JET 3270 Documentation
JET 3270 2.4E  
 
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Troubleshooting

Solutions to the following common problems are provided in this page:

  • Doesn't run under all web browsers
  • New version of JET 3270 doesn't run
  • New version of JET 3270 is still working as the old version did
  • Applet won't load under Internet Explorer
  • Can't get past "Connecting..." screen
  • Can't get past "Negotiating Options..." screen
  • Error when printing under Communicator under Linux
  • Two applets started after double-clicking under Communicator under Windows

    • Doesn't run under all web browsers

    Description: JET 3270 does not work correctly running under Internet Explorer 3.0 or Communicator 4.04.

    Cause: JET 3270 does not support these browsers, it supports Internet Explorer 5 and 4.01 SP 1 and Netscape Communicator 4.7, 4.6, 4.5, 4.07 and 4.06.

    Corrective Action: Run JET 3270 under Microsoft Internet Explorer 5 or 4.01 SP1 or Netscape Communicator 4.7, 4.6, 4.5, 4.07 or 4.06.

    New version of JET 3270 doesn't run

    Description: After installing earlier versions of JET 1.0 or JET Any Host then installing JET 3270, it does not work correctly.

    Cause: The JET 3270 installation process does not remove old files from the installation directory. These files can interfere with the proper operation of the new version of JET 3270.

    Corrective Action: Delete the installation directory ("C:\jet3270" by default) and reinstall JET 3270.

    New version of JET 3270 is still working as the old version did

    Description: Even though a new version of JET 3270 has been successfully installed, JET 3270 is still behaving exactly as it did for the previous version

    Cause: Browsers store loaded applets in their memory, and continue to use this code even if the Reload button is clicked, or the memory and/or disk cache is cleared.

    Corrective Action:

    Restart your browser, and reload the web page or page on the local hard drive that contains the reference to the JET 3270 applet.

    Delete all old versions of JET software.

    Applet won't load under Internet Explorer

    Description: Microsoft Internet Explorer was unable to load the JET 3270 applet.

    Cause:

    1. The browser has been configured to disable its Java support

    2. The browser could not find the JET 3270 applet files on the web server or the local hard drive

    3. A network communication error occurred while the browser was loading the applet files

    Corrective Action:

    1. Enable Java support. To do this, from the "View" menu select "Options...", select the "Security" tab. Click the "Enable Java Programs" box (in the "Active content" area) so that a tick is placed there.

    2. Ensure that the <APPLET> tag within the web page that was loaded correctly refers to JET3270.class and JET32704.cab. Refer to Configuration for more information.

      Ensure that all of the JET 3270 class files are correctly installed on the web server or local hard drive

    3. Ensure that there is a stable connection between the browser and the web server

    Can't get past "Connecting..." screen

    Description: The JET 3270 applet starts, and displays a screen containing the text "Connecting...", but does not get any further.

    Cause:

    1. The Domain Name Server used by the browser may be down or unable to resolve the name of the IBM host system.

    2. There may be no TN3270 Server program listening on the specified port on the IBM host system.

    3. A network Firewall may be preventing access to the IBM host system.

    Corrective Action:

    1. Ensure that the Domain Name Server used by the browser is active and able to resolve the name of the IBM host system.

    2. Ensure that there is a Telnet Server program listening on the port to which the JET 3270 applet is trying to connect. The default port number is 23. The <APPLET> tag that refers to the JET 3270 applet may override this value by containing a <PARAM NAME="port" ....> tag. Refer to Configuration for more information.

    3. Ensure that there is no firewall preventing the system on which the browser is running from reaching the IBM host system.

    Can't get past "Negotiating Options..." screen

    Description: The JET 3270 applet starts and successfully connects to the IBM host system, then displays a screen containing the text "Negotiating Options...", but does not get any further.

    Cause: The program listening on the port to which the JET 3270 applet has connected is probably not a compatible Telnet Server program.

    Corrective Action: Ensure that a TN3270 server program is listening.

    Error when printing under Communicator under Linux

    Description: A dialog box with a message like "Could not execute print command: [Ljava.lang.String;@805202f" appears after clicking Print on the print dialog box when running JET 3270 under Communicator on Linux. Clicking OK dismisses the dialog box but the terminal screen is not printed.

    Cause: Communicator for Linux does not support printing from Java applets properly.

    Corrective Action:

    Login as root on the Linux machine. Create a /usr/bin/lp file with the following contents: 

    #!/bin/sh
if echo $1 | grep '^-d' > /dev/null
then
    modified="`echo $1 | sed s/^-d/-P/`"
    shift
    set -- "$modified" "$@"
fi
if echo $1 | grep '^-t' > /dev/null
then
    modified="`echo $1 | sed s/^-t/-J/`"
    shift
    set -- "$modified" "$@"
fi
if echo $2 | grep '^-t' > /dev/null
then
    original1="$1"
    modified="`echo $2 | sed s/^-t/-J/`"
    shift; shift
    set -- "$original1" "$modified" "$@"
fi
exec /usr/bin/lpr "$@"
    Set the file's ownership and permissions with the following commands: 
    chown root:root /usr/bin/lp
chmod 755 /usr/bin/lp
     This workaround does not handle the "Copies" or "Print Command Options" fields on the print dialog box having values other than their defaults.

    Two applets started after double-clicking under Communicator under Windows

    Description: Double-clicking an HTML file to start Communicator and load JET 3270 under Windows results in two JET 3270 applets running.

    Cause: The default "open" action performed by Windows when opening an HTML file when Communicator is the default browser passes the file both as a command line argument and as a DDE message. Because of this Communicator loads the HTML page twice, resulting in two JET 3270 applets.

    Corrective Action:

    Edit the default open action so that it does not use DDE using the following instructions. Start Windows Explorer. From the View menu select Options. Select the File Types tab. Find Netscape Hypertext Document in the list of registered file types, select it and click Edit. Select the open action and click Edit. Remove the tick from the Use DDE checkbox. Click OK, Close and Close.

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