Terminal Services

Terminal Services is a component in Microsoft Windows that allows a user to access applications and data on a remote computer over a network. Terminal Services is a thin-client terminal server sort of computing environment developed by Microsoft.

Terminal Services allows Windows applications or even the entire desktop of a computer running terminal services to be accessible from a remote client computer.

Widely used these days with Microsoft Windows Server 2003, Terminal Services provides the ability to host multiple, simultaneous client sessions.

What is Terminal Services good for?

Terminal Services lets administrators install, configure, manage, and maintain applications centrally on a few servers.

Time is money...

This goes in hand with IT budgets and staffing. Managing software in a central location is usually much faster, easier, and cheaper than deploying applications to end-users' desktops. Centrally-deployed applications are also easier to maintain, especially as related to patching and upgrading.

Running applications from one central location also can be beneficial for the configuration of desktops. Since a terminal server hosts all the application logic which also runs on the server, the processing and storage requirements for client machines are minimal.

Terminal Services history

Terminal Services was first introduced in Windows NT 4.0 Terminal Server Edition. Unfortunately, this early implementation of Terminal Services in Windows NT did not gain too much popularity. Terminal Services has been significantly improved in Windows 2000 and even more in Windows Server 2003.

Both the underlying protocol as well as the service was again fundamentally overhauled for Windows Vista and Windows Server 2008.

Are there any limitations on the network connection?

In general, there are no explicit limitations for network connectivity related to terminal services. It can be used over a Local Area Network (LAN) as well as over a Wide Area Network (WAN).

Terminal Services in Windows XP

Windows includes the following two client applications which utilize Terminal Services:

• Remote Assistance
• Remote Desktop

The Remote Assistance component is available in all versions of Windows. Remote Assistance allows one user to assist another user.

The Remote Desktop application is available in Windows XP Professional, Media Center Edition, Windows Vista Business, Enterprise, and Ultimate. Remote Desktop allows a user to log into a remote system and access the desktop, applications, and data. Remote Desktop can also be used to control the system remotely.

Terminal Services on client versions of Windows versus server Windows

In the client versions of Windows, that is for example Windows XP, Terminal Services supports only one logged in user at a time. On the other hand, concurrent remote sessions are allowed in a server Windows operating system, for example the Microsoft Windows Server 2003.

What are the disadvantages of Terminal Services? 

As one may expect, running an application from a central location also has some disadvantages.

• The terminal server needs to be powerful enough to be able to handle all connections.
• The network needs to be sized appropriately so that it is not the bottleneck when terminal server sessions are established.
• The terminal server is the major source of risk of downtime. If the terminal server fails, the whole system fails unless a fail-over terminal server is in place.
• The functionality of the system as a whole is also affected by the network reliability. If the network is down, the whole system is down as well.
• Running applications from a terminal server can also be an issue from performance perspective. In some cases, no matter how good the network is, the performance associated with running an application locally on a desktop workstation can still overshadow the benefits of a terminal server environment.

Another disadvantage can be the availability of skilled administrator. Support for a terminal server needs to have the necessary knowledge and be available as the business needs commands. 

What Microsoft Terminal Services has to offer?

Terminal Services is a built-in component in Windows Server 2003. Terminal Services provides especially the following functionality:

Terminal Services and Group Policy

Terminal Services can be configured and managed through Group Policy settings. This is a new feature in Windows Server 2003 which allows administrators to take advantage of the flexibility and power of the Group Policy component to simplify the configuration and management of Windows Terminal servers. User accounts can be assigned permissions based on group policies.

Remote Administration Built in...

The remote administration mode is already built into the operating system and no longer requires installation of additional components. Allowing users to remotely connect to a server requires just a simple step of selecting a checkbox on the Remote tab of the System tool in Control Panel.

Remote Desktop Protocol (RDP)...

The Remote Desktop Protocol (RDP) has been very much enhanced in Windows Server 2003. The display and device redirection as well as the security have been enhanced. Terminal Services does not need a VPN tunnel anymore when connecting to it over a public network.

Session Directory component...

The terminal server can be configured with so called Session Directory component. This add-in allows to scale Terminal Services upwards. This is used by large enterprises that need a load-balanced terminal server network.

Alternatives to Terminal Services

What are the options for running terminal servers in today's enterprise environment? In addition to Windows products, CITRIX has been another major player in the market. Many companies chose to use Citrix instead of Terminal Services because it provides other important functionality. Read here for more details: CITRIX.