analysis patterns Daniel Jackson MIT Lab for Computer Science 6898 Advanced Topics in Software Design March 4 2002 what are analysis patterns background Martin Fowler 1996 based on experience applying object modelling to large corporate information systems focus on models themselves not process according to MF ideas from one context useful in another useful across business areas health finance manufacturing type models provide language of the business modelling Business Process Reengineering simple models obvious only in retrospect 2 plan look more deeply into one pattern Referring to objects apply Alloy express constraints formally investigate dynamic aspects too consider applications of pattern what problems does this fit 3 example naming motivation systems need to deal with entities using names humans use names to refer to entities how names entities are related can be tricky anything object oriented here patterns Referring to Objects Identification Scheme Object Merge 4 objects names sig Object sig Name sig Scheme objects set Object names set Name denotes names objects Name names denotes Object objects 5 static constraints fun UniqueIdentifiers s Scheme func s denotes fun NoAliases s Scheme inj s denotes fun AllNamed s Scheme s objects in ran s denotes fun AllDenote s Scheme s names in dom s denotes 6 play time 7 matching constraints to problems constraints UniqueIdentifiers NoAliases AllDenote AllNamed problems machine mac machine IP machine domain name person social security number aircraft flight number MIT class class number medical procedure health plan treatment code Java object heap address roadway number 8 dynamic constraints questions can the name object mapping change if an object exists at two times are its names the same if a name exists at two times are its objects the same can names be recycled 9 sample dynamic constraints fun RetainNames s s Scheme all o s objects s objects s denotes o s denotes o fun NamesSticky s s Scheme all n s names s names all o s objects s objects n o in s denotes iff n o in s denotes 10 a generic constraint fun FixedFor s s Scheme ns set Name os set Object let r ns os s denotes r s denotes r says for the names in ns and objects in os naming is fixed symmetrical in s and s surprising 11 varieties of dynamic constraint fun NamingFixed s s Scheme FixedFor s s Name Object fun Sticky s s Scheme FixedFor s s s names s names s objects s objects fun NSticky s s Scheme FixedFor s s s names s names Object fun OSticky s s Scheme FixedFor s s Name s objects s objects 12 play time 13 identification scheme sig SchemeName sig World schemes set Scheme names set Name scheme names schemes constraints naming constraints across schemes how can schemes change 14 a sample operation code refinement classification scheme each name refers to set of objects find need to refine classification by introducing new names fun SameNames s Scheme Object Object result o o s objects s denotes o s denotes o fun Refines s s Scheme s objects in s objects some SameNames s SameNames s NSticky s s AllDenote s AllDenote s AllNamed s AllNamed s 15 talking points conceptual patterns only useful to software engineers if they can see how to implement them models are not right or wrong they are more or less useful analysis design techniques may be rigorous but they don t have to be I try to develop very conceptual models that focus entirely on the problem yet my techniques are object oriented and hence reflect a design approach 16