4.8. Tips on Configuring Applications

This section contains tips on configuring applications and documents for use with SGD. This section includes the following topics:

4.8.1. Starting an Application or Desktop Session Without Displaying a Webtop

With SGD, you can start a single application or a full-screen desktop session without displaying the webtop. You can do this in any of the following ways:

  • Use My Desktop – My Desktop enables users to log in and display an application without displaying a webtop. Typically this is used for full-screen desktop applications. See Section 4.5.8, “Using My Desktop” for details.

  • Use SGD web services – Develop you own application for starting a single application from a URL. You can use this method to start an application from a bookmark or a favorite.

4.8.2. Using RANDR for Multiple Monitor Displays

SGD supports the RANDR X extension for multiple monitor displays. Using RANDR is the easiest way to configure SGD to work with multiple monitor displays.

To configure SGD to work with multiple monitors, perform the following configuration steps:

  1. (Optional) Configure the maximum display size.

  2. Configure the array to use RANDR.

  3. Configure the application objects to use RANDR.

4.8.2.1. Configure the Maximum Display Size

To avoid problems with clipped windows, you might want to increase the display resolution for the X Protocol Engine.

In the Administration Console, go to the Protocol Engines → X tab for each SGD server in the array and change the Client Window Size settings. In the Maximum Height and Maximum Width fields, type the highest display resolution you expect to support.

Note

Increasing the Maximum Width and Maximum Height attributes increases the memory requirements for applications on both client devices and SGD servers.

Alternatively, use the following command:

$ tarantella config edit --array \
--xpe-cwm-maxwidth pixels \
--xpe-cwm-maxheight pixels

The following example specifies a maximum display size of 3200 x 2048 pixels.

$ tarantella config edit --array \
--xpe-cwm-maxwidth 3200 \
--xpe-cwm-maxheight 2048

Repeat the configuration for each application that is displayed on multiple monitors.

4.8.2.2. Enable RANDR for the Array

By default, using the RANDR extension is disabled for the array.

Go to the Global Settings → Client Device tab in the Administration Console and select the RandR Extension check box.

You can also use the following command to to enable RANDR for the array:

tarantella config edit --array-xrandr-enabled 1

4.8.2.3. Enable the RANDR Extension for Applications

In the Administration Console, go to the Presentation tab for the application object and select the Window Size: RandR Extension check box.

You can also use the following command to enable RANDR for an application object:

$ tarantella object edit --name app-name --xrandr 1

4.8.3. Configuring Multiple Monitor Displays Without Using RANDR

The easiest way to configure SGD to work with multiple monitor displays is to use the RANDR extension, as described in Section 4.8.2, “Using RANDR for Multiple Monitor Displays”.

In some situations you may not want to or may not be able to use RANDR. This topic describes an alternative configuration method that does not use RANDR.

You can use multihead or dual head monitors with SGD. However, if any of your X applications are configured with a Window Type (--displayusing) setting of Client Window Management or Kiosk, you might have to change the application and monitor configuration to be able to use multiple monitors.

See also Section 4.2.1, “Configuring X Application Objects”.

To configure multiple monitors to work with X applications that have a Window Type setting of Client Window Management or Kiosk, perform the following configuration steps:

4.8.3.1. Disabling Shared Resources

SGD enables similar applications to share resources, to reduce memory overhead. This feature must be disabled for any applications that you want to display using multiple monitors.

In the Administration Console, go to the Performance tab for the application that is displayed on multiple monitors and deselect the Share Resources Between Similar Sessions check box.

Alternatively, use the following command:

$ tarantella object edit --name obj --share false

Repeat the configuration for each application that is displayed on multiple monitors.

4.8.3.2. Configuring the Correct Desktop Size

You must ensure that the SGD server sends the client device enough space to display all the monitors on the desktop.

Note

This increases the amount of memory used on the client device and on the SGD server.

You must configure SGD so that it sends the size of the entire desktop area to the client device, and not just the size of the primary monitor. The size of the entire desktop area is shown by the “virtual screen” in the following diagram.

Virtual Screen Size for Multihead Monitors

For example, if the dimensions of Monitor 1 in the diagram are 1200 x 768 and the dimension of Monitor 2 are 800 x 600, then the desktop size that needs to be configured is 2000 x 768.

4.8.3.2.1. Configuring Desktop Size for Client Window Management Applications

In the Administration Console, go to the Protocol Engines → X tab for the SGD server. For Client Window Size, type the dimensions in pixels of the virtual screen in the Maximum Height and Maximum Width fields.

Alternatively, use the following command:

$ tarantella config edit --array \
--xpe-cwm-maxwidth pixels --xpe-cwm-maxheight pixels

Repeat this configuration for each SGD server in the array.

4.8.3.2.2. Configuring Desktop Size for Kiosk Mode Applications

X applications can be displayed in kiosk mode on a multihead or dual head monitor.

You configure kiosk mode display features with the <KioskArea> entry in the <localsettings> section of the client profile, profile.xml on the client device. If the <localsettings> section is not present in the client profile, create a new section.

The <KioskArea> entry defines the screen area used by kiosk mode. The available values are as follows:

  • virtual – Uses the virtual screen size. All monitors are used.

  • 0 – Uses the primary monitor only. This is the default value.

  • 1 – Uses the secondary monitor only.

  • n – (Multihead monitors only). Uses the nth secondary monitor only.

For example, to span the kiosk mode display across all monitors:

<KioskArea>virtual</KioskArea>
Note

The desktop size for kiosk mode applications can also be configured from the webtop. Use the Span Multiple Monitors (Kiosk Mode) option in the Client Settings tab.

4.8.3.3. Setting Up the Monitors

Set up the monitors so that all the secondary monitors are to the right of the primary monitor, as shown in the previous diagram.

You have to do this because the X server cannot handle negative screen coordinates.

4.8.4. Improving the Performance of Windows Applications

When using Windows Remote Desktop Services, the performance of Windows applications might be poor. This is caused by using animation effects and other presentation settings in the Windows session. Performance is affected because these features require more screen updates and can greatly increase the bandwidth used. The problem is more severe on slower connections.

The causes of these problems can include the following:

  • Animated mouse cursors

  • Mouse cursor shadows

  • Screensavers

  • Animated icons in the notification area

  • Animated images in programs

  • Animated wallpaper

  • Images used as wallpaper

  • Font smoothing

By default, the SGD Remote Desktop Client, ttatsc, enables all of these features except for font smoothing.

You can turn off presentation features by configuring one or more attributes for the Windows application object. The attributes you can configure are listed in the following table.

Attribute

Description

Cursor Settings

Disables mouse pointer schemes and customizations.

Cursor Shadow

Disables the shadow on the mouse pointer.

Desktop Wallpaper

Disables the desktop wallpaper. Disabling the wallpaper can reduce the amount of data that is updated when users move items around the desktop.

Font Smoothing

Enables font smoothing for text in the application.

Full Window Drag

Disables the option to show the contents of a window while it is moved.

Menu Animations

Disables transition effects for menus and tooltips.

Theming

Disables desktop themes.

See also Section 4.1.9, “The SGD Remote Desktop Client”.

4.8.5. Improving the Performance of Java Desktop System Desktop Sessions or Applications

This section includes some tips on how to get the best user experience when using SGD with Java Desktop System.

You can improve performance of Java Desktop System desktop sessions and applications in the following ways:

  • Configure the X application object for Java Desktop System

  • Disable some default Java Desktop System settings

4.8.5.1. Configuring the X Application Object for Java Desktop System

For a Java Desktop System desktop session or application, ensure that you specify the correct command path for the X application object. Set the Application Command (--app) attribute to /usr/dt/config/Xsession.jds. Using a path of /usr/bin/gnome-session results in some Java Desktop System configuration parameters being lost and gives a poorer user experience.

To improve the display of animated effects, you can configure performance settings for the X application object. See Section 4.9.11, “An Application's Animation Appears 'Jumpy'”.

4.8.5.2. Disabling Default Java Desktop System Settings

The performance of Java Desktop System desktop sessions and applications can be affected by animation effects and other default desktop settings. Performance is affected because these features require more screen updates and can greatly increase the bandwidth used. The problem is more severe on slower connections.

Performance can often be improved by turning off, or modifying, some of the following Java Desktop System desktop features:

  • Anti-aliased fonts

  • Large fonts

  • Login screen, splash screen, About screen, and Logout screen

  • Animations

  • Desktop applets

  • Showing window contents when dragging

  • Desktop wallpaper

  • Themes

4.8.6. Documents and Web Applications

A document object can refer to any URL. This can be any document on the web, including Oracle Open Office documents, or Adobe™ Acrobat files. A document can also refer to a web application.

As it is the user's client device that actually fetches the URL, firewalls, or other security measures can prevent a user from accessing a document.

You can use SGD to access web applications. A web application is simply a web page, or any URL, that requires the user to supply a user name and password for access. To give users access to a web application, you create a document object that links to the URL of the web application.

Unlike passwords for application servers, SGD cannot cache the user names and passwords for accessing web applications. However, you can configure web authentication, so that users can access SGD from a web application without having to log in again. See Section 2.6.4, “Web Authentication” for details. Alternatively, you can authenticate SGD users to the web application.

When accessing web applications, use a secure (HTTPS) web server, so that all communication is encrypted using SSL before transmission.

4.8.7. Creating a Virtual Classroom

This section describes how to configure application objects for use in a virtual classroom.

You can use SGD shadowing to create a virtual classroom, where the pupils in the classroom shadow an application being demonstrated by a teacher.

To be able to do this, you have to create a teacher's application object and a classroom application object.

The teacher must start their application first, then the pupils start their classroom application to shadow the teacher. The classroom can only shadow Windows applications or X applications.

Only one person can use the teacher's application at any one time. If more than one person starts the teacher's application, the classroom shadows the application that was started last. For this reason, only give the teacher's application to one user. If you have several teachers, create separate application objects for each of them.

For the best results, configure the classroom application object as follows:

  • The classroom application must have a Color Depth of at least 16-bit.

  • The display size of the classroom application must be at least the size of the teacher's application.

  • Use a Window Type setting of Independent Window. The user experience may be poor if the application has a Window Type of Seamless Window or Client Window Management.

  • Disable the Share Resources Between Similar Sessions attribute for the application object.

When the teacher starts their application, information is stored on the SGD server about which application can be shadowed by the classroom. This information is not copied to the other members of the array. This means that if the classroom application is started on a different SGD server to the teacher's application, the classroom application fails because the information about which application can be shadowed is not available.

You can use load balancing groups to guarantee that the teacher and classroom applications are started on the same SGD server. You must set the load balancing group for the application server and the SGD server. Otherwise, only use classroom shadowing in an SGD array containing a single SGD server.

See also Section 4.9.9, “Using Shadowing to Troubleshoot a User's Problem”.

4.8.7.1. How to Create the Teacher's Application Object

  1. In the Administration Console, create a new Windows application object or X application object.

  2. Go to the Launch tab and type one of the following in the Login Script field:

    • unixclass.exp – If the application is an X application

    • winclass.exp – If the application is a Windows application

  3. Click Save.

  4. Configure any other settings you want for the teacher's application.

  5. Click the Hosting Application Servers tab and select the application servers that can run the application.

  6. On the Assigned User Profiles tab, assign the teacher's user profile to the application.

4.8.7.2. How to Create the Classroom Application Object

  1. In the Administration Console, create a new X application object.

    Note

    The classroom application is an X application, even if the teacher's application is a Windows application.

    The General tab is displayed.

  2. Go to the Launch tab and configure the application as follows:

    1. In the Application Command field, type /opt/tarantella/bin/bin/ttashadow.

    2. In the Arguments For Command field, type -readonly -silent -pointer $SHADOWDISPLAY.

    3. For the Connection Method, select the telnet option.

      Select this option even if telnet is disabled for the SGD server.

    4. In the Login Script field, type pupil.exp.

    5. In the Environment Variables field, configure the MYCLASS variable.

      The format is MYCLASS="name_of_teacher's_application". For example, MYCLASS=".../_ens/o=applications/ou=Finance/cn=XClaim".

  3. Click Save.

  4. Go to the Presentation tab.

  5. For Color Depth, select 16-bit - thousands of colors and click Save.

  6. Configure any other settings you want for the classroom application.

  7. Go to the Hosting Application Servers tab and select the application servers that can run the application.

    The ttashadow application is only available on servers where SGD is installed.

  8. Go to the Assigned User Profiles tab, assign the user profiles of all users in the class to the classroom application.

4.8.8. Configuring Common Desktop Environment Applications

The configuration required for Common Desktop Environment (CDE) applications depends on whether you want to run a desktop session or an individual application.

For CDE desktop sessions configured with a Connection Method of ssh, problems can occur when a user tries to exit from the CDE session. The CDE session might hang, making it impossible to log out normally from the system. See Section 4.8.8.3, “Using CDE and SSH”.

To avoid font problems when using CDE applications, it is best to use a font server as described in Section 4.2.4.1.2, “Using a Font Server”.

4.8.8.1. Configuring a CDE Desktop Session

To run a CDE desktop session through SGD, create an X application object with the settings shown in the following table.

Attribute

Setting

Application Command

The full path to the Xsession application, for example, /usr/dt/bin/Xsession.

On the command line, use --app pathname.

Keep Launch Connection Open

Select the Enabled check box.

On the command line, use --keepopen true.

Session Termination

Select Login Script Exit from the list.

On the command line, use --endswhen loginscript.

Window Type

Select Kiosk from the list.

On the command line, use --displayusing kiosk.

Window Size

Select the Scale to Fit Window check box.

Use this setting only if users suspend and resume the application on displays of different sizes.

On the command line, use --scalable true.

4.8.8.2. Configuring a CDE Application

To run a CDE application directly, rather than from the CDE Front Panel, create an X application object with the settings shown in the following table.

Attribute

Setting

Application Command

The full path to the application you want to run.

On the command line, use --app pathname.

Keep Launch Connection Open

Deselect the Enabled check box.

On the command line, use --keepopen false.

Note

This is the default value for this attribute.

Session Termination

Select No Visible Windows from the list.

On the command line, use --endswhen nowindows.

Note

This is the default value for this attribute.

Window Type

Select Client Window Management from the list.

On the command line, use --displayusing clientwm.

Window Manager

Type the following in the field:

/usr/dt/bin/dtwm -xrm "Dtwm*useFrontPanel: false" -xrm "Dtwm*ws0*backdrop*image: none"

On the command line, use --winmgr '/usr/dt/bin/dtwm -xrm "Dtwm*useFrontPanel: false" -xrm "Dtwm*ws0*backdrop*image: none"'.

Note

If you have problems running an individual CDE application, configure a CDE desktop session as shown in Section 4.8.8.1, “Configuring a CDE Desktop Session” and run the application from the CDE Front Panel.

4.8.8.3. Using CDE and SSH

For CDE desktop sessions configured with a Connection Method of ssh, problems can occur when a CDE desktop user tries to exit from the CDE session. The CDE session might hang, making a proper logout from the system impossible.

The CDE session displays a TT_ERR_NO_MATCH error message.

The workaround for this issue is as follows:

  • Log in to the CDE host as superuser (root) and type the following commands:

    # mkdir /etc/dt
    # mkdir /etc/dt/config
    # cp /usr/dt/config/sessionetc /etc/dt/config
    # cp /usr/dt/config/sessionexit /etc/dt/config
    # cp /usr/dt/config/sys.dtprofile /etc/dt/config
    # chgrp bin /etc/dt/config
    # chmod 555 /etc/dt/config/*
    # chown bin:bin /etc/dt/config/*
  • Add the following lines to the /etc/dt/config/sessionetc file:

    if [ "$SSH_TTY" !="" ]
    then
    SSHPTTY=`echo $SSH_TTY | cut -c6-15`
    ps -ef | grep -v grep | grep $SSHPTTY | grep Xsession | awk '{print $3}' >
    /var/dt/tmp/$DTUSERSESSION/sshd_pid
    fi
  • Add the following lines to the /etc/dt/config/sessionexit file:

    if [ -f /var/dt/tmp/$DTUSERSESSION/sshd_pid ]
    then
    /bin/kill -HUP ‘/bin/cat /var/dt/tmp/$DTUSERSESSION/sshd_pid‘
    /bin/rm /var/dt/tmp/$DTUSERSESSION/sshd_pid
    fi
  • Add the following line to the /etc/dt/config/sys.dtprofile file:

    dtstart_session[0]="/usr/local/bin/ssh-agent /usr/dt/bin/dtsession"

4.8.9. Configuring VMS Applications

You can use SGD to access X applications and character applications on a VMS application server.

To configure SGD to access applications on a VMS server, you have to perform the following configuration steps:

  1. Configure the login script used for the application.

  2. Configure the transport variable in the login script.

  3. Disable X security.

4.8.9.1. Configuring the Login Script Used for the Application

The login script used for the X application or character application must be configured.

In the Administration Console, go to the Applications → Launch tab for the application object you want to configure. In the Login Script box, type vms.exp.

Alternatively, use the following command:

$ tarantella object edit --name obj --login vms.exp

4.8.9.2. Configuring the Transport Variable in the Login Script

By default, the vms.exp login script sets the transport variable to TCPIP. This setting is correct for Digital TCP/IP stacks, including Ultrix Communications Extensions (UCX).

If you need to change this variable, edit the transport variable setting in the login script. The transport variable is set by the following entry in the login script:

set transport "TCPIP"

Login scripts are located in the /opt/tarantella/var/serverresources/expect directory.

4.8.9.3. Disabling X Security

To use VMS X applications, you must disable X security in SGD. This is because SGD does not support X authorization for VMS X applications.

In the Administration Console, go to the Global Settings → Security tab and deselect the X Authorization for X Display check box.

Alternatively, use the following command:

$ tarantella config edit --security-xsecurity 0

4.8.10. 3270 and 5250 Applications

SGD uses the third-party emulator application, TeemTalk for Unix, for 3270 and 5250 applications. See the TeemTalk for Unix User's Guides supplied with SGD for details.

The first time a user runs the 3270 or 5250 emulator, the tta3270.nv configuration file is created in the user's home directory on the SGD server.