1. ETAPS 991 Understanding Legacy Systems Arie van Deursen Tobias Kuipers Leon Moonen

2. ETAPS 992 Tooling Infrastructure Legacy Sources Lexical Analysis Syntax Analysis Data flow Analysis Repository Report Generator Cluster Analysis Visuali- zation Filter & Abstract

3. ETAPS 993 Redocumentation zContents decided by maintenance team. yTechnical system knowledge lost! zAutomatic extraction yManual: additional docs, overviews zTraining, changes, estimates,...

4. ETAPS 994 Understanding Variables z100 Kloc Cobol: y25,000 different variables! zCobol variable declarations: yAggregation + byte representation zNo types!

5. ETAPS 995 Type Inference for COBOL zGive each variable unique primitive type zInfer type-equiv. and subtype relations yx + y, x == y, x := y, literals,... yDB operations, calls, copybooks zPartial order of equivalence classes O’Callahan ‘97: C Henglein ‘99: Y2K WCRE’98, IWPC’99

6. ETAPS 996 Applications zY2K & Euro zConstant (de)propagation zProgram-level documentation zSystem-level signatures zLanguage migrations zObject identification

7. ETAPS 997 Object Identification zLegacy data structures yattributes zLegacy functionality ymethods Select Domain Concept s Persistent data types Progrs low fan in/out Combination: Candidate classes!

8. ETAPS 998 Concept Analysis zConcept (I, F ): I ymaximal set of items I  I F ysharing set of features F  F I  F zFrom feature table T  I  F ygenerate all concepts zLattice: (I1, F1)  (I2, F2 )  I1  I2 Siff/Reps’97 Lindig/Snelting’97 IWPC’98, ICSE’99

9. ETAPS 999 Concept Fields Progr. nrs One field Many fields

10. ETAPS 9910 System Understanding zAnalysis of legacy sources ySelect good parts yFilter out hopeless elements yCombine & present in novel ways zTool support rather than automation