Support for the Application Developer in Extended Transaction Models

17.06.2004

Foredragsholdere
Johan Fabry

Tid: Torsdag 17. juni 2004, kl 10:15 til 11:00
Sted: Møterom, Ifi (A130), alternativt U4 ved Realfagsbygget (ved stor detlakelse).

Tittel: "Support for the Application Developer in Extended Transaction Models"
Foredragsholder: Ph.D student Johan Fabry, Programming Technology Lab of the Vrije Universiteit Brussel.

Abstrakt:
If we consider transaction management in multi-tiered distributed systems, we see that the transaction manager is located at the database tier, and is steered by application code in the application tier (middle tier). In older systems, transactions are encoded within the application text, as part of the database access code. In new technologies, such as Enterprise JavaBeans, we see that database access is abstracted out as getter and setter calls on Entity Beans (= persistent objects), and that transaction management is declared separately.

Transaction management, as is, is ideally suited for executing transactions which only last a couple of milliseconds. If we start using transactions which last longer, say a couple of seconds, we will soon run into trouble: the probability of deadlocks increases dramatically with the duration of the transaction, and with such long transactions we will have to frequently abort transactions to break these deadlocks.

To address this, and other, issues, a number of advanced transaction management strategies (ATMS) have been proposed in the recent past.

These strategies require the programmer to provide some extra semantic information, which allows the transaction management strategy to more intelligently handle the transactions, which decreases the chances for deadlocks and improves transaction throughput. However, although this research has been around for a while, we see that none of these ATMS are in use in current-day commercial systems.

We believe that an important reason for the absence of these strategies is a lack of return-on investment: the programmer has to spend too much time specifying the extra semantic information, whereas the payoff in program speed and stability is only small.

Therefore, the goal of our Ph.D. research is to simplify specification of ATMS by the programmer, through abstraction. We want the programmer to be able to reason at a higher conceptual level about transaction management.

Looking at how this is handled in EJB, however, we see that declarative transaction management only provides a simple wrapper for transaction management, without adding the required functionality. In our presentation we will show how we want to go further than this, firstly by separating out transaction management from the code of the application, secondly by providing a higher level of abstraction for transaction management, and thirdly by mining the application code for useful transactional information.

Biografi:
Johan Fabry obtained the degrees of Licentiate in Computer Science in 1998 and a European Master in Object Oriented Sofware Engineering (EMOOSE) in 1999, at the Vrije Universiteit Brussel, Belgium, Ecole Des Mines De Nantes, France and Universidad De Chile, Chile. In October 1999 he received a four-year doctoral grant of the Institute for the Promotion of Innovation by Science and Technology in Flanders (IWT). He currently is a PhD student of the Programming Technology Lab of the Vrije Universiteit Brussel, funded by the IWT in the context of the CoDAMoS project.

His doctoral research focuses on the use of semantic information to optimise transaction management in distributed systems. Further research interests are aspect-oriented programming and logic meta-programming.



Eventuelle spørsmål i tilknytting til Fabrys forelesning kan rettes til førsteamanuensis Randi Karlsen, tlf 7764 4040.

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