Brooklyn entity creation API

gistfile1.java

/*
 * Below is an example of 0.5.0-M2 code using ApplicationBuilder:
 */

    public class MyExample extends ApplicationBuilder {
        protected void doBuild() {
            MySqlNode mysql = createChild(BasicEntitySpec.newInstance(MySqlNode.class)
                    .configure(MySqlNode.CREATION_SCRIPT_URL, myUrl));
        }
    }

/*
 * 0.5.0-M2 code within an entity, to create other entities:
 */

    @Override
    public void postConstruct() {
        super.postConstruct();

        // ugly cast caused by groovy use...
        MySqlNode mysql = (MySqlNode) addChild(
                getEntityManager().createEntity(BasicEntitySpec.newInstance(MySqlNode.class)
                        .configure(MySqlNode.CREATION_SCRIPT_URL, scriptUrl)) );

        // Or convenience (for groovy primarily):
        MySqlNode mysql2 = (MySqlNode) addChild(
                getEntityManager().createEntity(MutableMap.of(MySqlNode.CREATION_SCRIPT_URL, scriptUrl), MySqlNode.class));
    }

/*
 * For reference, pre 0.5.0-M2 code would call the constructor directly - now deprecated as horrible for distributed brooklyn.
 */

    // Java
    MySqlNode mysql = new MySqlNodeImpl(MutableMap.of(MySqlNode.CREATION_SCRIPT_URL, scriptUrl), this);
       
    // Groovy
    MySqlNode mysql = new MySqlNodeImpl(this, creationScriptUrl: scriptUrl)

/*
 * Below are some examples of what the code could look like:
 */

    // OPTION 1: buildEntity()
    // buildEntity returns something extending EntitySpec that has an additional build() method;
    // builder returned by buildEntity() so builder can have ref to ManagementContext
    MySqlNode mysql1 = addChild(
             getEntityManager().buildEntity(MySqlNode.class)
                    .configure(MySqlNode.CREATION_SCRIPT_URL, scriptUrl)
                    .build());

    // OPTION 2: getEntityContext()
    // The entityContext knows which entity is doing the calling, so knows who to add the child to etc
    // entityContext methods would be very similar to ApplicationBuilder's methods
    MySqlNode mysql2 = getEntityContext().createChild(BasicEntitySpec.newInstance(MySqlNode.class)
            .configure(MySqlNode.CREATION_SCRIPT_URL, scriptUrl));

    // OPTION 3: getEntityContext().buildEntity()
    MySqlNode mysql3 = getEntityContext().buildChild(MySqlNode.class)
            .configure(MySqlNode.CREATION_SCRIPT_URL, scriptUrl)
            .build();

    // OPTION 4: top-level methods, identical to those on ApplicationBuilder
    // But I like grouping methods, rather than sticking more and more on AbstractEntity.
    MySqlNode mysql4 = createChild(BasicEntitySpec.newInstance(MySqlNode.class)
            .configure(MySqlNode.CREATION_SCRIPT_URL, scriptUrl));

    // OPTION 5: we write custom EntitySpec classes for commonly used entities
    MySqlNode mysql5 = createChild(MySqlNode.Spec.newInstance()
            .creationScriptUrl(scriptUrl));