Suggestions from Alex for Brooklyn dependent entitiy configuration

brooklyn-dependent-entity-config.json

{
  "name":"web-and-db",
  "entities":[{
    "type":"brooklyn.entity.webapp.ElasticJavaWebAppService",
    "config":{
      "java.options":{
        "type":"Map",
        "operation":"put",
        "values":{
          "brooklyn.example.db.url":{
            "type":"DependentConfiguration",
            "source":"mysql",
            "sensor":"MySqlNode.MYSQL_URL",
            "acceptRegex":".+",
            "postprocessSed":"s/^(.+)$/jdbc:$1visitors?user=brooklyn&password=br00k11n/"
          }
        }
      }
    },
    "policy":{
      "type":"brooklyn.policy.ResizerPolicy",
      "config":{
        "sensor":"cluster.reqs.persec.average",
        "sizeLowerBound":1,
        "sizeUpperBound":5,
        "metricLowerBound":10,
        "metricUpperBound":100
      }
    },
    "comment":{
      "TODO: allow comment blocks (string or list of strings; ignored)",
      "TODO: allow an EntityFactory to be used as type as well as Entity",
      "TODO (?): for config of type Map allow operation on map (put or set)",
      "TODO (?): for config value of type DependentConfiguration allow some magic (",
      "note: the convention is that if there is a 'type' key in a map, we do special things",
      "note: if a value is simple e.g. a string or number we do the obvious thing",
      "TODO (?): for DependentConfiguration also allow accept and postprocess regexes (sed?)",
      "TODO (?): accept any recognised config 'flag' directly in the outer block (to simplify things)" 
    }
  },
  {
    "name":"mysql",
    "type":"brooklyn.entity.database.mysql.MySqlNode",
    "creationScriptUrl":"classpath://visitors-creation-script.sql"
  }],
  "locations":[
    "/v1/locations/0"
  ]
} 

brooklyn-dependent-entity-config.xml

<application name="web-and-db">
  <!-- TODO allow/use XML? -->
  <entities>
    <!-- TODO allow an EntityFactory to be used as type as well as Entity -->
    <entity type="brooklyn.entity.webapp.ElasticJavaWebAppService">
      <config>
        <!-- TODO MapProperty and DependentProperty are interpreted specially -->
        <MapProperty name="java.options" operation="put">
          <DependentProperty name="brooklyn.example.db.url">
            <source>mysql</source>
            <sensor>mysql.url</sensor>
            <accept type="regex">.+</accept>
            <postprocess type="sed">s/^(.+)$/jdbc:$1visitors?user=brooklyn&password=br00k11n/</postprocess>
          </<DependentProperty>
        </MapProperty>
      <config>
      <policies>
        <policy type="brooklyn.policy.ResizerPolicy">
          <property name="sensor">cluster.reqs.persec.average</property>
          <property name="sizeLowerBound">1</property>
          <property name="sizeUpperBound">5</property>
          <property name="metricLowerBound">10</property>
          <property name="metricUpperBound">100</property>
        </policy>
      </policies>
    </entity>
    <entity name="mysql" type="brooklyn.entity.database.mysql.MySqlNode">
      <config>
        <!-- TODO support 'flag' as a shortcut for a property name? (has benefit of allowing some error checking too);
                could do this above for policy also -->
        <property flag="creationScriptUrl">classpath://visitors-creation-script.sql</property>
      <config>
    </entity>
  </entities>
  <locations>
    <location id="/v1/locations/0"/>
  </locations>
</application>