Structure and Rules
There are two basic types of VTScada application: Standard and Script.
This is the type of application people use every day to monitor and control their system. At a technical level, it's worth noting that all standard VTScada applications are built (layered) on other applications. At the lowest level is the VTScada Library, which provides the development environment, tag and widget definitions, and all the user-interface elements that make up an application.
You may see the term OEM Application from time to time. An OEM application is simply a standard application, but one that is meant to provide tools for one or more other applications, in much the same way that the VTScada Library provides the tools such at the Tag Browser and Idea Studio, and all the familiar pages & widgets to standard applications. This is useful in many situations and essential for anyone building a set of subordinate applications, all monitored by one master application.
These are written in a text editor using the VTScada scripting language. Script applications are not based upon the VTScada Library Layer and therefore do not have access to the Display Manager, Idea Studio, built-in pages such as Reports and the HDV, the Alarm Notification System or any of the other tools and features provided in the VTScada Layer.
Several script application utilities are included with every copy of the VTScada. These include debugging and monitoring tools such as the Source Debugger, the VTScada Internet Monitor, etc. Most are not visible in the VTScada Application Manager by default but can be added as existing applications.
Script applications are seldom used for SCADA purposes.
Local vs. multi-server applications
A further distinction is whether an application is "local" or "multi-server". In both cases, these are standard applications. The difference is in whether a server list has been defined for the application.
If local, the application runs on only a single workstation and has no server list. If multi-server, then there is a server list and the application will run simultaneously on multiple servers and workstations, sharing data and tasks between them and automatically continuing without interruption should a server fail.
The application itself is the same whether local or multi-server. The difference is in the presence or absence of a server list.
