The ItemEditor Database Browser

Uses
Standalone Invocation
Invocation Inside a JVM
The GUI

Uses of the ItemEditor

The ItemEditor class is a very simple GUI for browsing and modifying any ItemSpace, including any InfinityDB database. It is very low-level, since it merely displays a vertically sorted list of Items. It can be used for:

Learning about ItemSpaces, Items and their various component types
checking the storage structures and data an application creates
creating application test input
configuring applications

It is very convenient to be able to 'see inside' an application, and debugging is very much simplified. It is easy to separate storage problems from retrieval problems, for example.

Standalone Invocation

To run an ItemEditor standalone:

%JDK_DIR%\bin\java -classpath %CP%;infinitydb.jar com.infinitydb.itemeditor.ItemEditor %1

The above is taken from installdir/examples/ItemEditor.bat. When the ItemEditor is run on an empty database it can be rather difficult to get going. It is easier to start off using it with an already populated ItemSpace. To do this easily, first run installdir/examples/DemoSnippets.bat in order to get a db file with some contents to see. This will create DemoSnippets.infdb.

Be sure not to open any db file from within multiple separate JVMs at the same time. Allowing multiple JVM's to open the same InfinityDB can easily corrupt the db. InfinityDB 1.0.40 and later can optionally use the java.nio file locking system to prevent this when run on Java 1.4 or later. The locking is not automatic, but must be requested by new InfinityDB.open() and InfinityDB.create() parameters, which is strongly suggested. See the javadoc.

Invocation Inside a JVM

To run ItemEditor on any ItemSpace visible within a running program, just use the constructor, with the ItemSpace as a parameter. If the ItemSpace provided is an InfinityDB, then the commit(), rollBack() and other methods are available, so the ItemEditor adds these commands to its File menu.

To see how to invoke ItemEditor from inside a running application, modify installdir/src/com/infinitydb/examples/DemoSnippets.java and uncomment:

    //db.commit();
    //new ItemSpace(db)

This will bring up an internal ItemEditor on the database created by DemoSnippets, which has a few typical Items.

The GUI

The main window shows a the set of Items near to the Item currently displayed in the text field at the bottom. As the text field is modified, it is continually parsed into an Item using the component printable representations. The horizontal bar in the main window is thin and separates two existing Items where the current Item would go if it is not in the ItemSpace. If the current Item is in the ItemSpace, it is highlighted in the main window. The arrow keys move up and down, and the mouse can select a visible Item. There is no scroll bar, because it would be difficult to place the slider, since an ItemSpace might have billions of Items, and the current relative position would require counting a large fraction of them, which would be too slow.

If an ItemSpace being viewed by an ItemEditor is modified by the running application that constructed it, scrolling the display with the arrow keys will refresh the view. All modifications performed by the ItemEditor will be immediately visible to the running application.

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