Large and complex computer based systems are the result of an evolutionary process which may take many years. Heterogeneity is an important characteristic of such systems; it applies to the technology and products used as well as to the different forms and sources of information about the system.

To support the development of large systems, this information has to be collected and integrated into architectural models. Hence, architecture elicitation of a large computer based system has to cope with the heterogeneity of technology and information sources. Some information can be extracted and prepared by tools, but the majority is usually inside documents and the heads of the developers. Therefore, in addition to tool support, this task requires a lot of abstraction which can only be done by humans.

This paper presents concepts and abstractions for integrative modeling, based on the Fundamental Modeling Concepts. The approach reflects experiences from many architecture elicitation projects. It provides the necessary abstractions to combine the information about the different system components, including third-party products and hardware, into one integrated architecture model. It covers modeling patterns and typical abstractions, supported by guidelines for the elicitation process.

The terminology and notation focuses on the communication about technical systems between persons being involved in system development. As a benefit, integrative models foster the efficient evolution of large systems, the introduction of new developers, or the handing over of a project.