Server Requirements and Licensing

A minimum recommended configuration for a Thin Client Server is:

  • Installation of VTScada, licensed for thin client connections.
  • Access across a network.
  • The server name should contain only letters, numbers and hyphens (as defined in Section 3.5 of RFC 1034 and Section 2.1 of RFC 1123 of the Internet Engineering Task Force). Characters such as underscores are not recognized by this standard and may cause unexpected behavior.
  • In the event that the clients connect to the Thin Client Server via proxy servers (common where a firewall is used), it is advisable that the proxy servers support the HTTP 1.1 protocol, rather than only HTTP 1.0.

VTS/IS Clusters and Server Lists

A cluster is defined as the list of machines configured in the VTScada Internet Setup dialog >Server Setup tab. Machines within the same cluster that are licensed to run full-production versions of VTScada share the sum of their licensed connection limits. These must be computers running VTScada that can see each other via VTScada Remote Procedure Calls (RPC). Machines with limited licenses (ex. demos, VTScadaLIGHT, developers licenses, SI licenses, Run-time licenses) can be configured in a cluster but do not pool their connection limit.

Licensing for VTScada Thin Client Servers

VTScada Thin Client Servers and the connections made to them are subject to the following licensing restrictions:

  • There is a limit to the number of concurrent thin client connections that can be hosted by the server.
    It is possible to have as few as 0 and as many as Unlimited connections depending on the licensing options you purchased with VTScada.
  • Thin client connection limits are pooled between full-production licenses. They are not pooled between instances of VTScada with limited licenses such as a developer's license, a demo license, a run-hours limited license or a VTScadaLIGHT license.
  • Limited license machines (excluding VTScadaLIGHT) can be joined into a cluster as backups and connections may failover to them in a limited capacity.
  • If your backup is running with a limited license, in the event of a failover, the backup will host active thin client connections in excess of its connection limit (to maintain system stability) but new thin client sessions cannot be started in excess of the failover server's limit.

Servers within a cluster that have full-production licenses will pool their licensed resources. For example, if one server in the cluster has a full-production license for 5 connections and another has 10, you will always have 15 available connections. If the 10-license server goes offline temporarily, your available license count will not drop to the remaining 5 but will remain at 15 on the server that is still running. No existing connections will be lost.

VTScadaLight licenses may have one Thin Client connection from the local network.
Remote computers must connect to the local network using a VPN.

 

You can find the number of licensed thin client connections for any server in the License Management dialog, available from the VTScada Application Manager (VAM).

The number of licenses in use is counted on the basis of concurrent sessions, regardless of whether these are from one computer or from many computers. Each connection to a VTScada Thin Client Server counts as one license in use. If, for example, you opened two tabs in Internet Explorer and connected to your VTScada Thin Client Server from each tab, then that would count as two licenses in use. Pop-up windows do not consume extra licenses.

An exception is that for support purposes, certain Trihedral-supplied debugging tools (such as the "Debugger", "Profiler", etc.) can always be accessed via the VTScada Thin Client, even if their use would exceed the license allocation.