Web-Linked Databases

This represents a different type of Web resource--namely, databases have been around a long time, but what's new is that they are now much cheaper and easier to use. Until two years ago, NPAC used essentially no commercial databases, except for a single research activity using parallel Oracle. Now, we have some dozen activities using them. These include

1. Newsgroup and ``chat'' multimedia messages stored in databases giving a searchable record of collaboration or discussion
2. Enterprise intranets with a Fortune 500 product catalog made available to the public through NPAC's Web database interface
3. Support of financial modelling ``on demand'' prototype with a database of stock information
4. Set of New York State images indexed in a database for educational use
5. Commercial CD-roms stored in databases for school reference
6. Storage of close-captioned text and metadata to index video
7. Electronic mail server with database replacing UNIX mail folders
8. Storage of full text of books to allow rapid search
9. Complete index of text in NPAC Web site
10. Index of customized chemistry information
11. Object database storage of three-dimensional maps of New York State
12. Publication and other information from NPAC's technical reports.

All these applications use Web-linked relational (Oracle) or object (Illustra) databases. The explosion at NPAC and other places of (relational) database use is easy to understand. Historically, we would have used flat files, or UNIX file system structure, to store such data. Note that Web site information organization or many UNIX mail systems use file systems to ``label'' data. The trend to substantially lower database prices (especially on PC platforms) and the convenience of Web interfaces has changed this, and given us systems that combine the indexing and secure storage capabilities of traditional databases with the friendly HTML or Java interfaces of the Web. Figure 8(a) shows a typical setup with a simple CGI Script linking Oracle to the Web. We have most experience with WOW, which has a very simple CGI Script, and the user query (input through an HTML form) is interpreted by Oracle's PL/SQL language. WoW PL/SQL libraries HTP and HPF that make it relatively easy to produce HTML pages that are passed from the database server to the client.

PL/SQL is a convenient high-level language for generating standard SQL queries, but it is Oracle specific. We expect the so called Java Database Connectivity (JDBC) with a host of Java methods for accessing any SQL database to be very important in the future.

In Figure 8(b), we emphasize that a complete Web delivery system could well involve many filters as data is stored in natural application oriented form, but transformed to suit network (e.g., compression) or browser (e.g., conversion to VRML). Java is a convenient language for building such filters.

Figure 28 illustrates the PL/SQL function to access a simple phone number database with simple HTML form (Figure 29 and resultant HTML Figure 30).

  

Figure 28: the PL/SQL Package for a Phone Example

  

Figure 29: Web Page Search Interface to Wow Phone Example