For most OCS plugins, the installation must be done both :
> On the server side : Creation of database tables and display in the GUI
> On the agent side : Copy of the script (.pm, .ps1 or .vbs depending on operating system) which will report the information
Note: You can install an OCS agent in your OCS server, it will thus upload its own informations as well as its plugins (if installed)
Otherwise, ocsinventory-agent is executed on the machine(s) on which the OCS agent is installed - servers or workstations (the OCS server being in passive mode as far as inventory is concerned)