org.diet4j.core

Class ModuleRegistry

java.lang.Object

org.diet4j.core.ModuleRegistry

Direct Known Subclasses:

AbstractModuleRegistry

public abstract class ModuleRegistry
extends Object

A ModuleRegistry is a place where Modules can be found and resolved. Typically, an application instantiates and uses only a single ModuleRegistry.

Field Summary

Fields

Modifier and Type	Field and Description
protected static ModuleRegistry	theSingleton The singleton instance of this class.

Constructor Summary

Constructors

Constructor and Description
ModuleRegistry()

Method Summary

Modifier and Type	Method and Description
abstract void	addModuleRegistryListener(ModuleRegistryListener newListener) Add a ModuleRegistry listener to be notified when new Modules become available etc.
protected abstract ClassLoader	createClassLoader(Module module, ClassLoader parentClassLoader) ModuleRegistries can also acts as a factory for the Modules' ClassLoaders.
abstract ModuleMeta[]	determineResolutionCandidates(ModuleRequirement req) Determine the ModuleMetas that are candidates to resolve a Module dependency, based on the knowledge of this ModuleRegistry.
abstract Module[]	determineRuntimeDependencies(Module theModule) Given a Module, this allows us to determine which other Modules it depends at run-time.
abstract Module[]	determineRuntimeUses(Module theModule) Given a Module, this allows us to determine which other Modules use it at run-time.
abstract ModuleMeta	determineSingleResolutionCandidate(ModuleRequirement req) Convenience method to determine the one and only ModuleMeta that is the only candidate to resolve a Module dependency, based on the knowledge of this ModuleRegistry.
abstract Module	getResolutionOf(ModuleMeta meta) Determine whether a certain ModuleMeta is resolved already, and if so, return it.
static ModuleRegistry	getSingleton() Obtain the singleton instance of this class, or a subclass.
abstract Set<String>	nameSet() Obtain the set of Module names currently contained in the registry.
abstract Set<String>	nameSet(Pattern regex) Obtain the set of Module names currently contained in the registry that match a naming pattern.
abstract void	removeModuleRegistryListener(ModuleRegistryListener oldListener) Remove a ModuleRegistry listener.
abstract Module	resolve(ModuleMeta meta) Recursively resolve this ModuleMeta into a Module.
abstract Module	resolve(ModuleMeta meta, boolean recursive) Resolve this ModuleMeta into a Module.

Methods inherited from class java.lang.Object

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

Field Detail

theSingleton

protected static ModuleRegistry theSingleton

The singleton instance of this class. Must be set by subclasses.

Constructor Detail

ModuleRegistry

public ModuleRegistry()

Method Detail

getSingleton

public static ModuleRegistry getSingleton()

Obtain the singleton instance of this class, or a subclass.

Returns:

the singleton instance, or null if not set

determineResolutionCandidates

public abstract ModuleMeta[] determineResolutionCandidates(ModuleRequirement req)

Determine the ModuleMetas that are candidates to resolve a Module dependency, based on the knowledge of this ModuleRegistry.

Parameters:

req - the ModuleRequirement that we attempt to resolve

Returns:

the ModuleMetas that are candidates for the resolution of the ModuleRequirement, in sequence from best matched to least matched if the ModuleRegistry makes such distinctions

determineSingleResolutionCandidate

public abstract ModuleMeta determineSingleResolutionCandidate(ModuleRequirement req)
                                                       throws NoModuleResolutionCandidateException,
                                                              ModuleResolutionCandidateNotUniqueException

Convenience method to determine the one and only ModuleMeta that is the only candidate to resolve a Module dependency, based on the knowledge of this ModuleRegistry. If there is more or less than one match, thrown an Exception.

Parameters:

req - the ModuleRequirement that we attempt to resolve

Returns:

the ModuleMeta that is the only candidate for the resolution of the ModuleRequirement

Throws:

NoModuleResolutionCandidateException - thrown if no ModuleMeta was found

ModuleResolutionCandidateNotUniqueException - thrown if there were more than one ModuleMeta found

resolve

public abstract Module resolve(ModuleMeta meta)
                        throws ModuleNotFoundException,
                               ModuleResolutionException

Recursively resolve this ModuleMeta into a Module.

Parameters:

meta - the ModuleMeta to resolve

Returns:

the resolved Module.

Throws:

ModuleNotFoundException - thrown if the Module could not be found

ModuleResolutionException - thrown if the Module could not be resolved

resolve

public abstract Module resolve(ModuleMeta meta,
                               boolean recursive)
                        throws ModuleNotFoundException,
                               ModuleResolutionException

Resolve this ModuleMeta into a Module.

Parameters:

meta - the ModuleMeta to resolve

recursive - resolve recursively if set to true

Returns:

the resolved Module.

Throws:

ModuleNotFoundException - thrown if the Module could not be found

ModuleResolutionException - thrown if the Module could not be resolved

getResolutionOf

public abstract Module getResolutionOf(ModuleMeta meta)

Determine whether a certain ModuleMeta is resolved already, and if so, return it. Do not attempt to resolve.

Parameters:

meta - the ModuleMeta whose resolution we check

Returns:

the Module to which the ModuleMeta has been resolved already, or null if not

determineRuntimeDependencies

public abstract Module[] determineRuntimeDependencies(Module theModule)

Given a Module, this allows us to determine which other Modules it depends at run-time. This is similar to the result of determineResolutionCandidates(), except that this returns one resolved Module for each dependency, not a set of ModuleMetas that may or may not be resolvable.

Parameters:

theModule - the Module whose run-time dependencies we want to determine

Returns:

the set of Modules that this Module depends on at run-time

See Also:

determineRuntimeUses(org.diet4j.core.Module)

determineRuntimeUses

public abstract Module[] determineRuntimeUses(Module theModule)

Given a Module, this allows us to determine which other Modules use it at run-time. This is the inverse relationship found by determineRuntimeDependencies. However, unlike determineRuntimeDependencies, the returned values may change dramatically during operation of the system as additional Modules become users.

Parameters:

theModule - the Module whose uses we want to determine at run-time

Returns:

the set of Modules that this Module currently is used by at run-time

See Also:

determineRuntimeDependencies(org.diet4j.core.Module)

createClassLoader

protected abstract ClassLoader createClassLoader(Module module,
                                                 ClassLoader parentClassLoader)

ModuleRegistries can also acts as a factory for the Modules' ClassLoaders.

Parameters:

module - the Module for which to create a ClassLoader

parentClassLoader - the ClassLoader to use as the parent ClassLoader

Returns:

the ClassLoader to use with the Module

nameSet

public abstract Set<String> nameSet()

Obtain the set of Module names currently contained in the registry.

Returns:

the set of Module names

nameSet

public abstract Set<String> nameSet(Pattern regex)

Obtain the set of Module names currently contained in the registry that match a naming pattern.

Parameters:

regex - the regular expression

Returns:

the set of Module names

addModuleRegistryListener

public abstract void addModuleRegistryListener(ModuleRegistryListener newListener)

Add a ModuleRegistry listener to be notified when new Modules become available etc.

Parameters:

newListener - the new listener to add

See Also:

removeModuleRegistryListener(org.diet4j.core.ModuleRegistryListener)

removeModuleRegistryListener

public abstract void removeModuleRegistryListener(ModuleRegistryListener oldListener)

Remove a ModuleRegistry listener.

Parameters:

oldListener - the listener to remove

See Also:

addModuleRegistryListener(org.diet4j.core.ModuleRegistryListener)