abbott@aerospace.aero.org (Russell J. Abbott) (06/29/89)
The current focus of the Aerospace Computer Aided System Engineering & Integration (CASEI) project is on developing a new, user-friendly front end to computing environments. Our immediate goal is to build a prototype substitute for Unix shells on Suns and the Finder on Mac II's. I'm not sure that this is the place to discuss it, but I'd like to start a discussion of the kinds of things one would want in a up-to-date front end. The following provides an example of the sorts of things we are thinking of. In general, the new front end will be visual (like the Mac) and "object oriented." When one logs on, one's directory/folder structure will be displayed as a tree in a window. (Actually it will be an arbitrary directed graph. There is no requirement that it actually be tree structured.) Each node of the graph corresponds to one directory/folder. The name of the node, i.e., the directory/folder name, will be displayed, but files/objects stored at a node will not be. When a node is clicked, a sub-window will pop up displaying the contents of that node. The directory/folder graph will actually include all directories/folders in the system, and perhaps on the available(?) network. One can examine the entire file system (permissions permitting) by traversing the graph. Some of the leaves may be "intensional directories." An intensional directory is a directory whose contents are specified by an expression rather than by a set of pointers. (A Unix path expression e.g., ~/abc/de*fg, is a simple example of a expression that may be used to define intensional directories.) The range of possible expressions is yet to be defined. Most likely it will never be fully defined since there is no reason to prevent users from writing their own interpreters for directory expressions. One intended use of intensional directories is to allow a more flexible structuring mechanism for one's files. For example, when doing software development one may want a single directory to contain source code, object code, and documentation for a module. Yet, one may also want a single directory or directory structure that contains all the documentation for an entire system. Intensional directories facilitate this by letting one build multiple structures over a base structure -- more or less as one does with "views" in database systems. Another reason we are interested in intensional directories is that we want to build a service through which users can find out about programs, tools, models, etc. in their environment. It is not clear exactly what sort of information retrieval or database service will eventually be built, but whatever the service is, it will presumably have a query language. Expressions in that language will be acceptable as intensional directory expressions. We'd appreciate any comments, suggestions, or recommendations of other work to examine. Russ Abbott & Nick Lubofsky abbott@aerospace.aero.org lubofsky@aerospace.aero.org P.S. We have also started a mailing/discussion list of potential users of the system. To get on the list, write to: abbott@aerospace.aero.org. To send a message to the entire list, write to: casei@ses.aero.org.