org.apache.jena.system

Class JenaSystem

java.lang.Object

org.apache.jena.system.JenaSystem

public class JenaSystem
extends Object

Jena "system" - simple controls for ensuring components are loaded and initialized.

All initialization should be concurrent and thread-safe. In particular, some subsystems need initialization some sort of order (e.g. ARQ before TDB).

This is achieved by "levels": levels less than 100 are considered "jena system levels" and are reserved.

• 0 - reserved
• 10 - jena-core
• 20 - RIOT
• 30 - ARQ
• 40 - TDB
• 9999 - other

See also the notes on Jena initialization.

Field Summary

Fields

Modifier and Type	Field and Description
static boolean	DEBUG_INIT Development support - flag to enable output during initialization.

Constructor Summary

Constructors

Constructor and Description
JenaSystem()

Method Summary

Modifier and Type	Method and Description
static void	forEach(java.util.function.Consumer<JenaSubsystemLifecycle> action) Call an action on each item in the registry.
static void	forEachReverse(java.util.function.Consumer<JenaSubsystemLifecycle> action) Call an action on each item in the registry but in the reverse enumeration order.
static JenaSubsystemRegistry	get() The current JenaSubsystemRegistry
static void	init() Initialize Jena.
static void	setSubsystemRegistry(JenaSubsystemRegistry thing) Set the JenaSubsystemRegistry.
static void	shutdown() Shutdown subsystems

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

DEBUG_INIT

public static boolean DEBUG_INIT

Development support - flag to enable output during initialization. Output to System.err, not a logger to avoid the risk of recursive initialization.

Constructor Detail

JenaSystem

public JenaSystem()

Method Detail

init

public static void init()

Initialize Jena.

This function is cheap to call when already initialized so can be called to be sure. A commonly used idom in jena is in static initailizers in key classes.

By default, initialization happens by using ServiceLoader.load to find JenaSubsystemLifecycle objects. See setSubsystemRegistry(org.apache.jena.system.JenaSubsystemRegistry) to intercept that choice.

shutdown

public static void shutdown()

Shutdown subsystems

setSubsystemRegistry

public static void setSubsystemRegistry(JenaSubsystemRegistry thing)

Set the JenaSubsystemRegistry. To have any effect, this function must be called before any other Jena code, and especially before calling JenaSystem.init().

get

public static JenaSubsystemRegistry get()

The current JenaSubsystemRegistry

forEach

public static void forEach(java.util.function.Consumer<JenaSubsystemLifecycle> action)

Call an action on each item in the registry. Calls are made sequentially and in increasing level order. The exact order within a level is not specified; it is not registration order.

Parameters:

action -

forEachReverse

public static void forEachReverse(java.util.function.Consumer<JenaSubsystemLifecycle> action)

Call an action on each item in the registry but in the reverse enumeration order. Calls are made sequentially and in decreasing level order. The "reverse" is opposite order to forEach(java.util.function.Consumer<org.apache.jena.system.JenaSubsystemLifecycle>), which may not be stable within a level. It is not related to registration order.

Parameters:

action -