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MetaFrame 1.8 Service Pack 2 and Feature Release 1: Frequently Asked Questions (FAQ), Part 2

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This is the second article in a two-part look at some of the frequently asked questions that Windows Thin Client expert Todd Mathers has received over the last couple of months regarding MetaFrame 1.8 Service Pack 2 and Feature Release 1.

This is the second article in a two-part look at some of the frequently asked questions that Windows Thin Client expert Todd Mathers has received over the last couple of months regarding MetaFrame 1.8 Service Pack 2 and Feature Release 1.

Todd is the author of Windows NT/2000 Thin Client Solutions: Implementing Terminal Services and Citrix MetaFrame(New Riders, 2000).

What Are the Latency-Reduction Options with FR1?

Whenever users running on a Terminal Server have issues with performance, typically the source of these problems can be traced to latency in keyboard and mouse response. Most Terminal Server administrators at one time or another have had to deal with complaints about sluggish keyboard typing and mouse clicks that "don't seem to be doing anything."

This, coupled with the growing use of MetaFrame as an application portal via the Internet (where bandwidth and availability are rarely a certainty), has prompted Citrix to look at ways to help reduce the effect that latency may have on the perceived performance of a MetaFrame server—hence the new suite of latency-reduction options available with FR1.

To properly enable these latency-reduction (LR) options, you will need to perform some configuration on both the ICA client and the MetaFrame server. For the LR options to function, the following criteria must be met:

  1. The MetaFrame server must be running FR1 and must have a valid license installed. The Japanese version of MetaFrame and MetaFrame for Unix 1.0 and 1.1 do not support the LR options.

  2. On a Windows NT 4.0 Terminal Server, you must have Service Pack 4 or higher installed.

  3. The user must be running an ICA client that supports the LR options. Currently, only the Win16, Win32, and Linux ICA clients support the SpeedScreen 3 LR options.

  4. The desired LR options must be configured on both the client and the server. For example, even though the text echo feature has been enabled for all applications on a MetaFrame server, unless an ICA client has also been configured to use text echoing, then it will not be enabled for that client. The reverse is also true. If a client is set up to use text echoing, but the option has been disabled for all applications on a MetaFrame server, then text echoing will not be available to the user.

Server-wide Latency-Reduction Settings

On the MetaFrame server, the latency-reduction options are configured using the SpeedScreen Latency Reduction Manager (LRM). This can be found under MetaFrame Tools on the Start menu, or can be started from a command prompt using ss3admin.exe. Figure 1 shows the main window for LRM, with a single server icon for the current server. With the initial version of LRM, you can only modify the settings for the server that you are currently logged onto. You cannot manage multiple servers from this single console. Later in this article, I will point out the required registry and data files for LRM. This information can be manually replicated to other MetaFrame servers to ensure a consistent server farm configuration.

Figure 1

The main window for the SpeedScreen Latency Reduction Manager.

To view the LR features for this server, you can either double-click on the server name, or right-click and select Server Properties. The Server Properties dialog box opens, as shown in Figure 2. Here you will configure the server-wide settings that will determine whether the LR features are enabled. I will look at application-specific features shortly.

Figure 2

SpeedScreen latency properties for the RADIUM server.

By default, the Enable Mouse Click Feedback option is enabled for all applications on the server. The objective of this feature is simple: to immediately change the user's local cursor to an hourglass in the event that latency is preventing the immediate processing of the user's mouse click. To the user, it appears that the mouse click has initiated work on the server, which in turn has resulted in the hourglass being displayed. This immediate feedback helps to eliminate the problem in which users perform multiple mouse clicks on an object because they have not received any visual notification that their request is being processed.

In the lower portion of the dialog box, you will find the latency threshold options. These settings apply only to those clients that have their LR settings configured as Auto. In this situation when the high latency threshold is exceeded, the LR options for the client are automatically enabled. These same options are automatically disabled if the opposite occurs and the latency drops below the lower latency threshold.

Depending on your environment, you may want to look at reducing the upper threshold from 500ms down to somewhere between 250ms and 350ms. Typically, once the latency rises above 300ms, the client will experience severe performance degradation. In this situation, the LR options (particularly text echoing) can work very well to reduce these latency effects.

The final server-wide LR option manages local text echoing. Basically, this feature works by echoing the text that you are entering locally on the desktop, matching property attributes such as text color and font, and then transparently updating the text on the server side as quickly as possible. This eliminates the impact that latency can have on text input, particularly for users with high typing speed.

The successful operation of text echoing depends on whether the application on the MetaFrame server is utilizing standard Windows API calls for text manipulation. This is necessary to ensure that things such as text boundaries and properties (font size and foreground and background color) are enforced properly. Some of the common problems that you may encounter with SpeedScreen text echoing and a nonstandard application include these:

  • The text fonts appear incorrectly sized, misaligned, or corrupted when the user is typing.

  • The text field's foreground and background colors are appearing incorrectly.

  • In the most severe case, the application may hang or crash.

Text echoing does introduce some minor text overrun if users are rapidly entering text in a Web text entry field, as shown in Figure 3. This is simply because the text fields on a Web page are not standard Windows text controls. When the echoed text is actually transmitted to the MetaFrame server, the control will update properly and the overrun text will display properly.

Figure 3

An example of text overrun caused by text echoing.

The potential problems that text echoing can introduce are the main reason why this option is not enabled by default on either the client or the server. Citrix recommends (and I agree) that text echoing not be enabled for all applications, but instead should be enabled and configured on an application-by-application basis.

Of course, this will depend on how many applications you are running and how severe your latency issues are. It certainly may be more effective to enable text echoing for all applications and then selectively disable it for those applications that are having issues.

Regardless of which approach you may decide to take, if you are planning to implement text echoing, you should be sure to perform your initial testing in either a nonproduction or a limited production environment.

Application-specific Local Text Echoing Options

In addition to configuring server-wide settings, you can configure local text echoing options on one or more specific applications. Mouse click feedback can be enabled or disabled only for a server and cannot be configured on a per-application basis. Figure 4 shows the RADIUM MetaFrame server application-specific settings for Paint Shop Pro and Microsoft Word.

Figure 4

Application-specific latency settings for Paint Shop Pro and Microsoft Word.

A new application is configured by either selecting New from the Application menu or right-clicking on the server name (RADIUM) and selecting Add New Application. This initiates the Add New Application Wizard, which provides a straightforward method of creating a new application entry. Under normal circumstances, the wizard is sufficient to either enable or disable text echoing for the particular application. You will not need to further customize these settings unless you are having issues with the application using normal text echoing and want to try to remedy the problem with some specific tuning.

In this case, you can access more detailed settings by opening the Properties dialog box for a specific application, as shown in Figure 5.

Figure 5

Detailed latency settings for a specific application in the Latency Reduction Manager.

On the Application Properties tab, you can configure text echoing options that affect all text input fields in the application. Besides enabling or disabling text echoing, you also have the option of explicitly setting how echoed text will be displayed. The default is for echoed text to appear in place, and I have yet to encounter an application in which this has had to be changed. You would probably want to change this option only if echoed text is appearing corrupted, overlapping or outside a text boundary.

In the extreme case, you can specify that the echoed text will appear in a floating bubble and can be moved independently of the application. An example of this is shown in Figure 6, with the Internet Explorer application configured with this option. As you can see, this should probably be used only if you must provide text echoing in a high-latency situation and the standard text echoing options are not working properly for the app—this option is almost certain to cause user confusion.

Figure 6

Internet Explorer with the floating echoed-text bubble.

If you click the Advanced button, a dialog box opens with one option that can be selected. From here, you can force SpeedScreen to operate in safe mode when processing all input fields in this application. This option affects SpeedScreen regardless of whether text echoing is enabled, and it is available even if text echoing is disabled. This option would be used if you were experiencing text corruption in an application even though local text echoing is not enabled.

Besides configuring text echoing for the entire application, you can configure it for specific text input fields. This is done from the Input Field Configuration tab, as shown in Figure 7.

Figure 7

The “Input Field Configuration” dialog box.

The options available here should really be considered as the last-resort options when trying to get text echoing to function with an application. Certainly the number of input fields in the application and the problems that you are encountering will play a large factor in whether the granularity available from this tab is worth the effort to configure. The process itself is quite straightforward. You simply start the application that you want to modify, click the New button on the Input Field Configuration tab, and then follow the wizard to select the specific field. Contrary to what you might believe, you will typically not be able to narrow the functionality to a single text input field. As a simple example, I have set up local text echoing for the REGMON utility, available from www.sysinternals.com/. After launching REGMON, I select the New button and follow the wizard prompts until I am asked to select the desired input field. I decided that I would like to choose the Include field in the filter configuration dialog box, as shown in Figure 8.

Figure 8

Selecting a specific input field to configure in the Latency Reduction Manager.

After selecting the field, the wizard populates the field class information, but no field name is defined. Continuing on with the wizard, I then select the Low option so that the text bubble automatically appears. After I complete the wizard, my new field is shown in the field list (see Figure 9).

Figure 9

The selected field in the “Configured Input Field” list.

If I then launch REGMON and open the filter dialog box, I see the local text echo bubble appear as expected (see Figure 10). But I see the same bubble appear regardless of which edit control I select in this dialog box. So, even though I wanted to configure only the specific Include text field, I inadvertently set it for all three text input fields. Now this may not appear to be a very big deal because in this case we probably would want it set for all three. But it does demonstrate how some unexpected behavior may occur.

Figure 10

The configured input field with the local text echo bubble.

The additional options for a specific text field (refer back to Figure 9) all relate to issues with SpeedScreen incorrecting detecting properties for a text field, such as font size, text or background color, and whether the field is a password field. If any of these options are appearing corrupted or incorrect for a field, you can manipulate these options to try to correct the problem.

Latency-Reduction Registry Settings

The server-wide latency-reduction settings are maintained in the registry key: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Citrix\ss3.

The six registry values are shown in this table:

Value

Description

ConfiguredApplicationCount

The number of application-specific LR settings that exist on this server. This value is used to determine whether data needs to be read from the ss3config data directory (discussed later).

CurrentVersion

SpeedScreen 3 version.

EnableLocalTextEcho

Server-wide text echoing; 1 is enabled, 0 is disabled.

EnableMouseFeedBack

Server-wide mouse feedback; 1 is enabled, 0 is disabled.

StartThreshold

The upper threshold for enabling LR on Auto-configured clients.

StopThreshold

The lower threshold for disabling LR on Auto-configured clients.

Because all of these options are configurable through the GUI tool, you should not directly modify them through the registry. This key can be exported and then imported into multiple MetaFrame servers to duplicate the Latency Reduction configuration. If application-specific settings exist, then the ss3config data directory will also need to be replicated.

Latency-Reduction File Settings

While the server-wide latency settings are maintained in the registry, any application-specific settings are maintained in individual files located in separate subdirectories under %SystemRoot%\system32\ss3config.

Each application that you configure will have its own subdirectory corresponding to the executable name (minus the .EXE extension). For example, if I have defined application latency settings for Microsoft Word, then a directory called WinWord will exist. Within the application directory will exist one of two subdirectory names: either BaseName, which corresponds to a configuration that affects all instances of the application, or FullPath, which corresponds to an application in a specific location.

Within this subdirectory you will find a file with an ss3 extension. This file contains the specific latency options that you have configured for the application. Figure 11 shows the filename for a latency configuration file for a specific installation of PaintShop Pro (psp.exe). The full pathname for the executable is used as the filename, except that the backslash and colon characters have been substituted with their ASCII character equivalent and are preceded by the percent sign (%). In this example, the characters :\ would be converted to %3A%5C.

Figure 11

The ss3 configuration file for a specific instance of Paint Shop Pro.

The contents of the ss3 file itself are generated by the LR Manager and should not be manually edited. By replicating the appropriate registry key and the ss3config directory to another server, you can automate the process of replicating the latency-reduction changes to all of the SP2/FR1 MetaFrame servers in your environment.

Client Latency-Reduction Settings

As I mentioned earlier, to take advantage of the SpeedScreen 3 Latency Reduction features, you are required to run an ICA client that supports these options. Currently only the 6.0 ICA clients for the Win16, Win32, and Linux platforms are supported.

The client-side LR options must be configured separately for each individual application set or custom ICA connection that is created. These options cannot be configured as client-wide defaults. Figure 12 shows the Default Options tab for an application set's properties. The options available here are identical to those found on the Options tab for an individual custom ICA connection.

Figure 12

SpeedScreen latency options for an application set on the Win32 client.

The one difference between the properties for an application set and a custom ICA connection are the default LR options when the object is created. The defaults are as follows:

ICA Connection Type

Default SpeedScreen Latency

Reduction Options

 

Application set

Off

Custom ICA connections

Auto Mouse click feedback is enabled. Local text echo is disabled.

Changing the setting from Auto to On will force the client to use latency reduction, regardless of how low the latency might actually be on the connection. As I mentioned earlier, local text echoing must be enabled on both the client and the server for it to actually be used.

Besides managing the LR options through the client GUI, you can also make the changes directly within the APPSRV.INI or PN.INI files. As with other APPSRV and PN settings, you can customize them for use within a preconfigured ICA client installation, thereby ensuring a consistent client configuration for deployment.

Two new values have been created for use in the .INI files:

  • ZLKeyboardMode

  • ZLMouseMode

The ZL prefix in the value names is short for "zero latency."

The integer numbers from 0 to 2 are the only valid values that can be assigned to these variables. The different integer values have the following meanings:

Value

Meaning

0 (zero)

Disabled

1 (one)

On

2 (two)

Auto

For example, if you wanted to configure the LR settings for Auto with both mouse feedback and keyboard echo enabled, then any of the following three pairs would be valid:

ZLKeyboardMode = 2         ZLKeyboardMode = 1

ZLMouseMode = 2              ZLMouseMode = 2

ZLKeyboardMode = 2

ZLMouseMode = 1

When reading the settings from the .INI file, only one setting is required to be set to 2 to enable the Auto option. So, for example, to have Auto with only mouse feedback enabled would be as follows:

ZLKeyboardMode = 0

ZLMouseMode = 2

You may have noticed that these values can also be found in the WFClient portion of the APPSRV.INI file. Unfortunately, modifying the values in this section does not provide client-wide changes to the latency-reduction options.

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