1) Introduction
This articles compares E3 Viewer and Windows Terminal Server, both used for Elipse E3 remote access purposes. We also analyze the pros and cons for each case.
Windows Terminal Server is a service developed in Windows NT 4.0. Its goal is to grant remote access to computers via RDP (Remote Desktop Protocol). This protocol is encapsulated on a TCP/IP connection, and transfers video, mouse, and keyboard data between server (the one accessed remotely) and client (the one that connects and operates the server remotely).
Similarly to Windows Terminal Server, the E3 Viewer is also a module developed for operating a system remotely (in this case, a project installed in an E3 Server). However, not only is Terminal Server more generic in nature, but the data transfer between client and server is implemented differently in these two modules.
2) RDP (Remote Desktop Protocol)
This protocol was developed by Microsoft for Windows systems in the NT family; that is, NT 4.0, Windows 2000 Server, Windows XP Professional, and Windows 2003. It enables the interaction between a client PC and a server machine (remotely) via video, mouse, and keyboard data transfer from the client machine.
Windows Terminal Service will work according to the Windows version installed:
- Number of accesses: Windows 2000 Server and Windows 2003 can have a large number of Windows Terminal Service licenses. However, these licenses are not free, and their cost is established by Microsoft. For a remote connection, use Windows XP Professional.
- Simultaneous access: for Windows 2000 Server and Windows 2003, there can be as many access points as the number of copies in the system. For XP Professional, when a remote connection opens, the local operation’s interface closes, returning to the typical Windows welcome screen.
- Dependencies: in order to access a PC remotely via Windows Terminal Server, you will need Remote Desktop Connection installed in the client machine. You can execute this software in any 32-bit Windows; that is, from Windows 95 on, any version can access a remote desktop.
Permission control takes place at E3 Server, which checks for the number of available E3Viewer and E3Studio copies, as well as their types.
3) E3 Viewer and REC (Remote Elipse Call)
REC is a protocol developed by Elipse Software for the communication between E3 Viewer, the responsible for operating and interfacing users from a certain domain, and E3 Server, which executes the domain.
This protocol was created to replace most connection functions offered by COM/DCOM services. These services were previously used for the communication between E3 modules, but had to change due to the use of TCP/IP ports allocated dynamically by these COM/DCOM services, among others. This hindered E3 Viewer operations via Internet, because maintaining these ports open can cause serious corporative network breaches problems.
E3 Viewer always uses the same communication port to access E3 Server, and data exchange always takes place via REC protocol; this guarantees a transparent process to the end-user.
The important points on E3 Viewer are:
- E3 Server will always control the number of copies and permissions available.
- Connection with E3 Viewer depends exclusively of a network path and of 6515 port released for network proxies and firewalls.
- This software implements the REC protocol; that is, all calls to E3 Server via E3 Viewer are sent via REC protocol. That means the protocol specifications can be hidden to the final user.
- Each E3 Viewer being executed on the network (Intranet or Internet) uses up one copy available in the server.
- The same E3 Viewer copy can be used in several machines on the network, as long as these machines are not accessing the E3 Server simultaneously.
- You can execute E3 in machines with either Windows 98 (E3 Viewer W98), Windows 2000, or XP Professional (E3 Viewer W2k), with the same functionalities as any operating systems.
4) Pros and Cons
We can now analyze the pros and cons of each option shown above. Let’s compare the use of multiple copies of E3 Viewer versus one single Viewer copy in Windows Terminal Server.
E3 VIEWER
Pros:
- Copy centralized in E3 Server.
- Not restricted by Windows settings.
- High graphic resolution, with zoom resources, automatic screen size fit, etc. Resolution only depends on the machine where Elipse E3 is running.
- Communication with Elipse E3 is optimized, so there is practically no latency in the communication between server and Viewer.
- You can block access to Windows desktop.
- User control not restricted by Windows.
Cons:
- E3 Viewer must be installed in all the machines where it will run, and its version must comply with the operating system.
WINDOWS TERMINAL SERVER
The following pros and cons of Terminal Server only apply when used with Windows 2000 Server, XP, or 2003 Server.
Pros:
- Copies set up in the server (Windows) in a centralized way.
- All “intelligence” runs in the server, requiring lighter clients than the ones needed if the Viewer were running in these machines.
- The project can be used in any type of Windows, via remote access.
- Ideal for projects where graphic quality doesn’t compromise the application.
- This is the ideal tool for debugging large-scale projects; it will grant access to all resources in the computer, complying with restrictions imposed by E3 Viewer, when necessary.
- Accessible by machines using other operating systems, such as Linux or Windows CE, as long as Remote Desktop is installed in this machine. This expands Elipse E3’s reach to other operating systems.
Cons:
- Requires server configurations that grant multiple accesses, including settings, among others (only for Windows 2000 Server and 2003).
- Additional accesses charged as independent copies; this generates extra cost for Windows 2000 Server and 2003.
- Requires Remote Desktop Connection module installed in all client machines.
- Requires a more resourceful server, because it will execute heavier operating systems; meanwhile, it will also handle the received remote connections, in addition to E3 Server, which will execute the E3 domain.
- Simpler graphic interface, because video data are transferred via network. Additionally, the operation can be slower than the one for E3 Viewer.
