How to Customize HTML Preview in Access Gateway Advanced Edition

Summary

This article describes how to customize HTML Preview in Citrix Access Gateway Advanced Edition.

By default, Access Gateway Advanced Edition is configured to support the HTML rendering of Microsoft Word, Excel, Visio, Power Point, and Adobe Acrobat files.

For HTML rendering to occur, Microsoft Office products must be installed on at least one of the Access Gateway Advanced Edition servers in the farm. Additionally, if the administrator wishes to have PDF document types rendered in HTML, the administrator must also install pdftohtml.exe version 0.36. This program can be obtained from SourceForge at http://pdftohtml.sourceforge.net/

The program should be installed in the <programfiles>\Citrix\Access Gateway Enterprise\PDF folder. If the administrator wishes to place the executable for PDF conversions outside of the Access Gateway Advanced Edition install path, a registry key should be modified so Access Gateway Advanced Edition knows where to find the executable and will activate this type of HTML rendering.

Caution! This fix requires you to edit the registry. Using Registry Editor incorrectly can cause serious problems that may require you to reinstall your operating system. Citrix cannot guarantee that problems resulting from the incorrect use of Registry Editor can be solved. Use Registry Editor at your own risk. Be sure to back up the registry before you edit it.

The registry key is located at:

HKEY_LOCAL_MACHINE\SOFTWARE\citrix\msam\activationservice\enginemanager\previewengine

ValueName: PDFConverter
ValueType: string
Default Value: <installpath>\Citrix\Access Gateway Enterprise\PDF\pdftohtml.exe

In order for HTML-rendered .pdf files to show embedded images, the administrator must also install GhostScript version 8.14, or later. Access Gateway Advanced Edition was tested using version 8.14. GhostScript can be downloaded from http://www.ghostscript.com/ . After installing the application, the administrator must add the path to the bin directory where the GhostScript executable file is located to the server’s environmental variables PATH variable. (Restarting the server may be necessary at this point).

Adding Other File Types to be Associated and Rendered through Existing Rendering Handlers

Supported file type for each handler

When a handler is loaded it reports the file type list that can be supported, this is determined by the handler list and whether required component exists or not. The handler reads the file type list from the registry, if such a file type list doesn’t exist in the registry, a default list is returned.

The following table indicates what is set by default. The registry keys do not exist by default and must be created in order to associate additional file types with handlers.

Note: The registry key values must begin and end with a colon.

Procedure

This sample procedure causes .txt file types to have the preview option available in the choice page and be rendered as HTML for previewing.

1. Create registry key “caps” under:

HKEY_LOCAL_MACHINE\SOFTWARE\citrix\msam\activationservice\enginemanager\previewengine

2. Under the following key, add the values below:

HKEY_LOCAL_MACHINE\SOFTWARE\citrix\msam\activationservice\enginemanager\previewengine\caps

Value Name: WORDHANDLER
Value Type: String
Values: ":.doc:.ans:.mcw:.rtf:.txt:" (remove the quotes when adding the values)

3. Stop and restart the following services using the server configuration console:

Citrix Activation Host Service
Citrix Activation Engine Service

4. In the Files shares tab of the Access Gateway User Interface, click on a .txt file and notice Preview is available in the Choice page. Select the option and view the text file as rendered HTML.

Controlling Cache Behavior

Cache is used by the Engine Manager service to boost performance, the default settings should work well in most cases. The only key you should modify for this is CacheSize which by default is set to 10000. If drive space becomes an issue, lower this number. The setting should never be less than 2.

In simple terms, the number 10000 refers to the number of folders that appear in \Citrix\Access Gateway Enterprise\ActivationCache before the items begin to overwrite. The order for replacing items is based on oldest and least used. So if the first cached item created is used everyday, it is not overwritten.

CacheSize

Control the maximum count of cache items.