README.md: various notes added

- current printing stack explained
- future with CUPS 3.0 commented
- the current s-c-p status mentioned
- add the note for looking for co-developer

Author: zdohnal

README.md

@@ -2,8 +2,77 @@
 
 [![Build Status](https://travis-ci.org/OpenPrinting/system-config-printer.svg?branch=master)](https://travis-ci.org/OpenPrinting/system-config-printer)
 
-This is a graphical tool for CUPS administration. It uses IPP to
-configure a CUPS server.
+This is a graphical tool for CUPS administration - system-config-printer (s-c-p).
+It uses IPP to configure a CUPS server. Additionally it provides dBUS interface
+for several operations which aren't directly available in cupsd, and automatic USB
+printer installation daemon for non-IPP-over-USB printers.
+
+The alternatives for the graphical configuration tool are CUPS Web
+interface, desktop control-center or lpadmin command line tool if you need
+to install printer manually which may not be needed in recent cases.
+
+WHEN I DO NOT NEED PRINTER SETUP TOOL AS S-C-P?
+-----------------------------------------------
+
+If the application where you print from has an up-to-date print dialog
+(uses the current CUPS API) and your printer is set up for driverless printing
+(has AirPrint/IPP Everywhere/IPP-over-USB support, opened port 631, lies in your local network
+and Avahi is running, IPP and mDNS is enabled in your firewall, ipp-usb is installed if
+your printer is connected by USB), you don't to install the printer at all. The dialog
+is able to pick up the printer right before you open the dialog and it disappears
+once you don't need it (reappearing next time you open the dialog again).
+This appearing and disappearing printer is called CUPS temporary queue.
+
+The devices supporting AirPrint/IPP Everywhere appear since 2010 (IPP-over-USB devices a bit later),
+so if your device was made after 2010, there is a great chance it supports the standards.
+
+From the dialogs I'm aware of the temporary queues are currently supported in any GTK3
+based application (evince, gvim, gedit, firefox if you are on GNOME and choose system
+dialog for printing...) and in Libreoffice.
+
+FUTURE WITH CUPS 3.0:
+---------------------
+
+CUPS 3.0 will divide the current CUPS in several modules - command line tools, library,
+CUPS Local server and CUPS Sharing server. CUPS Local server will be designed as lightweight
+for desktop usage, supporting only CUPS temporary queues. CUPS Sharing server will be more like
+the current cupsd, supporting permanent driverless queues, suited for servers.
+
+system-config-printer is often used on desktops where will be CUPS Local server installed by default.
+Since the server will support only CUPS temporary queues, system-config-printer will need to work
+with IPP services which are on localhost (USB devices, printer applications and permanent driverless
+queues from CUPS Sharing server if installed as well), in local network or defined by printer profiles,
+if system-config-printer should work with CUPS 3.0.
+
+IS S-C-P REQUIRED IN SYSTEM WITH CUPS 3.0?
+------------------------------------------
+
+Regarding printer setup tools OpenPrinting current plans are to integrate printer setup dialog into
+common print dialog, which would enable non-driverless printer installation (via printer application)
+right when user needs it - right before the printing.
+
+dBUS interface (but probably not the same methods) will be available in CUPS 3.0 project
+and since non-driverless devices are less common with time OpenPrinting group agreed there
+won't be an automatic installation mechanism for them.
+
+So the standalone configuration tool like system-config-printer isn't a priority in system with CUPS 3.0,
+but it can exist together with CUPS 3.0 if updated. The next point is connected to the matter.
+
+NEW DEVELOPER OR CO-MAINTAINER WANTED:
+--------------------------------------
+
+I'm looking for a new developer or co-maintainer for system-config-printer and pycups,
+who would update/help to update them to the current standards.
+
+In case of system-config-printer it consists:
+- migration to GTK 4,
+- migration of dbus code because dbus-python is deprecated,
+- support for installing printer applications from various sources (.rpm, .deb, snap, flatpak),
+- support for managing IPP services instead of permanent CUPS queues.
+- implementation of unit tests and overall updating the python code to current PEPs
+
+The project is kept in maintenance mode (accepting and testing sent patches, limited new development)
+until there is such a person.
 
 Build requirements:
 -------------------
@@ -56,3 +125,10 @@ How to uninstall:
 ```
 $ sudo make uninstall
 ```
+
+Translations:
+-------------
+
+Translations are available at [Fedora Weblate](https://translate.fedoraproject.org).
+If you want to update translations, please update it in Weblate. The Weblate then creates
+automatic PR, which keeps upstream project and Weblate project in synch.