ObjectStore Inspector User Guide

Appendix C

Working with Metaknowledge

Introduction

Metaknowledge is data that describes the way ObjectStore database information is presented in Inspector. It is distinct from information contained within an ObjectStore database.

In this chapter

This chapter covers the following topics:

Overview of Metaknowledge

Importing Metaknowledge

Updating Metaknowledge

Ignoring Metaknowledge

Overview of Metaknowledge

What is metaknowledge?

Metaknowledge is information about the way ObjectStore database information is presented in Inspector. The metaknowledge associated with a database is updated when you do any of the following:

Make certain changes in the main database view:
Create a data view
Change the default instance format
Modify the string format interpretation/display rules
Create a user-defined method

Where is metaknowledge saved?

Metaknowledge is saved as a file in one of three places:

In the file system

The metaknowledge is saved in the <install>\db_gph directory as a file named <flie_name>.gph.

With the ObjectStore database Tip: This choice is recommended so that the metaknowledge is always stored with the database: if the database is moved, its metaknowledge is moved with it. However, it requires that you have write access to the database.
With the Inspector database

The metaknowledge is saved in a dedicated root named
__ivitos_meta_knowledge.

The default for saving metaknowledge is set on the Standard page of the Options dialog box. See Inspector Options to learn how to set Inspector options.

Importing Metaknowledge

You can import metaknowledge from one database to another. This feature enables you to leverage metaknowledge across databases with similar schemas.

Tips

Before importing another database's metaknowledge,

Make sure that the schemas of the two databases are as close to identical as possible. Importing metaknowledge to a database with a different schema will probably not provide the results you expect.
Importing metaknowledge merges the existing metaknowledge with the metaknowledge you import.
Importing metaknowledge forces Inspector to close all open windows and dialog boxes, except for the main database view window.
Save the existing metaknowledge using File | Save As. You can always reimport the current metaknowledge if the new one does not provide the results you were expecting.

How to import metaknowledge

To import metaknowledge:

In Inspector, open the database into which you want to import metaknowledge.
Click File | Import Metaknowledge on the menu bar.

The Open dialog box appears.
Select the database whose metaknowledge you want to import and click OK.

Inspector displays a dialog box asking you to confirm whether or not you want to import another database's metaknowledge.
Click Yes to continue; otherwise, click No.
Inspector compares the schemas of the source and target databases. If they are different, it displays a message enabling you to cancel the operation.
Click Yes to continue; otherwise, click No.
If you choose to continue, Inspector displays a dialog box that identifies the differences between the current metaknowledge and the one you are importing.
Click OK to continue.

Updating Metaknowledge

You might want to update the metaknowledge if you believe the database schema has changed since you first opened it in Inspector - for example, it has a new class or new data members.

How to update metaknowledge

To update metaknowledge:

In Inspector, open the database whose metaknowledge you want to update.
Click File | Update Metaknowledge on the menu bar.

Inspector displays a message that asks you to confirm that you want to update the database's metaknowledge.
Click Yes to continue; otherwise, click No.
If you are continuing, Inspector first compares Inspector's version of the schema with that of the actual database.

If they are the same, Inspector displays a message notifying you that no update is required.
If they are not the same, Inspector displays a message enabling you to cancel the operation.
Click Yes to continue; otherwise click No.

Ignoring Metaknowledge

When you open a database in Inspector, you can open it without the metaknowledge that was saved with it. You might want to do this when

You want to start working with a database from scratch.
The schema stored in Inspector's metaknowledge is not the same as that of the actual database and you do not want to update them.
You have set an option that requires the metaknowledge to be recalculated and you do not want to update the metaknowledge at this time.

How to ignore metaknowledge

To ignore metaknowledge, click the Ignore Metaknowledge check box in the Open dialog box.

Tip: When you ignore metaknowledge, Inspector displays the Review Incompatibility Errors dialog box. See Importing Metaknowledge.

Copyright © 1999 Object Design, Inc. All rights reserved.

Updated: 05/07/99 16:44:14