private void fillServiceClients() {
    serviceClients.put("hdfs", Role.HDFS_CLIENT.toString());
    serviceClients.put("glusterfs", Role.GLUSTERFS_CLIENT.toString());
    serviceClients.put("hbase", Role.HBASE_CLIENT.toString());
    serviceClients.put("mapreduce", Role.MAPREDUCE_CLIENT.toString());
    serviceClients.put("zookeeper", Role.ZOOKEEPER_CLIENT.toString());
    serviceClients.put("hive", Role.HIVE_CLIENT.toString());
    serviceClients.put("hcat", Role.HCAT.toString());
    serviceClients.put("oozie", Role.OOZIE_CLIENT.toString());
    serviceClients.put("pig", Role.PIG.toString());
    serviceClients.put("mahout", Role.MAHOUT.toString());
    serviceClients.put("sqoop", Role.SQOOP.toString());
    serviceClients.put("yarn", Role.YARN_CLIENT.toString());
    serviceClients.put("kerberos", Role.KERBEROS_CLIENT.toString());
    serviceClients.put("accumulo", Role.ACCUMULO_CLIENT.toString());
  }
Contains metadata about actions supported by services
ambari-server/src/main/java/org/apache/ambari/server/metadata/ActionMetadata.java