X-Git-Url: https://git.octo.it/?a=blobdiff_plain;f=src%2Fjava.c;h=2d310c6f4c2947f2df3cf311d8d7f8c496aaa03b;hb=fb9f56e5af1a63d94c80a2ea6f067aeb7787f397;hp=83fec35c556ec3ddbdaefe1afaf1fae3ef838d43;hpb=aede1532622a544e16fbb3fbd1a096230f047745;p=collectd.git

diff --git a/src/java.c b/src/java.c
index 83fec35c..2d310c6f 100644
--- a/src/java.c
+++ b/src/java.c
@@ -35,33 +35,90 @@
 /*
  * Types
  */
-struct java_plugin_s /* {{{ */
+struct cjni_jvm_env_s /* {{{ */
 {
-  char *class_name;
-  jclass class_ptr;
-  jobject object_ptr;
+  JNIEnv *jvm_env;
+  int reference_counter;
+};
+typedef struct cjni_jvm_env_s cjni_jvm_env_t;
+/* }}} */
+
+struct java_plugin_class_s /* {{{ */
+{
+  char     *name;
+  jclass    class;
+  jobject   object;
+};
+typedef struct java_plugin_class_s java_plugin_class_t;
+/* }}} */
 
-#define CJNI_FLAG_ENABLED 0x0001
-  int flags;
+struct java_plugin_config_s /* {{{ */
+{
+  char *name;
+  oconfig_item_t *ci;
+};
+typedef struct java_plugin_config_s java_plugin_config_t;
+/* }}} */
 
-  jmethodID m_init;
-  jmethodID m_read;
-  jmethodID m_write;
-  jmethodID m_shutdown;
+#define CB_TYPE_CONFIG       1
+#define CB_TYPE_INIT         2
+#define CB_TYPE_READ         3
+#define CB_TYPE_WRITE        4
+#define CB_TYPE_FLUSH        5
+#define CB_TYPE_SHUTDOWN     6
+#define CB_TYPE_LOG          7
+#define CB_TYPE_NOTIFICATION 8
+struct cjni_callback_info_s /* {{{ */
+{
+  char     *name;
+  int       type;
+  jclass    class;
+  jobject   object;
+  jmethodID method;
 };
-typedef struct java_plugin_s java_plugin_t;
+typedef struct cjni_callback_info_s cjni_callback_info_t;
 /* }}} */
 
 /*
  * Global variables
  */
 static JavaVM *jvm = NULL;
+static pthread_key_t jvm_env_key;
 
+/* Configuration options for the JVM. */
 static char **jvm_argv = NULL;
 static size_t jvm_argc = 0;
 
-static java_plugin_t *java_plugins     = NULL;
-static size_t         java_plugins_num = 0;
+/* List of class names to load */
+static java_plugin_class_t  *java_classes_list = NULL;
+static size_t                java_classes_list_len;
+
+/* List of `config_item_t's for Java plugins */
+static java_plugin_config_t *java_plugin_configs     = NULL;
+static size_t                java_plugin_configs_num = 0;
+
+/* List of config, init, and shutdown callbacks. */
+static cjni_callback_info_t *java_callbacks      = NULL;
+static size_t                java_callbacks_num  = 0;
+static pthread_mutex_t       java_callbacks_lock = PTHREAD_MUTEX_INITIALIZER;
+
+/*
+ * Prototypes
+ *
+ * Mostly functions that are needed by the Java interface (``native'')
+ * functions.
+ */
+static void cjni_callback_info_destroy (void *arg);
+static cjni_callback_info_t *cjni_callback_info_create (JNIEnv *jvm_env,
+    jobject o_name, jobject o_callback, int type);
+static int cjni_callback_register (JNIEnv *jvm_env, jobject o_name,
+    jobject o_callback, int type);
+static int cjni_read (user_data_t *user_data);
+static int cjni_write (const data_set_t *ds, const value_list_t *vl,
+    user_data_t *ud);
+static int cjni_flush (int timeout, const char *identifier, user_data_t *ud);
+static void cjni_log (int severity, const char *message, user_data_t *ud);
+static int cjni_notification (const notification_t *n, user_data_t *ud);
 
 /* 
  * C to Java conversion functions
@@ -99,9 +156,6 @@ static int ctoj_string (JNIEnv *jvm_env, /* {{{ */
   /* Decrease reference counter on the java.lang.String object. */
   (*jvm_env)->DeleteLocalRef (jvm_env, o_string);
 
-  DEBUG ("java plugin: ctoj_string: ->%s (%s);",
-      method_name, (string != NULL) ? string : "");
-
   return (0);
 } /* }}} int ctoj_string */
 
@@ -123,9 +177,6 @@ static int ctoj_int (JNIEnv *jvm_env, /* {{{ */
 
   (*jvm_env)->CallVoidMethod (jvm_env, object_ptr, m_set, value);
 
-  DEBUG ("java plugin: ctoj_int: ->%s (%i);",
-      method_name, (int) value);
-
   return (0);
 } /* }}} int ctoj_int */
 
@@ -147,9 +198,6 @@ static int ctoj_long (JNIEnv *jvm_env, /* {{{ */
 
   (*jvm_env)->CallVoidMethod (jvm_env, object_ptr, m_set, value);
 
-  DEBUG ("java plugin: ctoj_long: ->%s (%"PRIi64");",
-      method_name, (int64_t) value);
-
   return (0);
 } /* }}} int ctoj_long */
 
@@ -171,81 +219,78 @@ static int ctoj_double (JNIEnv *jvm_env, /* {{{ */
 
   (*jvm_env)->CallVoidMethod (jvm_env, object_ptr, m_set, value);
 
-  DEBUG ("java plugin: ctoj_double: ->%s (%g);",
-      method_name, (double) value);
-
   return (0);
 } /* }}} int ctoj_double */
 
-/* Convert a value_t to a java.lang.Number */
-static jobject ctoj_value_to_number (JNIEnv *jvm_env, /* {{{ */
-    value_t value, int ds_type)
+/* Convert a jlong to a java.lang.Number */
+static jobject ctoj_jlong_to_number (JNIEnv *jvm_env, jlong value) /* {{{ */
 {
-  if (ds_type == DS_TYPE_COUNTER)
+  jclass c_long;
+  jmethodID m_long_constructor;
+
+  /* Look up the java.lang.Long class */
+  c_long = (*jvm_env)->FindClass (jvm_env, "java.lang.Long");
+  if (c_long == NULL)
   {
-    jclass c_long;
-    jmethodID m_long_constructor;
+    ERROR ("java plugin: ctoj_jlong_to_number: Looking up the "
+        "java.lang.Long class failed.");
+    return (NULL);
+  }
 
-    jlong tmp_long;
+  m_long_constructor = (*jvm_env)->GetMethodID (jvm_env,
+      c_long, "<init>", "(J)V");
+  if (m_long_constructor == NULL)
+  {
+    ERROR ("java plugin: ctoj_jlong_to_number: Looking up the "
+        "`Long (long)' constructor failed.");
+    return (NULL);
+  }
 
-    /* Look up the java.lang.Long class */
-    c_long = (*jvm_env)->FindClass (jvm_env, "java.lang.Long");
-    if (c_long == NULL)
-    {
-      ERROR ("java plugin: ctoj_value_to_number: Looking up the "
-          "java.lang.Long class failed.");
-      return (NULL);
-    }
+  return ((*jvm_env)->NewObject (jvm_env,
+        c_long, m_long_constructor, value));
+} /* }}} jobject ctoj_jlong_to_number */
 
-    m_long_constructor = (*jvm_env)->GetMethodID (jvm_env,
-        c_long, "<init>", "(J)V");
-    if (m_long_constructor == NULL)
-    {
-      ERROR ("java plugin: ctoj_value_to_number: Looking up the "
-          "`Long (long)' constructor failed.");
-      return (NULL);
-    }
+/* Convert a jdouble to a java.lang.Number */
+static jobject ctoj_jdouble_to_number (JNIEnv *jvm_env, jdouble value) /* {{{ */
+{
+  jclass c_double;
+  jmethodID m_double_constructor;
 
-    tmp_long = (jlong) value.counter;
-    return ((*jvm_env)->NewObject (jvm_env,
-          c_long, m_long_constructor, tmp_long));
-  }
-  else if (ds_type == DS_TYPE_GAUGE)
+  /* Look up the java.lang.Long class */
+  c_double = (*jvm_env)->FindClass (jvm_env, "java.lang.Double");
+  if (c_double == NULL)
   {
-    jclass c_double;
-    jmethodID m_double_constructor;
-
-    jdouble tmp_double;
+    ERROR ("java plugin: ctoj_jdouble_to_number: Looking up the "
+        "java.lang.Double class failed.");
+    return (NULL);
+  }
 
-    /* Look up the java.lang.Long class */
-    c_double = (*jvm_env)->FindClass (jvm_env, "java.lang.Double");
-    if (c_double == NULL)
-    {
-      ERROR ("java plugin: ctoj_value_to_number: Looking up the "
-          "java.lang.Double class failed.");
-      return (NULL);
-    }
+  m_double_constructor = (*jvm_env)->GetMethodID (jvm_env,
+      c_double, "<init>", "(D)V");
+  if (m_double_constructor == NULL)
+  {
+    ERROR ("java plugin: ctoj_jdouble_to_number: Looking up the "
+        "`Double (double)' constructor failed.");
+    return (NULL);
+  }
 
-    m_double_constructor = (*jvm_env)->GetMethodID (jvm_env,
-        c_double, "<init>", "(D)V");
-    if (m_double_constructor == NULL)
-    {
-      ERROR ("java plugin: ctoj_value_to_number: Looking up the "
-          "`Double (double)' constructor failed.");
-      return (NULL);
-    }
+  return ((*jvm_env)->NewObject (jvm_env,
+        c_double, m_double_constructor, value));
+} /* }}} jobject ctoj_jdouble_to_number */
 
-    tmp_double = (jdouble) value.gauge;
-    return ((*jvm_env)->NewObject (jvm_env,
-          c_double, m_double_constructor, tmp_double));
-  }
+/* Convert a value_t to a java.lang.Number */
+static jobject ctoj_value_to_number (JNIEnv *jvm_env, /* {{{ */
+    value_t value, int ds_type)
+{
+  if (ds_type == DS_TYPE_COUNTER)
+    return (ctoj_jlong_to_number (jvm_env, (jlong) value.counter));
+  else if (ds_type == DS_TYPE_GAUGE)
+    return (ctoj_jdouble_to_number (jvm_env, (jdouble) value.gauge));
   else
-  {
     return (NULL);
-  }
 } /* }}} jobject ctoj_value_to_number */
 
-/* Convert a data_source_t to a org.collectd.protocol.DataSource */
+/* Convert a data_source_t to a org.collectd.api.DataSource */
 static jobject ctoj_data_source (JNIEnv *jvm_env, /* {{{ */
     const data_source_t *dsrc)
 {
@@ -256,11 +301,11 @@ static jobject ctoj_data_source (JNIEnv *jvm_env, /* {{{ */
 
   /* Look up the DataSource class */
   c_datasource = (*jvm_env)->FindClass (jvm_env,
-      "org.collectd.protocol.DataSource");
+      "org.collectd.api.DataSource");
   if (c_datasource == NULL)
   {
     ERROR ("java plugin: ctoj_data_source: "
-        "FindClass (org.collectd.protocol.DataSource) failed.");
+        "FindClass (org.collectd.api.DataSource) failed.");
     return (NULL);
   }
 
@@ -331,56 +376,280 @@ static jobject ctoj_data_source (JNIEnv *jvm_env, /* {{{ */
   return (o_datasource);
 } /* }}} jobject ctoj_data_source */
 
-/* Convert a data_set_t to a java.util.List<DataSource> */
+/* Convert a oconfig_value_t to a org.collectd.api.OConfigValue */
+static jobject ctoj_oconfig_value (JNIEnv *jvm_env, /* {{{ */
+    oconfig_value_t ocvalue)
+{
+  jclass c_ocvalue;
+  jmethodID m_ocvalue_constructor;
+  jobject o_argument;
+  jobject o_ocvalue;
+
+  m_ocvalue_constructor = NULL;
+  o_argument = NULL;
+
+  c_ocvalue = (*jvm_env)->FindClass (jvm_env,
+      "org.collectd.api.OConfigValue");
+  if (c_ocvalue == NULL)
+  {
+    ERROR ("java plugin: ctoj_oconfig_value: "
+        "FindClass (org.collectd.api.OConfigValue) failed.");
+    return (NULL);
+  }
+
+  if (ocvalue.type == OCONFIG_TYPE_BOOLEAN)
+  {
+    jboolean tmp_boolean;
+
+    tmp_boolean = (ocvalue.value.boolean == 0) ? JNI_FALSE : JNI_TRUE;
+
+    m_ocvalue_constructor = (*jvm_env)->GetMethodID (jvm_env, c_ocvalue,
+        "<init>", "(Z)V");
+    if (m_ocvalue_constructor == NULL)
+    {
+      ERROR ("java plugin: ctoj_oconfig_value: Cannot find the "
+          "`OConfigValue (boolean)' constructor.");
+      return (NULL);
+    }
+
+    return ((*jvm_env)->NewObject (jvm_env,
+          c_ocvalue, m_ocvalue_constructor, tmp_boolean));
+  } /* if (ocvalue.type == OCONFIG_TYPE_BOOLEAN) */
+  else if (ocvalue.type == OCONFIG_TYPE_STRING)
+  {
+    m_ocvalue_constructor = (*jvm_env)->GetMethodID (jvm_env, c_ocvalue,
+        "<init>", "(Ljava/lang/String;)V");
+    if (m_ocvalue_constructor == NULL)
+    {
+      ERROR ("java plugin: ctoj_oconfig_value: Cannot find the "
+          "`OConfigValue (String)' constructor.");
+      return (NULL);
+    }
+
+    o_argument = (*jvm_env)->NewStringUTF (jvm_env, ocvalue.value.string);
+    if (o_argument == NULL)
+    {
+      ERROR ("java plugin: ctoj_oconfig_value: "
+          "Creating a String object failed.");
+      return (NULL);
+    }
+  }
+  else if (ocvalue.type == OCONFIG_TYPE_NUMBER)
+  {
+    m_ocvalue_constructor = (*jvm_env)->GetMethodID (jvm_env, c_ocvalue,
+        "<init>", "(Ljava/lang/Number;)V");
+    if (m_ocvalue_constructor == NULL)
+    {
+      ERROR ("java plugin: ctoj_oconfig_value: Cannot find the "
+          "`OConfigValue (Number)' constructor.");
+      return (NULL);
+    }
+
+    o_argument = ctoj_jdouble_to_number (jvm_env,
+        (jdouble) ocvalue.value.number);
+    if (o_argument == NULL)
+    {
+      ERROR ("java plugin: ctoj_oconfig_value: "
+          "Creating a Number object failed.");
+      return (NULL);
+    }
+  }
+  else
+  {
+    return (NULL);
+  }
+
+  assert (m_ocvalue_constructor != NULL);
+  assert (o_argument != NULL);
+
+  o_ocvalue = (*jvm_env)->NewObject (jvm_env,
+      c_ocvalue, m_ocvalue_constructor, o_argument);
+  if (o_ocvalue == NULL)
+  {
+    ERROR ("java plugin: ctoj_oconfig_value: "
+        "Creating an OConfigValue object failed.");
+    (*jvm_env)->DeleteLocalRef (jvm_env, o_argument);
+    return (NULL);
+  }
+
+  (*jvm_env)->DeleteLocalRef (jvm_env, o_argument);
+  return (o_ocvalue);
+} /* }}} jobject ctoj_oconfig_value */
+
+/* Convert a oconfig_item_t to a org.collectd.api.OConfigItem */
+static jobject ctoj_oconfig_item (JNIEnv *jvm_env, /* {{{ */
+    const oconfig_item_t *ci)
+{
+  jclass c_ocitem;
+  jmethodID m_ocitem_constructor;
+  jmethodID m_addvalue;
+  jmethodID m_addchild;
+  jobject o_key;
+  jobject o_ocitem;
+  int i;
+
+  c_ocitem = (*jvm_env)->FindClass (jvm_env, "org.collectd.api.OConfigItem");
+  if (c_ocitem == NULL)
+  {
+    ERROR ("java plugin: ctoj_oconfig_item: "
+        "FindClass (org.collectd.api.OConfigItem) failed.");
+    return (NULL);
+  }
+
+  /* Get the required methods: m_ocitem_constructor, m_addvalue, and m_addchild
+   * {{{ */
+  m_ocitem_constructor = (*jvm_env)->GetMethodID (jvm_env, c_ocitem,
+      "<init>", "(Ljava/lang/String;)V");
+  if (m_ocitem_constructor == NULL)
+  {
+    ERROR ("java plugin: ctoj_oconfig_item: Cannot find the "
+        "`OConfigItem (String)' constructor.");
+    return (NULL);
+  }
+
+  m_addvalue = (*jvm_env)->GetMethodID (jvm_env, c_ocitem,
+      "addValue", "(Lorg/collectd/api/OConfigValue;)V");
+  if (m_addvalue == NULL)
+  {
+    ERROR ("java plugin: ctoj_oconfig_item: Cannot find the "
+        "`addValue (OConfigValue)' method.");
+    return (NULL);
+  }
+
+  m_addchild = (*jvm_env)->GetMethodID (jvm_env, c_ocitem,
+      "addChild", "(Lorg/collectd/api/OConfigItem;)V");
+  if (m_addchild == NULL)
+  {
+    ERROR ("java plugin: ctoj_oconfig_item: Cannot find the "
+        "`addChild (OConfigItem)' method.");
+    return (NULL);
+  }
+  /* }}} */
+
+  /* Create a String object with the key.
+   * Needed for calling the constructor. */
+  o_key = (*jvm_env)->NewStringUTF (jvm_env, ci->key);
+  if (o_key == NULL)
+  {
+    ERROR ("java plugin: ctoj_oconfig_item: "
+        "Creating String object failed.");
+    return (NULL);
+  }
+
+  /* Create an OConfigItem object */
+  o_ocitem = (*jvm_env)->NewObject (jvm_env,
+      c_ocitem, m_ocitem_constructor, o_key);
+  if (o_ocitem == NULL)
+  {
+    ERROR ("java plugin: ctoj_oconfig_item: "
+        "Creating an OConfigItem object failed.");
+    (*jvm_env)->DeleteLocalRef (jvm_env, o_key);
+    return (NULL);
+  }
+
+  /* We don't need the String object any longer.. */
+  (*jvm_env)->DeleteLocalRef (jvm_env, o_key);
+
+  /* Call OConfigItem.addValue for each value */
+  for (i = 0; i < ci->values_num; i++) /* {{{ */
+  {
+    jobject o_value;
+
+    o_value = ctoj_oconfig_value (jvm_env, ci->values[i]);
+    if (o_value == NULL)
+    {
+      ERROR ("java plugin: ctoj_oconfig_item: "
+          "Creating an OConfigValue object failed.");
+      (*jvm_env)->DeleteLocalRef (jvm_env, o_ocitem);
+      return (NULL);
+    }
+
+    (*jvm_env)->CallVoidMethod (jvm_env, o_ocitem, m_addvalue, o_value);
+    (*jvm_env)->DeleteLocalRef (jvm_env, o_value);
+  } /* }}} for (i = 0; i < ci->values_num; i++) */
+
+  /* Call OConfigItem.addChild for each child */
+  for (i = 0; i < ci->children_num; i++) /* {{{ */
+  {
+    jobject o_child;
+
+    o_child = ctoj_oconfig_item (jvm_env, ci->children + i);
+    if (o_child == NULL)
+    {
+      ERROR ("java plugin: ctoj_oconfig_item: "
+          "Creating an OConfigItem object failed.");
+      (*jvm_env)->DeleteLocalRef (jvm_env, o_ocitem);
+      return (NULL);
+    }
+
+    (*jvm_env)->CallVoidMethod (jvm_env, o_ocitem, m_addvalue, o_child);
+    (*jvm_env)->DeleteLocalRef (jvm_env, o_child);
+  } /* }}} for (i = 0; i < ci->children_num; i++) */
+
+  return (o_ocitem);
+} /* }}} jobject ctoj_oconfig_item */
+
+/* Convert a data_set_t to a org.collectd.api.DataSet */
 static jobject ctoj_data_set (JNIEnv *jvm_env, const data_set_t *ds) /* {{{ */
 {
-  jclass c_arraylist;
+  jclass c_dataset;
   jmethodID m_constructor;
   jmethodID m_add;
+  jobject o_type;
   jobject o_dataset;
   int i;
 
-  /* Look up the java.util.ArrayList class */
-  c_arraylist = (*jvm_env)->FindClass (jvm_env, "java.util.ArrayList");
-  if (c_arraylist == NULL)
+  /* Look up the org.collectd.api.DataSet class */
+  c_dataset = (*jvm_env)->FindClass (jvm_env, "org.collectd.api.DataSet");
+  if (c_dataset == NULL)
   {
     ERROR ("java plugin: ctoj_data_set: Looking up the "
-        "java.util.ArrayList class failed.");
+        "org.collectd.api.DataSet class failed.");
     return (NULL);
   }
 
-  /* Search for the `ArrayList (int capacity)' constructor. */
+  /* Search for the `DataSet (String type)' constructor. */
   m_constructor = (*jvm_env)->GetMethodID (jvm_env,
-      c_arraylist, "<init>", "()V");
+      c_dataset, "<init>", "(Ljava.lang.String;)V");
   if (m_constructor == NULL)
   {
     ERROR ("java plugin: ctoj_data_set: Looking up the "
-        "`ArrayList (void)' constructor failed.");
+        "`DataSet (String)' constructor failed.");
     return (NULL);
   }
 
-  /* Search for the `boolean add  (Object element)' method. */
+  /* Search for the `void addDataSource (DataSource)' method. */
   m_add = (*jvm_env)->GetMethodID (jvm_env,
-      c_arraylist, "add", "(Ljava/lang/Object;)Z");
+      c_dataset, "addDataSource", "(Lorg.collectd.api.DataSource;)V");
   if (m_add == NULL)
   {
     ERROR ("java plugin: ctoj_data_set: Looking up the "
-        "`add (Object)' method failed.");
+        "`addDataSource (DataSource)' method failed.");
+    return (NULL);
+  }
+
+  o_type = (*jvm_env)->NewStringUTF (jvm_env, ds->type);
+  if (o_type == NULL)
+  {
+    ERROR ("java plugin: ctoj_data_set: Creating a String object failed.");
     return (NULL);
   }
 
-  o_dataset = (*jvm_env)->NewObject (jvm_env, c_arraylist, m_constructor);
+  o_dataset = (*jvm_env)->NewObject (jvm_env,
+      c_dataset, m_constructor, o_type);
   if (o_dataset == NULL)
   {
-    ERROR ("java plugin: ctoj_data_set: "
-        "Creating an ArrayList object failed.");
+    ERROR ("java plugin: ctoj_data_set: Creating a DataSet object failed.");
+    (*jvm_env)->DeleteLocalRef (jvm_env, o_type);
     return (NULL);
   }
 
+  /* Decrease reference counter on the java.lang.String object. */
+  (*jvm_env)->DeleteLocalRef (jvm_env, o_type);
+
   for (i = 0; i < ds->ds_num; i++)
   {
     jobject o_datasource;
-    jboolean status;
 
     o_datasource = ctoj_data_source (jvm_env, ds->ds + i);
     if (o_datasource == NULL)
@@ -391,15 +660,7 @@ static jobject ctoj_data_set (JNIEnv *jvm_env, const data_set_t *ds) /* {{{ */
       return (NULL);
     }
 
-    status = (*jvm_env)->CallBooleanMethod (jvm_env,
-        o_dataset, m_add, o_datasource);
-    if (!status)
-    {
-      ERROR ("java plugin: ctoj_data_set: ArrayList.add returned FALSE.");
-      (*jvm_env)->DeleteLocalRef (jvm_env, o_datasource);
-      (*jvm_env)->DeleteLocalRef (jvm_env, o_dataset);
-      return (NULL);
-    }
+    (*jvm_env)->CallVoidMethod (jvm_env, o_dataset, m_add, o_datasource);
 
     (*jvm_env)->DeleteLocalRef (jvm_env, o_datasource);
   } /* for (i = 0; i < ds->ds_num; i++) */
@@ -441,20 +702,20 @@ static int ctoj_value_list_add_value (JNIEnv *jvm_env, /* {{{ */
 static int ctoj_value_list_add_data_set (JNIEnv *jvm_env, /* {{{ */
     jclass c_valuelist, jobject o_valuelist, const data_set_t *ds)
 {
-  jmethodID m_setdatasource;
+  jmethodID m_setdataset;
   jobject o_dataset;
 
   /* Look for the `void setDataSource (List<DataSource> ds)' method. */
-  m_setdatasource = (*jvm_env)->GetMethodID (jvm_env, c_valuelist,
-      "setDataSource", "(Ljava/util/List;)V");
-  if (m_setdatasource == NULL)
+  m_setdataset = (*jvm_env)->GetMethodID (jvm_env, c_valuelist,
+      "setDataSet", "(Lorg.collectd.api.DataSet;)V");
+  if (m_setdataset == NULL)
   {
     ERROR ("java plugin: ctoj_value_list_add_data_set: "
-        "Cannot find the `void setDataSource (List<DataSource> ds)' method.");
+        "Cannot find the `void setDataSet (DataSet)' method.");
     return (-1);
   }
 
-  /* Create a List<DataSource> object. */
+  /* Create a DataSet object. */
   o_dataset = ctoj_data_set (jvm_env, ds);
   if (o_dataset == NULL)
   {
@@ -465,7 +726,7 @@ static int ctoj_value_list_add_data_set (JNIEnv *jvm_env, /* {{{ */
 
   /* Actually call the method. */
   (*jvm_env)->CallVoidMethod (jvm_env,
-      o_valuelist, m_setdatasource, o_dataset);
+      o_valuelist, m_setdataset, o_dataset);
 
   /* Decrease reference counter on the List<DataSource> object. */
   (*jvm_env)->DeleteLocalRef (jvm_env, o_dataset);
@@ -473,6 +734,7 @@ static int ctoj_value_list_add_data_set (JNIEnv *jvm_env, /* {{{ */
   return (0);
 } /* }}} int ctoj_value_list_add_data_set */
 
+/* Convert a value_list_t (and data_set_t) to a org.collectd.api.ValueList */
 static jobject ctoj_value_list (JNIEnv *jvm_env, /* {{{ */
     const data_set_t *ds, const value_list_t *vl)
 {
@@ -485,11 +747,11 @@ static jobject ctoj_value_list (JNIEnv *jvm_env, /* {{{ */
   /* First, create a new ValueList instance..
    * Look up the class.. */
   c_valuelist = (*jvm_env)->FindClass (jvm_env,
-      "org.collectd.protocol.ValueList");
+      "org.collectd.api.ValueList");
   if (c_valuelist == NULL)
   {
     ERROR ("java plugin: ctoj_value_list: "
-        "FindClass (org.collectd.protocol.ValueList) failed.");
+        "FindClass (org.collectd.api.ValueList) failed.");
     return (NULL);
   }
 
@@ -576,11 +838,95 @@ static jobject ctoj_value_list (JNIEnv *jvm_env, /* {{{ */
   }
 
   return (o_valuelist);
-} /* }}} int ctoj_value_list */
+} /* }}} jobject ctoj_value_list */
+
+/* Convert a notification_t to a org.collectd.api.Notification */
+static jobject ctoj_notification (JNIEnv *jvm_env, /* {{{ */
+    const notification_t *n)
+{
+  jclass c_notification;
+  jmethodID m_constructor;
+  jobject o_notification;
+  int status;
+
+  /* First, create a new Notification instance..
+   * Look up the class.. */
+  c_notification = (*jvm_env)->FindClass (jvm_env,
+      "org.collectd.api.Notification");
+  if (c_notification == NULL)
+  {
+    ERROR ("java plugin: ctoj_notification: "
+        "FindClass (org.collectd.api.Notification) failed.");
+    return (NULL);
+  }
+
+  /* Lookup the `Notification ()' constructor. */
+  m_constructor = (*jvm_env)->GetMethodID (jvm_env, c_notification,
+      "<init>", "()V");
+  if (m_constructor == NULL)
+  {
+    ERROR ("java plugin: ctoj_notification: Cannot find the "
+        "`Notification ()' constructor.");
+    return (NULL);
+  }
+
+  /* Create a new instance. */
+  o_notification = (*jvm_env)->NewObject (jvm_env, c_notification,
+      m_constructor);
+  if (o_notification == NULL)
+  {
+    ERROR ("java plugin: ctoj_notification: Creating a new Notification "
+        "instance failed.");
+    return (NULL);
+  }
+
+  /* Set the strings.. */
+#define SET_STRING(str,method_name) do { \
+  status = ctoj_string (jvm_env, str, \
+      c_notification, o_notification, method_name); \
+  if (status != 0) { \
+    ERROR ("java plugin: ctoj_notification: jtoc_string (%s) failed.", \
+        method_name); \
+    (*jvm_env)->DeleteLocalRef (jvm_env, o_notification); \
+    return (NULL); \
+  } } while (0)
+
+  SET_STRING (n->host,            "setHost");
+  SET_STRING (n->plugin,          "setPlugin");
+  SET_STRING (n->plugin_instance, "setPluginInstance");
+  SET_STRING (n->type,            "setType");
+  SET_STRING (n->type_instance,   "setTypeInstance");
+  SET_STRING (n->message,         "setMessage");
+
+#undef SET_STRING
+
+  /* Set the `time' member. Java stores time in milliseconds. */
+  status = ctoj_long (jvm_env, ((jlong) n->time) * ((jlong) 1000),
+      c_notification, o_notification, "setTime");
+  if (status != 0)
+  {
+    ERROR ("java plugin: ctoj_notification: ctoj_long (setTime) failed.");
+    (*jvm_env)->DeleteLocalRef (jvm_env, o_notification);
+    return (NULL);
+  }
+
+  /* Set the `interval' member.. */
+  status = ctoj_int (jvm_env, (jint) n->severity,
+      c_notification, o_notification, "setSeverity");
+  if (status != 0)
+  {
+    ERROR ("java plugin: ctoj_notification: ctoj_int (setSeverity) failed.");
+    (*jvm_env)->DeleteLocalRef (jvm_env, o_notification);
+    return (NULL);
+  }
+
+  return (o_notification);
+} /* }}} jobject ctoj_notification */
 
 /*
  * Java to C conversion functions
  */
+/* Call a `String <method> ()' method. */
 static int jtoc_string (JNIEnv *jvm_env, /* {{{ */
     char *buffer, size_t buffer_size,
     jclass class_ptr, jobject object_ptr, const char *method_name)
@@ -614,8 +960,6 @@ static int jtoc_string (JNIEnv *jvm_env, /* {{{ */
     return (-1);
   }
 
-  DEBUG ("java plugin: jtoc_string: ->%s() = %s", method_name, c_str);
-
   sstrncpy (buffer, c_str, buffer_size);
 
   (*jvm_env)->ReleaseStringUTFChars (jvm_env, string_obj, c_str);
@@ -624,6 +968,7 @@ static int jtoc_string (JNIEnv *jvm_env, /* {{{ */
   return (0);
 } /* }}} int jtoc_string */
 
+/* Call a `long <method> ()' method. */
 static int jtoc_long (JNIEnv *jvm_env, /* {{{ */
     jlong *ret_value,
     jclass class_ptr, jobject object_ptr, const char *method_name)
@@ -641,12 +986,10 @@ static int jtoc_long (JNIEnv *jvm_env, /* {{{ */
 
   *ret_value = (*jvm_env)->CallLongMethod (jvm_env, object_ptr, method_id);
 
-  DEBUG ("java plugin: jtoc_long: ->%s() = %li",
-      method_name, (long int) *ret_value);
-
   return (0);
 } /* }}} int jtoc_long */
 
+/* Call a `double <method> ()' method. */
 static int jtoc_double (JNIEnv *jvm_env, /* {{{ */
     jdouble *ret_value,
     jclass class_ptr, jobject object_ptr, const char *method_name)
@@ -664,9 +1007,6 @@ static int jtoc_double (JNIEnv *jvm_env, /* {{{ */
 
   *ret_value = (*jvm_env)->CallDoubleMethod (jvm_env, object_ptr, method_id);
 
-  DEBUG ("java plugin: jtoc_double: ->%s() = %g",
-      method_name, (double) *ret_value);
-
   return (0);
 } /* }}} int jtoc_double */
 
@@ -710,6 +1050,8 @@ static int jtoc_value (JNIEnv *jvm_env, /* {{{ */
   return (0);
 } /* }}} int jtoc_value */
 
+/* Read a List<Number>, convert it to `value_t' and add it to the given
+ * `value_list_t'. */
 static int jtoc_values_array (JNIEnv *jvm_env, /* {{{ */
     const data_set_t *ds, value_list_t *vl,
     jclass class_ptr, jobject object_ptr)
@@ -774,7 +1116,7 @@ static int jtoc_values_array (JNIEnv *jvm_env, /* {{{ */
     BAIL_OUT (-1);
   }
 
-  values = calloc (values_num, sizeof (value_t));
+  values = (value_t *) calloc (values_num, sizeof (value_t));
   if (values == NULL)
   {
     ERROR ("java plugin: jtoc_values_array: calloc failed.");
@@ -813,7 +1155,7 @@ static int jtoc_values_array (JNIEnv *jvm_env, /* {{{ */
   return (0);
 } /* }}} int jtoc_values_array */
 
-/* Convert a org.collectd.protocol.ValueList to a value_list_t. */
+/* Convert a org.collectd.api.ValueList to a value_list_t. */
 static int jtoc_value_list (JNIEnv *jvm_env, value_list_t *vl, /* {{{ */
     jobject object_ptr)
 {
@@ -862,7 +1204,8 @@ static int jtoc_value_list (JNIEnv *jvm_env, value_list_t *vl, /* {{{ */
     ERROR ("java plugin: jtoc_value_list: jtoc_long (getTime) failed.");
     return (-1);
   }
-  vl->time = (time_t) tmp_long;
+  /* Java measures time in milliseconds. */
+  vl->time = (time_t) (tmp_long / ((jlong) 1000));
 
   status = jtoc_long (jvm_env, &tmp_long,
       class_ptr, object_ptr, "getInterval");
@@ -901,93 +1244,676 @@ static jint JNICALL cjni_api_dispatch_values (JNIEnv *jvm_env, /* {{{ */
     return (-1);
   }
 
-  plugin_dispatch_values (&vl);
+  status = plugin_dispatch_values (&vl);
 
   sfree (vl.values);
 
-  return (0);
+  return (status);
 } /* }}} jint cjni_api_dispatch_values */
 
-static JNINativeMethod jni_api_functions[] =
-{
-  { "DispatchValues", "(Lorg/collectd/protocol/ValueList;)I", cjni_api_dispatch_values }
-};
-static size_t jni_api_functions_num = sizeof (jni_api_functions)
-  / sizeof (jni_api_functions[0]);
-
-/*
- * Functions
- */
-static int cjni_config_add_jvm_arg (oconfig_item_t *ci) /* {{{ */
+static jobject JNICALL cjni_api_get_ds (JNIEnv *jvm_env, /* {{{ */
+    jobject this, jobject o_string_type)
 {
-  char **tmp;
+  const char *ds_name;
+  const data_set_t *ds;
+  jobject o_dataset;
 
-  if ((ci->values_num != 1) || (ci->values[0].type != OCONFIG_TYPE_STRING))
+  ds_name = (*jvm_env)->GetStringUTFChars (jvm_env, o_string_type, 0);
+  if (ds_name == NULL)
   {
-    WARNING ("java plugin: `JVMArg' needs exactly one string argument.");
-    return (-1);
+    ERROR ("java plugin: cjni_api_get_ds: GetStringUTFChars failed.");
+    return (NULL);
   }
 
-  tmp = (char **) realloc (jvm_argv, sizeof (char *) * (jvm_argc + 1));
-  if (tmp == NULL)
-  {
-    ERROR ("java plugin: realloc failed.");
-    return (-1);
-  }
-  jvm_argv = tmp;
+  ds = plugin_get_ds (ds_name);
+  DEBUG ("java plugin: cjni_api_get_ds: "
+      "plugin_get_ds (%s) = %p;", ds_name, (void *) ds);
 
-  jvm_argv[jvm_argc] = strdup (ci->values[0].value.string);
-  if (jvm_argv[jvm_argc] == NULL)
-  {
-    ERROR ("java plugin: strdup failed.");
-    return (-1);
-  }
-  jvm_argc++;
+  (*jvm_env)->ReleaseStringUTFChars (jvm_env, o_string_type, ds_name);
 
-  return (0);
-} /* }}} int cjni_config_add_jvm_arg */
+  if (ds == NULL)
+    return (NULL);
 
-static int cjni_config_load_plugin (oconfig_item_t *ci) /* {{{ */
+  o_dataset = ctoj_data_set (jvm_env, ds);
+  return (o_dataset);
+} /* }}} jint cjni_api_get_ds */
+
+static jint JNICALL cjni_api_register_config (JNIEnv *jvm_env, /* {{{ */
+    jobject this, jobject o_name, jobject o_config)
 {
-  java_plugin_t *jp;
+  return (cjni_callback_register (jvm_env, o_name, o_config, CB_TYPE_CONFIG));
+} /* }}} jint cjni_api_register_config */
 
-  if ((ci->values_num != 1) || (ci->values[0].type != OCONFIG_TYPE_STRING))
-  {
-    WARNING ("java plugin: `LoadPlugin' needs exactly one string argument.");
-    return (-1);
+static jint JNICALL cjni_api_register_init (JNIEnv *jvm_env, /* {{{ */
+    jobject this, jobject o_name, jobject o_config)
+{
+  return (cjni_callback_register (jvm_env, o_name, o_config, CB_TYPE_INIT));
+} /* }}} jint cjni_api_register_init */
+
+static jint JNICALL cjni_api_register_read (JNIEnv *jvm_env, /* {{{ */
+    jobject this, jobject o_name, jobject o_read)
+{
+  user_data_t ud;
+  cjni_callback_info_t *cbi;
+
+  cbi = cjni_callback_info_create (jvm_env, o_name, o_read, CB_TYPE_READ);
+  if (cbi == NULL)
+    return (-1);
+
+  DEBUG ("java plugin: Registering new read callback: %s", cbi->name);
+
+  memset (&ud, 0, sizeof (ud));
+  ud.data = (void *) cbi;
+  ud.free_func = cjni_callback_info_destroy;
+
+  plugin_register_complex_read (cbi->name, cjni_read, &ud);
+
+  (*jvm_env)->DeleteLocalRef (jvm_env, o_read);
+
+  return (0);
+} /* }}} jint cjni_api_register_read */
+
+static jint JNICALL cjni_api_register_write (JNIEnv *jvm_env, /* {{{ */
+    jobject this, jobject o_name, jobject o_write)
+{
+  user_data_t ud;
+  cjni_callback_info_t *cbi;
+
+  cbi = cjni_callback_info_create (jvm_env, o_name, o_write, CB_TYPE_WRITE);
+  if (cbi == NULL)
+    return (-1);
+
+  DEBUG ("java plugin: Registering new write callback: %s", cbi->name);
+
+  memset (&ud, 0, sizeof (ud));
+  ud.data = (void *) cbi;
+  ud.free_func = cjni_callback_info_destroy;
+
+  plugin_register_write (cbi->name, cjni_write, &ud);
+
+  (*jvm_env)->DeleteLocalRef (jvm_env, o_write);
+
+  return (0);
+} /* }}} jint cjni_api_register_write */
+
+static jint JNICALL cjni_api_register_flush (JNIEnv *jvm_env, /* {{{ */
+    jobject this, jobject o_name, jobject o_flush)
+{
+  user_data_t ud;
+  cjni_callback_info_t *cbi;
+
+  cbi = cjni_callback_info_create (jvm_env, o_name, o_flush, CB_TYPE_FLUSH);
+  if (cbi == NULL)
+    return (-1);
+
+  DEBUG ("java plugin: Registering new flush callback: %s", cbi->name);
+
+  memset (&ud, 0, sizeof (ud));
+  ud.data = (void *) cbi;
+  ud.free_func = cjni_callback_info_destroy;
+
+  plugin_register_flush (cbi->name, cjni_flush, &ud);
+
+  (*jvm_env)->DeleteLocalRef (jvm_env, o_flush);
+
+  return (0);
+} /* }}} jint cjni_api_register_flush */
+
+static jint JNICALL cjni_api_register_shutdown (JNIEnv *jvm_env, /* {{{ */
+    jobject this, jobject o_name, jobject o_shutdown)
+{
+  return (cjni_callback_register (jvm_env, o_name, o_shutdown,
+        CB_TYPE_SHUTDOWN));
+} /* }}} jint cjni_api_register_shutdown */
+
+static jint JNICALL cjni_api_register_log (JNIEnv *jvm_env, /* {{{ */
+    jobject this, jobject o_name, jobject o_log)
+{
+  user_data_t ud;
+  cjni_callback_info_t *cbi;
+
+  cbi = cjni_callback_info_create (jvm_env, o_name, o_log, CB_TYPE_LOG);
+  if (cbi == NULL)
+    return (-1);
+
+  DEBUG ("java plugin: Registering new log callback: %s", cbi->name);
+
+  memset (&ud, 0, sizeof (ud));
+  ud.data = (void *) cbi;
+  ud.free_func = cjni_callback_info_destroy;
+
+  plugin_register_log (cbi->name, cjni_log, &ud);
+
+  (*jvm_env)->DeleteLocalRef (jvm_env, o_log);
+
+  return (0);
+} /* }}} jint cjni_api_register_log */
+
+static jint JNICALL cjni_api_register_notification (JNIEnv *jvm_env, /* {{{ */
+    jobject this, jobject o_name, jobject o_notification)
+{
+  user_data_t ud;
+  cjni_callback_info_t *cbi;
+
+  cbi = cjni_callback_info_create (jvm_env, o_name, o_notification,
+      CB_TYPE_NOTIFICATION);
+  if (cbi == NULL)
+    return (-1);
+
+  DEBUG ("java plugin: Registering new notification callback: %s", cbi->name);
+
+  memset (&ud, 0, sizeof (ud));
+  ud.data = (void *) cbi;
+  ud.free_func = cjni_callback_info_destroy;
+
+  plugin_register_notification (cbi->name, cjni_notification, &ud);
+
+  (*jvm_env)->DeleteLocalRef (jvm_env, o_notification);
+
+  return (0);
+} /* }}} jint cjni_api_register_notification */
+
+static void JNICALL cjni_api_log (JNIEnv *jvm_env, /* {{{ */
+    jobject this, jint severity, jobject o_message)
+{
+  const char *c_str;
+
+  c_str = (*jvm_env)->GetStringUTFChars (jvm_env, o_message, 0);
+  if (c_str == NULL)
+  {
+    ERROR ("java plugin: cjni_api_log: GetStringUTFChars failed.");
+    return;
+  }
+
+  if (severity < LOG_ERR)
+    severity = LOG_ERR;
+  if (severity > LOG_DEBUG)
+    severity = LOG_DEBUG;
+
+  plugin_log (severity, "%s", c_str);
+
+  (*jvm_env)->ReleaseStringUTFChars (jvm_env, o_message, c_str);
+} /* }}} void cjni_api_log */
+
+/* List of ``native'' functions, i. e. C-functions that can be called from
+ * Java. */
+static JNINativeMethod jni_api_functions[] = /* {{{ */
+{
+  { "dispatchValues",
+    "(Lorg/collectd/api/ValueList;)I",
+    cjni_api_dispatch_values },
+
+  { "getDS",
+    "(Ljava/lang/String;)Lorg/collectd/api/DataSet;",
+    cjni_api_get_ds },
+
+  { "registerConfig",
+    "(Ljava/lang/String;Lorg/collectd/api/CollectdConfigInterface;)I",
+    cjni_api_register_config },
+
+  { "registerInit",
+    "(Ljava/lang/String;Lorg/collectd/api/CollectdInitInterface;)I",
+    cjni_api_register_init },
+
+  { "registerRead",
+    "(Ljava/lang/String;Lorg/collectd/api/CollectdReadInterface;)I",
+    cjni_api_register_read },
+
+  { "registerWrite",
+    "(Ljava/lang/String;Lorg/collectd/api/CollectdWriteInterface;)I",
+    cjni_api_register_write },
+
+  { "registerFlush",
+    "(Ljava/lang/String;Lorg/collectd/api/CollectdFlushInterface;)I",
+    cjni_api_register_flush },
+
+  { "registerShutdown",
+    "(Ljava/lang/String;Lorg/collectd/api/CollectdShutdownInterface;)I",
+    cjni_api_register_shutdown },
+
+  { "registerLog",
+    "(Ljava/lang/String;Lorg/collectd/api/CollectdLogInterface;)I",
+    cjni_api_register_log },
+
+  { "registerNotification",
+    "(Ljava/lang/String;Lorg/collectd/api/CollectdNotificationInterface;)I",
+    cjni_api_register_notification },
+
+  { "log",
+    "(ILjava/lang/String;)V",
+    cjni_api_log },
+};
+static size_t jni_api_functions_num = sizeof (jni_api_functions)
+  / sizeof (jni_api_functions[0]);
+/* }}} */
+
+/*
+ * Functions
+ */
+/* Allocate a `cjni_callback_info_t' given the type and objects necessary for
+ * all registration functions. */
+static cjni_callback_info_t *cjni_callback_info_create (JNIEnv *jvm_env, /* {{{ */
+    jobject o_name, jobject o_callback, int type)
+{
+  const char *c_name;
+  cjni_callback_info_t *cbi;
+  const char *method_name;
+  const char *method_signature;
+
+  switch (type)
+  {
+    case CB_TYPE_CONFIG:
+      method_name = "config";
+      method_signature = "(Lorg/collectd/api/OConfigItem;)I";
+      break;
+
+    case CB_TYPE_INIT:
+      method_name = "init";
+      method_signature = "()I";
+      break;
+
+    case CB_TYPE_READ:
+      method_name = "read";
+      method_signature = "()I";
+      break;
+
+    case CB_TYPE_WRITE:
+      method_name = "write";
+      method_signature = "(Lorg/collectd/api/ValueList;)I";
+      break;
+
+    case CB_TYPE_FLUSH:
+      method_name = "flush";
+      method_signature = "(ILjava/lang/String;)I";
+      break;
+
+    case CB_TYPE_SHUTDOWN:
+      method_name = "shutdown";
+      method_signature = "()I";
+      break;
+
+    case CB_TYPE_LOG:
+      method_name = "log";
+      method_signature = "(ILjava/lang/String;)V";
+      break;
+
+    case CB_TYPE_NOTIFICATION:
+      method_name = "notification";
+      method_signature = "(LLorg/collectd/api/Notification;)I";
+      break;
+
+    default:
+      ERROR ("java plugin: cjni_callback_info_create: Unknown type: %#x",
+          type);
+      return (NULL);
+  }
+
+  c_name = (*jvm_env)->GetStringUTFChars (jvm_env, o_name, 0);
+  if (c_name == NULL)
+  {
+    ERROR ("java plugin: cjni_callback_info_create: "
+        "GetStringUTFChars failed.");
+    return (NULL);
+  }
+
+  cbi = (cjni_callback_info_t *) malloc (sizeof (*cbi));
+  if (cbi == NULL)
+  {
+    ERROR ("java plugin: cjni_callback_info_create: malloc failed.");
+    (*jvm_env)->ReleaseStringUTFChars (jvm_env, o_name, c_name);
+    return (NULL);
+  }
+  memset (cbi, 0, sizeof (*cbi));
+  cbi->type = type;
+
+  cbi->name = strdup (c_name);
+  if (cbi->name == NULL)
+  {
+    pthread_mutex_unlock (&java_callbacks_lock);
+    ERROR ("java plugin: cjni_callback_info_create: strdup failed.");
+    (*jvm_env)->ReleaseStringUTFChars (jvm_env, o_name, c_name);
+    return (NULL);
+  }
+
+  (*jvm_env)->ReleaseStringUTFChars (jvm_env, o_name, c_name);
+
+  cbi->class  = (*jvm_env)->GetObjectClass (jvm_env, o_callback);
+  if (cbi->class == NULL)
+  {
+    ERROR ("java plugin: cjni_callback_info_create: GetObjectClass failed.");
+    free (cbi);
+    return (NULL);
+  }
+
+  cbi->object = o_callback;
+
+  cbi->method = (*jvm_env)->GetMethodID (jvm_env, cbi->class,
+      method_name, method_signature);
+  if (cbi->method == NULL)
+  {
+    ERROR ("java plugin: cjni_callback_info_create: "
+        "Cannot find the `%s' method with signature `%s'.",
+        method_name, method_signature);
+    free (cbi);
+    return (NULL);
+  }
+
+  (*jvm_env)->NewGlobalRef (jvm_env, o_callback);
+
+  return (cbi);
+} /* }}} cjni_callback_info_t cjni_callback_info_create */
+
+/* Allocate a `cjni_callback_info_t' via `cjni_callback_info_create' and add it
+ * to the global `java_callbacks' variable. This is used for `config', `init',
+ * and `shutdown' callbacks. */
+static int cjni_callback_register (JNIEnv *jvm_env, /* {{{ */
+    jobject o_name, jobject o_callback, int type)
+{
+  cjni_callback_info_t *cbi;
+  cjni_callback_info_t *tmp;
+#if COLLECT_DEBUG
+  const char *type_str;
+#endif
+
+  cbi = cjni_callback_info_create (jvm_env, o_name, o_callback, type);
+  if (cbi == NULL)
+    return (-1);
+
+#if COLLECT_DEBUG
+  switch (type)
+  {
+    case CB_TYPE_CONFIG:
+      type_str = "config";
+      break;
+
+    case CB_TYPE_INIT:
+      type_str = "init";
+      break;
+
+    case CB_TYPE_SHUTDOWN:
+      type_str = "shutdown";
+      break;
+
+    default:
+      type_str = "<unknown>";
   }
+  DEBUG ("java plugin: Registering new %s callback: %s",
+      type_str, cbi->name);
+#endif
+
+  pthread_mutex_lock (&java_callbacks_lock);
+
+  tmp = (cjni_callback_info_t *) realloc (java_callbacks,
+      (java_callbacks_num + 1) * sizeof (*java_callbacks));
+  if (tmp == NULL)
+  {
+    pthread_mutex_unlock (&java_callbacks_lock);
+    ERROR ("java plugin: cjni_callback_register: realloc failed.");
+
+    (*jvm_env)->DeleteGlobalRef (jvm_env, cbi->object);
+    free (cbi);
+
+    return (-1);
+  }
+  java_callbacks = tmp;
+  java_callbacks[java_callbacks_num] = *cbi;
+  java_callbacks_num++;
+
+  pthread_mutex_unlock (&java_callbacks_lock);
+
+  free (cbi);
+  return (0);
+} /* }}} int cjni_callback_register */
+
+/* Increase the reference counter to the JVM for this thread. If it was zero,
+ * attach the JVM first. */
+static JNIEnv *cjni_thread_attach (void) /* {{{ */
+{
+  cjni_jvm_env_t *cjni_env;
+  JNIEnv *jvm_env;
+
+  cjni_env = pthread_getspecific (jvm_env_key);
+  if (cjni_env == NULL)
+  {
+    /* This pointer is free'd in `cjni_jvm_env_destroy'. */
+    cjni_env = (cjni_jvm_env_t *) malloc (sizeof (*cjni_env));
+    if (cjni_env == NULL)
+    {
+      ERROR ("java plugin: cjni_thread_attach: malloc failed.");
+      return (NULL);
+    }
+    memset (cjni_env, 0, sizeof (*cjni_env));
+    cjni_env->reference_counter = 0;
+    cjni_env->jvm_env = NULL;
 
-  jp = (java_plugin_t *) realloc (java_plugins,
-      sizeof (*java_plugins) * (java_plugins_num + 1));
-  if (jp == NULL)
+    pthread_setspecific (jvm_env_key, cjni_env);
+  }
+
+  if (cjni_env->reference_counter > 0)
+  {
+    cjni_env->reference_counter++;
+    jvm_env = cjni_env->jvm_env;
+  }
+  else
+  {
+    int status;
+    JavaVMAttachArgs args;
+
+    assert (cjni_env->jvm_env == NULL);
+
+    memset (&args, 0, sizeof (args));
+    args.version = JNI_VERSION_1_2;
+
+    status = (*jvm)->AttachCurrentThread (jvm, (void *) &jvm_env, (void *) &args);
+    if (status != 0)
+    {
+      ERROR ("java plugin: cjni_thread_attach: AttachCurrentThread failed "
+          "with status %i.", status);
+      return (NULL);
+    }
+
+    cjni_env->reference_counter = 1;
+    cjni_env->jvm_env = jvm_env;
+  }
+
+  DEBUG ("java plugin: cjni_thread_attach: cjni_env->reference_counter = %i",
+      cjni_env->reference_counter);
+  assert (jvm_env != NULL);
+  return (jvm_env);
+} /* }}} JNIEnv *cjni_thread_attach */
+
+/* Decrease the reference counter of this thread. If it reaches zero, detach
+ * from the JVM. */
+static int cjni_thread_detach (void) /* {{{ */
+{
+  cjni_jvm_env_t *cjni_env;
+  int status;
+
+  cjni_env = pthread_getspecific (jvm_env_key);
+  if (cjni_env == NULL)
+  {
+    ERROR ("java plugin: cjni_thread_detach: pthread_getspecific failed.");
+    return (-1);
+  }
+
+  assert (cjni_env->reference_counter > 0);
+  assert (cjni_env->jvm_env != NULL);
+
+  cjni_env->reference_counter--;
+  DEBUG ("java plugin: cjni_thread_detach: cjni_env->reference_counter = %i",
+      cjni_env->reference_counter);
+
+  if (cjni_env->reference_counter > 0)
+    return (0);
+
+  status = (*jvm)->DetachCurrentThread (jvm);
+  if (status != 0)
+  {
+    ERROR ("java plugin: cjni_thread_detach: DetachCurrentThread failed "
+        "with status %i.", status);
+  }
+
+  cjni_env->reference_counter = 0;
+  cjni_env->jvm_env = NULL;
+
+  return (0);
+} /* }}} JNIEnv *cjni_thread_attach */
+
+/* Callback for `pthread_key_create'. It frees the data contained in
+ * `jvm_env_key' and prints a warning if the reference counter is not zero. */
+static void cjni_jvm_env_destroy (void *args) /* {{{ */
+{
+  cjni_jvm_env_t *cjni_env;
+
+  if (args == NULL)
+    return;
+
+  cjni_env = (cjni_jvm_env_t *) args;
+
+  if (cjni_env->reference_counter > 0)
+  {
+    ERROR ("java plugin: cjni_jvm_env_destroy: "
+        "cjni_env->reference_counter = %i;", cjni_env->reference_counter);
+  }
+
+  if (cjni_env->jvm_env != NULL)
+  {
+    ERROR ("java plugin: cjni_jvm_env_destroy: cjni_env->jvm_env = %p;",
+        (void *) cjni_env->jvm_env);
+  }
+
+  /* The pointer is allocated in `cjni_thread_attach' */
+  free (cjni_env);
+} /* }}} void cjni_jvm_env_destroy */
+
+/* Boring configuration functions.. {{{ */
+static int cjni_config_add_jvm_arg (oconfig_item_t *ci) /* {{{ */
+{
+  char **tmp;
+
+  if ((ci->values_num != 1) || (ci->values[0].type != OCONFIG_TYPE_STRING))
+  {
+    WARNING ("java plugin: `JVMArg' needs exactly one string argument.");
+    return (-1);
+  }
+
+  tmp = (char **) realloc (jvm_argv, sizeof (char *) * (jvm_argc + 1));
+  if (tmp == NULL)
   {
     ERROR ("java plugin: realloc failed.");
     return (-1);
   }
-  java_plugins = jp;
-  jp = java_plugins + java_plugins_num;
+  jvm_argv = tmp;
 
-  memset (jp, 0, sizeof (*jp));
-  jp->class_name = strdup (ci->values[0].value.string);
-  if (jp->class_name == NULL)
+  jvm_argv[jvm_argc] = strdup (ci->values[0].value.string);
+  if (jvm_argv[jvm_argc] == NULL)
   {
     ERROR ("java plugin: strdup failed.");
     return (-1);
   }
+  jvm_argc++;
+
+  return (0);
+} /* }}} int cjni_config_add_jvm_arg */
+
+static int cjni_config_load_plugin (oconfig_item_t *ci) /* {{{ */
+{
+  java_plugin_class_t *tmp;
+
+  if ((ci->values_num != 1) || (ci->values[0].type != OCONFIG_TYPE_STRING))
+  {
+    WARNING ("java plugin: `LoadPlugin' needs exactly one string argument.");
+    return (-1);
+  }
+
+  tmp = (java_plugin_class_t *) realloc (java_classes_list,
+      (java_classes_list_len + 1) * sizeof (*java_classes_list));
+  if (tmp == NULL)
+  {
+    ERROR ("java plugin: realloc failed.");
+    return (-1);
+  }
+  java_classes_list = tmp;
+  tmp = java_classes_list + java_classes_list_len;
 
-  jp->class_ptr  = NULL;
-  jp->object_ptr = NULL;
-  jp->flags      = 0;
-  jp->m_init     = NULL;
-  jp->m_read     = NULL;
-  jp->m_write    = NULL;
-  jp->m_shutdown = NULL;
+  memset (tmp, 0, sizeof (*tmp));
+  tmp->name = strdup (ci->values[0].value.string);
+  if (tmp->name == NULL)
+  {
+    ERROR ("java plugin: strdup failed.");
+    return (-1);
+  }
+  tmp->class = NULL;
+  tmp->object = NULL;
 
-  java_plugins_num++;
+  java_classes_list_len++;
 
   return (0);
 } /* }}} int cjni_config_load_plugin */
 
+static int cjni_config_plugin_block (oconfig_item_t *ci) /* {{{ */
+{
+  java_plugin_config_t *tmp;
+  char *name;
+  size_t i;
+
+  if ((ci->values_num != 1) || (ci->values[0].type != OCONFIG_TYPE_STRING))
+  {
+    WARNING ("java plugin: `Plugin' blocks "
+        "need exactly one string argument.");
+    return (-1);
+  }
+
+  name = strdup (ci->values[0].value.string);
+  if (name == NULL)
+  {
+    ERROR ("java plugin: cjni_config_plugin_block: strdup faiiled.");
+    return (-1);
+  }
+
+  for (i = 0; i < java_plugin_configs_num; i++)
+  {
+    if (strcmp (java_plugin_configs[i].name, name) == 0)
+    {
+      WARNING ("java plugin: There is more than one <Plugin \"%s\"> block. "
+          "This is currently not supported - "
+          "only the first block will be used!",
+          name);
+      free (name);
+      return (0);
+    }
+  }
+
+  tmp = (java_plugin_config_t *) realloc (java_plugin_configs,
+      (java_plugin_configs_num + 1) * sizeof (*java_plugin_configs));
+  if (tmp == NULL)
+  {
+    ERROR ("java plugin: cjni_config_plugin_block: realloc failed.");
+    free (name);
+    return (-1);
+  }
+  java_plugin_configs = tmp;
+  tmp = java_plugin_configs + java_plugin_configs_num;
+
+  tmp->name = name;
+  tmp->ci = oconfig_clone (ci);
+  if (tmp->ci == NULL)
+  {
+    ERROR ("java plugin: cjni_config_plugin_block: "
+        "oconfig_clone failed for `%s'.",
+        name);
+    free (name);
+    return (-1);
+  }
+
+  DEBUG ("java plugin: cjni_config_plugin_block: "
+      "Successfully copied config for `%s'.",
+      name);
+
+  java_plugin_configs_num++;
+  return (0);
+} /* }}} int cjni_config_plugin_block */
+
 static int cjni_config (oconfig_item_t *ci) /* {{{ */
 {
   int success;
@@ -1018,6 +1944,14 @@ static int cjni_config (oconfig_item_t *ci) /* {{{ */
       else
         errors++;
     }
+    else if (strcasecmp ("Plugin", child->key) == 0)
+    {
+      status = cjni_config_plugin_block (child);
+      if (status == 0)
+        success++;
+      else
+        errors++;
+    }
     else
     {
       WARNING ("java plugin: Option `%s' not allowed here.", child->key);
@@ -1025,6 +1959,11 @@ static int cjni_config (oconfig_item_t *ci) /* {{{ */
     }
   }
 
+  DEBUG ("java plugin: jvm_argc = %zu;", jvm_argc);
+  DEBUG ("java plugin: java_classes_list_len = %zu;", java_classes_list_len);
+  DEBUG ("java plugin: java_plugin_configs_num = %zu;",
+      java_plugin_configs_num);
+
   if ((success == 0) && (errors > 0))
   {
     ERROR ("java plugin: All statements failed.");
@@ -1033,202 +1972,232 @@ static int cjni_config (oconfig_item_t *ci) /* {{{ */
 
   return (0);
 } /* }}} int cjni_config */
+/* }}} */
 
-static int cjni_init_one_plugin (JNIEnv *jvm_env, java_plugin_t *jp) /* {{{ */
+/* Free the data contained in the `user_data_t' pointer passed to `cjni_read'
+ * and `cjni_write'. In particular, delete the global reference to the Java
+ * object. */
+static void cjni_callback_info_destroy (void *arg) /* {{{ */
 {
-  jmethodID constructor_id;
-  int status;
+  JNIEnv *jvm_env;
+  cjni_callback_info_t *cbi;
+
+  DEBUG ("java plugin: cjni_callback_info_destroy (arg = %p);", arg);
+
+  cbi = (cjni_callback_info_t *) arg;
 
-  jp->class_ptr = (*jvm_env)->FindClass (jvm_env, jp->class_name);
-  if (jp->class_ptr == NULL)
+  /* This condition can occurr when shutting down. */
+  if (jvm == NULL)
   {
-    ERROR ("cjni_init_one_plugin: FindClass (%s) failed.",
-        jp->class_name);
-    return (-1);
+    sfree (cbi);
+    return;
   }
 
-  constructor_id = (*jvm_env)->GetMethodID (jvm_env, jp->class_ptr,
-      "<init>", "()V");
-  if (constructor_id == NULL)
+  if (arg == NULL)
+    return;
+
+  jvm_env = cjni_thread_attach ();
+  if (jvm_env == NULL)
   {
-    ERROR ("cjni_init_one_plugin: Could not find the constructor for `%s'.",
-        jp->class_name);
-    return (-1);
+    ERROR ("java plugin: cjni_callback_info_destroy: cjni_thread_attach failed.");
+    return;
   }
 
-  jp->object_ptr = (*jvm_env)->NewObject (jvm_env, jp->class_ptr,
-      constructor_id);
-  if (jp->object_ptr == NULL)
+  (*jvm_env)->DeleteGlobalRef (jvm_env, cbi->object);
+
+  cbi->method = NULL;
+  cbi->object = NULL;
+  cbi->class  = NULL;
+  free (cbi);
+
+  cjni_thread_detach ();
+} /* }}} void cjni_callback_info_destroy */
+
+/* Call the CB_TYPE_READ callback pointed to by the `user_data_t' pointer. */
+static int cjni_read (user_data_t *ud) /* {{{ */
+{
+  JNIEnv *jvm_env;
+  cjni_callback_info_t *cbi;
+  int status;
+  int ret_status;
+
+  if (jvm == NULL)
   {
-    ERROR ("cjni_init_one_plugin: Could create a new `%s' object.",
-        jp->class_name);
+    ERROR ("java plugin: cjni_read: jvm == NULL");
     return (-1);
   }
 
-  jp->m_init = (*jvm_env)->GetMethodID (jvm_env, jp->class_ptr,
-      "Init", "()I");
-  DEBUG ("java plugin: cjni_init_one_plugin: "
-      "jp->class_name = %s; jp->m_init = %p;",
-      jp->class_name, (void *) jp->m_init);
+  if ((ud == NULL) || (ud->data == NULL))
+  {
+    ERROR ("java plugin: cjni_read: Invalid user data.");
+    return (-1);
+  }
 
-  jp->m_read = (*jvm_env)->GetMethodID (jvm_env, jp->class_ptr,
-      "Read", "()I");
-  DEBUG ("java plugin: cjni_init_one_plugin: "
-      "jp->class_name = %s; jp->m_read = %p;",
-      jp->class_name, (void *) jp->m_read);
+  jvm_env = cjni_thread_attach ();
+  if (jvm_env == NULL)
+    return (-1);
 
-  jp->m_write = (*jvm_env)->GetMethodID (jvm_env, jp->class_ptr,
-      "Write", "(Lorg/collectd/protocol/ValueList;)I");
-  DEBUG ("java plugin: cjni_init_one_plugin: "
-      "jp->class_name = %s; jp->m_write = %p;",
-      jp->class_name, (void *) jp->m_write);
+  cbi = (cjni_callback_info_t *) ud->data;
 
-  jp->m_shutdown = (*jvm_env)->GetMethodID (jvm_env, jp->class_ptr,
-      "Shutdown", "()I");
-  DEBUG ("java plugin: cjni_init_one_plugin: "
-      "jp->class_name = %s; jp->m_shutdown = %p;",
-      jp->class_name, (void *) jp->m_shutdown);
+  ret_status = (*jvm_env)->CallIntMethod (jvm_env, cbi->object,
+      cbi->method);
 
-  if (jp->m_init != NULL)
+  status = cjni_thread_detach ();
+  if (status != 0)
   {
-    status = (*jvm_env)->CallIntMethod (jvm_env, jp->object_ptr,
-        jp->m_init);
-    if (status != 0)
-    {
-      ERROR ("cjni_init_one_plugin: Initializing `%s' object failed "
-          "with status %i.", jp->class_name, status);
-      return (-1);
-    }
+    ERROR ("java plugin: cjni_read: cjni_thread_detach failed.");
+    return (-1);
   }
-  jp->flags |= CJNI_FLAG_ENABLED;
 
-  return (0);
-} /* }}} int cjni_init_one_plugin */
+  return (ret_status);
+} /* }}} int cjni_read */
 
-static int cjni_init_plugins (JNIEnv *jvm_env) /* {{{ */
+/* Call the CB_TYPE_WRITE callback pointed to by the `user_data_t' pointer. */
+static int cjni_write (const data_set_t *ds, const value_list_t *vl, /* {{{ */
+    user_data_t *ud)
 {
-  size_t j;
+  JNIEnv *jvm_env;
+  cjni_callback_info_t *cbi;
+  jobject vl_java;
+  int status;
+  int ret_status;
 
-  for (j = 0; j < java_plugins_num; j++)
-    cjni_init_one_plugin (jvm_env, &java_plugins[j]);
+  if (jvm == NULL)
+  {
+    ERROR ("java plugin: cjni_write: jvm == NULL");
+    return (-1);
+  }
 
-  return (0);
-} /* }}} int cjni_init_plugins */
+  if ((ud == NULL) || (ud->data == NULL))
+  {
+    ERROR ("java plugin: cjni_write: Invalid user data.");
+    return (-1);
+  }
 
-static int cjni_init_native (JNIEnv *jvm_env) /* {{{ */
-{
-  jclass api_class_ptr;
-  int status;
+  jvm_env = cjni_thread_attach ();
+  if (jvm_env == NULL)
+    return (-1);
 
-  api_class_ptr = (*jvm_env)->FindClass (jvm_env, "org.collectd.java.CollectdAPI");
-  if (api_class_ptr == NULL)
+  cbi = (cjni_callback_info_t *) ud->data;
+
+  vl_java = ctoj_value_list (jvm_env, ds, vl);
+  if (vl_java == NULL)
   {
-    ERROR ("cjni_init_native: Cannot find API class `org.collectd.java.CollectdAPI'.");
+    ERROR ("java plugin: cjni_write: ctoj_value_list failed.");
     return (-1);
   }
 
-  status = (*jvm_env)->RegisterNatives (jvm_env, api_class_ptr,
-      jni_api_functions, (jint) jni_api_functions_num);
+  ret_status = (*jvm_env)->CallIntMethod (jvm_env,
+      cbi->object, cbi->method, vl_java);
+
+  (*jvm_env)->DeleteLocalRef (jvm_env, vl_java);
+
+  status = cjni_thread_detach ();
   if (status != 0)
   {
-    ERROR ("cjni_init_native: RegisterNatives failed with status %i.", status);
+    ERROR ("java plugin: cjni_write: cjni_thread_detach failed.");
     return (-1);
   }
 
-  return (0);
-} /* }}} int cjni_init_native */
+  return (ret_status);
+} /* }}} int cjni_write */
 
-static int cjni_init (void) /* {{{ */
+/* Call the CB_TYPE_FLUSH callback pointed to by the `user_data_t' pointer. */
+static int cjni_flush (int timeout, const char *identifier, /* {{{ */
+    user_data_t *ud)
 {
   JNIEnv *jvm_env;
-  JavaVMInitArgs vm_args;
-  JavaVMOption vm_options[jvm_argc];
-
+  cjni_callback_info_t *cbi;
+  jobject o_identifier;
   int status;
-  size_t i;
-
-  if (jvm != NULL)
-    return (0);
-
-  jvm_env = NULL;
-
-  memset (&vm_args, 0, sizeof (vm_args));
-  vm_args.version = JNI_VERSION_1_2;
-  vm_args.options = vm_options;
-  vm_args.nOptions = (jint) jvm_argc;
-
-  for (i = 0; i < jvm_argc; i++)
-  {
-    DEBUG ("java plugin: cjni_init: jvm_argv[%zu] = %s", i, jvm_argv[i]);
-    vm_args.options[i].optionString = jvm_argv[i];
-  }
-  /*
-  vm_args.options[0].optionString = "-verbose:jni";
-  vm_args.options[1].optionString = "-Djava.class.path=/home/octo/collectd/bindings/java";
-  */
+  int ret_status;
 
-  status = JNI_CreateJavaVM (&jvm, (void **) &jvm_env, (void **) &vm_args);
-  if (status != 0)
+  if (jvm == NULL)
   {
-    ERROR ("cjni_init: JNI_CreateJavaVM failed with status %i.",
-	status);
+    ERROR ("java plugin: cjni_flush: jvm == NULL");
     return (-1);
   }
-  assert (jvm != NULL);
-  assert (jvm_env != NULL);
 
-  /* Call RegisterNatives */
-  status = cjni_init_native (jvm_env);
-  if (status != 0)
+  if ((ud == NULL) || (ud->data == NULL))
   {
-    ERROR ("cjni_init: cjni_init_native failed.");
+    ERROR ("java plugin: cjni_flush: Invalid user data.");
     return (-1);
   }
 
-  cjni_init_plugins (jvm_env);
+  jvm_env = cjni_thread_attach ();
+  if (jvm_env == NULL)
+    return (-1);
 
-  return (0);
-} /* }}} int cjni_init */
+  cbi = (cjni_callback_info_t *) ud->data;
 
-static int cjni_read_one_plugin (JNIEnv *jvm_env, java_plugin_t *jp) /* {{{ */
-{
-  int status;
+  o_identifier = NULL;
+  if (identifier != NULL)
+  {
+    o_identifier = (*jvm_env)->NewStringUTF (jvm_env, identifier);
+    if (o_identifier == NULL)
+    {
+      ERROR ("java plugin: cjni_flush: NewStringUTF failed.");
+      return (-1);
+    }
+  }
 
-  if ((jp == NULL)
-      || ((jp->flags & CJNI_FLAG_ENABLED) == 0)
-      || (jp->m_read == NULL))
-    return (0);
+  ret_status = (*jvm_env)->CallIntMethod (jvm_env,
+      cbi->object, cbi->method, (jint) timeout, o_identifier);
 
-  DEBUG ("java plugin: Calling: %s.Read()", jp->class_name);
+  (*jvm_env)->DeleteLocalRef (jvm_env, o_identifier);
 
-  status = (*jvm_env)->CallIntMethod (jvm_env, jp->object_ptr,
-      jp->m_read);
+  status = cjni_thread_detach ();
   if (status != 0)
   {
-    ERROR ("java plugin: cjni_read_one_plugin: "
-        "Calling `Read' on an `%s' object failed with status %i.",
-        jp->class_name, status);
+    ERROR ("java plugin: cjni_flush: cjni_thread_detach failed.");
     return (-1);
   }
 
-  return (0);
-} /* }}} int cjni_read_one_plugin */
+  return (ret_status);
+} /* }}} int cjni_flush */
 
-static int cjni_read_plugins (JNIEnv *jvm_env) /* {{{ */
+/* Call the CB_TYPE_LOG callback pointed to by the `user_data_t' pointer. */
+static void cjni_log (int severity, const char *message, /* {{{ */
+    user_data_t *ud)
 {
-  size_t j;
+  JNIEnv *jvm_env;
+  cjni_callback_info_t *cbi;
+  jobject o_message;
+
+  if (jvm == NULL)
+    return;
 
-  for (j = 0; j < java_plugins_num; j++)
-    cjni_read_one_plugin (jvm_env, &java_plugins[j]);
+  if ((ud == NULL) || (ud->data == NULL))
+    return;
 
-  return (0);
-} /* }}} int cjni_read_plugins */
+  jvm_env = cjni_thread_attach ();
+  if (jvm_env == NULL)
+    return;
+
+  cbi = (cjni_callback_info_t *) ud->data;
+
+  o_message = (*jvm_env)->NewStringUTF (jvm_env, message);
+  if (o_message == NULL)
+    return;
 
-static int cjni_read (void) /* {{{ */
+  (*jvm_env)->CallVoidMethod (jvm_env,
+      cbi->object, cbi->method, (jint) severity, o_message);
+
+  (*jvm_env)->DeleteLocalRef (jvm_env, o_message);
+
+  cjni_thread_detach ();
+} /* }}} void cjni_log */
+
+/* Call the CB_TYPE_NOTIFICATION callback pointed to by the `user_data_t'
+ * pointer. */
+static int cjni_notification (const notification_t *n, /* {{{ */
+    user_data_t *ud)
 {
   JNIEnv *jvm_env;
-  JavaVMAttachArgs args;
+  cjni_callback_info_t *cbi;
+  jobject o_notification;
   int status;
+  int ret_status;
 
   if (jvm == NULL)
   {
@@ -1236,89 +2205,200 @@ static int cjni_read (void) /* {{{ */
     return (-1);
   }
 
-  jvm_env = NULL;
-  memset (&args, 0, sizeof (args));
-  args.version = JNI_VERSION_1_2;
+  if ((ud == NULL) || (ud->data == NULL))
+  {
+    ERROR ("java plugin: cjni_read: Invalid user data.");
+    return (-1);
+  }
 
-  status = (*jvm)->AttachCurrentThread (jvm, (void **) &jvm_env, &args);
-  if (status != 0)
+  jvm_env = cjni_thread_attach ();
+  if (jvm_env == NULL)
+    return (-1);
+
+  cbi = (cjni_callback_info_t *) ud->data;
+
+  o_notification = ctoj_notification (jvm_env, n);
+  if (o_notification == NULL)
   {
-    ERROR ("java plugin: cjni_read: AttachCurrentThread failed with status %i.",
-        status);
+    ERROR ("java plugin: cjni_notification: ctoj_notification failed.");
     return (-1);
   }
 
-  cjni_read_plugins (jvm_env);
+  ret_status = (*jvm_env)->CallIntMethod (jvm_env,
+      cbi->object, cbi->method, o_notification);
 
-  status = (*jvm)->DetachCurrentThread (jvm);
+  (*jvm_env)->DeleteLocalRef (jvm_env, o_notification);
+
+  status = cjni_thread_detach ();
   if (status != 0)
   {
-    ERROR ("java plugin: cjni_read: DetachCurrentThread failed with status %i.",
-        status);
+    ERROR ("java plugin: cjni_read: cjni_thread_detach failed.");
     return (-1);
   }
 
+  return (ret_status);
+} /* }}} int cjni_notification */
+
+/* Iterate over `java_classes_list' and create one object of each class. This
+ * will trigger the object's constructors, to the objects can register callback
+ * methods. */
+static int cjni_load_plugins (JNIEnv *jvm_env) /* {{{ */
+{
+  size_t i;
+
+  for (i = 0; i < java_classes_list_len; i++)
+  {
+    java_plugin_class_t *class;
+    jmethodID constructor_id;
+
+    class = java_classes_list + i;
+
+    DEBUG ("java plugin: Loading class %s", class->name);
+
+    class->class = (*jvm_env)->FindClass (jvm_env, class->name);
+    if (class->class == NULL)
+    {
+      ERROR ("java plugin: cjni_load_plugins: FindClass (%s) failed.",
+          class->name);
+      continue;
+    }
+
+    constructor_id = (*jvm_env)->GetMethodID (jvm_env, class->class,
+        "<init>", "()V");
+    if (constructor_id == NULL)
+    {
+      ERROR ("java plugin: cjni_load_plugins: Could not find the constructor for `%s'.",
+          class->name);
+      continue;
+    }
+
+    class->object = (*jvm_env)->NewObject (jvm_env, class->class,
+        constructor_id);
+    if (class->object == NULL)
+    {
+      ERROR ("java plugin: cjni_load_plugins: Could create a new `%s' object.",
+          class->name);
+      continue;
+    }
+
+    (*jvm_env)->NewGlobalRef (jvm_env, class->object);
+  } /* for (i = 0; i < java_classes_list_len; i++) */
+
   return (0);
-} /* }}} int cjni_read */
+} /* }}} int cjni_load_plugins */
 
-static int cjni_write_one_plugin (JNIEnv *jvm_env, /* {{{ */
-    java_plugin_t *jp, jobject vl_java)
+/* Iterate over `java_plugin_configs' and `java_callbacks' and call all
+ * `config' callback methods for which a configuration is available. */
+static int cjni_config_plugins (JNIEnv *jvm_env) /* {{{ */
 {
   int status;
+  size_t i;
+  size_t j;
 
-  if ((jp == NULL)
-      || ((jp->flags & CJNI_FLAG_ENABLED) == 0)
-      || (jp->m_write == NULL))
-    return (0);
+  for (i = 0; i < java_plugin_configs_num; i++)
+  {
+    jobject o_ocitem;
 
-  DEBUG ("java plugin: Calling: %s.Write(ValueList)", jp->class_name);
+    if (java_plugin_configs[i].ci == NULL)
+      continue;
 
-  status = (*jvm_env)->CallIntMethod (jvm_env, jp->object_ptr,
-      jp->m_write, vl_java);
-  if (status != 0)
+    for (j = 0; j < java_callbacks_num; j++)
+    {
+      if (java_callbacks[j].type != CB_TYPE_CONFIG)
+        continue;
+
+      if (strcmp (java_plugin_configs[i].name, java_callbacks[j].name) == 0)
+        break;
+    }
+
+    if (j >= java_callbacks_num)
+    {
+      NOTICE ("java plugin: Configuration for `%s' is present, but no such "
+          "configuration callback has been registered.",
+          java_plugin_configs[i].name);
+      continue;
+    }
+
+    DEBUG ("java plugin: Configuring %s", java_plugin_configs[i].name);
+
+    o_ocitem = ctoj_oconfig_item (jvm_env, java_plugin_configs[i].ci);
+    if (o_ocitem == NULL)
+    {
+      ERROR ("java plugin: cjni_config_plugins: ctoj_oconfig_item failed.");
+      continue;
+    }
+
+    status = (*jvm_env)->CallIntMethod (jvm_env,
+        java_callbacks[j].object, java_callbacks[j].method, o_ocitem);
+    WARNING ("java plugin: Config callback for `%s' returned status %i.",
+        java_plugin_configs[i].name, status);
+  } /* for (i = 0; i < java_plugin_configs; i++) */
+
+  return (0);
+} /* }}} int cjni_config_plugins */
+
+/* Iterate over `java_callbacks' and call all CB_TYPE_INIT callbacks. */
+static int cjni_init_plugins (JNIEnv *jvm_env) /* {{{ */
+{
+  int status;
+  size_t i;
+
+  for (i = 0; i < java_callbacks_num; i++)
   {
-    ERROR ("java plugin: cjni_write_one_plugin: "
-        "Calling `Write' on an `%s' object failed with status %i.",
-        jp->class_name, status);
-    return (-1);
+    if (java_callbacks[i].type != CB_TYPE_INIT)
+      continue;
+
+    DEBUG ("java plugin: Initializing %s", java_callbacks[i].name);
+
+    status = (*jvm_env)->CallIntMethod (jvm_env,
+        java_callbacks[i].object, java_callbacks[i].method);
+    if (status != 0)
+    {
+      ERROR ("java plugin: Initializing `%s' failed with status %i. "
+          "Removing read function.",
+          java_callbacks[i].name, status);
+      plugin_unregister_read (java_callbacks[i].name);
+    }
   }
 
   return (0);
-} /* }}} int cjni_write_one_plugin */
+} /* }}} int cjni_init_plugins */
 
-static int cjni_write_plugins (JNIEnv *jvm_env, /* {{{ */
-    const data_set_t *ds, const value_list_t *vl)
+/* Iterate over `java_callbacks' and call all CB_TYPE_SHUTDOWN callbacks. */
+static int cjni_shutdown_plugins (JNIEnv *jvm_env) /* {{{ */
 {
-  size_t j;
-
-  jobject vl_java;
+  int status;
+  size_t i;
 
-  vl_java = ctoj_value_list (jvm_env, ds, vl);
-  if (vl_java == NULL)
+  for (i = 0; i < java_callbacks_num; i++)
   {
-    ERROR ("java plugin: cjni_write_plugins: ctoj_value_list failed.");
-    return (-1);
-  }
+    if (java_callbacks[i].type != CB_TYPE_SHUTDOWN)
+      continue;
 
-  for (j = 0; j < java_plugins_num; j++)
-    cjni_write_one_plugin (jvm_env, &java_plugins[j], vl_java);
+    DEBUG ("java plugin: Shutting down %s", java_callbacks[i].name);
 
-  (*jvm_env)->DeleteLocalRef (jvm_env, vl_java);
+    status = (*jvm_env)->CallIntMethod (jvm_env,
+        java_callbacks[i].object, java_callbacks[i].method);
+    if (status != 0)
+    {
+      ERROR ("java plugin: Shutting down `%s' failed with status %i. ",
+          java_callbacks[i].name, status);
+    }
+  }
 
   return (0);
-} /* }}} int cjni_write_plugins */
+} /* }}} int cjni_shutdown_plugins */
+
 
-static int cjni_write (const data_set_t *ds, const value_list_t *vl) /* {{{ */
+static int cjni_shutdown (void) /* {{{ */
 {
   JNIEnv *jvm_env;
   JavaVMAttachArgs args;
   int status;
+  size_t i;
 
   if (jvm == NULL)
-  {
-    ERROR ("java plugin: cjni_write: jvm == NULL");
-    return (-1);
-  }
+    return (0);
 
   jvm_env = NULL;
   memset (&args, 0, sizeof (args));
@@ -1327,108 +2407,159 @@ static int cjni_write (const data_set_t *ds, const value_list_t *vl) /* {{{ */
   status = (*jvm)->AttachCurrentThread (jvm, (void **) &jvm_env, &args);
   if (status != 0)
   {
-    ERROR ("java plugin: cjni_write: AttachCurrentThread failed with status %i.",
+    ERROR ("java plugin: cjni_shutdown: AttachCurrentThread failed with status %i.",
         status);
     return (-1);
   }
 
-  cjni_write_plugins (jvm_env, ds, vl);
+  /* Execute all the shutdown functions registered by plugins. */
+  cjni_shutdown_plugins (jvm_env);
+
+  /* Release all the global references to callback functions */
+  for (i = 0; i < java_callbacks_num; i++)
+  {
+    if (java_callbacks[i].object != NULL)
+    {
+      (*jvm_env)->DeleteGlobalRef (jvm_env, java_callbacks[i].object);
+      java_callbacks[i].object = NULL;
+    }
+    sfree (java_callbacks[i].name);
+  }
+  java_callbacks_num = 0;
+  sfree (java_callbacks);
 
-  status = (*jvm)->DetachCurrentThread (jvm);
-  if (status != 0)
+  /* Release all the global references to directly loaded classes. */
+  for (i = 0; i < java_classes_list_len; i++)
   {
-    ERROR ("java plugin: cjni_write: DetachCurrentThread failed with status %i.",
-        status);
-    return (-1);
+    if (java_classes_list[i].object != NULL)
+    {
+      (*jvm_env)->DeleteGlobalRef (jvm_env, java_classes_list[i].object);
+      java_classes_list[i].object = NULL;
+    }
+    sfree (java_classes_list[i].name);
   }
+  java_classes_list_len = 0;
+  sfree (java_classes_list);
 
-  return (0);
-} /* }}} int cjni_write */
+  /* Destroy the JVM */
+  DEBUG ("java plugin: Destroying the JVM.");
+  (*jvm)->DestroyJavaVM (jvm);
+  jvm = NULL;
+  jvm_env = NULL;
 
-static int cjni_shutdown_one_plugin (JNIEnv *jvm_env, /* {{{ */
-    java_plugin_t *jp)
-{
-  int status;
+  pthread_key_delete (jvm_env_key);
 
-  if ((jp == NULL)
-      || ((jp->flags & CJNI_FLAG_ENABLED) == 0)
-      || (jp->m_shutdown == NULL))
-    return (0);
+  /* Free the JVM argument list */
+  for (i = 0; i < jvm_argc; i++)
+    sfree (jvm_argv[i]);
+  jvm_argc = 0;
+  sfree (jvm_argv);
 
-  status = (*jvm_env)->CallIntMethod (jvm_env, jp->object_ptr,
-      jp->m_shutdown);
-  if (status != 0)
+  /* Free the copied configuration */
+  for (i = 0; i < java_plugin_configs_num; i++)
   {
-    ERROR ("cjni_shutdown_one_plugin: Destroying an `%s' object failed "
-        "with status %i.", jp->class_name, status);
-    return (-1);
+    sfree (java_plugin_configs[i].name);
+    oconfig_free (java_plugin_configs[i].ci);
   }
-  jp->flags &= ~CJNI_FLAG_ENABLED;
+  java_plugin_configs_num = 0;
+  sfree (java_plugin_configs);
 
   return (0);
-} /* }}} int cjni_shutdown_one_plugin */
+} /* }}} int cjni_shutdown */
 
-static int cjni_shutdown_plugins (JNIEnv *jvm_env) /* {{{ */
+/* Register ``native'' functions with the JVM. Native functions are C-functions
+ * that can be called by Java code. */
+static int cjni_init_native (JNIEnv *jvm_env) /* {{{ */
 {
-  size_t j;
+  jclass api_class_ptr;
+  int status;
+
+  api_class_ptr = (*jvm_env)->FindClass (jvm_env, "org.collectd.api.Collectd");
+  if (api_class_ptr == NULL)
+  {
+    ERROR ("cjni_init_native: Cannot find API class `org.collectd.api.Collectd'.");
+    return (-1);
+  }
 
-  for (j = 0; j < java_plugins_num; j++)
-    cjni_shutdown_one_plugin (jvm_env, &java_plugins[j]);
+  status = (*jvm_env)->RegisterNatives (jvm_env, api_class_ptr,
+      jni_api_functions, (jint) jni_api_functions_num);
+  if (status != 0)
+  {
+    ERROR ("cjni_init_native: RegisterNatives failed with status %i.", status);
+    return (-1);
+  }
 
   return (0);
-} /* }}} int cjni_shutdown_plugins */
+} /* }}} int cjni_init_native */
 
-static int cjni_shutdown (void) /* {{{ */
+/* Initialization: Create a JVM, load all configured classes and call their
+ * `config' and `init' callback methods. */
+static int cjni_init (void) /* {{{ */
 {
   JNIEnv *jvm_env;
-  JavaVMAttachArgs args;
+  JavaVMInitArgs vm_args;
+  JavaVMOption vm_options[jvm_argc];
+
   int status;
   size_t i;
 
-  if (jvm == NULL)
+  if (jvm != NULL)
     return (0);
 
-  jvm_env = NULL;
-  memset (&args, 0, sizeof (args));
-  args.version = JNI_VERSION_1_2;
-
-  status = (*jvm)->AttachCurrentThread (jvm, (void **) &jvm_env, &args);
+  status = pthread_key_create (&jvm_env_key, cjni_jvm_env_destroy);
   if (status != 0)
   {
-    ERROR ("java plugin: cjni_read: AttachCurrentThread failed with status %i.",
-        status);
+    ERROR ("java plugin: cjni_init: pthread_key_create failed "
+        "with status %i.", status);
     return (-1);
   }
 
-  cjni_shutdown_plugins (jvm_env);
-
-  (*jvm)->DestroyJavaVM (jvm);
-  jvm = NULL;
   jvm_env = NULL;
 
+  memset (&vm_args, 0, sizeof (vm_args));
+  vm_args.version = JNI_VERSION_1_2;
+  vm_args.options = vm_options;
+  vm_args.nOptions = (jint) jvm_argc;
+
   for (i = 0; i < jvm_argc; i++)
   {
-    sfree (jvm_argv[i]);
+    DEBUG ("java plugin: cjni_init: jvm_argv[%zu] = %s", i, jvm_argv[i]);
+    vm_args.options[i].optionString = jvm_argv[i];
   }
-  sfree (jvm_argv);
-  jvm_argc = 0;
+  /*
+  vm_args.options[0].optionString = "-verbose:jni";
+  vm_args.options[1].optionString = "-Djava.class.path=/home/octo/collectd/bindings/java";
+  */
+
+  status = JNI_CreateJavaVM (&jvm, (void **) &jvm_env, (void **) &vm_args);
+  if (status != 0)
+  {
+    ERROR ("cjni_init: JNI_CreateJavaVM failed with status %i.",
+	status);
+    return (-1);
+  }
+  assert (jvm != NULL);
+  assert (jvm_env != NULL);
 
-  for (i = 0; i < java_plugins_num; i++)
+  /* Call RegisterNatives */
+  status = cjni_init_native (jvm_env);
+  if (status != 0)
   {
-    sfree (java_plugins[i].class_name);
+    ERROR ("cjni_init: cjni_init_native failed.");
+    return (-1);
   }
-  sfree (java_plugins);
-  java_plugins_num = 0;
+
+  cjni_load_plugins (jvm_env);
+  cjni_config_plugins (jvm_env);
+  cjni_init_plugins (jvm_env);
 
   return (0);
-} /* }}} int cjni_shutdown */
+} /* }}} int cjni_init */
 
 void module_register (void)
 {
   plugin_register_complex_config ("java", cjni_config);
   plugin_register_init ("java", cjni_init);
-  plugin_register_read ("java", cjni_read);
-  plugin_register_write ("java", cjni_write);
   plugin_register_shutdown ("java", cjni_shutdown);
 } /* void module_register (void) */