The Worldox system consists of a number of components:

File Server - stores the document repository (also called the 'DocVault') and Worldox Index Files.  Typically, the File Server uses the same hardware as the Application Server.
Application Server - stores a master copy of the Worldox executable and global configuration files.  All installation is performed via network share from the Indexer PC.  Executables are never launched on or registered with the Application Server itself – it is just used for storage of the application and configuration files.  Typically, the Application Server uses the same hardware as the File Server.
Indexer PC - runs the WDIndex application, which performs background processing to ensure that the Index Files are kept up to date.  WDIndex also runs nightly maintenance, and may be used for other background processing applications that are part of the deployment.  The Indexer PC is not a server, and it is recommended that it run on workstation grade hardware and operating systems (see minimum system requirements below).
The Indexer PC needs to remain logged on 24x7.  For this reason, users may not use the Indexer PC for day to day operations such as scanning or regular office use.
WDIndex does not run as a Windows service.  Trumpet performs most configuration work from the Indexer PC.
User Workstations - the Worldox executables are mirrored from the Application Server to the Workstation's local disks, then launched from the local disk.

NOTE:  There is no database server component (and outside of simple file serving, there is no server component at all).

For Externally Hosted Terminal Server deployments only

The above description is accurate with the following two changes: The WDIndex application may run on the file server (no separate Indexer PC), and the User Workstations will be virtualized Terminal Server sessions.  Running WDIndex on the file server adds considerable effort in ensuring that WDIndex is not inadvertently shut down, so it is only recommended for externally hosted Terminal Server deployments.