Research Overview—Dr. Bryon K. Ehlmann

My research interests are in the area of database systems and data modeling. More specifically, my research is concerned with incorporating more knowledge of relationship semantics into database management systems (DBMSs). An example of a relationship is that between employees and car pools. The semantics of this relationship are that an employee may or may not “belong to” a single car pool and every car pool must have two or more employees. Also, if one of only two employees in a car pool leaves the car pool, it should cease to exist. If a DBMS can be made aware of such semantics, then the system can automatically maintain them. This increases the integrity of the data stored in the database and increases the productivity of developing computerized information systems since much programming is eliminated.

To this end, I have developed the Object Relationship Notation (ORN). ORN can be readily integrated at a conceptual level into data models, e.g., UML class diagrams, and at an implementation level into data definition languages (DDLs), e.g., ODMG ODL and SQL. ORN facilitates the specification of a wide variety of common relationship types, more so than the REFERENCES clause of SQL. To verify ORN’s definition and utility, I have integrated it into a prototype database modeling tool, called the ORN Simulator; a prototype object DBMS, called Object Relater Plus (OR+); and a relational database via a tool called ORN Additive. “Selected Papers on ORN” can be accessed by clicking on this link.

The ORN Simulator is an OR+ application that allows one to model a database and immediately simulate its operation. The user defines object classes, e.g., employees and car pools, and associations, e.g., “belongs to,” in the context of an ORN-extended ERD or UML class diagram. The model represented by the diagram comes alive in the sense that the user can easily create and manipulate a prototype database that conforms to the model. As the user creates and deletes objects and creates and destroys association links, the association semantics as specified by ORN are automatically maintained and readily observed. Students of software engineering and database management, worldwide, can use the ORN Simulator as an aid in learning the concepts of data modeling, logical database design, and transaction processing. The “ORN Simulator” can be accessed by clicking on this link.

The ORN Simulator is built using Object Relater Plus (OR+). OR+ is an object DBMS that is built on top of Object Store, a commercial object DBMS. It provides Object Store with a more ODMG standardized interface and, more importantly, enhances it with ORN. The “OR+ ODDL User’s Guide” and “OR+ ODML User’s Guide” can be accessed by clicking on these links.

The ORN Additive tool was developed to show that ORN can be added to a relational database system. This allows associations model in ORN-extended UML diagrams to be more easily implemented in SQL, without requiring the development and maintenance of complex constraints and triggers. ORN Additive essentially allows ORN to be given for the foreign key constraints that are defined in Microsoft SQL Server databases. The “ORN Additive User’s Guide” can be accessed by clicking on this link.

References to all of my research publications can be accessed by clicking on the “Publications” link.