Package io.helidon.service.configuration.api

Class ServiceConfiguration

java.lang.Object

io.helidon.service.configuration.api.ServiceConfiguration

public abstract class ServiceConfiguration
extends Object

An abstract encapsulation of an automatically discovered configuration for a given service.

For the purposes of configuration, a service is normally represented as a client library that connects to a remote provider of business value. Typically the client library needs to be configured in some way in order to function at all. Instances of this class aim to provide such configuration in as automated a manner as possible.

ServiceConfiguration instances are typically produced by ServiceConfigurationProvider instances. Obtaining a ServiceConfiguration by any other means may result in undefined behavior.

Author:

Laird Nelson

See Also:

getInstance(String), ServiceConfigurationProvider

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	ServiceConfiguration(String serviceIdentifier) Creates a new ServiceConfiguration.

Method Summary

Modifier and Type	Method and Description
static ServiceConfiguration	getInstance(String serviceIdentifier) Returns the sole ServiceConfiguration implementation in effect for the current Systems and identified by the supplied serviceIdentifier, if there is one, or null if there is no such ServiceConfiguration.
static ServiceConfiguration	getInstance(String serviceIdentifier, Properties coordinates) Returns the sole ServiceConfiguration implementation in effect for the current Systems and identified by the supplied serviceIdentifier and suitable for the supplied coordinates, if there is one, or null if there is no such ServiceConfiguration.
String	getProperty(String propertyName) Returns a value for the property described by the supplied propertyName, or null if no such property value exists.
abstract String	getProperty(String propertyName, String defaultValue) Returns a value for the property described by the supplied propertyName, or the value of the supplied defaultValue parameter if no such property value exists.
abstract Set<String>	getPropertyNames() Returns an unmodifiable and unchanging Set of Strings representing the names of properties whose values may be retrieved with the getProperty(String) method.
String	getServiceIdentifier() Returns the identifier of the service this ServiceConfiguration implementation provides configuration for.

Methods inherited from class java.lang.Object

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

Constructor Detail

ServiceConfiguration

protected ServiceConfiguration(String serviceIdentifier)

Creates a new ServiceConfiguration.

Parameters:

serviceIdentifier - the identifier of the service this ServiceConfiguration implementation will provide configuration for; must not be null

Throws:

NullPointerException - if serviceIdentifier is null

See Also:

getServiceIdentifier()

Method Detail

getServiceIdentifier

public final String getServiceIdentifier()

Returns the identifier of the service this ServiceConfiguration implementation provides configuration for.

This method never returns null.

Returns:

the identifier of the service this ServiceConfiguration implementation provides configuration for; never null

See Also:

ServiceConfiguration(String)

getPropertyNames

public abstract Set<String> getPropertyNames()

Returns an unmodifiable and unchanging Set of Strings representing the names of properties whose values may be retrieved with the getProperty(String) method.

Implementations of this method must not return null.

Implementations of this method must ensure that the Set returned may be used without the end user having to peform explicit synchronization.

Implementations of this method may return the same Set instance with each invocation, or different Set instances with different contents.

Returns:

an unmodifiable and unchanging Set of Strings representing the names of properties whose values may be retrieved with the getProperty(String) method

getProperty

public final String getProperty(String propertyName)

Returns a value for the property described by the supplied propertyName, or null if no such property value exists.

This method may return null.

Parameters:

propertyName - the name of the property whose value should be returned; must not be null

Returns:

a value for the property described by the supplied propertyName, or null

See Also:

getProperty(String, String)

getProperty

public abstract String getProperty(String propertyName,
                                   String defaultValue)

Returns a value for the property described by the supplied propertyName, or the value of the supplied defaultValue parameter if no such property value exists.

Implementations of this method may return null if defaultValue is null.

Implementations of this method may return the same or different values for each invocation with the same parameters.

Parameters:

propertyName - the name of the property whose value should be returned; may be null in which case the value of the supplied defaultValue parameter will be returned instead

defaultValue - the value to return if a value for the named property could not be found; may be null

Returns:

a value for the property described by the supplied propertyName, or the value of the supplied defaultValue parameter

getInstance

public static final ServiceConfiguration getInstance(String serviceIdentifier)

Returns the sole ServiceConfiguration implementation in effect for the current Systems and identified by the supplied serviceIdentifier, if there is one, or null if there is no such ServiceConfiguration.

Parameters:

serviceIdentifier - the service identifier for which a ServiceConfiguration should be sought; must not be null

Returns:

the sole ServiceConfiguration implementation in effect for the current Systems and identified by the supplied serviceIdentifier, if there is one, or null

Throws:

NullPointerException - if serviceIdentifier is null

ServiceConfigurationError - if there was a problem loading Java services

See Also:

getInstance(String, Properties)

getInstance

public static final ServiceConfiguration getInstance(String serviceIdentifier,
                                                     Properties coordinates)

Returns the sole ServiceConfiguration implementation in effect for the current Systems and identified by the supplied serviceIdentifier and suitable for the supplied coordinates, if there is one, or null if there is no such ServiceConfiguration.

This method may—and often does—return null.

While the current implementation of this method performs no caching other than that performed as a side effect by ServiceLoader method invocations, caching is deliberately not a component of the specification of this method's behavior.

Parameters:

serviceIdentifier - the service identifier for which a ServiceConfiguration should be sought; must not be null

coordinates - a Properties object containing coordinates that might assist a ServiceConfiguration implementation in implementing its getPropertyNames() and getProperty(String) methods; may be null

Returns:

the sole ServiceConfiguration implementation in effect for the current Systems and identified by the supplied serviceIdentifier, if there is one, or null

Throws:

NullPointerException - if serviceIdentifier is null

ServiceConfigurationError - if there was a problem loading Java services