| 摘要 |
Changes and/or expansions to an application system are inevitable. An application system is modified and expanded many times during its lifetime. Today's application systems are complex. They can contain code that is written in more than one programming language. Data definitions may exist out of the domain of an application system; however, these very data are manipulated by an application system. Thus, there are many relationships among these data and the programs of the application system; one affects the other. The modification of one of these components triggers silently a series of changes. These changes are not apparent and not in sequence. A network of computers (or network) is a set of related computers, and a computer may contain one or more application systems or part of an application system. The affected components can be anywhere in the network. To guarantee the integrity of the network all the affected components must be found and corrected; else this change can and will have disastrous results. To fix this problem an army of sophisticated programmers is needed, a resent example is the Y2K bug, because the required information is not readily available, it has to be extracted from the application systems as they exist in its current format. This is expensive, time consuming andnext to impossible if it has be done on daily basis. To solve the problem, a diagnostic system is required to convert the format of an application system to a format that a user can draw immediate knowledge of the relations and the affects of the program objects and the data objects. The terms program and data objects are subjective, and thus a user must determine what these objects are. Since part of an application system can be written in different programming languages we must find a way to allow the user to describe the required objects in many different programming languages. In other words, a universal grammar is required -that can recognize the syntax of program and data objects in any programming language- and to construct an engine (called parser) that can recognize the user's specified objects and relate them in the required way to achieve the application system's objectives
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