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COCOMO II
資管研一 張永昌
Agenda Overall Model Definition COCOMO II Models for the Software Marketplace
Sectors COCOMO II Model Rationale and Elaboration Development Effort Estimates Software Economies and Diseconomies of Scale Previous Approaches Scaling Drivers
Precedentedness (PREC) and Development Flexibility (FLEX)
Architecture / Risk Resolution (RESL) Team Cohesion (TEAM) Process Maturity (PMAT)
Adjusting Nominal Effort Development Schedule Estimation Using COCOMO II
Lines of Code Function Points Converting Function Points to Lines of Code
Breakage
Overall Model Definition COCOMO II strategy:
Preserve the openness of the original COCOMO;
Key the structure of COCOMO II to the future software marketplace sectors described earlier;
Key the inputs and outputs of the COCOMO II submodels to the level of information available;
Enable the COCOMO II submodels to be tailored to a project's particular process strategy.
COCOMO II Models for the Software Marketplace Sectors
COCOMO II capability for estimation: Application Generator System Integration Infrastructure
Two life cycle : Early Design Post-Architecture
COCOMO II Model Rationale and Elaboration
Three-stage The earliest phases or spiral cycles will
generally involve prototyping, using the Application Composition model capabilities.
The next phases or spiral cycles will generally involve exploration of architectural alternatives or incremental development strategies.
Once the project is ready to develop and sustain a fielded system, it should have a life- cycle architecture, which provides more accurate information on cost driver inputs, and enables more accurate cost estimates.
Development Effort Estimates
Bnominal (Size) A PM
PM : Person Months (人月)
A : constant
Size : Size of software development
units = KSLOC ( units of thousands of source lines of code )
B : scale factor
Software Economies and Diseconomies of Scale
B < 1.0 : the project exhibits economies of scale.
B = 1.0 : the economies and diseconomies of scale are in balance.
B > 1.0 : the project exhibits diseconomies of scale.
Previous Approaches Original COCOMO :
Organic B=1.05 Semidetached B=1.12 Embedded B=1.20
Ada COCOMO : Embedded ( COCOMO ) B : 1.04~1.24
COCOMO II : combin : COCOMO and Ada COCOMO Arcgitecture 、 Risk ( Ada COCOMO ) =>RESL add : Precedentedness
(PREC) 、 Development Flexibility (FLEX) 、 Team Cohesion (TEAM)
Scaling Drivers
iw0.010.91B
Precedentedness (PREC) and Development Flexibility (FLEX)
Feature Very Low
Nominal / High
Extra High
Precedentedness
Organizational understanding of product objectives
General Considerable
Thorough
Experience in working with related software Systems
Moderate Considerable
Extensive
Concurrent development of associated new hardware and operational procedures
Extensive Moderate Some
Need for innovative data processingarchitectures, algorithms
Considerable Some Minimal
Development Flexibility
Need for software conformance with preestablished requirements
Full Considerable
Basic
Need for software conformance with external interface specifications
Full Considerable
Basic
Premium on early completion High Medium Low
Architecture / Risk Resolution (RESL)
Team Cohesion (TEAM)
Process Maturity (PMAT) organized around : Software
Engineering Institute’s Capability Maturity Model (CMM)
two ways of rating Process Maturity : CMM Maturity level
Overall Maturity Level p CMM Level 1 (lower half) p CMM Level 1 (upper half) p CMM Level 2 p CMM Level 3 p CMM Level 4 p CMM Level 5
Key Process Areas ( KPAs )
18
1 18
5
100
%5
i
iKPA
KPAs:
Adjusting Nominal Effort Early Design Model
Post-Architecture Model
7
1nominaladjusted PMPM
iiEM
17
1nominaladjusted PMPM
iiEM
Development Schedule Estimation
100
%)(67.3 )01.12.028.0( SCED
PMTDEV B
Using COCOMO II
Determining Size Lines of Code
Function Points
Counting Procedure for Unadjusted Function Points1.Determine function counts by type.2. Determine complexity-level function counts.
Apply complexity weights.
Compute Unadjusted Function Points.
Converting Function Points to Lines of Code
Breakage
原本額外
百分比BRAK
%20100000
20000: ex