Requiem for the PC?
Visara Lowers the Cost of Ownership with QNX-Based NCs 

Bill Phelps, Visara Inc.

Will the high cost of ownership drive most corporations to throw out their PCs? No one can say for sure. One thing is certain, however: Budget-minded businesses are taking a second look at the high cost of maintaining vast arsenals of personal computers. And as they do, many are seeing the value of 'thin' network computers, or NCs. After all, why install an application in dozens, hundreds, or even thousands of PCs, when you can install it just once on a server and make it instantly available to every user in the enterprise?

Nevertheless, NCs have yet to achieve the widespread acceptance that many industry analysts predicted. Why? Because, until now, most NCs have been designed to support next-generation Java applications - rather than the thousands of existing Windows, Unix, and mainframe applications that businesses have already invested in.

And there's another problem: hidden costs. For example, let's say you own a mainframe system. To upgrade to NCs, you typically need to install dedicated cabling; you can't use your existing wiring infrastructure. That's hardly an incentive to upgrade, when installing Ethernet cables for just 50 users costs an average of US $12,500.

Enter Visara. Our company is changing the rules - and market acceptance - of NCs with a new concept: the 'network computing terminal,' or NCT. Unlike any other solution, the NCT allows users to access their existing Windows, mainframe, Unix, intranet, and Internet applications - all from one low-cost device. The result? Corporate users are lowering their computing costs by as much as 35 percent.

Who's interested?

Potential users of the NCT fall into two general categories:

• companies using mainframe systems that want to provide their terminal users with access to Windows applications, corporate intranets, and the Internet
• companies that want to consolidate their existing Windows applications on a server, thereby eliminating the cost - and security problems - of maintaining programs and data on multiple PCs

For users of mainframe and mid-range systems, the NCT offers a unique feature: the ability to connect to existing coax, Twinax, Token Ring, and/or Ethernet cabling. The result is a plug-and-play migration to network computing, with no need to rewire. In fact, since the NCT also includes a resident web browser, email client, and TCP/IP stack, mainframe users gain immediate access to the Internet. No NT server is required.

For owners of both mainframe- and Windows-based systems, the NCT also supports the Citrix ICA protocol, which allows this diskless device to access the full range of Windows applications - everything from Microsoft Word and Excel to enterprise-level applications like SAP. And since the NCT's TCP/IP stack includes telnet, users can also access applications running on Unix servers.

Choosing the OS

To give a thin-client computer like the NCT all this functionality, we faced several challenges:

• embed an operating system and a full suite of applications within the NCT, without breaching the device's severe memory limitations
• deliver a high level of reliability so users can have constant access to their applications - even if the network server goes down
• provide graphical interfaces in several international languages to reduce training and speed up customer installation
• provide access to Windows applications without the need for high-end hardware

We faced one other challenge: time-to-market. Because of customer demand, we had to deliver manufactured product less than seven months from the start of software development.

With these criteria in mind, we evaluated a number of OSes - including VxWorks and Windows CE - before choosing the QNX realtime OS.

A small memory footprint

The memory footprint of the OS was crucial. We compete in an extremely price-sensitive market which means there is a real premium on memory in the NCT. In fact, to ensure the NCT could be competitively priced, we had to limit flash memory to 8M.

QNX offered a real advantage here. First, it's highly modular, so even services like file systems and device I/O are provided by optional modules. As a result, we weren't forced to waste memory on OS services we didn't need.

What's more, all QNX modules are designed to consume as little memory as possible. You can, for example, fit the OS itself, plus the QNX windowing system, TCP/IP stack, HTML 3.2 web browser, email client, and other applications into less than 2M of flash or ROM. Using these standard QNX modules, along with several custom modules, our engineering team managed to fit full network computer functionality into just 6.2M of flash, leaving plenty of room for enhancements.

Being able to embed a complete OS within the NCT also helped avoid a problem common to NCs: long bootup times. Most NCs don't have a resident OS and, as a result, have to wait for processing time on a server to become available - which often takes two or three minutes. The NCT boots up in just 25 seconds.

Minimal downtime

To be commercially viable, the NCT had to cost much less to maintain, and deliver more uptime, than a desktop PC. Reliability was essential, in both the hardware and the software.

On the hardware side, the NCT has no moving parts - no fan, no hard drive, and no floppy drive - making the unit almost maintenance-free. It also has a sealed outer case, so it can run reliably even in dirty industrial environments.

On the software side, the NCT takes advantage of QNX's advanced 'Universal Process Model' (UPM) architecture, where every application, OS module, and device driver executes as a separate memory-protected process. When we were comparing OSes, we were swayed by QNX's reputation in the industry for being very fault-tolerant. And in our own evaluations, QNX's memory-protection model came out on top for avoiding downtime.

In OSes without UPM architecture, hard-to-detect programming errors like corrupt C pointers can cause drivers to corrupt other programs or the OS kernel. Either way, the user has to reboot. With UPM, however, QNX stops these faults from occurring. The OS can automatically restart any process that attempts to corrupt memory and thus restore full service. No reboot is required.

As it turns out, the NCT will function even if the network server goes down. Users can, for example, continue to send email and access the web. Better yet, the network administrator doesn't have to reboot every user's terminal once the server comes back online. This efficiency is partially due to QNX's UPM architecture, and to QNX's small footprint, which allows us to store a complete OS and various applications right on the NCT itself.

Faster time-to-market

With the need to deliver product in less than seven months, reducing software development time was critical to us. We estimate that, by using QNX, our design team cut the development schedule by over 30 percent.

First, QNX provided most of the core functionality we required. This included off-the-shelf components, such as QNX's windowing system, IP stack, and web browser. It also included source and object code that enabled our engineers to develop a unique protocol for attaching the NCT to 3270 coax cabling. With all these components available from QNX, we only had to develop software unique to the NCT - such as the emulation clients for TN3270 and TN5250.

Second, QNX allowed our engineers to begin software development for the x86-based NCT before the target hardware was ready. Using QNX's self-hosted development environment, we were able to write, debug, and test all of our software - including device drivers - right on our own PCs. We didn't have to repeatedly download the code to the target to test every modification.

Third, QNX significantly reduced debugging and testing by allowing us to run every driver and application in its own memory-protected address space. Without this feature, a single memory violation in a hardware driver can take days or even weeks to track down. With QNX memory protection, on the other hand, our engineers found they could immediately identify the exact module and instruction that caused the fault. What's more, we didn't have to rebuild the entire OS kernel every time a driver was changed or fixed. Since every QNX driver runs as a separate MMU-protected process, we simply had to recompile the driver and restart it.

And fourth, QNX offered the Photon Application Builder (PhAB), a code-generating GUI builder that enabled our team to respond quickly to customer requests during beta testing. Developing the NCT's interface could have been a real stumbling block. We had no previous GUI experience - all existing Visara products simply displayed lines of text. As it turned out, we had no problem at all with PhAB. Because our engineers were pressed for time, they didn't have the opportunity to take the PhAB training that QNX Software offered. Nevertheless, all our GUI projects were completed on time and on budget, which is a tribute to PhAB's ease of use.

The international connection

To target international users, we took advantage of PhAB's built-in language editor, which allowed us to translate the NCT's setup menus and configuration panels into several languages. The configuration panels we created with PhAB have greatly simplified the installation process. In numerous customer evaluations, we've found that users could install the product easily - without having to use the installation manual.

High-performance access to Windows

Given that most Windows applications eat up lots of RAM and CPU cycles, it's hard to imagine that a thin client like the NCT, which uses a low-cost processor and limited memory, can deliver enough performance. Especially when most people have become accustomed to the raw speed of Pentium-based PCs.

The NCT addresses the performance problem in two ways. First, the resident QNX RTOS is highly efficient, requiring very few CPU cycles compared to a desktop OS. Second, the NCT doesn't run Windows applications locally, but instead uses the Citrix ICA protocol to access Windows applications running on a multiuser NT platform, such as Citrix WinFrame or Microsoft Terminal Server Edition.

ICA is a low-bandwidth protocol that carries only screen, keyboard, and mouse events between the server and the NCT; the application itself executes 100 percent on the server. Rather than slowing things down, this approach can actually improve the user performance of data-intensive applications, since data no longer has to travel back and forth on the network. As a result, a high-end CPU and lots of memory simply aren't needed for the NCT.

Remote maintenance

As we've seen, having an OS and a full suite of applications inside the NCT addresses the shortcomings of other NC designs, such as long bootup times and loss of service if the network fails. But it also means that a customer's NCT terminals may need to be updated with new software from time to time. In fact, we've already completed a variety of enhancements, including support for Token Ring and Twinax with 100Mbit Ethernet, audio, and numerous additional terminal emulations.

To simplify the upgrade process, each NCT contains flash memory update utilities. As a result, the system administrator can easily download enhancements and updates from any FTP server on the network. The NCT was designed with upgrades and custom features in mind. The administrator can, for example, schedule program updates during non-working hours so that users aren't interrupted.

Thin clients create fat savings

We've looked at several ways in which the NCT can reduce cost of ownership. But how much are NCT customers really saving?

Since the NCT offers several migration options, the amount varies from customer to customer. To start, let's look at our biggest installation to date - a US government agency that is using the NCT to replace the green-screen, fixed-function terminals for its 3270 system.

The agency wanted to provide their users with intranet access, while maintaining their existing 3270 host connection. With the NCT they were able to keep their coax cabling infrastructure in place, as well as their 3270 peripheral infrastructure (i.e. 3270 controllers). And with the resident web browser in the NCT, they didn't have to invest in servers for intranet access (as required by most thin clients). The agency does eventually want to provide Windows access from the NCT, but their current needs don't dictate the purchase of servers - a tremendous savings up front. Altogether, the agency estimates that using the NCT has resulted in a 35 percent savings, compared to other solutions.

Other customers have moved to category 5 cabling and have invested in servers for access to Windows applications. Their savings come mainly from lower administrative costs, since they only have to install and maintain their Windows applications on a server, not on every user's desktop. These customers report savings of 18 to 25 percent, still a significant reduction.

Given these numbers, it's no surprise the NCT is becoming increasingly popular across a variety of corporations, including auto manufacturers, banks, healthcare providers, insurance companies, railways, power utilities, and, of course, government agencies. And it's not necessarily because PCs cost so much - but because the NCT costs so little.

For more information on the NCT from Visara, visit www.Visara.com.