Entity-author example

gistfile1.java

/**
 * Everyone uses this interface when dealing with MySqlNode instances.
 */
@ImplementedBy(MySqlNodeImpl.class)
public interface MySqlNode extends Entity, Startable {

    // Note needs this generic to make sub-classing simple
    public static class Recipe<T extends MySqlNode> extends SoftwareProcessEntity.Recipe<T> {
        private PortRange port = PortRanges.fromString("3306, 13306+");
        private String creationScriptContents;
        
        public static Recipe<MySqlNode> newInstance() {
            return new Recipe<MySqlNode>(MySqlNode.class);
        }
        public Recipe(Class<T> type) {
            super(type);
            version("5.5.25a"); // TODO Or some better way to pass in defaults?
            mirrorUrl(URI.create("http://www.mirrorservice.org/sites/ftp.mysql.com/"));
            
        }
        public Recipe port(PortRange val) {
            this.port = val;
            return this;
        }
        public Recipe creationScriptContents(String val) {
            this.creationScriptContents = val;
            return this;
        }

        // TODO There could be a reflection-based method for use by groovy that takes a map
        // and then looks for the similarly named methods to call. This would allow also allow 
        // us to easily fail early if given invalid configuration options etc.
    }
    
    public static final AttributeSensor<String> MYSQL_URL = new BasicAttributeSensor<String>(String.class, "mysql.url");

    public static final AttributeSensor<Integer> PORT = new BasicAttributeSensor<Integer>(Integer.class, "mysql.port");

    // TODO How to relate the port attribute to the Recipe.port() config?
    // In the current Brooklyn, we use PortAttributeSensorAndConfigKey which is concise+nifty.
    // But could we somehow make it more obvious to the entity-author that a port is being 
    // chosen and being set?
}


/**
 * Instances of the entity are only constructed by the framework...
 */
public class MySqlNodeImpl extends SoftwareProcessEntityImpl implements MySqlNode {

    final MySqlNode.Recipe recipe;

    public MySqlNodeImpl(MySqlNode.Recipe recipe) {
        super(recipe);
        this.recipe = recipe;
    }

    @Override
    protected void connectSensors() {
        // blah, blah; code is very similar to what an entity-author would currently write
    }
}

would like to use the config keys in recipe, to allow inheritance and to cut down on redundancy.

rather than @ImplementedBy could we have Recipe have a function which returns the type the framework should implement? then say e.g.

public Recipe() { super(MySqlNodeImpl.class) }

can we merge this new Recipe and the existing Factory ?
not sure i like either name though. :)

EntitySpec ? (and subclass MySqlNode.Spec)

and could resuscitate @ImplementedBy when used with default EntitySpec, i.e. EntitySpec (aka Recipe) has a method

getImplementationClass() { return implementationClassInConstructor ?: getClass().getAnnotion(ImplementedBy.class)... }

?