The integration of different applications (simulators) is the main motivation for TCAD systems. Hence, two important classification criteria for TCAD systems are concepts and support for tool integration on the data level, the task level, and the presentation level, and concepts and support for application development.
Frameworks can, by their facilities and support, be categorized in integration frameworks and development frameworks. Using a development framework, existing simulators can be split up into separate tools (Tool B in Figure 2.2) of well-defined functionality, allowing tool developers to concentrate on their particular task.
It is of course always possible to integrate another tool into an existing set of tools, the decisive criterion is the initial effort and the maintenance effort involved in the integration. Another criterion for proper integration framework design is whether adaptions of already integrated tools are required when other, new tools are integrated or changed. A development framework must provide functionality that can be re-used by newly created applications as well as both conceptual and implementation support.
It is very common that some (e.g. commercial) applications are not available in source code. For these applications (Tool A in Figure 2.2) a so-called wrapper approach must be taken. It consists of a (uni- or bi-directional) converter on the data level which translates a tool-specific data representation into the framework standard data level representation. On the task level, a corresponding task macro is required to include the execution of the converter. The framework is disguised by ``wrapping software'' (the converter and some task level code) to provide a foreign tool with an entirely familiar environment.