Cluster Daemon

Introduction

The intent of the cluster daemon is to enable the remote control of the JOnAS clustered instances through a JMX interface.

In a cluster configuration, the cluster daemon is the bootstrap of the JOnAS instances.

There is at least one cluster daemon instance per machine.

Cluster daemon

Configuration

In the same manner as a classic JOnAS instance, the cluster daemon reads its configuration in a directory pointed to by a JONAS_BASE variable (or JONAS_ROOT if JONAS_BASE is not set). All the default JONAS_BASE subdirectories and files are not required; the mandatory ones are:

element	description
$JONAS_BASE/conf	Configuration directory
$JONAS_BASE/logs	Log directory
$JONAS_BASE/conf/carol.properties	Carol configuration file describing the protocol and its parameters (used for the JMX interface)
$JONAS_BASE/conf/trace.properties	Trace/Error log configuration file
$JONAS_BASE/conf/jonas.properties	This file must be present for enabling the cluster daemon starting but its content is not read, the file can be empty
$JONAS_BASE/conf/clusterd.xml	Cluster daemon configuration file, lists the local JOnAS instances and describes their environment (see below)

clusterd.xml

The JOnAS instances controlled by a cluster daemon are configured in the clusterd.xml file.


<?xml version="1.0"?>
<cluster-daemon xmlns="http://www.objectweb.org/jonas/ns"
	  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	  xsi:schemaLocation="http://www.objectweb.org/jonas/ns
	  http://www.objectweb.org/jonas/ns/jonas-clusterd_4_8.xsd">
	  	  
   <name>cd1</name>
   <domain-name>domainSample</domain-name>
   <jonas-interaction-mode>loosely-coupled</jonas-interaction-mode>

   <server>
      <name>node1</name>
      <description>Web instance</description>
      <java-home>/usr/java/jdk-ia32/sun/j2sdk1.4.2_10</java-home>
      <jonas-root>/home/pelletib/pkg/jonas_root_sb48</jonas-root>
      <jonas-base>/home/pelletib/tmp/newjc48/jb1</jonas-base>
      <xprm></xprm>
      <auto-boot>false</auto-boot>
   </server>

...

</cluster-daemon>

element	description
name	Cluster daemon instance name. Used for building the connector url.
domain-name	Domain name to use for launching the JOnAS instance when it is not specified in the start command
jonas-interaction-mode	Starting mode of the JOnAS instances: `loosely-coupled` corresponds to background and `tighly-coupled` corresponds to foreground
server/name	Name of the JOnAS instance
server/description	Description of the JOnAS instance
server/java-home	JDK home directory to use for launching the JOnAS instance
server/jonas-root	JOnAS binaries directory to use for launching the JOnAS instance
server/jonas-base	JOnAS configuration directory to use for launching the JOnAS instance
server/xprms	JVM parameters to set when launching the JOnAS instance
server/auto-boot	If true, start the JOnAS instance when launching the cluster daemon

domain.xml

The cluster daemons must be specified and associated to the JOnAS instances in the domain.xml file for permitting the remote control of the cluster.

...
<cluster-daemon>
   <name>cd1</name>
   <description>cluster daemon 1</description>
   <location>
      <url>service:jmx:rmi://host/jndi/rmi://host:port/jrmpconnector_cd</url>
   </location>
</cluster-daemon>
...
<server>
  <name>node1</name>
  <cluster-daemon>cd1</cluster-daemon>
  ...
</server>
...

The JMX remote url of the cluster daemon adheres to the following syntax:

service:jmx:rmi://host/jndi/rmi://host:port/protocolconnector_name with the following meanings:

host: ip alias or ip address of the machine that hosts the cluster daemon (by default localhost, can be overridden through the carol.properties file)
port: tcp listen port of the registry embedded in the cluster daemon (by default 1806, can be overridden through the carol.properties file)
protocol: protocol used for accessing the JMX interface (by default irmi, can be overridden through the carol.properties file)
name: cluster daemon instance name (defined in the clusterd.xml file)

Running the Cluster Daemon

The cluster daemon is started using the command jclusterd. The possible options are:

option	description
start	Start the cluster daemon.
stop	Stop the cluster daemon.
-DdomainName	Domain name to use for starting the JOnAS instance. This value is used when it is defined both here and in the clusterd.xml file.
-carolFile	Path to the carol.properties file to use. If not specified, the file is loaded from $JONAS_BASE/conf. If the file is not found, the default values (localhost, 1806, irmi) are used.
-confFile	Path to the clusterd.xml file to load. If not specified, the file is loaded from $JONAS_BASE/conf.

JMX Interface

The cluster daemon provides a JMX interface that enables control of the JOnAS instances. The following operations are available:

Operation	Description
String getServersList()	Return the list of JOnAS instances
int pingJOnAS(String name)	Ping a JOnAS instance identified by its name
void startJOnAS(String name)	Start a JOnAS instance identified by its name
String startAllJOnAS(String domainName, String prm)	Start all the JOnAS instances known in the cluster daemon configuration. The parameter `domainName` (optional) enables the ability to specifiy the domain name. The parameter `prm` (optional) enables the ability to set some JVM parameters.
void stopJOnAS(String name)	Stop a JOnAS instance identified by its name
String stopAllJOnAS()	Stop all the JOnAS instances known in the cluster daemon configuration
String getJavaHome4Server(String name)	Get the JAVA_HOME defined for a JOnAS server
String getJonasRoot4Server(String name)	Get the JONAS_ROOT defined for a JOnAS server
String getJonasBase4Server(String name)	Get the JONAS_BASE defined for a JOnAS server
void reloadConfiguration()	Reload the configuration file of the cluster daemon
void addServer(String name, String description, String javaHome, String jonasRoot, String jonasBase)	Add a definition of a JOnAS instance to the cluster daemon configuration. The change is saved in the configuration file.
void removeServer(String name)	Remove a definition of a JOnAS instance in the cluster daemon configuration. The change is saved in the configuration file.
void modifyServer(String name, String description, String javaHome, String jonasRoot, String jonasBase)	Modify the definition of a JOnAS instance in the cluster daemon configuration. The change is saved in the configuration file.