Interface Models and Function Point Calculation

Transcription

1 Interface Models and Function Point Calculation Jeannie Bellows Senior Consultant Who is Castek?

2 Who is Castek? Global organization, headquartered in Toronto, Canada with offices in Ottawa, Canada and Dallas, Texas Castek RBG - a reuse knowledge transfer consulting group based in Cary North Carolina 73 employees - projected to grow to over 200 in fiscal 999 Annual investment of 25% - 30% of revenue into applied and advanced research and development 3 Who is Castek? Began working with reusable assets in Enterprise Objects Collaborated with TI Software (now Sterling Software) to create the CBD96 standards in 995 / 996 We ve become a global organization of evangelists, consultants and fixed price delivery teams all focused on component-based development 4

3 Who is Castek? 5 Presentation Resources IFPUG Counting Practices Manual Jones, Capers, Applied Software Measurement: Assuring Productivity and Quality, 2d ed. (McGraw-Hill, 996) Mapping the OO-Jacobson Approach into Function Point Analysis (Copyright TOOLS, 997) Practical experience with Castek components and client applications 6

4 Presentation Content Examine the role that the Interface plays in function point calculation Interface as defined by CBD96 The goal is not to fully present counting rules, but to map IFPUG counting types to the interface 7 Agenda Function point analysis and the interface model Tailoring the IFPUG counting process to use the component interface Function point analysis and application development using components Summary 8

5 Objectives of Function Point Analysis Measures software by quantifying its functionality provided to the user based primarily on logical design (IFPUG) Measures software development and maintenance independently of technology used for implementation (IFPUG) 9 FPA Objectives and Interfaces The interface describes behavior visible to the user The interface is pure specification, it does not define any implementation details The interface actually meets the objectives of function point analysis better than traditional methods! 0

6 The Traditional Approach Typical artifacts used to count using structured design techniques: Activity Hierarchy Diagram Application Screens Database Structures (ERD) The CBD Approach Artifacts used to count function points using the CBD approach Specification types Specification type attributes Specification type relationships Public operations Artifacts that can be used but are not presented here Use Cases Domain Models 2

7 Castek s Approach Reviewed IFPUG techniques Reviewed applicability of function points in a CBD environment Mapped IFPUG constructs to COOL:Gen CBD constructs Formalized assumptions and simplification rule 3 The Component Interface Interface Interface XYZ Operation(s) Type model An interface is a logical grouping of semantically related operations A type model describes the vocabulary of the interface by describing the parameters and other information necessary to understand and use the operations. An operation is a service available for consumption by a user 4

8 Example Component The example we are going to use is an Organizational Structure Component The component allows businesses to define and maintain the structure of an organization This component is purely fictional and any resemblance to an actual component is purely coincidental 5 IFPUG Counting Process Step Determine the type of function point count Step 2 Identify the boundary for counting Step 3 Count unadjusted function points Step 4 Determine the adjustment factor Step 5 Calculate the final adjusted function point count 6

9 IFPUG Counting Process Step Determine the type of function point count Step 2 Step 3 Step 4 Identify the boundary for counting Count unadjusted function points Determine the adjustment factor Count Data Function Types Count Transactional Function Types Step 5 Calculate the final adjusted function point count 7 Data Function Types IFPUG Data function types represent the functionality provided to the user to meet internal and external data requirements. It refers to logically related groups of data A specification type represents a domain concept, or a logically related group of data Each specification type defined in the type model is a Data Function Type 8

10 The Interface Type Model Interface XYZ Graphically illustrates types and their relationships from the business perspective Describes the vocabulary used by the public operations of the interface Also called Specification Type Model Used to count Data Function Types 9 IFPUG Counting Process Step 3A Count Data Function Types Identify Internal Logical Files (ILF) Identify External Interface Files (EIF) Determine Complexity and Function Point Contribution 20

11 Internal Logical Files (ILF) IFPUG A user identifiable group of logically related data or control information maintained through an elementary process of the application 2 ILF and the Interface Type Model A type is counted as an ILF if it is maintained within the counting boundary IORG_ORGANIZATION Organization Unit Party Organization Unit Attribute Position Resource 22

12 External Interface Files (EIF) IFPUG A user identifiable group of logically related data or control information referenced by the counted application but maintained within the boundary of another application 23 EIF and Interface Type Example Party is an External Interface File because it is maintained outside of the counting boundary. IORG_ORGANIZATION IPTY_PARTY Org Unit Attribute Organization Unit Position Party (EIF) Resource Party (ILF) 24

13 Determine Data Function Type Complexity Complexity of ILFs and EIFs is determined by the associated number of data element types (DETs) and record element types (RETs) 25 Data Element Types (DET) IFPUG A unique user recognizable, non-recursive field on the ILF or EIF 26

14 DETs and the Interface Type Model Count each attribute and each foreign key as one Data Element Type IORG_ORGANIZATION Organization Attribute code name description value Organization Unit type name parent Position code title Party instance id last name first name Resource number 27 Record Element Types (RET) IFPUG A user recognizable subgroup of data elements within an ILF or EIF 28

15 Record Element Types and CBD Most types defined in the interface model will correspond to one RET Multiple RETs may exist when inheritance or subtyping is used Multiple RETs may exist when aggregation relationships are used 29 Multiple RET Example Aggregation Relationship - One ILF, Two RETs Project Team Employee name function number Inheritance - One ILF, Two RETs Person instance id last name first name Employee number 30

16 Data Function Type Complexity Rate the functional complexity based on the IFPUG DET/RET complexity matrix: ILF/EIF to 9 DET 20 to 50 DET 5 or more DET RET Low Low Average 2 to 5 RET Low Average High 6 or more RET Average High High 3 Determine Function Point Contribution Assign function point contribution based on the IFPUG translation table: ILFs Functional Complexity Rating Unadjusted Function Points Low 7 Average 0 High 5 EIFs Functional Complexity Rating Unadjusted Function Points Low 5 Average 7 High 0 32

17 Data Function Type Count Example Internal Logical Files Internal Logical Files (ILF) RET DET Complexity FPs Organization Unit 3 Low 7 Organization Unit Attribute Position Resource Low Low Low Unadjusted Function Points 28 External Interface Files External Interface Files (EIF) RET DET Complexity FPs Party Unadjusted Function Points 3 Low IFPUG Counting Process Step Determine the type of function point count Step 2 Step 3 Step 4 Identify the boundary for counting Count unadjusted function points Determine the adjustment factor Count Data Function Types Count Transactional Function Types Step 5 Calculate the final adjusted function point count 34

18 Count Transactional Function Types IFPUG Transactional function types represent the functionality provided to the user for processing of data A public operation is a discrete unit of functionality defined on an interface In most cases, each public operation of an interface is a transactional function type 35 IFPUG Counting Process Step 3B Count Transactional Function Types Identify External Inputs (EI) Identify External Outputs (EO) Identify External Inquiries (EQ) Determine complexity and function point contribution for each. 36

19 External Input (EI) IFPUG An elementary process that processes data or control information that comes from outside the application's boundary. Processed data maintains one or more ILFs. Processed control information may or may not maintain an ILF 37 EI and the Interface Type Model Count each public operation that maintains an ILF as an External Input IORG_ORGANIZATION Organization Unit Attribute Organization Unit Position Party Resource Assign Resource to Position List Organization Resources Remove Resource from Position Add Organizational Unit Departmental Resource Report Get Resource Name 38

20 Determine External Input Complexity Complexity of EIs is determined by the number of file types referenced (FTR) and data element types (DET) 39 IFPUG FTR and DET Defined File Types Referenced (FTR) An ILF read or maintained or an EIF read by a function type Data Element Type (DET) A unique user recognizable, non-recursive field maintained on an ILF by the EI 40

21 Determine Complexity & Contribution Rate the functional complexity based on the IFPUG FTR/DET complexity matrix: External Input (EI) to 4 DET 5 to 5 DET 0 to FTR 2 FTR > 2 FTR Low Low Average Low Average High > 5 DET Average High High Translate the external inputs to unadjusted function points using the IFPUG matrix: Functional Complexity Rating Unadjusted Function Points Low 3 Average 4 High 6 4 External Input Example The operation specification is used to determine the number of File Types Referenced and Data Element Types for the EI. FTRs organization position party resource DETs instance_id code instance_id number The pre and post-conditions help to determine which ILFs and EIFs are referenced and/or maintained. Assign Resource to Position Purpose: Imports: organization instance_id position code party instance_id Exports: resource number Pre-condition: Organization exists AND Position exists AND Party exists Post-condition: An instance of Resource is created for the input Organization, Position and Party 42

22 EI Function Point Contribution Example Use FTRs and DETs to determine complexity and function point contribution External Inputs (EI) FTR DET Complexity FPs Assign Resource to Position 4 4 Average 4 Remove Resource From Pos 3 3 Average 4 Add Organizational Unit 4 Low 3 Unadjusted Function Points 43 External Output (EO) IFPUG An elementary process that generates data or control information sent outside the application's boundary 44

23 EO and the Interface Type Model Count each public operation that sends data outside the system boundary as an External Output IORG_ORGANIZATION Organization Unit Attribute Organization Unit Position Party Resource Assign Resource to Position List Organization Resources Remove Resource from Position Add Organizational Unit Departmental Resource Report Get Resource Name 45 Determine Complexity & Contribution Complexity of EO is determined by the number of file types referenced (FTR) and data element types (DET) FTR is a file read when the EO is processed DET is a unique user recognizable, non-recursive field that appears on the EO The IFPUG complexity matrix for EO s is slightly different than the matrix for EI s The IFPUG External Output matrix is used to determined Function point contribution 46

24 External Output Example The operation specification is used to determine the number of File Types Referenced and Data Element Types for the EO. FTRs organization position party resource DETs instance_id title instance_id last_name first_name number The pre and post-conditions help to determine which ILFs and IEFs are referenced. Departmental Resource Report Purpose: Imports: organization instance_id Exports: organization_unit name report_line (occurs 000) position title party last_name party first_name resource number total_number_of_resources Pre-condition: Organization exists. Post-condition: A report naming all resources for the organization is created. 47 External Inquiry (EQ) IFPUG An elementary process made up of an input-output combination that results in data retrieval. The output side contains no derived data. No ILF is maintained during processing. 48

25 EQ and the Interface Type Model Count each public operation that retrieves information from an ILF or EIF as an External Inquiry IORG_ORGANIZATION Organization Unit Attribute Organization Unit Position Party Resource Assign Resource to Position List Organization Resources Remove Resource from Position Add Organizational Unit Departmental Resource Report Get Resource Name 49 External Inquiry Example The operation specification is used to determine the number of File Types Referenced and Data Element Types for the EQ. FTRs organization position resource party DETs instance_id code number last_name first_name The complexity of the input is considered separately from the complexity of the output. Only the highest complexity is counted. Get Resource Name Purpose: Imports: organization instance_id position code resource number Exports: party last_name party first_name Pre-condition: Organization exists AND Position exists and Resource exists for that Position. Post-condition: Resource first and last name are returned 50

26 Determine Complexity & Contribution Complexity of EQ is determined by the number of file types referenced (FTR) and data element types (DET) Input complexity is determined using the same matrices as EIs Output complexity is determined using the same matrices as EOs The EQ complexity is calculated as the higher of the input or output complexity 5 The Component Interface Interface Interface XYZ Operation(s) Type model The interface is the counting boundary The types within the type model are data function types (ILF and EIF) The operations are transactional function types (EI, EQ and EO) 52

27 FPA and Application Development Function Points for a business application cannot be derived by summing the function points of consumed components!!! 23 BUSINESS SYSTEM Type A IXYZ_COMPO NE NT 450 Function Points Type B Process Process 2 Type C Process 3 Process 4 IORG_ORG ANIZAT ION 98 Function Points 53 FPA and Application Development Function points can be used as a tool to help determine the benefit of a purchased component by counting functions that specifically match requirements. Function points can be used to estimate cost required for software development. 54

28 FPA and Application Development Count the function points associated to the functionality that the application will use Business Process associated with 6 function points 23 Business System External Inputs (EI) Maintain Project Resources FTR DET Complexity FPs 4 4 High 6 Component satisfies part of the functionality required. IORG_ORG ANIZAT ION External Inputs (EI) Remove Resource From Position Assign Resource to Position FTR DET Complexity FPs 3 3 Average Average 4 55 Summary Interface type models provide user visible functions making them a good source for function point counting CBD hides complexity which may lower function point counts Components need an application context for meaningful function point evaluation 56 Summary

29 Questions / Discussions Contact me at jbellows@castek.com