Ivan Luković, University of Novi Sad, Faculty of Technical Sciences & University of Montenegro, Faculty of Science, Podgorica 10th Workshop DAAD Ivanjica, 6 – JCSE W-2010 / Ivan Luković Face-off: Should we teach Synthesis Algorithm and Related "Theoretical" Topics in Database Courses?

JCSE W-2010 / Ivan LukovićIvanjica, 6 – / 25 Agenda Heritage and Alternatives in Databases Past and Present Issues and Experiences

JCSE W-2010 / Ivan LukovićIvanjica, 6 – / 25 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

JCSE W-2010 / Ivan LukovićIvanjica, 6 – / 25 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

JCSE W-2010 / Ivan LukovićIvanjica, 6 – / 25 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

JCSE W-2010 / Ivan LukovićIvanjica, 6 – / 25 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

JCSE W-2010 / Ivan LukovićIvanjica, 6 – / 25 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

JCSE W-2010 / Ivan LukovićIvanjica, 6 – / 25 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

JCSE W-2010 / Ivan LukovićIvanjica, 6 – / 25 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

JCSE W-2010 / Ivan LukovićIvanjica, 6 – / 25 Agenda Heritage and Alternatives in Databases Past and Present Issues and Experiences

JCSE W-2010 / Ivan LukovićIvanjica, 6 – / 25 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

JCSE W-2010 / Ivan LukovićIvanjica, 6 – / 25 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

JCSE W-2010 / Ivan LukovićIvanjica, 6 – / 25 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

JCSE W-2010 / Ivan LukovićIvanjica, 6 – / 25 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

JCSE W-2010 / Ivan LukovićIvanjica, 6 – / 25 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

JCSE W-2010 / Ivan LukovićIvanjica, 6 – / 25 Agenda Heritage and Alternatives in Databases Past and Current State Issues and Experiences

JCSE W-2010 / Ivan LukovićIvanjica, 6 – / 25 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!

JCSE W-2010 / Ivan LukovićIvanjica, 6 – / 25 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?

JCSE W-2010 / Ivan LukovićIvanjica, 6 – / 25 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!

JCSE W-2010 / Ivan LukovićIvanjica, 6 – / 25 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!

JCSE W-2010 / Ivan LukovićIvanjica, 6 – / 25 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

JCSE W-2010 / Ivan LukovićIvanjica, 6 – / 25 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.

JCSE W-2010 / Ivan LukovićIvanjica, 6 – / 25 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

JCSE W-2010 / Ivan LukovićIvanjica, 6 – / 25 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

JCSE W-2010 / Ivan LukovićIvanjica, 6 – / 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?

Ivan Luković, University of Novi Sad, Faculty of Technical Sciences & University of Montenegro, Faculty of Science, Podgorica 10th Workshop DAAD Ivanjica, 6 – JCSE W-2010 / Ivan Luković Face-off: Should we teach Synthesis Algorithm and Related "Theoretical" Topics in Database Courses?