On Wed, October 13, 2010 9:10 am, Tom Morris wrote: > I thought the whole point of having fields in a database record was to > avoid having to do string parsing, with all its problems, to recover > your original data.
Well, that's one of the side effects of good database design, but it's not the whole point. The main point of database design is to collect similar data into a single structure, and then connect it to other, related data structures in such a way that related data can be pulled together quickly, and errors caused by different data being entered for the same fields (data anomalies) are minimized. The OpenLibrary catalog "database" is not a database in the commonly understood sense (which is why I usually refer to it as a "repository" and not a "database"). Rather, it is a collection of name/value pairs (the values of which can be another collection of name/value pairs) all munged together into a single string. > If multiple fields are going to be munged together into a single > string, what are the escaping rules for delimiters contained in the > original strings? What are the parsing rules? The strings are encoded using JSON (JavaScript Object Notation). A quick Google search should tell you more than you ever wanted to know about JSON. Conceptually, it is virtually identical to XML encoding, although the syntax is different which is why it's only conceptually identical. Data can easily be converted to and from XML losslessly, and with the ascendancy of AJAX, JSON may (hopefully) become obsolete. When parsing catalog data furnished by OpenLibrary be aware that the schema is not fixed; you may (probably would) encounter fields which are not documented anywhere. This may be data which was collected by a user interface at some point in the past but which is no longer being collected, or it may be data that is now being collected but the purpose (and constraints) of which are not yet documented. So long as you only use the provided web interface, and do not expect data integrity, you should be fine. _______________________________________________ Ol-discuss mailing list Ol-discuss@archive.org http://mail.archive.org/cgi-bin/mailman/listinfo/ol-discuss To unsubscribe from this mailing list, send email to ol-discuss-unsubscr...@archive.org
