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Java的面向对象数据库系统的源代码

Handle Sample
-------------

This sample demonstrates the use of handles in Ozone to access persistent
objects. It also demonstrates one way to use Ozone in the context of a
JSP/Servlet web application, where handles can be quite useful. This web
application was developed and tested using Tomcat 4 from the Apache
foundation. Other JSP/Servlet contexts ought to work just as well.

The example consists of a simple database of Songs.  There are two types
of persistent objects in the example:  song.Song and song.SongCollection.

A single song.SongCollection is created in Ozone as a named object (its name is
_AllSongs). The song.SongCollection contains a Java2 collection that indexes
songs by their title (irrespective of case). Each song that is added to
the collection is also a persistent Ozone object.  However, the song.Song
objects are created anonymously -- they do not have names that Ozone is
aware of.

There are two ways to access any song in the database:  by title, which
relies on the Java collection's index, or by handle, which bypasses the
song.SongCollection to go directly to Ozone to retrieve the song.Song.

Building It
-----------
There are two useful build targets available.

1) The default target builds handle.jar which includes a command line application
demonstrating handles.

Simply run ozoneAnt in the handle directory to build this target.

A second "webapp" target builds handle.war, a web application archive suitable for
use in any Servlet 2.2/JSP 1.1 (or higher) environemnt such as Apache's Tomcat.
In order to build the webapp target, you must have a suitable Servlet/JSP context
installed and properly configured on your system.

Run "ozoneAnt webapp" in the handle directory to build the war file.


Running it
----------
Add build/handle.jar to your classpath and start an Ozone server.

Command line program:
 Add build/handle.jar to your classpath and run "ojvm song.SongApp".
 It will display command line usage information.

Web application:
 Copy build/handle.war to your Servlet/JSP context's webapps directory.
 Add the user name your web server runs as (e.g. www-data) to ozone
   ozoneAdmin newuser -name=www-data -id=133
 On Windows the tomcat and ozone user will most likely be the same so no action is required.
 Configure your web server & JSP context if needed.
 Restart your JSP context (e.g. tomcat).

 Once you have everything configured properly, the starting page for the web application for
 a default tomcat installation should be http://localhost:8080/handle/index.jsp.
 I should be something similar on another web server.
 Start by clicking "Add song" (addSong.jsp) to create some songs in the database.
 After creating several songs, select "Show all songs" (showAllSongs.jsp) to view & edit the songs.

About the logfile
-----------------
 The web application uses log4j to write a log file.
 By default, the log file will be written to ./handle.log.  However, it may not be obvious
 where that directory is when running in your servlet/JSP context, and the user your web
 server is running as might not have write permission in that directory.
 If you are interested in contents of the log file, you may find it helpful to adjust
 its location.
 To do so, edit conf/log4j.properties before building the webapp target.