There are literally hundreds of different types of client devices that can be used to access Terminal Server environments. While that list is always changing and it's not practical to discuss all of them here, these client devices can be broadly broken down into four groups:
Traditional computer workstations, including standard Windows PCs and Macintosh computers.
Thin client devices, including devices that are based on Windows CE, Windows XP Embedded, or Linux on-a-chip. These devices have no local hard drives and typically boot off of servers or have embedded operating systems. While some of these devices may have local web browsers or terminal emulators, they usually run most applications from backend servers.
Traditional computers, managed as thin client devices. These devices are usually standard computers, complete with local operating systems and hard drives that are created with disk "images." If one stops working properly, it's replaced with a new computer or it's "re-imaged." Significant troubleshooting time is not wasted.
Mobile wireless devices, including dedicated wireless devices and palmsized computers.
Traditional computer workstations are currently deployed in almost every organization throughout the world. From a Terminal Server standpoint, if traditional computers are out there and paid for, then why not use them? Terminal Server works well when accessed from standard computers, whether users access their hosted applications through the locally installed RCD client or through a web portal.
Additionally, because traditional computers have local processors and hard drives, the RDC client can cache certain information and graphics locally. This increases performance, especially over high-latency/low-speed connections.
However, as more applications become server-based and as more companies use Terminal Server, traditional computers quickly become overkill for many users. They are expensive to maintain and users often break them through "trial and error" misconfiguration.
Already deployed in most locations.
Users are comfortable with them.
Local processor and storage allows for better session performance.
No perception of "IT is taking this away from us."
Local, non-Terminal Server applications can also be used.
Many peripherals are available and compatible.
Expensive to purchase and maintain.
Proprietary for each user.
Difficult to troubleshoot.
Must be manually configured or complex scripts and policies must be created.
Require local IT staff for support.
Prone to being broken by "curious" users.
Increased risk of "accidental" local data storage, which is not secure and not backed up.
Target for thieves in unsecured environment.
Many more options and models make it harder to enforce standards.
High power consumption.
Many moving parts that can break or get dirty.
Thin client devices and appliances are purpose-built machines used primarily for accessing server-based computing environments, including web browsing, terminal emulation, and Terminal Server sessions. These devices usually have no local hard drives or moving parts.
There are several flavors of thin client devices, most easily categorized by their local operating system. Most of these devices run some form of chip-based Windows (Windows CE.NET or XP embedded), Linux, or Java. In order to connect into the Terminal Server environment, they need to have the appropriate local RDP client software installed.
There are several advantages to using thin client devices. Because they don't have any in-depth local configuration, users are not able to break them as easily as a standard PC. They have few (if any) moving parts, so there is less to break. If something does break, it's usually cheaper and easier to replace the entire terminal.
For example, one company headquartered in Euclid, Ohio has manufacturing facilities in Ontario, Canada. Their entire manufacturing shop floor is run off of applications on Terminal Servers located in Euclid. All application access in Canada is done via thin client devices. Due to the harshness of the manufacturing environment, traditional PCs were always breaking. The thin client devices they chose had no moving parts—not even cooling fans—so they don't break nearly as often. When a thin client device does break, the shop foreman goes to the closet and grabs a replacement terminal. The user connects back into his session right where he left off with only a few minutes of total downtime.
However, be careful that you're not fooled by the seemingly endless advantages of thin client devices, because several major drawbacks exist.
First and foremost is the fact that with thin client devices, all major processing must be done somewhere else. With full-blown PCs, you have the option of running applications centrally. With thin clients, all applications must be run centrally. Do you, as an administrator, really want your clients surfing the web or writing email to their kids with valuable server processing time? Of course, many thin clients now have local browsers and local email programs, but you get the idea.
Low maintenance costs. If one breaks, throw it away, plug in a replacement, connect back into the session, done.
No local user troubleshooting.
No local IT staff is needed.
Little-to-no local user configuration, so users can't break them (as easily).
Low power consumption.
No black market value, so they're less likely to be stolen.
Less flexibility than PCs.
Essentially, all applications must run through host server.
If they are purchased to replace PCs, people will be upset. ("We just spent $2500 on new PCs, and now they're replacing them?")
In politically charged environments, users perceive that their full PC's are being "taken" from them.
Thin client devices are a great option, but unless you have a compelling reason not to use PCs, be careful of the "nothing" approach (as in "all or nothing") that you get with thin clients.
It is possible to combine the traditional computer workstation hardware with the management style of thin client devices to create a solution that has some of the advantages of each.
This option entails keeping full computer workstations for every user, but building a standard workstation image that is deployed to all users. All applications (except maybe a web browser) are server-based. The idea is that if a computer workstation breaks, a new hard drive or new workstation can be brought in to replace it.
One company that did this created a "five minute rule." Basically, the desktop computer technicians would visit an end user whenever they had a problem and called the helpdesk. If it was something simple, they fixed it. However, if the desktop technician could not fix the problem within five minutes, the user's computer was wiped clean and a new image was put on.
This worked well because all of their applications were delivered via Terminal Server and all of the users' data was stored on the network. All of the users' computers in the entire company had the same image, which was just a base operating system, a web browser, and the RDP client software.
Current hardware can be utilized.
Efficient use of time for IT staff.
The hardware still breaks.
"Mobile wireless devices" are a legitimate option when deciding how your users will access their applications. As with all mobile wireless devices, the primary drawback is still battery life. There are two classes of wireless devices, LAN devices and public WAN devices.
LAN devices are usually laptop computers or Windows CE / Pocket PC devices with 802.11 wireless network cards. Most people just buy full-blown laptops with wireless LAN cards.
The wireless public WAN is the system that for which you pay a monthly access fee. There are many networks throughout the world, and most are based on CDPD, CDMA, PCS, GPRS, GSM, or similar networks. Of the millions of palm-sized computers out there today, many of them run the Microsoft RDP client. They can be used for wireless, go-anywhere access to business applications.
Access to critical applications from anywhere.
Expensive service (US $30–$100 per user per month).
Tiny screens on devices.
Not practical for everyday use.