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New SpeedScreen Technologies In Presentation Server 4.5

Wednesday, 15 November 2006 by Michel Roth

Sumit Dhawan of Citrix has done a write-up of new Speedscreen Technologies in Presentation Server 4.5. These new technologies are aimed at enhancing the end user experience. I think that this is another sign that Citrix is back on track. At BriForum Europe I had an interesting talk with Brian Madden on what is the key factor in any successful application delivery infrastructure. We came to the same conclusion: the end user experence. Even, when you're able to manage a 1000 server farm by yourself, this doesn't do squat for you if the end user experience is crappy.

In my presentation at BriForum Europe I spent quite some time on the subject of the user experience of users connected to Citrix applications via a WAN (low bandwidth-high latency) connection. The use of applications hosted on the Citrix platform has shifted dramatically in graphical intensity over time. Years ago it was only some word processing or email but these days it's normal that entire desktops with all business line applications are available to users connecting trough a WAN. This has severe implications in terms of perceived performance, because the bandwidth requirements of seemingly "normal" applications like Acrobat Reader and Internet Explorer running trough ICA can be quite intensive. If the WAN connection also has a high latency or high jitter then the user experience will be degraded even more.

Citrix has recognized these problems and has -although I think these problems are near to impossible to solve due to the nature of the RDP and ICA protocols- updated the SpeedScreen Technologies in Presentation Server 4.5 to try and optimize the user experience when dealing with graphically intense applications and/or are accessing Citrix application over a high latency connection. Quoting Sumit:

Frame-based display
"With Project Ohio, we have added technology to optimize tossing the redundant packets for new types of applications being written or when apps are accessed over high latency networks. The tossing algorithm has been enhanced so that now we are looking for more graphics constructs. It now detects complete self contained 'Frames'. This way the server can either toss the entire frame or send the entire frame to the client as a self-contained entity. This has the following benefits:

1. Less data on the wire due to improved tossing operation
2. Better responsiveness for end users because the entire frame gets updated at once rather than in parts.

Progressive Display
This is the most visible change for Ohio. When enabled, the first/initial display of any complex image is always displayed using the highest (the progressive) compression setting, to provide a fast initial response over a slow line. This initial/crude display is then sharpened up as background activity so long as the bitmap itself has not now been overwritten, and that no new drawing is happening. New drawing always takes precedence over sharpening.

This will improve the usability for any user working over a lower bandwidth connection. There are several common use cases that will benefit from this enhancement - such as scrolling through a document or graphs, images, etc. For example - we are noticing that healthcare PACS based applications (X-Ray, etc.) are going to perform in a manner where it is hard to tell that they are running remotely.

There are other ICA enhancements made to provide better responsiveness to end users. You will likely notice those with your graphics apps or high latency networks right away. If you have either one of those two, take a look at Ohio Tech Preview."

I will be testing Presentation Server 4.5 on these new technologies and see what kind of difference they make. I'll post my results here. In the mean while, be sure to read Sumit's entire article here.