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1 Analysis of MBASE Model-Clashes Mohammed Al-Said USC-CSE.

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1 1 Analysis of MBASE Model-Clashes Mohammed Al-Said USC-CSE

2 2 Agenda: Background, Informal definition of models and model clashes Research Goals and Objectives MasterNet Project Model-Clashes Formalizing Models and Model Clashes definition Examples of formal modeling

3 3 Definition of a Model : Model (Webster): A description or analogy used to help visualize or analyze something; a pattern of something to be made. –Includes product models, process models, property models, success models. –Models are used extensively in Software Engineering. –MBASE is a framework, explicitly utilize and integrate those models. – Models inconsistencies are major source of S/W problems.

4 4 Win-Win Business Case Analysis Software Warranties QFD 10X Six Sigma Award Fees JAD RAD One View: Models Needing Integration MBASE Success Models Product Models Property Models Process Models Spiral Waterfall Risk Management Business Process Reengineering CMM’s Peopleware IPT’s Objectory Groupware UML CORBA COM Architectures Product Lines OO Analysis & Design Domain Ontologies COTS GOTS COCOMO COCOTS Checkpoint System Dynamics Metrics - ilities Simulation and Modeling

5 5 Product ModelProcess ModelProperty ModelSuccess Model Product Model  Structure clash  Traceability clash  Architecture style clash  COTS-driven product vs. Waterfall (requirements- driven) process  Interdependent multiprocessor product vs. linear performance scalability model  4GL-based product vs. low development cost and performance scalability Process Model  Multi-increment development process vs. single- increment support tools  Evolutionary development process vs. Rayleigh-curve cost model  Waterfall process model vs. "I'll know it when I see it" (IKIWISI) prototyping success model Property Model  Minimize cost and schedule vs. maximize quality (Quality is free)  Fixed-price contract vs. easy- to-change, volatile requirements Success Model  Golden Rule vs. stakeholder win- win Examples of Model-Clashes:

6 6 Research Goals and Objectives: Understand and exemplify the nature of MBASE model clashes. Gain insight and find effective approaches to identifying and resolving model clashes. Provide a rigorous foundation for software and system modeling (primarily via MBASE). Deduce properties and possible consequences of model clashes. Produce a foundation for the development of software engineering decision tools.

7 7 Research Approach: Study informal model-clashes using real life projects. Informally understand MBASE assumptions and model-clashes. Determine fundamental syntax and semantics for MBASE models (first and second order logic, -calculus). Create a framework to identify model clashes. Derive formal model-clash results. Discover approaches to resolving model clashes: how much can a model be weakened (i.e. dropping or modifying assumptions)?. can models be strengthened to resolve some clashes?.

8 8 Bank of America’ MasterNet Project: The task in 1980 - Develop the MasterNet system update and automate the online generation of monthly statements for the bank’s trust accounts. Estimate: $22M, 2 years to complete. Project developer: Premier Systems Scale up an existing small-trust system. Result: Took five years, cost $80 million Example of Model-Clashes: Consequences: The system was rejected by Bank of America Tarnished BofA’s reputation The total number of institutional accounts dropped from 800 to 700 Managed assets shrank from $38 billion to $34 billion. Loss of the business.

9 9 MasterNet Model-Clashes

10 10 Formal MBASE Model Definition: MBASE is a structure U*  U  = set of Product, Process, Property, and Success elements. (e.g., systems components; schedule; effort; win conditions) Example of n-place Predicates (i.e., T,F assignments) would be R(x) = “x is a requirement” ; S(y) = “y is a stakeholder” Example of constants are “dollars”, “man months”, “object”… Example of n-place Functions f (r1,r2,…., rn)=l “l is a level of service for requirements r1,r2,…,rn” Whenever a formal sentence, , is true in U, we say U is a model for , written as ï U  but drop U when it’s understood. * As defined in Enderton H book “a mathematical introduction to logic” p.79.

11 11 Model-Clash definition: Given ï K1 , ï K2 , (we call ,  “assumptions” for models K1 and K2). A model clash occurs when Ì K { ,  }for all substructures K of U If å  ›1 and   ›2 and ï Κ1 Φ and ï Κ2  Then the models K1 and K2, clash {K1  K2} Ì{ Φ   }  K1  K and K2  K  Ì Κ { Φ   }

12 12 A clash between one assumption and implication of another assumption : Φ: å  :  á —å Example: Many Features <> Tight budget & Schedule (less features) Example: Formalizing a model-clash:

13 13 WATERFALL: Φ : Complete Requirements are known before Implementation  =  x  y Ix  Ry I: Implementation R: Requirements COTS: Í: C ode exists before having complete requirements Í:  x  y Rx  Iy Assume MBASE model Κ, Κ1: Waterfall:  =  x  y Ix  Ry é  1 Κ2: COTS:  =  x  y Rx  Iy é  2 Is ï Κ › consistent? ( i,e ï Κ {    })? Example: Formalizing a model-clash:

14 14 Proof: After skolemization and substitution we have  = Ia á Rb  = —Ia á —Rb   and  are not logically equivalent (by truth table)  ï Κ  and Ì Κ  or  ï Κ  and Ì Κ   › is inconsistent.  Model clash between Waterfall and COTS.

15 15 Questions?

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