ebardes / easyjndi

EasyJNDI

The purpose of this project is to create a JNDI framework that uses easy to edit XML files.

Environment

• Java 7 or higher.
• Apache Common DBCP. Optional if you don't use the DSAdapter.

JNDI uses two system properties to define the JNDI framework and where to locate resources. Normally there's a property file called jndi.properties included in the JAR file which automatically set Context.INITIAL_CONTEXT_FACTORY and Context.PROVIDER_URL to com.digi_dmx.XMLContextFactory and %{user.home}/jndi respectively. In some rare cases, where there are multiple JNDI providers it may be necessary to set it manually by

System.setProperty(Context.INITIAL_CONTEXT_FACTORY, "com.digi_dmx.XMLContextFactory");

How To Use

The first requirement is that anything stored must implement the interface javax.naming.Referenceable. Many JDBC DataSources already implement it. Since each JDBC implementation is unique and isn't always clear what fields are required. I find it best to run a small program like this to generate the first file.

import java.util.Hashtable;

import javax.naming.Context;
import javax.naming.InitialContext;
import javax.naming.NamingException;

import org.postgresql.ds.PGSimpleDataSource;

public class DSSetup
{
	public static void main(String[] args) throws NamingException
	{
		PGSimpleDataSource dataSource = new PGSimpleDataSource();
		dataSource.setServerName("postgres.example.com");
		dataSource.setDatabaseName("database");
		dataSource.setUser("user");
		dataSource.setPassword("*****");
		/*
		 * Any additional parameters and tuning
		 */
		dataSource.setConnectTimeout(5);
		// dataSource.setProperty(name, value);
		
		/*
		 * Create a context overriding JNDI defaults
		 */
		Hashtable<String, Object> env = new Hashtable<>();
		env.put(Context.INITIAL_CONTEXT_FACTORY, "com.digi_dmx.XMLContextFactory");
		env.put(Context.PROVIDER_URL, "/settings");
		Context c = new InitialContext(env);
		
		/*
		 * This will create a file called /settings/jdbc/postgres.xml 
		 */
		c.bind("jdbc/postgres", dataSource);
	}
}

This is the file it creates.

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<context class="org.postgresql.ds.PGSimpleDataSource" factory="org.postgresql.ds.common.PGObjectFactory">
    <attr name="serverName" value="postgres.example.com"/>
    <attr name="databaseName" value="database"/>
    <attr name="user" value="user"/>
    <attr name="password" value="*****"/>
    <attr name="connectTimeout" value="5"/>
</context>

Helpers

There are lots of classes that don't implement Referenceable.

URIValue

com.digi_dmx.URIValue encapsulates a java.net.URI object. Useful for saving references to servers and web services.

An example of how this could be used is to manage Redis services might look like.

URIValue uri = InitialContext.doLookup("url/redis");

Set<HostAndPort> jedisClusterNodes = new HashSet<HostAndPort>();
//Jedis Cluster will attempt to discover cluster nodes automatically
jedisClusterNodes.add(new HostAndPort(uri.getHost(), uri.getPort()));
JedisCluster jc = new JedisCluster(jedisClusterNodes);
jc.set("foo", "bar");

FileLocation

com.digi_dmx.FileLocation encapsulates a java.io.File object. Useful for saving references file locations.

StringValue

com.digi_dmx.StringValue encapsulates a java.lang.String object.

Database Helper

Unfortunately, the database implementations for MariaDB and MySQL DataSources don't implement Referencable.

import com.digi_dmx.ds.DSAdapter;

...

		DSAdapter ds = new DSAdapter();
		ds.setDriver(org.mariadb.jdbc.Driver.class.getName());
		ds.setUrl("jdbc:mariadb://localhost/database");
		ds.setUsername("user");
		ds.setPassword("****");

		new InitialContext().bind("jdbc/mariadb", ds);

The DataSource functionality is implemented by Apache Commons DBCP sub-project.