The {@link net.jini.config.ConfigurationException} class is the superclass of all exceptions thrown if a problem occurs when obtaining configuration information. {@link net.jini.config.NoSuchEntryException} is the subclass thrown for a missing configuration entry. {@link net.jini.config.ConfigurationNotFoundException} is the subclass thrown for missing configuration source locations and if default options are requested but not available.

The {@link net.jini.config.ConfigurationFile} class is the standard default configuration provider, which reads text written in a subset of the expression syntax in the Java(TM) programming language from files and URLs to produce configuration objects.

The {@link net.jini.config.AbstractConfiguration} class is a skeletal implementation of the Configuration interface, used to simplify writing implementations.

The {@link net.jini.config.EmptyConfiguration} class implements a Configuration with no entries. Applications can use an instance of this class to simplify handling cases where no configuration is specified rather than, for example, checking for a null configuration.

The net.jini.config.GroovyConfig class is a new configuration provider, it uses Groovy configuration objects, this is potentially the most powerful configuration mechanism.

Using Configuration

The names that applications and subsystems use for configuration entries should be chosen carefully to avoid conflicts. One possible approach is to use fully qualified class names as the component for configurable applications and utilities, and to use fully qualified package names as the component for services. For each entry, the decision should be made whether to supply a default or to throw NoSuchEntryException if there is no matching entry. Components should document which configuration entries they use, as well as the expected type and default, if any, for each entry.

Example

    import java.rmi.*;
    import net.jini.config.*;
    import net.jini.export.*;
    public class Example implements Remote {
        public static void main(String[] args) throws Exception {
            Configuration config = ConfigurationProvider.getInstance(args);
            Exporter exporter = (Exporter) config.getEntry(
                "Example", "exporter", Exporter.class);
            Remote proxy = exporter.export(new Example());
            System.out.println(proxy);
            exporter.unexport(true);
        }
    }

Here are the contents of a ConfigurationFile source file to export the object using an JRMP exporter:

    import net.jini.jrmp.*;
    Example {
        exporter = new JrmpExporter();
    }

Here are the contents of another ConfigurationFile to export the object using a Jini extensible remote invocation (Jini ERI) exporter over HTTP on a specific port:

    import net.jini.jeri.*;
    import net.jini.jeri.http.*;
    Example {
        exporter = new BasicJeriExporter(HttpServerEndpoint.getInstance(12000));
    }

This application can be configured to export the object in either of these ways (or more with other configuration files) by passing an argument that specifies the location of one of the configuration files:

    java Example jrmp.config

    java Example jeri.config

Loggers and Logging Levels

This implementation of the ConfigurationProvider, AbstractConfiguration, ConfigurationFile, and EmptyConfiguration classes uses the {@link java.util.logging.Logger} named net.jini.config to log information at the following logging levels:

net.jini.config

Level	Description
{@link java.util.logging.Level#INFO INFO}	problems adding new prohibited methods for ConfigurationFile
{@link com.sun.jini.logging.Levels#FAILED FAILED}	problems getting a configuration using ConfigurationProvider, or problems getting entries, including getting entries that are not found, from the configuration implementation classes
{@link java.util.logging.Level#FINE FINE}	returning default values from the configuration implementation classes
{@link java.util.logging.Level#FINER FINER}	getting existing entries from the configuration implementation classes, creating a ConfigurationFile, or adding new prohibited methods for ConfigurationFile

See the {@link com.sun.jini.logging.LogManager} class for one way to use the FAILED logging level in standard logging configuration files.