JNDI - Java Naming and Directory Interface

Object storing

There are several ways an object satisfies the condition to be bound to a JDNI context.

  • serializable objects: Serializable
  • referenceable objects and references: Reference, ObjectFactory, Referenceable, RefAddr
  • objects with attributes: DirContext
  • remote objects: Remote  

Let’s look at the real life example: how we bind DataSource and UserTransaction to a JNDI context

MySQL

package com.mysql.jdbc.jdbc2.optional;

public class MysqlDataSource extends ConnectionPropertiesImpl implements DataSource, Referenceable, Serializable {

    //....
    public Reference getReference() throws NamingException {
        String factoryName = "com.mysql.jdbc.jdbc2.optional.MysqlDataSourceFactory";
        Reference ref = new Reference(this.getClass().getName(), factoryName, (String)null);
        ref.add(new StringRefAddr("user", this.getUser()));
        ref.add(new StringRefAddr("password", this.password));
        ref.add(new StringRefAddr("serverName", this.getServerName()));
        ref.add(new StringRefAddr("port", "" + this.getPort()));
        ref.add(new StringRefAddr("databaseName", this.getDatabaseName()));
        ref.add(new StringRefAddr("url", this.getUrl()));
        ref.add(new StringRefAddr("explicitUrl", String.valueOf(this.explicitUrl)));

        try {
            this.storeToRef(ref);
            return ref;
        } catch (SQLException var4) {
            throw new NamingException(var4.getMessage());
        }
    }
    //....
}

Yes, it implements Referenceable, and defines an ObjectFactory: com.mysql.jdbc.jdbc2.optional.MysqlDataSourceFactory

H2

package org.h2.jdbcx;

public class JdbcDataSource extends TraceObject implements XADataSource, DataSource, ConnectionPoolDataSource, Serializable, Referenceable {

    //....
    public Reference getReference() {
        this.debugCodeCall("getReference");
        String var1 = JdbcDataSourceFactory.class.getName();
        Reference var2 = new Reference(this.getClass().getName(), var1, (String)null);
        var2.add(new StringRefAddr("url", this.url));
        var2.add(new StringRefAddr("user", this.userName));
        var2.add(new StringRefAddr("password", this.convertToString(this.passwordChars)));
        var2.add(new StringRefAddr("loginTimeout", String.valueOf(this.loginTimeout)));
        var2.add(new StringRefAddr("description", this.description));
        return var2;
    }
    //....

}

It also implements Referenceable, and defines an ObjectFactory: org.h2.jdbcx.JdbcDataSourceFactory

JBoss JTA

package com.arjuna.ats.internal.jta.transaction.arjunacore;

public class UserTransactionImple extends BaseTransaction implements UserTransaction, ObjectFactory {
    //....
}

You can see, UserTrancation implmentation class UserTransactionImple doesn’t implement Referenceable, but actions as ObjectFactory.

Now, let’s look at the bind code:

package com.arjuna.ats.jta.utils;

public class JNDIManager {
    //....
    public static void bindJTAUserTransactionImplementation(InitialContext initialContext) throws NamingException {
        String utImplementation = getUserTransactionImplementationClassname();
        Reference ref = new Reference(utImplementation, utImplementation, (String)null);
        initialContext.rebind(getUserTransactionJNDIName(), ref);
    }
    //....
}

Yes, JBoss JTA binds UserTransaction using Reference with its ObjectFactory. As said above, UserTransactionImple is both the bound target and the ObjectFactory.

Object binding

So once the object can be bound, the binding operation is simple.

context.bind("cn=favorite", fruit);

Object lookup / list / search

context.lookup(..)