A deep-rooted legacy of access

Even as Web services grow, they'll never completely choke out terminal-based remote access.

Client/server is dead. Long live Web services - or so many in the software industry would have users believe. Now that Web-based front ends are uniformly included with enterprise applications (and Web services promise even more functionality on all sorts of roving devices), old-fashioned terminal services applications such as Citrix seem doomed.

Yet the Web has not spelled the demise of Citrix-like services. The truth is, analysts and users say, Web apps - despite their thin-client, platform independence - often still have a pretty major downside: poor performance for remote users.

"Basically, if your application is working fine today and all you want to do is provide remote access to it, then you'd be insane not to use a terminal server-based technology like Citrix," says Brian Madden, an independent industry consultant.

Citrix and other terminal services are easy to use and deploy, especially for legacy applications that aren't Web-enabled. Providing the remote access doesn't require reworking the application or using a particular device by end users.

"With Citrix, you can be up and running in literally less than 24 hours, fully deployed. You simply can't beat that," says Mike Hughes, IS manager at Campbell Group, a Portland, Ore., timber investment and management firm.

Campbell Group struggled to provide remote access to an internal Microsoft Access-based accounting program until it hit on Citrix, Hughes says. "We tried it, and boom, it worked. When we saw how easy Citrix was, it became the way we provide remote access for everything. It's easy to manage and quick to deploy."

Hughes and one other IT staffer manage application access for about 200 PCs and servers and 150 employees at eight offices in four states. "The simpler we can keep it, the better it is. We're saving so much on manpower by not having to constantly touch those remote machines," Hughes says.

The choice is not so clear-cut if your applications already are Web-enabled.

"If the Web front end is already built-in, and it isn't costing you anything, then you'd be nuts not to use the browser," says Jason Brougham, enterprise network manager at American Medical Response, an ambulance services firm in Greenwood Village, Colo. "Citrix servers aren't free, and . . . with Citrix, you pay for an additional client license on top of your Windows license for a Windows-based app. That can add up."

Still, moving to a Web-enabled version of an application could cost more than Citrix, says Brougham, offering as an example an ERP application upgrade for Web access alone. "You have to weigh the benefits of that half-million-dollar investment in the new version, and the downtime and resources to do the upgrade, especially if you don't need the other new features. Plus, you have to look at the training costs. Going from a client/server-based app to a Web app is never the same," he says.

Madden uses e-mail as an example. "Would you rather use Hotmail or Microsoft Outlook? Outlook is much better and easier to use. For every single screen, you don't have to click 'Next' and wait for it to send your request to the server and wait for it to send it back. That's a real value," he says.

Citrix delivers an experience similar to traditional Outlook. "Citrix gives you the same level of access as a Web app, but it also delivers this rich Windows 32-bit GUI," he says.

Bandwidth and security

Choosing between Citrix or a Web app also depends on the bandwidth requirements of the particular application. "If the database is sitting in Denver, and the user is sitting in Florida, and the application needs to return hundreds of records, a Web app is going to be slow," Brougham says. "At that point, you can either pay to increase the bandwidth on your WAN or you can use Citrix and put the client piece on a server next to the application so it runs at Mach 2. The performance is incredible, and in that case, the bandwidth with Citrix is a lot less than a Web-based app."

This is because Citrix is more of a screen-scraping technology, delivering keystrokes and screen changes over the wire. Web apps, on the other hand, need to deliver every JPEG image, document and so on. This makes Citrix more of a known quantity when it comes to bandwidth, whereas Web apps are more spiky and less predictable.

"Citrix is like a constant stream of 10K bit/sec usage rate on your WAN, whereas with the Web, if you're using a bunch of JPEGs and Word documents, you could be pulling down a page of 400K," Brougham says. "All that takes time and bandwidth to move back and forth between a remote location and the centralized database or Web server."

The richer, the better

Thin clients like browser and Citrix-like terminal services, are not the only way to provide remote access to applications, especially in the emerging world of Web services. Distributed 32-bit rich clients sometimes make more sense than either of those options.

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Citrix also can be more secure to use than Web-based apps, which can be a real boon in the face of federal requirements such as the Health Insurance Portability and Accountability Act.

"If you're typing private health information into a Citrix-based app, you're typing it onto a server in a hardened data center and just the keystrokes go across the wire, not the record," Brougham says. "With a Web-based app, the data all gets pulled down and could be cached in the browser."

Plus, Citrix doesn't require that remote users access applications via a VPN, which can be tough to deploy and manage.

"Citrix is much more secure than a VPN," Campbell Group's Hughes says. "When I allow a user with a home computer to VPN into my office, I end up opening a nice big hole to an unsecured computer over which I have very limited control." If the home user's computer has been compromised, the VPN would provide a tunnel for an attack straight into the corporate network.

"With Citrix, I can have a nice tight perimeter and don't have to let people punch holes through with unsecured machines. Instead, they visit our Web site, log on and they're good to go," he says.

Citrix and Web service

Web access advocates will argue that the browser is the best way to go if you plan to use Web services-based applications, such as those that use Microsoft's .Net platform or Sun's Java and Java 2 Platform Enterprise Edition. But that's really an apples-to-oranges comparison because Web services-based applications rely on "rich" or "smart" clients, and are not thin-client-based, analysts and users say. Thin clients such as Citrix actually play nicely in a .Net environment.

Citrix vs. Web access: Points of differentiation

The remote application access decision usually is between traditional

terminal services or new Web-enabled applications. Consider these issues.
BANDWIDTH. Web applications are bursty, while Citrix applications are streaming. You always know how much bandwidth Citrix will use, while Web stuff tends to spike, making traffic loads harder to get a handle on.
RESPONSE. Web apps tend to have slower response times — every time you click on “Next,” you’ve got to wait for data to upload or download. Depending on the application, performance could suffer vs. what it would be using Citrix.
SECURITY. Web apps might hold data in the browser’s cache, which can be a security risk. Citrix uses SSL security and only keystrokes traverse the link, making it very secure.
OFFLINE. Neither Citrix nor a Web-enabled application provides much of an offline experience because they both require access to a central server.
EXPENSE. Citrix requires licensing costs for the server and the clients, whereas a Web client is free. Web-enabled apps might require costly upgrades.
PRODUCTIVITY. Citrix gives you the illusion of using that fat 32-bit client, while Web apps are more stripped down. Web apps, then, might require additional training time and dollars.
PLATFORM CHOICE. Both Citrix and Web apps can pretty much run on anything. Still, some Web apps are too RAM-intensive to run on a dumb terminal, whereas Citrix can always run on one.

"You might develop a .Net application that is very smart and can use all these back-end Web services to pull data from a million different systems," Madden, the consultant, says. "But the client piece has high requirements. It needs a certain amount of RAM and, in the case of .Net, it requires that .Net Framework be running on the client, which means it has to be some kind of Windows PC."

As such, terminal services will be around for a long time, he says. "In five or 10 years, let's say, all applications are .Net-like Web services-based applications. We'll [still] have a need to deploy these applications to Java PCs, Linux machines, Macs, PCs, smart phones and so on," he says. "And terminal services will provide that access and a rich interface, plus the manageability of a thin client."

Some users, including Campbell Group, use a combination of Web services and Citrix today. "You really can't publish a .Net application in a browser interface and retain a lot of functionality," Hughes says. "It makes more sense to deploy it through Citrix because then you can centralize it and make it easier to maintain, while retaining the rich GUI. They work together fine."

Cummings is a freelance writer in North Andover, Mass. She can be reached at jocummings@comcast.net .

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