[Geronimo Wiki] Update of "DerbySystem GBean" by JohnSisson

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The following page has been changed by JohnSisson:
http://wiki.apache.org/geronimo/DerbySystem_GBean

The comment on the change is:
DerbySystem GBean documentation - any comments on the layout before I do more?

New page:
'''Contents'''
[[TableOfContents]]

= Overview =
The `DerbySystem` GBean instantiates a single instance of the Derby database engine and the environment in which it runs.  In Derby terminology this is known as a "Derby System".  Refer to the [http://incubator.apache.org/derby/manuals/index.html Derby Developer's Guide] for detailed information on a Derby System.

= GBean Attributes =

== derbySystemHome ==
The `derbySystemHome` attribute of the `DerbySystem` GBean sets the `derby.system.home` environment variable that specifies Derby's system directory.[[BR]][[BR]]
In the default configuration, the `derbySystemHome` attribute of the DerbySystem GBean is set to `var/derby` that is relative to the `geronimo` directory.[[BR]][[BR]]
When Derby is initialised, it looks in its system directory for an optional `derby.properties` configuration file, and also attempts to find existing databases (each in a subdirectory of the system directory) that are in its system.  Derby also creates new databases as subdirectories of the system directory.  If you specify a directory in the `derbySystemHome` attribute at startup that does not exist, Derby will create the directory.
[[BR]][[BR]]
Note that if you change the value of the `DerbySystem` GBean's `derbySystemHome` attribute whilst Derby is running, the change does not take effect until the DerbySystem GBean is restarted.

= Derby log files =
A derby.log file will be created in the Derby system directory.  The amount of information logged to this file can be controlled via the derby.properties file (read below).

= Further configuration of Derby =
A `derby.properties file` can optionally be placed in the Derby system directory to further control the operation of the Derby System.  Refer to the [http://incubator.apache.org/derby/manuals/index.html Tuning Derby manual] for further information on the Derby properties.[[BR]][[BR]]

The following is a sample `derby.properties` file:
{{{
#
#Security settings (read Derby documentation before playing with this)
#
#derby.connection.requireAuthentication=true
#derby.authentication.provider=BUILTIN

# User and pswd list for BUILTIN authentication provider 
#
#derby.user.john=johnspassword
#derby.user.system=manager

###############################
# Derby Logging Properties
###############################

# append to derby.log when server is booted
derby.infolog.append=false

# log connections and disconnections
derby.drda.logConnections=true

###############################
# Problem Diagnosis Properties
###############################

# write a detailed list of locks when a transaction times out
derby.locks.deadlockTrace=true

# Report all errors to the derby.log file.
derby.stream.error.logSeverityLevel=0

# Log SQL statements to aid problem diagnosis
derby.language.logStatementText=true

# Network Server Tracing
#derby.drda.traceAll=true
}}}