CAPS Printing Coordinator

The Printing Coordinator is the main application in the CAPS universe. It manages available printing devices (aka printing providers) and offers their information to clients via DBUS.

The other way round, it accepts print jobs from clients and forwards them to the dedicated (and online) printing devices.

Neither the client, nor the printing device need to know how to communicate with the Printing Coordinator. Both use their own library to deal with it:

the client uses the libcapsclient
the printing device uses the libcapsprovider

Client Side

The client side are all kind of applications which want to print something. They can retrieve the list of available printers, query their capabilities, send print job to it and track the print job's status to keep the user informed about any print progress.

Printer Device Side

At the printer device side self hosted printer drivers run - one individual process per printer device. Each process has full control over its own printer device, checks its state, receives print jobs from the printing coordinator, processes them and finally sends the resulting printing data to the printer device. And it reports all printer device state changes to the printing coordinator to keep the clients e.g. the user informed.