Agenda

1. Face-off: Should we teach Synthesis Algorithm and Related "Theoretical" Topics in Database Courses? Ivanjica, 6 – 10. 9. 2010.

2. Agenda • Heritage and Alternatives in Databases • Past and Present • Issues and Experiences Ivanjica, 6 – 10. 9. 2010.

3. Heritage and Alternatives in Databases • A brief history of data models • Many data models and paradigms in database (db) design during the last four decades • Implementation data models • provided by commercial DBMSs • Conceptual data models • mostly used in the db design process • to create conceptual db schema specifications • that may be characterized as platform independent (PIM) • Still "theoretical" data models • provided by some DBMSs • designated as very "new" and "promising", but • a number of their commercial applications in industry practice is still rather small Ivanjica, 6 – 10. 9. 2010.

4. Heritage and Alternatives in Databases • A brief history of data models • Implementation data models • the most favorable is still Relational Data Model (RDM) • a long tradition and considerable popularity • very extensive commercial usage and broad application • we may believe that it will continue • thanking to its sound theoretical, i.e. mathematical background • many logical problems, their solutions, and principles concerning db design are formally defined at the level of RDM • Conceptual data models • the most favorable is still Entity-Relationship (ER) data model • also a long tradition Ivanjica, 6 – 10. 9. 2010.

5. Heritage and Alternatives in Databases • Design approaches • A typical scenario of db schema design process • (1) create the first an ER database schema and then • (2) transform it into the relational database schema • Many advantages • A number of CASE tools providing such transformation process • It is based on applying well-known mapping rules • with a common belief that such rules will guarantee the satisfaction of the Third Normal Form condition (3NF) per se Ivanjica, 6 – 10. 9. 2010.

6. Heritage and Alternatives in Databases • Design approaches • A typical scenario of db schema design process • (1) create the first an ER database schema and then • (2) transform it into the relational database schema • Unfortunately, a reality is different • many obstacles or pitfalls may appear on that road • Serious disadvantages - lack of semantic problem • some mapping rules may be characterized only as advisable • the transformation process depends not only on the formal mapping rules, but also on the problem domain semantics • many examples in which the same structure of ER db schema should not be transformed into the same relational db schema structure • due to the different semantics assigned to the ER structure Ivanjica, 6 – 10. 9. 2010.

7. Heritage and Alternatives in Databases • Design approaches • A typical scenario of db schema design process • (1) create the first an ER database schema and then • (2) transform it into the relational database schema • Main consequences • a designer is forced to make some further corrections of a relational db schema • obtained by the transformation algorithm • the source and target db schemas become unsynchronized • the quality of such designed db schemas is highly dependant of designers' • theoretical knowledge and previous experience • perception power and ability to recognize an influence of the problem domain semantics onto the transformation process Ivanjica, 6 – 10. 9. 2010.

8. Heritage and Alternatives in Databases • Design approaches • Many principles concerning db design are formally defined at the level of RDM, but unfortunately • Only some of them are widely exploited in practice • An alternative approach • db schema design based on well-known synthesis algorithm • originally defined by [Beeri C., Bernstein P.A.; 1979] • provides a powerful formalization of the relational db schema design process, but • suffers from a number of problems blocking its practical usage • still rarely exploited in practice Ivanjica, 6 – 10. 9. 2010.

9. Heritage and Alternatives in Databases • Our research results provide • Raising the synthesis algorithm to the level of its practical application • in large db design projects • in the scope of Model Driven Software Development (MDSD) process • Overcoming the problems of db schema design based on ER data model and transformations into RDM • we have made necessary improvements of the synthesis algorithm and • embedded it into our MDSD tool, named IIS*Case • presented two years ago Ivanjica, 6 – 10. 9. 2010.

10. Agenda • Heritage and Alternatives in Databases • Past and Present • Issues and Experiences Ivanjica, 6 – 10. 9. 2010.

11. Past and Present • Academy World • Past (app. two decades before) • theoretical and formal foundations of databases used to teach in detail • with considerably less problems felt by teachers • students did not complain much about it • they were to learn it, and they learned it Ivanjica, 6 – 10. 9. 2010.

12. Past and Present • Academy World • Current state • faculties are fighting for students • surviving formula for both state and private faculties is • STUDENTS + LESSONS = MONEY • deans are frightened of loosing students • a majority of students are frightened of theory, mathematical formalisms, and reading books in general • they believe that Internet is the only source they are supposed to consult for everything in their life • just a brief look at Wikipedia, Facebook / forums and Google Services is enough for everything • they are always complaining about theory and "deep" formalisms, by default • as a result, significantly reduced level of theoretical knowledge is transferred to students, in average Ivanjica, 6 – 10. 9. 2010.

13. Past and Present • Research World • Past (app. two or three decades before) • theoretical and formal foundations of relational databases used to develop intensively • many logical problems in db design were resolved at the level of RDM • a heritage that must be tailored in any new data model being developed • in late 90's, theoretical and formal approaches in databases were almost forgotten • they were not "fashionable" enough for hot research • Current state • coming back to the roots, through XML data model • the same fundamental principles and ideas evolved • employing MDSD and DSL approaches is promising Ivanjica, 6 – 10. 9. 2010.

14. Past and Present • Software Industry World • Past (app. two or three decades before) • a considerable number of large and medium-size companies • from various industry and government sectors • having their own informatics departments • with the main goal not only to support the maintenance of a company IS, but to really perform its development • large software development centers • employed predominantly high (academic) educated people • invested a lot of money in various training programs • to raise the level of technological, as well as the methodological knowledge necessary for IS development • at the same time, a lot of rather small software companies • specialized for IS development and outsourcing software services Ivanjica, 6 – 10. 9. 2010.

15. Past and Present • Software Industry World • Current state • large and medium-size companies from various business sectors mostly become just buyers of software systems • many functions of the former informatics departments have been outsourced • reducing their responsibilities only to a minimum of maintenance • reducing the number and education profile of the staff • sellers are predominantly large software companies • offering their general purpose software systems that • may be localized, parameterized or customized • are usually independent of any particular DBMS Ivanjica, 6 – 10. 9. 2010.

16. Agenda • Heritage and Alternatives in Databases • Past and Current State • Issues and Experiences Ivanjica, 6 – 10. 9. 2010.

17. Issues and Experiences • Deans' messages • Please, slow down with your theory and database schemas, otherwise I will run out of all my students! • You should realize that today's students are not the same as you were! • How do you imagine to earn your salary without students? • Of course, theory is very important. You should preserve the quality of lecturing process for sure, but be careful to provide a high ratio of passed students! • Take an elective course and do there whatever you want, but don't touch in basic, mandatory courses! Ivanjica, 6 – 10. 9. 2010.

18. Issues and Experiences • Students' messages • Positive: • Theory is really valuable to recognize all important issues in databases. • Pragmatic, funny, or possibly negative? • Who even cares about theory in database design process? It is completely unnecessary. • Please, teach us only the practice. We need just a practice. • We are always doing design in an intuitive and practical way. • I know the process very well. Just simply draw up some tables and link them by foreign keys. It is really easy, isn't it? Ivanjica, 6 – 10. 9. 2010.

19. Issues and Experiences • Colleagues' messages • Average students fill great troubles in adopting the theory and mathematical formalisms of RDM • just like formalisms in other areas, such as languages and compilers • They even couldn't perceive the synthesis algorithm, at all • A common advise: remove the synthesis algorithm and "high" theory from the database courses • this is reported by many colleagues from various universities • Alternatively, you may include such topics in the elective advanced courses, but with a special care! Ivanjica, 6 – 10. 9. 2010.

20. Issues and Experiences • Messages from software sellers • Suggestive, and usually accepted without any serious analysis in a today's high-speed life • What company is to develop its own database and IS? It is time consuming and does not pay off, at all! • Just buy our solution. It will resolve all your problems in the best way and it is the cheapest solution for you! • Many satisfied customers of our solution testify that for many years. • If you buy our solution, you may choose any DBMS you like. You will not be dependant of any DBMS provider. • We can efficiently and easily customize a solution for you to ideally fit to your business! Ivanjica, 6 – 10. 9. 2010.

21. Issues and Experiences • Main issues • Unfortunately, unforeseen and not seriously perceived side effects and expenses • DBMS independence: • database schema will contain only tables, columns, primary keys, and probably simple foreign key constraints • nothing more than that • a power of DBMS is exploited in a really small extent • everything else is an enormously complex middle-layer business logic deployed at application servers • latter on, a customer has to pay a great amount of money for its maintenance and trivial customizations, just to that seller Ivanjica, 6 – 10. 9. 2010.

22. Issues and Experiences • Main issues • Unfortunately, unforeseen and not seriously perceived side effects and expenses • "Easy" customizations may result in: • careless adding a mass of new tables and columns • poorly controlled, chaotic and erroneous database solutions • However, all these messages are fully pragmatic! • Even, there is a new message from all sides: • We are aware of future potential problems, but let us resolve our urgent problems, ASAP! • And finally, who cares about the far future. Ivanjica, 6 – 10. 9. 2010.

23. Issues and Experiences • Academic experiences from FTS • currently, two courses • Databases, 4+3, VII semester, mandatory for all CS students • about 80 students per year •  20% 9's and 10's on the scale of grades 5-10 • includes theory and formalisms (RDM, relational algebra, functional dependencies and normal forms) • Database Systems, 3+3, VIII semester, elective • No. of students: • 7 in the first running year, 42,8% of 10's • 22 in the second running year, 41% of 10's • includes the synthesis algorithm and related "heavy" formalisms, but • also includes a GUI tool that provide its practical application in database design process Ivanjica, 6 – 10. 9. 2010.

24. Issues and Experiences • Academic experiences from FTS • from this academic year, three courses • Databases I, 4+4, V semester, mandatory for all CS & CE students • about 140 students per year • basic theory and formalisms • Databases II, 2+2, VII semester, mandatory for all CS students • about 80 students per year • moderate theory and formalisms • Database Systems, 3+3, VIII semester, elective • No. of students: • we may expect 20 students per year • strong theory and formalisms, but also • balance between theory and practice Ivanjica, 6 – 10. 9. 2010.

25. Issues and Experiences • We believe that • a respectable academic education system • preserving the balance between theory and practice • combined with customized training programs • a utilization of theoretical foundations combined with MDSD and DSL approaches • throughout the whole database development process has a considerable potential to do much more for software industry than it really does today • Who is responsible for the far future and strategy decisions? Ivanjica, 6 – 10. 9. 2010.

26. Face-off: Should we teach Synthesis Algorithm and Related "Theoretical" Topics in Database Courses? End of presentation Ivanjica, 6 – 10. 9. 2010.