Derby Network Server sample program

The Network Server sample demo program (NsSample) is a simple JDBC application that interacts with the Derby Network Server. The program:

1. Starts the Derby Network Server.
2. Connects to the Network Server and creates the database if not already created. The Network Client driver is loaded automatically.
3. Checks to see if the schema is already created, and if not,
4. Creates the schema, which includes the SAMPLETBL table and corresponding indexes.
5. Connects to the database.
6. Loads the schema by inserting data.
7. Starts client threads to perform database related operations.
8. Has each of the clients perform DML operations (select, insert, delete, update) using JDBC calls; in particular, one client opens an embedded connection to perform database operations, while the other client opens a client connection to the Derby Network Server to perform database operations.
9. Waits for the client threads to finish the tasks.
10. Shuts down the Derby Network Server at the end of the demo.

The following files in the DERBY_INSTALL\demo\programs\nserverdemo\ directory are needed to run the sample program (DERBY_INSTALL is the directory where you installed Derby):

• NsSample.java
  This is the entry point into the demo application. The program starts up two clients. One client opens an embedded connection to perform database operations, while the other client opens a client connection to the Derby Network Server to perform database operations. This program provides the following constants that can be changed to modify the sample demo:
  • NUM_ROWS - The number of rows that must be initially loaded into the schema.
  • ITERATIONS - The number of iterations for which each client thread does database related work.
  • NUM_CLIENT_THREADS - The number of clients that you want to run the program against.
  • NETWORKSERVER_PORT - The port on which the network server is running.
  You can also modify the program to exclude starting the Network Server as part of the sample program. Make sure to recompile the Java files before running the program if you make any changes to the source code.
• NsSampleClientThread.java
  This file contains two Java classes:
  • The NsSampleClientThread class extends Thread and does all the necessary work by instantiating a NsSampleWork instance.
  • The NsSampleWork class contains everything required to perform DML operations using JDBC calls. The doWork method in the NsSampleWork class represents all the work done as part of this sample program.
• NetworkServerUtil.java
  This file contains helper methods to start the Derby Network Server and to shut down the server.
• Compiled class files:
  • NsSample.class
  • NsSampleClientThread.class
  • NetworkServerUtil.class

Running the Network Server demo program

To run the Derby Network Server demonstration program:

1. Open a command prompt and change directories to the DERBY_INSTALL\demo\programs\ directory.
2. Set the CLASSPATH to the current directory (".") and also include the following jar files in order to use the Derby Network Server and the Derby Client Network JDBC Driver.
   • derbynet.jar
     The Network Server jar file. It must be in your CLASSPATH to use any of the Derby Network Server functions.
   • derbyclient.jar
     This jar file must be in your CLASSPATH to use the Derby Client Network JDBC Driver.
   • derby.jar
     The Derby database engine jar file.
3. Test the CLASSPATH settings by running the following java command:

   java org.apache.derby.tools.sysinfo

   This command will show the Derby jar files that are in the CLASSPATH along with their respective versions.
4. Once you have set up your environment correctly, execute the application from the
   DERBY_INSTALL\demo\programs\ directory:
   

   java nserverdemo.NsSample [driverType]

   • Where the possible values for driverType are:
     • derbyClient (default)

Running the demo program will also create new directories and files:

• NSSampledb
  This directory makes up the NSSampledb database.
• derby.log
  This log file contains Derby progress and error messages.