DCOP

DCOP ( D esktop CO mmunication P rotocol ), is a light communication system between the process and the software components of a system. Its principal use is to make it possible different the applications to interact and share complex tasks. DCOP is primarily a system of “remote control”, which can make benefit an application or a script from the assistance of the other applications. It is built with the top of the protocol of interclients exchanges of X.

The use of DCOP provides new possibilities without owe récrire entirely of new software. The applications and libraries of KDE largely use DCOP, and the majority of these applications can be controlled by scripts via DCOP.

In the recent versions of KDE, all the applications provide a minimal support of DCOP, even if the developer explicitly did not code this support in the application. For example, all the applications can receive an instruction quit .

An application in line of named order “dcop” can be used to communicate with the applications since a Shell. “kdcop” is the graphic equivalent which makes it possible to explore the interface of the application.

For example, the office of KDE provides a means of changing the bottom of screen with various intervals. In fact, it directly does not provide an interface to pass at the bottom of following screen if you do not like the precedent, nor to remove those which you do not like.

These functionalities can be added in very little time, by using dcop. The order:

dcop kdesktop KBackgroundIface changeWallpaper

passes to the following office, and this one:

dcop kdesktop KBackgroundIface currentWallpaper 1

recover the name of the bottom of screen on desk 1. (KDE, like the majority of the Environment of office, makes it possible to have virtual offices ). While combining both in a short Shell script, you can pass to the following image and remove the preceding one as follows:

OLDWALLPAPER= `dcop kdesktop KBackgroundIface currentWallpaper 1 ` dcop kdesktop KBackgroundIface changeWallpaper rm " $OLDWALLPAPER"

As you can see it, DCOP very simply makes possible the addition of new functionalities.

The software Kommander allows the graphic creation of application thanks to DCOP

The model of DCOP

The model is simple. Each application using DCOP is a customer; they communicate between them thanks to a waiter DCOP, which functions like a router, sending the messages to the good destination.

Two types of actions are possible: “to call”, which awaits data in return, and “sends and forgets”, which is not blocking.

DB, a system similar to DCOP and standardized by Freedesktop.org, was strongly influenced by this one and will replace it in the future KDE4.

External bonds

  • Presentation of DCOP
  • DCOP - Documentation
  • Tutorial to create an interface DCOP

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