Wednesday, August 20, 2008

Creating an Actual SQLite Connection Profile (minus the UI)

Hi there!

So now we have the majority of our work done. We have a driver-wrapper plug-in, a driver definition, and an overridden catalog loader. What's next? Wrapping the functionality in a nice, easy to use connection profile!

Note: Previous articles in this series cover the following topics: Catalog Loaders, Driver Templates, and the Driver Framework.

Many moons ago, we talked at a high level about the driver template & driver definition frameworks. It's now time to talk briefly about the connection profile framework.

It all boils down to this... A connection profile manages a connection to something. Right now in DTP we connect to JDBC databases and file systems for the most part. But the Sybase WorkSpace product also uses DTP to connect to application servers, LDAP, UDDI repositories, and much more. So it's not limited in any way.

With that in mind, a JDBC database connection profile, such as the one we want to create for SQLite, just needs to manage a JDBC connection under the covers. We'll add a layer on top of that to attach the SQL Model to the connection so we can display the database specifics in the Data Source Explorer tree.

In the DTP Ganymede (1.6) release, we've really simplified creating a new connection profile if it's associated with a db definition vendor/version and a driver template. So we'll take advantage of that for SQLite.

To create a connection profile, we will go to the org.eclipse.datatools.enablement.sqlite plug-in project and create a couple of classes and two extension points. These steps are kind of chicken & egg - the order isn't really important so long as you get them all done.

Step 1: Create a new connection factory and connection class for SQLite. These are the actual raw connections that our SQLite connection profile will manage for us.

The connection class is pretty easy. We're just going to extend the Generic JDBC JDBCConnection class for SQLite so we have our own specialized version of it.

That code looks like this:
package org.eclipse.datatools.enablement.sqlite.connection;

import org.eclipse.datatools.connectivity.IConnectionProfile;
import org.eclipse.datatools.connectivity.db.generic.JDBCConnection;

public class SQLITEJDBCConnection extends JDBCConnection {

/**
* @param profile
* @param factoryClass
*/
public SQLITEJDBCConnection(IConnectionProfile profile,
Class factoryClass) {
super(profile, factoryClass);
}
}

The connection factory requires a little more work, but not much more:
package org.eclipse.datatools.enablement.sqlite.connection;

import org.eclipse.datatools.connectivity.IConnection;
import org.eclipse.datatools.connectivity.IConnectionProfile;
import org.eclipse.datatools.connectivity.db.generic.JDBCConnectionFactory;

public class SQLITEJDBCConnectionFactory extends JDBCConnectionFactory {

public SQLITEJDBCConnectionFactory() {
super();
}

public IConnection createConnection(IConnectionProfile profile) {
SQLITEJDBCConnection connection = new SQLITEJDBCConnection(profile, getClass());
connection.open();
return connection;
}
}

Basically in the connection factory, we're just creating one of our new SQLiteJDBCConnection class instances for the profile that's passed in.

Step 2: We want to add a new extension point to the plugin.xml in the org.eclipse.datatools.enablement.sqlite plug-in project: org.eclipse.datatools.connectivity.connectionProfile.
This extension point has a couple of nodes we're going to create beneath it: connectionFactory and connectionProfile.

Let's define our connectionProfile first, so we have the connection profile ID to use for the connectionFactory.



You can see from the screen that we're giving our connection profile the following properties:
  • id = org.eclipse.datatools.enablement.sqlite.connectionProfile
  • category = org.eclipse.datatools.connectivity.db.category (this ensures that our connection profile shows up under the "Databases" category in the DSE)
  • name = SQLite Connection Profile
  • icon = icons/jdbc_16.gif (you can copy this from the Generic JDBC connection profile plug-in)
  • pingFactory = org.eclipse.datatools.enablement.sqlite.connection.SQLITEJDBCConnectionFactory (our new connection factory class we created in step 1)
Then we define our connectionFactory:



Our connectionFactory extension has the following properties:
  • id = java.sql.Connection (this maps to the type of connection this connection factory/connection class maps back to -- in this case, a JDBC connection)
  • class = org.eclipse.datatools.enablement.sqlite.connection.SQLITEJDBCConnectionFactory (our connection factory class)
  • profile = org.eclipse.datatools.enablement.sqlite.connectionProfile (our SQLite connection profile ID from the connectionProfile extension)
  • name = SQLite Connection Factory
So now we have a connection profile for SQLite in DTP. Now all we need is a user interface (wizard, wizard page, property page, and driver UI) and we'll be golden!

That's what we'll cover next time.
--Fitz

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