before they're passed to your functions. These Java classes reside in the
I<org.collectd.api> namespace.
+The I<Java> plugin will create one object of each class configured with the
+B<LoadPlugin> option. The constructor of this class can then register "callback
+methods", i.E<nbsp>e. methods that will be called by the daemon when
+appropriate.
+
The available classes are:
=over 4
+=item B<org.collectd.api.Collectd>
+
+All API functions exported to Java are implemented as static functions of this
+class. See L<"EXPORTED API FUNCTIONS"> below.
+
=item B<org.collectd.api.OConfigValue>
Corresponds to C<oconfig_value_t>, defined in F<src/liboconfig/oconfig.h>.
Corresponds to C<value_list_t>, defined in F<src/plugin.h>.
+=item B<org.collectd.api.Notification>
+
+Corresponds to C<notification_t>, defined in F<src/plugin.h>.
+
=back
In the remainder of this document, we'll use the short form of these names, for
example B<ValueList>. In order to be able to use these abbreviated names, you
need to B<import> the classes.
-The API functions that are available from Java are implemented as I<static>
-functions of the B<org.collectd.api.Collectd> class.
-See L<"CALLING API FUNCTIONS"> below for details.
+=head1 EXPORTED API FUNCTIONS
+
+All collectd API functions that are available to Java plugins are implemented
+as I<publicE<nbsp>static> functions of the B<Collectd> class. This makes
+calling these functions pretty straight forward. For example, to send an error
+message to the daemon, you'd do something like this:
+
+ Collectd.logError ("That wasn't chicken!");
+
+The following are the currently exported functions.
+
+=head2 registerConfig
+
+Signature: I<int> B<registerConfig> (I<String> name,
+I<CollectdConfigInterface> object);
+
+Registers the B<config> function of I<object> with the daemon.
+
+Returns zero upon success and non-zero when an error occurred.
+
+See L<"config callback"> below.
+
+=head2 registerInit
+
+Signature: I<int> B<registerInit> (I<String> name,
+I<CollectdInitInterface> object);
+
+Registers the B<init> function of I<object> with the daemon.
+
+Returns zero upon success and non-zero when an error occurred.
+
+See L<"init callback"> below.
+
+=head2 registerRead
+
+Signature: I<int> B<registerRead> (I<String> name,
+I<CollectdReadInterface> object)
+
+Registers the B<read> function of I<object> with the daemon.
+
+Returns zero upon success and non-zero when an error occurred.
+
+See L<"read callback"> below.
+
+=head2 registerWrite
+
+Signature: I<int> B<registerWrite> (I<String> name,
+I<CollectdWriteInterface> object)
+
+Registers the B<write> function of I<object> with the daemon.
+
+Returns zero upon success and non-zero when an error occurred.
+
+See L<"write callback"> below.
+
+=head2 registerFlush
+
+Signature: I<int> B<registerFlush> (I<String> name,
+I<CollectdFlushInterface> object)
+
+Registers the B<flush> function of I<object> with the daemon.
+
+Returns zero upon success and non-zero when an error occurred.
+
+See L<"flush callback"> below.
+
+=head2 registerShutdown
+
+Signature: I<int> B<registerShutdown> (I<String> name,
+I<CollectdShutdownInterface> object);
+
+Registers the B<shutdown> function of I<object> with the daemon.
+
+Returns zero upon success and non-zero when an error occurred.
+
+See L<"shutdown callback"> below.
+
+=head2 registerLog
+
+Signature: I<int> B<registerLog> (I<String> name,
+I<CollectdLogInterface> object);
+
+Registers the B<log> function of I<object> with the daemon.
+
+Returns zero upon success and non-zero when an error occurred.
+
+See L<"log callback"> below.
+
+=head2 registerNotification
+
+Signature: I<int> B<registerNotification> (I<String> name,
+I<CollectdNotificationInterface> object);
+
+Registers the B<notification> function of I<object> with the daemon.
+
+Returns zero upon success and non-zero when an error occurred.
+
+See L<"notification callback"> below.
+
+=head2 registerMatch
+
+Signature: I<int> B<registerMatch> (I<String> name,
+I<CollectdMatchFactoryInterface> object);
+
+Registers the B<createMatch> function of I<object> with the daemon.
+
+Returns zero upon success and non-zero when an error occurred.
+
+See L<"match callback"> below.
+
+=head2 registerTarget
+
+Signature: I<int> B<registerTarget> (I<String> name,
+I<CollectdTargetFactoryInterface> object);
+
+Registers the B<createTarget> function of I<object> with the daemon.
+
+Returns zero upon success and non-zero when an error occurred.
+
+See L<"target callback"> below.
+
+=head2 dispatchValues
+
+Signature: I<int> B<dispatchValues> (I<ValueList>)
+
+Passes the values represented by the B<ValueList> object to the
+C<plugin_dispatch_values> function of the daemon. The "data set" (or list of
+"data sources") associated with the object are ignored, because
+C<plugin_dispatch_values> will automatically lookup the required data set. It
+is therefore absolutely okay to leave this blank.
+
+Returns zero upon success or non-zero upon failure.
+
+=head2 getDS
+
+Signature: I<DataSet> B<getDS> (I<String>)
+
+Returns the appropriate I<type> or B<null> if the type is not defined.
+
+=head2 logError
+
+Signature: I<void> B<logError> (I<String>)
+
+Sends a log message with severity B<ERROR> to the daemon.
+
+=head2 logWarning
+
+Signature: I<void> B<logWarning> (I<String>)
+
+Sends a log message with severity B<WARNING> to the daemon.
+
+=head2 logNotice
+
+Signature: I<void> B<logNotice> (I<String>)
+
+Sends a log message with severity B<NOTICE> to the daemon.
+
+=head2 logInfo
+
+Signature: I<void> B<logInfo> (I<String>)
+
+Sends a log message with severity B<INFO> to the daemon.
+
+=head2 logDebug
+
+Signature: I<void> B<logDebug> (I<String>)
+
+Sends a log message with severity B<DEBUG> to the daemon.
=head1 REGISTERING CALLBACKS
When starting up, collectd creates an object of each configured class. The
constructor of this class should then register "callbacks" with the daemon,
using the appropriate static functions in B<Collectd>,
-see L<"CALLING API FUNCTIONS"> below. To register a callback, the object being
+see L<"EXPORTED API FUNCTIONS"> above. To register a callback, the object being
passed to one of the register functions must implement an appropriate
interface, which are all in the B<org.collectd.api> namespace.
Interface: B<org.collectd.api.CollectdConfigInterface>
-Signature: I<int> B<config> (I<OConfigItem>)
+Signature: I<int> B<config> (I<OConfigItem> ci)
This method is passed a B<OConfigItem> object, if both, method and
configuration, are available. B<OConfigItem> is the root of a tree representing
To signal success, this method has to return zero. Anything else will be
considered an error condition and the plugin will be disabled entirely.
+See L<"registerConfig"> above.
+
=head2 init callback
Interface: B<org.collectd.api.CollectdInitInterface>
To signal success, this method has to return zero. Anything else will be
considered an error condition and the plugin will be disabled entirely.
+See L<"registerInit"> above.
+
=head2 read callback
Interface: B<org.collectd.api.CollectdReadInterface>
This method is called periodically and is supposed to gather statistics in
whatever fashion. These statistics are represented as a B<ValueList> object and
-sent to the daemon using B<dispatchValues>, see L<"CALLING API FUNCTIONS">
-below.
+sent to the daemon using L<dispatchValues|"dispatchValues">.
To signal success, this method has to return zero. Anything else will be
considered an error condition and cause an appropriate message to be logged.
Java "read"-methods are not suspended for increasing intervals like C
"read"-functions.
+See L<"registerRead"> above.
+
=head2 write callback
Interface: B<org.collectd.api.CollectdWriteInterface>
-Signature: I<int> B<write> (I<ValueList>)
+Signature: I<int> B<write> (I<ValueList> vl)
This method is called whenever a value is dispatched to the daemon. The
corresponding C "write"-functions are passed a C<data_set_t>, so they can
To signal success, this method has to return zero. Anything else will be
considered an error condition and cause an appropriate message to be logged.
+See L<"registerWrite"> above.
+
+=head2 flush callback
+
+Interface: B<org.collectd.api.CollectdFlushInterface>
+
+Signature: I<int> B<flush> (I<int> timeout, I<String> identifier)
+
+This method is called when the daemon received a flush command. This can either
+be done using the C<USR1> signal (see L<collectd(1)>) or using the I<unixsock>
+plugin (see L<collectd-unixsock(5)>).
+
+If I<timeout> is greater than zero, only values older than this number of
+seconds should be flushed. To signal that all values should be flushed
+regardless of age, this argument is set to a negative number.
+
+The I<identifier> specifies which value should be flushed. If it is not
+possible to flush one specific value, flush all values. To signal that all
+values should be flushed, this argument is set to I<null>.
+
+To signal success, this method has to return zero. Anything else will be
+considered an error condition and cause an appropriate message to be logged.
+
+See L<"registerFlush"> above.
+
=head2 shutdown callback
Interface: B<org.collectd.api.CollectdShutdownInterface>
To signal success, this method has to return zero. Anything else will be
considered an error condition and cause an appropriate message to be logged.
-=head2 Example
+See L<"registerShutdown"> above.
-This short example demonstrates how to register a read callback with the
-daemon:
+=head2 log callback
- import org.collectd.api.Collectd;
- import org.collectd.api.ValueList;
-
- import org.collectd.api.CollectdReadInterface;
-
- public class Foobar implements CollectdReadInterface
- {
- public Foobar ()
- {
- Collectd.registerRead ("Foobar", this);
- }
-
- public int read ()
- {
- ValueList vl;
-
- /* Do something... */
-
- Collectd.dispatchValues (vl);
- }
- }
+Interface: B<org.collectd.api.CollectdLogInterface>
-=head1 CALLING API FUNCTIONS
+Signature: I<void> B<log> (I<int> severity, I<String> message)
-All collectd API functions that are available to Java plugins are implemented
-as I<publicE<nbsp>static> functions of the B<org.collectd.api.Collectd> class.
-This makes calling these functions pretty straight forward.
+This callback can be used to receive log messages from the daemon.
-The following are the currently exported functions. For information on the
-interfaces used, please see L<"REGISTERING CALLBACKS"> above.
+The argument I<severity> is one of:
-=head2 registerConfig
+=over 4
-Signature: I<int> B<registerConfig> (I<String> name,
-I<CollectdConfigInterface> object);
+=item *
-Registers the B<config> function of I<object> with the daemon.
+org.collectd.api.Collectd.LOG_ERR
-Returns zero upon success and non-zero when an error occurred.
+=item *
-=head2 registerInit
+org.collectd.api.Collectd.LOG_WARNING
-Signature: I<int> B<registerInit> (I<String> name,
-I<CollectdInitInterface> object);
+=item *
-Registers the B<init> function of I<object> with the daemon.
+org.collectd.api.Collectd.LOG_NOTICE
-Returns zero upon success and non-zero when an error occurred.
+=item *
-=head2 registerRead
+org.collectd.api.Collectd.LOG_INFO
-Signature: I<int> B<registerRead> (I<String> name,
-I<CollectdReadInterface> object)
+=item *
-Registers the B<read> function of I<object> with the daemon.
+org.collectd.api.Collectd.LOG_DEBUG
-Returns zero upon success and non-zero when an error occurred.
+=back
-=head2 registerWrite
+The function does not return any value.
-Signature: I<int> B<registerWrite> (I<String> name,
-I<CollectdWriteInterface> object)
+See L<"registerLog"> above.
-Registers the B<write> function of I<object> with the daemon.
+=head2 notification callback
-Returns zero upon success and non-zero when an error occurred.
+Interface: B<org.collectd.api.CollectdNotificationInterface>
-=head2 registerShutdown
+Signature: I<int> B<notification> (I<Notification> n)
-Signature: I<int> B<registerShutdown> (I<String> name,
-I<CollectdShutdownInterface> object);
+This callback can be used to receive notifications from the daemon.
-Registers the B<shutdown> function of I<object> with the daemon.
+To signal success, this method has to return zero. Anything else will be
+considered an error condition and cause an appropriate message to be logged.
-Returns zero upon success and non-zero when an error occurred.
+See L<"registerNotification"> above.
-=head2 dispatchValues
+=head2 match callback
-Signature: I<int> B<dispatchValues> (I<ValueList>)
+The match (and target, see L<"target callback"> below) callbacks work a bit
+different from the other callbacks above: You don't register a match callback
+with the daemon directly, but you register a function which, when called,
+creates an appropriate object. The object creating the "match" objects is
+called "match factory".
-Passes the values represented by the B<ValueList> object to the
-C<plugin_dispatch_values> function of the daemon. The "data set" (or list of
-"data sources") associated with the object are ignored, because
-C<plugin_dispatch_values> will automatically lookup the required data set. It
-is therefore absolutely okay to leave this blank.
+See L<"registerMatch"> above.
-Returns zero upon success or non-zero upon failure.
+=head3 Factory object
-=head2 getDS
+Interface: B<org.collectd.api.CollectdMatchFactoryInterface>
-Signature: I<DataSet> B<getDS> (I<String>)
+Signature: I<CollectdMatchInterface> B<createMatch>
+(I<OConfigItem> ci);
-Returns the approrpate I<type> or B<null> if the type is not defined.
+Called by the daemon to create "match" objects.
-=head2 logError
+Returns: A new object which implements the B<CollectdMatchInterface> interface.
-Signature: I<void> B<logError> (I<String>)
+=head3 Match object
-Sends a log message with severity B<ERROR> to the daemon.
+Interface: B<org.collectd.api.CollectdMatchInterface>
-=head2 logWarning
+Signature: I<int> B<match> (I<DataSet> ds, I<ValueList> vl);
-Signature: I<void> B<logWarning> (I<String>)
+Called when processing a chain to determine whether or not a I<ValueList>
+matches. How values are matches is up to the implementing class.
-Sends a log message with severity B<WARNING> to the daemon.
+Has to return one of:
-=head2 logNotice
+=over 4
-Signature: I<void> B<logNotice> (I<String>)
+=item *
-Sends a log message with severity B<NOTICE> to the daemon.
+B<Collectd.FC_MATCH_NO_MATCH>
-=head2 logInfo
+=item *
-Signature: I<void> B<logInfo> (I<String>)
+B<Collectd.FC_MATCH_MATCHES>
-Sends a log message with severity B<INFO> to the daemon.
+=back
-=head2 logDebug
+=head2 target callback
-Signature: I<void> B<logDebug> (I<String>)
+The target (and match, see L<"match callback"> above) callbacks work a bit
+different from the other callbacks above: You don't register a target callback
+with the daemon directly, but you register a function which, when called,
+creates an appropriate object. The object creating the "target" objects is
+called "target factory".
-Sends a log message with severity B<DEBUG> to the daemon.
+See L<"registerTarget"> above.
+
+=head3 Factory object
+
+Interface: B<org.collectd.api.CollectdTargetFactoryInterface>
+
+Signature: I<CollectdTargetInterface> B<createTarget>
+(I<OConfigItem> ci);
+
+Called by the daemon to create "target" objects.
+
+Returns: A new object which implements the B<CollectdTargetInterface>
+interface.
+
+=head3 Target object
+
+Interface: B<org.collectd.api.CollectdTargetInterface>
+
+Signature: I<int> B<invoke> (I<DataSet> ds, I<ValueList> vl);
+
+Called when processing a chain to perform some action. The action performed is
+up to the implementing class.
+
+Has to return one of:
+
+=over 4
+
+=item *
+
+B<Collectd.FC_TARGET_CONTINUE>
+
+=item *
+
+B<Collectd.FC_TARGET_STOP>
+
+=item *
+
+B<Collectd.FC_TARGET_RETURN>
+
+=back
+
+=head1 EXAMPLE
+
+This short example demonstrates how to register a read callback with the
+daemon:
+
+ import org.collectd.api.Collectd;
+ import org.collectd.api.ValueList;
+
+ import org.collectd.api.CollectdReadInterface;
+
+ public class Foobar implements CollectdReadInterface
+ {
+ public Foobar ()
+ {
+ Collectd.registerRead ("Foobar", this);
+ }
+
+ public int read ()
+ {
+ ValueList vl;
+
+ /* Do something... */
+
+ Collectd.dispatchValues (vl);
+ }
+ }
=head1 SEE ALSO
projects / collectd.git / blobdiff