External Inquiry

An inquiry is a combination of input and output, where user sends some data to inquire about as input and the system responds to the user with the output of inquiry processed. The complexity of a query is more than External Input and External Output. Query is said to be unique if its input and output are unique in terms of format and data.

      Simple - if query needs low processing and yields small amount of output data

      Complex - if query needs high process and yields large amount of output data

      Average - in between simple and complex.

Each of these parameters in the system is given weightage according to their class and complexity. The table below mentions the weightage given to each parameter:

Parameter

Simple

Average

Complex

Inputs

3

4

6

Outputs

4

5

7

Enquiry

3

4

6

Files

7

10

15

Interfaces

5

7

10

The table above yields raw Function Points. These function points are adjusted according to the environment complexity. System is described using fourteen different characteristics:

      Data communications

      Distributed processing

      Performance objectives

      Operation configuration load

      Transaction rate

      Online data entry,

      End user efficiency

      Online update

      Complex processing logic

      Re-usability

      Installation ease

      Operational ease

      Multiple sites

      Desire to facilitate changes

These characteristics factors are then rated from 0 to 5, as mentioned below:

      No influence

      Incidental

      Moderate

      Average

      Significant

      Essential

All ratings are then summed up as N. The value of N ranges from 0 to 70 (14 types of characteristics x 5 types of ratings). It is used to calculate Complexity Adjustment Factors (CAF), using the following formulae:

CAF = 0.65 + 0.01N

Then,

Delivered Function Points (FP)= CAF x Raw FP

This FP can then be used in various metrics, such as:

      Cost = $ / FP

      Quality = Errors / FP

      Productivity = FP / person-month