size measurement method 2009. [ISO 2020].  

It is important to measure the size of the functional user requirements of software because it is known than there is a statistical correlation between software functional user requirement size and the work effort to develop that portion of the software.  Typically, the larger the functional user requirement size, the more it costs to develop the software (and the longer it usually takes to complete).  With function points, we have a way to measure the size of the functional user requirements of a software application.

SNAP is a methodology for sizing the non-functional user requirements of software, using units of measure called SNAP points.

The SNAP APM is similar to the IFPUG CPM, but for SNAP.

The APM is structured in a similar manner to the CPM, and this will be clarified in the presentation.

SNAP is intended to size non-functional user software requirements by means of documented definitions, guidance and practices.  SNAP is also intended to help address the “zero function point” problem where software is developed having no function point count but work effort is required; it is possible for an enhancement to have 0 function points but, say, 50 SNAP points.

Login as a member to access this resource.

Non-Members: $20.00, purchase the publication here: https://ifpug.memberclicks.net/fpaelementary