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Coding a DCOM Client

Author: Gopalan Suresh Raj
Date Submitted: February 10th 2000
Level of Difficulty: Advanced
Subjects Covered: IDL, DCOM, J++
Pre-required Reading: Component Object Model, Coding a DCOM Server Component from IDL

To work with any of these samples you will need the following:

Microsoft Visual J++ ver 6.0

The Steps involved in developing the DCOM Client are

Add a new project StockDCOMClient to the StockDCOM project
Add COM wrapper of SimpleStocks to StockDCOMClient
Add code to Form1.java
Build and run the client

Add a new project StockDCOMClient to the StockDCOM project

From Project Explorer | StockDCOMClient | StockDCOMClient Properties | ClassPath uncheck the "Merge all Project-specific ClassPaths in solution" check box.

2. Add COM wrapper of SimpleStocks to StockDCOMClient

From Project Explorer | StockDCOMClient | Add | COM Wrapper check the checkbox listed with "SimpleStocks 1.0 Type Library".
Click "OK" to confirm list of COM Wrappers. Notice that the stockmarketlib folder was created under the StockDCOMClient project.
Notice the java source files that have been generated: StockMarket.java and IStockMarket.java

3. Add code to Form1.java

Form1.java

import com.ms.wfc.app.*;
import com.ms.wfc.core.*;
import com.ms.wfc.ui.*;
import com.ms.wfc.html.*;

/**
* This class can take a variable number of parameters on the command
* line. Program execution begins with the main() method. The class
* constructor is not invoked unless an object of type 'Form1' is
* created in the main() method.
*/
public class Form1 extends Form {

String editValue = null;
/**
   * TODO: make sure all your constructors/initialization code
   * paths have the following line:
   *   initForm();
   */
public Form1() {
    // Required for Visual J++ Form Designer support
    initForm();

// TODO: Add any constructor code after initForm call
}

/**
   * Form1 overrides dispose so it can clean up the
   * component list.
   *
   * TODO: have dispose call
   *   components.dispose();
   */
public void dispose() {
    super.dispose();
    components.dispose();
}

private void edit1_Leave(Object source, Event e) {
    String editValue = edit1.getText();
    try {
      stockmarketlib.IStockMarket market = (stockmarketlib.IStockMarket)new stockmarketlib.StockMarket();
      String str = "$ "+market.get_price(editValue);
      edit2.setText(str);

      System.out.println( "The price of "+editValue+" is " + market.get_price(editValue) );
    }
    catch (com.ms.com.ComFailException exception) {
      System.out.println( "COM Exception:" );
    }
}

private void button1_click(Object source, Event e) {
System.exit(0);
}

/**
   * NOTE: The following code is required by the Visual J++ form
   * designer. It can be modified using the form editor. Do not
   * modify it using the code editor.
   */
Container components = new Container();
Label label1 = new Label();
Edit edit1 = new Edit();
Label label2 = new Label();
Edit edit2 = new Edit();
Button button1 = new Button();

private void initForm() {
    this.setText("StockDCOM Client");
    this.setAutoScaleBaseSize(new Point(5, 13));
    this.setClientSize(new Point(292, 157));

    label1.setLocation(new Point(8, 32));
    label1.setSize(new Point(136, 16));
    label1.setTabIndex(0);
    label1.setTabStop(false);
    label1.setText("Enter the Stock Symbol");

    edit1.setLocation(new Point(168, 32));
    edit1.setSize(new Point(100, 20));
    edit1.setTabIndex(1);
    edit1.setText("MY_COMPANY");
    edit1.addOnLeave(new EventHandler(this.edit1_Leave));

    label2.setLocation(new Point(8, 80));
    label2.setSize(new Point(128, 23));
    label2.setTabIndex(2);
    label2.setTabStop(false);
    label2.setText("Price of my company is");

    edit2.setLocation(new Point(168, 72));
    edit2.setSize(new Point(100, 20));
    edit2.setTabIndex(3);
    edit2.setText("$ 0.0");
    edit2.setReadOnly(true);

    button1.setLocation(new Point(112, 120));
    button1.setSize(new Point(75, 23));
    button1.setTabIndex(4);
    button1.setText("Exit");
    button1.addOnClick(new EventHandler(this.button1_click));

    this.setNewControls(new Control[] {
                        button1,
                        edit2,
                        label2,
                        edit1,
                        label1});
}

/**
   * The main entry point for the application.
   *
   * @param args Array of parameters passed to the application
   * via the command line.
   */
public static void main(String args[]) {
    Application.run(new Form1());
}
}

4. Build and run the client

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