9.4 Installation and Usage of Basic Plugins 341
plugin provides a textual user interface (console) to administrate a run-
ning agency. The AgentLauncher plugin starts agents while launching the
If you store the AgencyShell plugin in the plugins directory, you can commu-
nicate with a running agency using a textual user interface (sometimes also
called a shell or console).
Using the textual user interface of Tracy, you can administrate the whole
agency, including starting and stopping agents, listing all agents currently
residing on this agency, and so forth. You can also start and stop plugins and
administrate them if they provide their own commands for the shell.
When the AgencyShell plugin is star ted, it uses the Java authentica-
tion and authorization system to log in users (i.e., ﬁle jaas.login is read to
select the login module which deﬁnes how users have to authenticate). The
login module that was mentioned previously identiﬁes the user as the one
who is actually starting Tracy. Other login modules, especially the one that
comes with the Taas plugin requires the user to authenticate with a user
name and a password, which are veriﬁed against a Tracy user management
After the user has logged in, AgencyShell provides a simple textual user
interface comparable to a Unix shell or a DOS command prompt. In gen-
eral, the console provides two focus points. The ﬁrst is that of the agency,
which is actually the one that you enter after logging in. In this focus you
can only administrate the agency. The second focus is that of a plugin. To
change focus from the agency to one of the plugins, you must enter com-
mand cf (change focus), which will be explained below. The following set of
commands can be used in the agency focus as well as in a plugin focus.
author [--help] Prints the author of a component according to the
docs [--help] Prints a URL where documentation can be found for this
component according to the current focus.
exit [--help] Exits the shell without closing the agency. Note that this
command can only be used at the agency focus.