tcamp@uncecs.edu (Ted A. Campbell) (03/29/91)
(from TCS BITS -- newsletter of the Triangle Computer Society, Raleigh--Durham--Chapel Hill, NC) WHAT'S AVAILABLE FOR DATA INTEGRATION? A Query This month I would like to interrupt my usual tirade of potshots and clever suggestions to ask a question. How can we integrate and link data of different sorts? Let me give the particular example that prompts this question. The Space Flight Simulator utilizes a number of different data formats to describe stars and planets and satellites: *.fd files contain "focal data", i.e., specific data on a particular orbital focus (a star, planet, or large natural satellite of a planet that could be orbited by a spacecraft); *.spd files contain "spherical projection data", i.e., data in the form of latitude, longitude and altitude coordinates by which places can be located on a spherical surface (each orbital focus typically has a linked *.spd file that describes the surface of the planet or satellite). Two matters might be noted about these data files. In the first place, they are presently linked together directly, with one line in the *.fd file specifying the filename for a linked *.spd file. Secondly, there are other linkages between the data that could be made: for instance, I could link somehow all the planets in a stellar system (unfortunately we only have data on one), and then each planet might have linked data on its satellites. What I am beginning to see the need for is some way to link data of differing formats: the *.fd files have a specific number of fields; the *.spd files have fields for as many points on (or above or below) the surface as one needs to describe. Moreover, I am thinking, could I somehow link pure (ASCII?) text to this data? Could there be a text file briefly describing each orbital focus in addition to the *.fd file for it? Could there be text associated with specific points in the *.spd file? Then as the spacecraft entered the gravitational field of an orbital focus, the program could display text about the focus, and as the spacecraft passed over specific points on the surface of the orbital focus, the program could give some details about this point in text format. Of course, the data could be linked simply file-to-file, but I am wondering if there could be a more universal linkage system. I have seen hypertext systems that utilize text databases wth linked items, and some of these can even integrate text and graphics. I am wondering, though, if there are existing mechanisms by which wildly different data--text, spreadsheets, databases of various sorts, graphics of various formats, etc.--could be linked to each other. The idea I have been toying with is what I would describe as a "data socket": a single file that describes another file (or i/o stream), and whose purpose it is to give in a somewhat more universal format a description of the data available in the target file and (more importantly) to link its data to other data files (or streams) with different data formats relevant to the data in the target file. Thus, a "data socket" file might describe a star system (the solar system), but could somehow explain links to datafiles that describe planetary surfaces, planetary satellite systems, text files with planetary information and description, and perhaps graphics files with images of the planets described. Perhaps, then, the data socket could also point in another direction to a data socket describing (data about) the star around which this planetary system is organized, and this could be linked in turn to data sockets pointing to information about other stars. Could we link data to data and build an, er, uh, "Encyclopedia Galactica" (apologies to Isaac Asimov)? Could I eventually link (through a long chain of data sockets) my Space Flight data to the eighteenth-century religious data that I have in quite a different area in my computer? The trick, it seems to me, is to find a near-universal way of describing and then linking data of wildly different flavors; and I'll await your suggestions and reflections on this with considerable interest. (TCS Bits readers: this column is being posted simultaneously to a couple of newsgroups on the Internet as well.) - Ted A. Campbell Duke Divinity School internet: tcamp@uncecs.edu