comp230 week 5 lab instructions

VBScript Modular Programming Lab

Objectives In this lab, students will complete the following objectives.

Create a VBScript program using NotePad++. Use procedures to modularize a VBScript program. Create a library of procedures. Run library procedures from a separate VBScript program.

Lab DiagramDuring your session you will have access to the following lab configuration.

Connecting to your labFor this lab, we will only need to connect to Vlab-PC1.

Vlab-PC1

To start simply click on the named Workstation from the device list (located on the left hand side of the screen) and click Power on in the tools bar. In some cases the devices may power on automatically.

During the boot-up process an activity indicator will be displayed in the name tab.

Black—Powered Off Orange—Working on your request Green—Ready to access

If the remote console is not displayed automatically in the main window (or popup) click the Connect icon located in the tools bar to start your session.

COMP230_Wk 5_Modular_Lab 1 Revision Date: 1213

If the remote console does not appear please try the following option.

Switch between the HTML 5 and Java client versions in the tools bar.

In the event this does not resolve your connectivity problems please visit our Help / Support pages for additional resolution options.

Task 1: Analyze the Batch Script File PC_Tests.cmd

Open NotePad++ and use File/Open to view the C:\comp230\PC_Tests.cmd script file in the Editor window. If the file is not there, it can be extracted from the Doc Sharing file PC_Tests.zip.

One of the drawbacks of using VBScript instead of a full-featured programming language such as C++ or Java is the fact that VBScript does not have the capability to clear the command prompt screen. This is one of the things we need to do with our menu-driven PC_Tests program each time the menu is re-displayed. Because we can’t do this in VBScript, we will do it in a Batch script file.

An listing of the the PC_Tests.cmd Batch script shown below. The script performs the following tasks.

Clear the screen (CLS).

Display the menu using echo commands.


Prompt the User and store the input into choice.

Run the PC_Tests.vbs program and send it the choice value (1..5) as an argument (//nologo hides the scripting host heading).

When the PC_Tests.vbs program exits and returns to the Batch script, execute a Pause.

After the user presses a key to end the pause, go to the start of the script to clear the screen and re-display the menu.

A sample Batch script run of Option 1 is shown below.

Task 2: Analyze the Code in the PC_Tests.vbs Program

1) Open the PC_Tests.vbs program in NotePad++. It contains code that can tell us many important things about the computer and the Windows Operating System. Each menu option is represented by a “Case” in the Select Case statement. Select Case is an alternate way of coding an if/else statement with multiple options. Option 1 from the menu is handled by Case “1” in the Select Case statement. The VBScript code shows how to access the values of Windows Environmental variables using the WScript.Shell object’s ExpandEnvironmentStrings( ) function. Note that the environmental variables must be delimited with the % character. Do a search for Windows Environmental Variables. They can provide a wealth of information about the computer and the operating system. A Run of this code is shown below (your specific output will depend on configuration of your computer).


2) Option 2 from the menu is handled by Case “2” in the Select Case statement. The Case “2” code segment shows the “Check System Memory” routine. The somewhat cryptic code shown below utilizes an extremely important tool called Windows Machine Instrumentation (WMI). WMI allows you to access many underlying objects and attributes managed by the Windows OS.

The variable strComputer’s value “.” refers to the local computer rather than a remote computer. See where strComputer is used when you are defining objWMIService. The ExecQuery method is used to send a query (“Select * from Win32_ComputerSystem”) to the operating system.

Note that the memory size is divided by 1M (1048576) so the answer can be expressed in Mbytes instead of Bytes. The run is shown below the script code.

3) Option 3 from the menu is handled by Case “3” in the Select Case statement. The Case “3” code segment shows the “Check Operating System Version” routine. Note that this program makes use of the same objWMIService definition as the last program.


Again we use the ExecQuery method to send a query to the Windows OS. Note, however, that query has a different target (“Select * from Win32_OperatingSystem). Notice also that the ExecQuery method always returns a collection object colOperatingSystems. An ExecQuery can return more than one record so we need to handle the display in a For Each/Next loop.

4) Option 4 from the menu is handled by Case “4” in the Select Case statement. The Case “4” code segment shows the “Check Printers Status” routine. This routine, like the last two, defines the objWMIService object in exactly the same way. This time the W32_Printer is queried. A run of the Check Printers Status routine is shown on the next page.


5) Option 5 is handled by Case “5” in the Select Case statement. The “Check Logical Drive Information” routine also uses the objWMIService. The ExecQuery method sends a query to the W32_LogicalDisk object and the query is modified with Where FreeSpace > 0. The where clause ensures we will not display the CDROM or DVD drives. The Size and FreeSpace are divided by 1G (1073741824) to display the sizes in Gbytes.


6) Open a Windows CLI as Administrator and run the PC_Tests.cmd Batch file (C:\comp230\PC_Tests.cmd <Enter>). The Batch script will clear the screen and display the PC Tests menu. After a choice is made, the PC_Tests.vbs program is run using cscript.

7) Run all of the PC Tests and see what happens when you enter incorrect menu choices. Is there any error-handling incorrect menu choices? Make sure that everything is functional before you start your Task 3 modifications.

Task 3: Make the PC_Tests.vbs Program Modular

Programs and scripts can be easier to write, modify, and debug when the major tasks of the program are written as separate identifiable modules. VBScript allows for two kinds of modules: functions and procedures. Functions are unique in that they always return a value. Functions are typically used to input a single value or to perform a calculation. Procedures, however, do not return a value. Procedures, rather, perform a task.

1) Our first modification to the PC_Tests.vbs will involve re-writing the five tasks described in Task 2 as separate procedures. Before we get started, Save As the PC_Tests.vbs program as Mod1_PCTests.vbs.

Cut and copy all of the code for Case “1” in the Select Case statement and paste it below the Select Case statement. Add a line above this code that reads: Sub System_Information. After the last line of the pasted code, add the line End Sub. Go back to Case “1” in the Select Case statement and add the line Call System_Information. The completed procedure (or SubRoutine) for System_Information is shown below the modified Select Case statement.

Continue these modifications until each of the PC Test routines have been re-written as procedures (Subs). Make sure that all lines are properly indented for the Subs and the Select Case statement.


2) Before you do a final save of Mod1_PCTests.vbs and close the script, you need to do one more modification. You need to add error-handling in the VBScript program for incorrect menu choices in the Batch script. Add a default Case (case Else) in the Select Case statement between the Case “5” subroutine call and the End Select statement. The error-handling routine Beeps the speaker twice (sending an ASCII code 7 to screen two times) and displays an appropriate error message.

Save your Mod1_PCTests.vbs program and open the PC_Tests.cmd Batch script in NotePad++. Change the script to be executed from PC_Tests.vbs to Mod1_PCTests.vbs as shown below. Save the new Batch script as Mod1_PCTests.cmd.

3) Open the Windows CLI (Command Prompt) in the C:\comp230 directory and run the Mod1_PCTests.cmd Batch script which will call the Mod1_PCTests.vbs program. In your run, show error-handling and successful execution of all five PC Tests.


Note: Please edit your Run for each menu option so that the Menu is shown only once for option 1 and thereafter just show the selected option choice and the subroutine output. To save space in the lab-report document, please edit your run to show only the first Printer and the first Hard Drive. You must also show error-handling in your Run. A Sample Edited Run is shown at the end of the lab.

Copy your Mod1_PCTests.vbs program and your complete edited Run in your lab-report document in the specified textboxes.

Task 4: Create a Library of PC Test Functions Accessible by any VBScript

Most high-level programming languages allow for the creation of libraries of common used Procedures and Functions. Although, creating libraries is not an explicit capability of Windows Scripting Host (WSH), it is possible to access procedures and functions defined in one VBScript program from another VBScript program. As you develop functions and procedures that you would like to re-use in other programs, this can be a useful thing to know.

1) Our second modifcation of our PC_Tests VBScript program will involve creating a pseudo-library of PC Test routines and calling them from a very simplified VBScript program.

2) Open the Mod1_PCTests.vbs program in NotePad++ and immediately save it as Mod2_PCTests.vbs.

3) Highlight all of the procedures you have defined with your mouse and press <Ctrl>X to cut them from the script and put them in the clipboard.

4) Select File/New to open a blank script. Use <Ctrl>V to paste the procedures (in the clipboard) into this new script file. Insert an appropriate header for this at the beginning of this library script and save it as PCT_Library.vbs.

5) Now that we have our library, we need to find a way to access it from our simplified Mod2_PCTests.vbs program. Add the following code just above the Select Case statement. Line 5 defines a Scripting.FileSystem object called fso.

Line 6 opens the library script that we saved earlier and assigns the file object to vbsLib. Line 7 reads the library script file into a global string variable called librarySubs. Lines 8, 9, and 10 close the files and reset the vbsLib and fso objects by assigning them to Nothing.


6) The only other change we need to make Mod2_PCTests.vbs is one that will give us access to the library string. That line is shown below. This should be the last line before the beginning of the Select Case statement. From the previous step, we know that all of the PCT_Library.vbs file content has been loaded into the string variable librarySubs. The command ExecuteGlobal librarySubs on line 11 gives us access to all of the procedures and functions contained within that string as if they were directly implemented within the Mod2_PCTests.vbs script.

7) The executable code for Mod2_PCTests.vbs has been greatly simplified by creating and using the PCT_Library.vbs file as a container for the procedures we want to use. The final code for Mod2_PCTest.vbs (minus the programmer header) is shown below.

Save your Mod2_PCTests.vbs program.

Task 5: Save Mod2_PCTests, Create Mod2_PCTests.cmd, Run Program, and Submit Final Codes and Runs

1) Open the Mod1_PCTests.cmd Batch script in NotePad++. Change script to be executed from Mod1_PC_Tests.vbs to Mod2_PCTests.vbs as shown below. Save the new Batch script as Mod2_PCTests.cmd.


2) Open the Windows CLI as Administrator and run the Modular PC Tests script Mod2_PCTests.vbs from the Mod2_PCTests.cmd Batch scripts.

Note: If you receive an error message on the “ExecuteGlobal librarySubs” line, you need to check the PCT_Library.vbs file for errors.

3) In your run, show error-handling and successful execution of all five PC Tests.

Note: Please edit your Run for each menu option so that the Menu is shown only once for option 1 and thereafter just show the selected option choice and the subroutine output. To save space in the lab-report document, please edit your run to show only the first Printer and the first Hard Drive. You must also show error-handling in your Run. A Sample Edited Run is shown at the end of the lab.

Copy your Mod2_PCTests.vbs program and your complete edited Run in your lab-report document in the specified textboxes.

Sample Run of Mod1_PCTests and Mod2_PCTests:


comp230 week 5 lab instructions

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