Concepts

PICA relies on several important concepts:

PICA Server

Host that stores the source objects known to PICA.

PICA Client

Any host with a way to connect to it (usually SSH).

Objects

Objects are ``entities'' we want installed in our servers. One entity, once installed, can be different depending on the server it is to be installed in. For this purpose, objects are represented with files which can contain special directives, interpreted by the Perl PreProcessor (one of the PICA components). There are two types of entities (also called ``distribution files'', or ``distributed files''): files and alarms.

Files

Regular files to be installed in a given path of the remote machine.

Alarms

Alarms are executable files, to be installed in special directories which PICA takes care of. Alarms are executed from time to time, and they are supposed to produce some output if there is something to notify. Furthermore, alarms can have dependencies, which are files that have to be (re)installed if the alarm depending on them is (re)installed.

Hosts

Your (theoretically remote) machines. You are supposed to have your configuration files in one host, to copy them in a bunch of machines. These machines are the ``hosts''.

Groups

PICA recognized two types of groups: host groups and object groups. Groups are used to organize and easily manage large collections of objects. More on groups later.

Attributes

Attributes are object properties. There are mandatory and optional attributes, depending on the type of object (file or alarm).

Variables

You can use ``variables'' that can be referred to in the preprocessor and the files to be distributed. Sometimes we use the adjective ``local'' to refer to object variables, and ``group'' to refer to those of...you get the idea.

Definitions

They are variables defined as command line arguments (more on that later).

Local directories

Directories needed by PICA to find executables or source objects (directories in the PICA server).

Remote directories

Directories where PICA installs objects (directories in the PICA client).