Nijssen's research interests in the field of computer science have developed over the years. In the 1970s he was focussed on information systems and database technology.
Conceptual schema and relational database design, 1989 In 1989 Nijssen and
Terry Halpin published 'the book
Conceptual schema and relational database design: a fact oriented approach. The introduction it declared the background of this work: :"Prof. G. M. Nijssen, the originator of NIAM design method, had for a long time given a higher priority to working on new aspects of the method and advancing it, than to writing a textbook about it; but at last, here it is. The NIAM method was initiated in the early 1970s, at a time when most researchers in the data base and information system field still were discussing
data modeling on the level of record structures. Only a few acknowledged the need for semantic data modeling. Among these few was Prof. Nijssen, who realized its enormous potential for the practice of data base and information system development..." The introduction further explained, that NIAM was further developed in cooperation with several other scientists, such as with E.D. Falkenberg. Nijssen and Halpin stipulated: :"... the numerous fruitful discussions which ... with Prof.
E.D. Falkenberg, while he was at the University of Stuttgart, Siemens Research center and at the University of Queensland. Some of these discussions were enjoyed in "high places", such as the Rigi and Saas Fee, in Switzerland. Various ideas contained in the NIAM design method were originated by Prof. Falkenberg, for example, the basic set of concepts and some aspects of the design procedure, including an algorithm for designing subtypes." Nijssen and Halpin further explain: :"While the "great debate" in 1974 between proponents of the
CODASYL Network Model (
C. W. Bachman) and of the
Relational Model (Dr
E. F. Codd) was the focus of attention in database research world, it was Prof. Falkenberg who said that:
The debate is irrelevant for semantic data modeling. Now, years later, the debate on
semantic data modeling is indeed concerned with issues quite different from those emphasised in the conventional
data models."
CogNIAM Back in the Netherlands in the 1990s Nijssen developed
Cognition enhanced Natural language Information Analysis Method (CogNIAM). Hereby he focused entirely on the most productive protocol for the development of business requirements and integrated business modeling. == Publications ==