Nirvana Scheduling : Tasks

Tasks are executed by either time based (calendar) or conditional triggers. There are a number of tasks that can be executed by the Nirvana Scheduling engine. Each task corresponds to a unit of work that performs an operation on the desired object within a Nirvana realm.

This section will discuss the available tasks that can be declared within a Nirvana scheduling script :

• Task Expressions
• Store Tasks
• Interface Tasks
• Memory Tasks
• Counter Tasks
• Timer Tasks
• Config Tasks

To view examples of scheduling scripts, please click here.

Task Expressions

Task expressions are comprised of the object on which you wish to perform the operation, and the required parameters. For more information on the grammar for task expressions, please see the writing scripts help file. The following sections will describe the task objects and the parameters required to perform them. The example below demonstrates both Interface, Logger and Counter tasks.

scheduler realmInterfaceSchedule {

declare Interface myNHP ("nhp0");
declare Counter myCounter("myExhaustedThreads");

when (myNHP.idleThreads == 0) {

Logger.report("NHP0 Interface has no idles Threads");
myCounter.inc();

}

when (myCounter >= 5) {

Logger.report("Increasing the accept thread count on NHP0");
myNHP.threads("+10");
myCounter.reset();

}

}

Store Tasks - Channel / Queue operations

Store tasks can be used by first of all declaring the desired object as in the following syntax:

declare Store myChannel("/customer/sales");

The table below lists those tasks available on a Store object, such that the task expression will look like :

when (myChannel.numOfEvents < 100) {

myChannel.maintain();

}

Interface Tasks - Nirvana Interface operations

Interface tasks are operations that can be performed on all interfaces or individually declared interfaces. To declare an interface use the following syntax as an example:

declare Interface myNHP("nhp0");

The table below lists those tasks that can be executed on an Interface object, such that the task expression will look like :

when (myNHP.connections > 1000) {

myNHP.threads("+10");

}

MemoryManager Triggers - Nirvana JVM Memory Management operations

MemoryManager triggers are declared using the following syntax as an example:

declare MemoryManager mem;

The table below lists those triggers that can be evaluated on the memory management object, such that the task expression will look like :

when (mem.freeMemory < 1000000) {

}

Counter Tasks - Counter tasks

Counter tasks allow you to increment, decrement, set and reset a local counter within the Nirvana scheduling engine. Counter tasks are declared using the following syntax as an example:

declare Counter counter1 ("myCounter");

The counter task can be executing by referencing the Counter object itself, and calling one of a number of available tasks. The basic counter task expression will look like :

when ( counter1 > 5) {

counter1.reset();

}

The table below shows the tasks that can be executed on the Counter task.

Timer Tasks - Timer operations

Timer tasks allow you to start, stop and reset the timer. Time tasks are declared using the following syntax as an example:

declare Timer reportTimer ("myTimer");

The timer task can be executed by referencing the timer object itself, such that the task expression will look like :

when ( reportTimer == 60 ) {

reportTimer.reset();

}

The table below shows the tasks that can be executed on the Counter task.

Config Tasks - Channel / Queue based triggers

Config tasks can be used to set any configuration value available in the Config panel for a realm. Any configuration value can be used as part of a trigger task expression. Config tasks are declared using the following syntax as an example (below example refers to the 'GlobalValues' configuration group:

declare Config myGlobal ("GlobalValues");
declare Config myAudit ("AuditSettings");
declare Config myClientTimeout ("ClientTimeoutValues");
declare Config myCluster ("ClusterConfig");
declare Config myEventStorage ("EventStorage");
declare Config myFanout ("FanoutValues");
declare Config myJVM ("JVMManagement");
declare Config myJoinConfig ("JoinConfig");
declare Config myRecovery ("RecoveryDaemon");
declare Config myTXMgr ("TransactionManager");

The table below lists those tasks that can be evaluated on a config object, such that the task expression will look like :

when (myGlobal.MaxNoOfConnections == -1) {

myGlobal.MaxNoOfConnections(1000);

}