Chapter 10. MBean Services Miscellany - JBoss Application Server 4.0.1 release2 Guide 英文版指南文档
This chapter discusses useful MBean services that are not discussed elsewhere either because they are utility services not necessary for running JBoss, or they don't fit into a current section of the book.
The management of system properties can be done using the system properties service. It supports setting of the VM global property values just as java.lang.System.setProperty method and the VM command line arguments do.
Its configurable attributes include:
Properties: a specification of multiple property name=value pairs using the java.util.Properites.load(java.io.InputStream) method format. Each property=value statement is given on a separate line within the body of the Properties attribute element.
URLList: a comma separated list of URL strings from which to load properties file formatted content. If a component in the list is a relative path rather than a URL it will be treated as a file path relative to the <jboss-dist>/server/<config> directory. For example, a component of conf/local.properties would be treated as a file URL that points to the <jboss-dist>/server/default/conf/local.properties file when running with the default configuration file set.
The following illustrates the usage of the system properties service with an external properties file.
<mbean code="org.jboss.varia.property.SystemPropertiesService"
name="jboss.util:type=Service,name=SystemProperties">
<!-- Load properties from each of the given comma separated URLs -->
<attribute name="URLList">
http://somehost/some-location.properties,
./conf/somelocal.properties
</attribute>
</mbean>The following illustrates the usage of the system properties service with an embedded properties list.
<mbean code="org.jboss.varia.property.SystemPropertiesService"
name="jboss.util:type=Service,name=SystemProperties">
<!-- Set properties using the properties file style. -->
<attribute name="Properties">
property1=This is the value of my property
property2=This is the value of my other property
</attribute>
</mbean>Note that
JavaBean property editors are used in JBoss to read data types from service files and to for editing values in the JMX console. The java.bean.PropertyEditorManager class controls the java.bean.PropertyEditor instances in the system. The property editor manager can be managed in JBoss using the org.jboss.varia.property.PropertyEditorManagerService MBean. The property editor manager service is configured in deploy/properties-service.xml and supports the following attributes:
BootstrapEditors: This is a listing of property_editor_class=editor_value_type_class pairs defining the property editor to type mappings that should be preloaded into the property editor manager. The value type of this attribute is a string so that it may be set from a string without requiring a custom property editor.
Editors: This serves the same function as the BootstrapEditors attribute, but its type is java.util.Properties. Setting it from a string value in a service file requires a custom property editor for properties objects already be loaded. JBoss provides a suitable property editor.
EditorSearchPath: This attribute allows one to set the editor packages search path on the PropertyEditorManager editor packages search path. Since there can be only one search path, setting this value overrides the default search path established by JBoss. If you set this, make sure to add the JBoss search path, org.jboss.util.propertyeditor and org.jboss.mx.util.propertyeditor, to the front of the new search path.
With all of the independently deployed services available in JBoss, running multiple instances on a given machine can be a tedious exercise in configuration file editing to resolve port conflicts. The binding service allows you centrally configure the ports for multiple JBoss instances. After the service is normally loaded by JBoss, the ServiceConfigurator queries the service binding manager to apply any overrides that may exist for the service. The service binding manager is configured in conf/jboss-service.xml. The set of configurable attributes it supports include:
ServerName: This is the name of the server configuration this JBoss instance is associated with. The binding manager will apply the overrides defined for the named configuration.
StoreFactoryClassName: This is the name of the class that implements the ServicesStoreFactory interface. You may provide your own implementation, or use the default XML based store org.jboss.services.binding.XMLServicesStoreFactory. The factory provides a ServicesStore instance responsible for providing the names configuration sets.
StoreURL: This is the URL of the configuration store contents, which is passed to the ServicesStore instance to load the server configuration sets from. For the XML store, this is a simple service binding file.
The following is a sample service binding manager configuration that uses the ports-01 configuration from the sample-bindings.xml file provided in the JBoss examples directory.
<mbean code="org.jboss.services.binding.ServiceBindingManager"
name="jboss.system:service=ServiceBindingManager">
<attribute name="ServerName">ports-01</attribute>
<attribute name="StoreURL">
../docs/examples/binding-manager/sample-bindings.xml
</attribute>
<attribute name="StoreFactoryClassName">
org.jboss.services.binding.XMLServicesStoreFactory
</attribute>
</mbean>The structure of the binding file is shown in Figure 10.1, “The binding service file structure”.
The elements are:
service-bindings: The root element of the configuration file. It contains one or more server elements.
server: This is the base of a JBoss server instance configuration. It has a required name attribute that defines the JBoss instance name to which it applies. This is the name that correlates with the ServiceBindingManager ServerName attribute value. The server element content consists of one or more service-config elements.
service-config: This element represents a configuration override for an MBean service. It has a required name attribute that is the JMX ObjectName string of the MBean service the configuration applies to. It also has a required delegateClass name attribute that specifies the class name of the ServicesConfigDelegate implementation that knows how to handle bindings for the target service. Its contents consists of an optional delegate-config element and one or more binding elements.
binding: A binding element specifies a named port and address pair. It has an optional name that can be used to provide multiple binding for a service. An example would be multiple virtual hosts for a web container. The port and address are specified via the optional port and host attributes respectively. If the port is not specified it defaults to 0 meaning choose an anonymous port. If the host is not specified it defaults to null meaning any address.
delegate-config: The delegate-config element is an arbitrary XML fragment for use by the ServicesConfigDelegate implementation. The hostName and portName attributes only apply to the AttributeMappingDelegate of the example and are there to prevent DTD aware editors from complaining about their existence in the AttributeMappingDelegate configurations. Generally both the attributes and content of the delegate-config are arbitrary, but there is no way to specify and a element can have any number of attributes with a DTD.
The two ServicesConfigDelegate implementations are AttributeMappingDelegate and XSLTConfigDelegate. The AttributeMappingDelegate class is an implementation of the ServicesConfigDelegate that expects a delegate-config element of the form:
<delegate-config portName="portAttrName" hostName="hostAttrName">
<attribute name="someAttrName">someHostPortExpr</attribute>
<!-- ... -->
</delegate-config>The portAttrName is the attribute name of the MBean service to which the binding port value should be applied, and the hostAttrName is the attribute name of the MBean service to which the binding host value should be applied. If the portName attribute is not specified then the binding port is not applied. Likewise, if the hostName attribute is not specified then the binding host is not applied. The optional attribute element(s) specify arbitrary MBean attribute names whose values are a function of the host and/or port settings. Any reference to ${host} in the attribute content is replaced with the host binding and any ${port} reference is replaced with the port binding. The portName, hostName attribute values and attribute element content may reference system properties using the ${x} syntax that is supported by the JBoss services descriptor.
The sample listing illustrates the usage of AttributeMappingDelegate.
<service-config name="jboss:service=Naming"
delegateClass="org.jboss.services.binding.AttributeMappingDelegate">
<delegate-config portName="Port"/>
<binding port="1099" />
</service-config>Here the jboss:service=Naming MBean service has its Port attribute value overridden to 1099. The corresponding setting from the jboss1 server configuration overrides the port to 1199.
The XSLTConfigDelegate class is an implementation of the ServicesConfigDelegate that expects a delegate-config element of the form:
<delegate-config>
<xslt-config configName="ConfigurationElement"><![CDATA[
Any XSL document contents...
]]>
</xslt-config>
<xslt-param name="param-name">param-value</xslt-param>
<!-- ... -->
</delegate-config>The xslt-config child element content specifies an arbitrary XSL script fragment that is to be applied to the MBean service attribute named by the configName attribute. The named attribute must be of type org.w3c.dom.Element . The optional xslt-param elements specify XSL script parameter values for parameters used in the script. There are two XSL parameters defined by default called host and port, and their values are set to the configuration host and port bindings.
The XSLTConfigDelegate is used to transform services whose port/interface configuration is specified using a nested XML fragment. The following example maps the Tomcat servlet container listening port to 8180 and maps the AJP listening port to 8109:
<!-- jbossweb-tomcat50.sar -->
<service-config name="jboss.web:service=WebServer"
delegateClass="org.jboss.services.binding.XSLTFileDelegate"
>
<delegate-config>
<xslt-config configName="ConfigFile"><![CDATA[
<xsl:stylesheet
xmlns:xsl='http://www.w3.org/1999/XSL/Transform' version='1.0'>
<xsl:output method="xml" />
<xsl:param name="port"/>
<xsl:variable name="portAJP" select="$port - 71"/>
<xsl:variable name="portHttps" select="$port + 363"/>
<xsl:template match="/">
<xsl:apply-templates/>
</xsl:template>
<xsl:template match = "Connector">
<Connector>
<xsl:for-each select="@*">
<xsl:choose>
<xsl:when test="(name() = 'port' and . = '8080')">
<xsl:attribute name="port"><xsl:value-of select="$port" />
</xsl:attribute>
</xsl:when>
<xsl:when test="(name() = 'port' and . = '8009')">
<xsl:attribute name="port"><xsl:value-of select="$portAJP" />
</xsl:attribute>
</xsl:when>
<xsl:when test="(name() = 'redirectPort')">
<xsl:attribute name="redirectPort"><xsl:value-of select="$portHttps" />
</xsl:attribute>
</xsl:when>
<xsl:when test="(name() = 'port' and . = '8443')">
<xsl:attribute name="port"><xsl:value-of select="$portHttps" />
</xsl:attribute>
</xsl:when>
<xsl:otherwise>
<xsl:attribute name="{name()}"><xsl:value-of select="." />
</xsl:attribute>
</xsl:otherwise>
</xsl:choose>
</xsl:for-each>
<xsl:apply-templates/>
</Connector>
</xsl:template>
<xsl:template match="*|@*">
<xsl:copy>
<xsl:apply-templates select="@*|node()"/>
</xsl:copy>
</xsl:template>
</xsl:stylesheet>
]]>
</xslt-config>
</delegate-config>
<binding port="8180"/>
</service-config> JBoss ships with service binding configuration file for starting up to three separate JBoss instances on one host. Here we will walk through the steps to bring up the two instances and look at the sample configuration. Start by making two server configuration file sets called jboss0 and jboss1 by running the following command from the book examples directory:
[examples]$ ant -Dchap=chap10 -Dex=1 run-example
This creates duplicates of the server/default configuration file sets as server/jboss0 and server/jboss1, and then replaces the conf/jboss-service.xml descriptor with one that has the ServiceBindingManager configuration enabled as follows:
<mbean code="org.jboss.services.binding.ServiceBindingManager"
name="jboss.system:service=ServiceBindingManager">
<attribute name="ServerName">${jboss.server.name}</attribute>
<attribute name="StoreURL">${jboss.server.base.dir}/chap10ex1-bindings.xml</attribute>
<attribute name="StoreFactoryClassName">
org.jboss.services.binding.XMLServicesStoreFactory
</attribute>
</mbean>Here the configuration name is ${jboss.server.name}. JBoss will replace that with name of the actual JBoss server configuration that we pass to the run script with the -c option. That will be either jboss0 or jboss1, depending on which configuration is being run. The binding manager will find the corresponding server configuration section from the chap10ex1-bindings.xml and apply the configured overrides. The jboss0 configuration uses the default settings for the ports, while the jboss1 configuration adds 100 to each port number.
To test the sample configuration, start two JBoss instances using the jboss0 and jboss1 configuration file sets created previously. You can observe that the port numbers in the console log are different for the jboss1 server. To test out that both instances work correctly, try accessing the web server of the first JBoss on port 8080 and then try the second JBoss instance on port 8180.
Java includes a simple timer based capability through the java.util.Timer and java.util.TimerTask utility classes. JMX also includes a mechanism for scheduling JMX notifications at a given time with an optional repeat interval as the javax.management.timer.TimerMBean agent service.
JBoss includes two variations of the JMX timer service in the org.jboss.varia.scheduler.Scheduler and org.jboss.varia.scheduler.ScheduleManager MBeans. Both MBeans rely on the JMX timer service for the basic scheduling. They extend the behavior of the timer service as described in the following sections.
The Scheduler differs from the TimerMBean in that the Scheduler directly invokes a callback on an instance of a user defined class, or an operation of a user specified MBean.
InitialStartDate: Date when the initial call is scheduled. It can be either:
NOW: date will be the current time plus 1 seconds
A number representing the milliseconds since 1/1/1970
Date as String able to be parsed by SimpleDateFormat with default format pattern "M/d/yy h:mm a". If the date is in the past the Scheduler will search a start date in the future with respect to the initial repetitions and the period between calls. This means that when you restart the MBean (restarting JBoss etc.) it will start at the next scheduled time. When no start date is available in the future the Scheduler will not start.
For example, if you start your Schedulable everyday at Noon and you restart your JBoss server then it will start at the next Noon (the same if started before Noon or the next day if start after Noon).
InitialRepetitions: The number of times the scheduler will invoke the target's callback. If -1 then the callback will be repeated until the server is stopped.
StartAtStartup: A flag that determines if the Scheduler will start when it receives its startService life cycle notification. If true the Scheduler starts on its startup. If false, an explicit startSchedule operation must be invoked on the Scheduler to begin.
SchedulePeriod: The interval between scheduled calls in milliseconds. This value must be bigger than 0.
SchedulableClass: The fully qualified class name of the org.jboss.varia.scheduler.Schedulable interface implementation that is to be used by the Scheduler . The SchedulableArguments and SchedulableArgumentTypes must be populated to correspond to the constructor of the Schedulable implementation.
SchedulableArguments: A comma separated list of arguments for the Schedulable implementation class constructor. Only primitive data types, String and classes with a constructor that accepts a String as its sole argument are supported.
SchedulableArgumentTypes: A comma separated list of argument types for the Schedulable implementation class constructor. This will be used to find the correct constructor via reflection. Only primitive data types, String and classes with a constructor that accepts a String as its sole argument are supported.
SchedulableMBean: Specifies the fully qualified JMX ObjectName name of the schedulable MBean to be called. If the MBean is not available it will not be called but the remaining repetitions will be decremented. When using SchedulableMBean the SchedulableMBeanMethod must also be specified.
SchedulableMBeanMethod: Specifies the operation name to be called on the schedulable MBean. It can optionally be followed by an opening bracket, a comma separated list of parameter keywords, and a closing bracket. The supported parameter keywords include:
NOTIFICATION which will be replaced by the timers notification instance (javax.management.Notification)
DATE which will be replaced by the date of the notification call (java.util.Date)
REPETITIONS which will be replaced by the number of remaining repetitions (long)
SCHEDULER_NAME which will be replaced by the ObjectName of the Scheduler
Any fully qualified class name which the Scheduler will set to null.
A given Scheduler instance only support a single schedulable instance. If you need to configure multiple scheduled events you would use multiple Scheduler instances, each with a unique ObjectName. The following is an example of configuring a Scheduler to call a Schedulable implementation as well as a configuration for calling a MBean.
<server>
<mbean code="org.jboss.varia.scheduler.Scheduler"
name="jboss.docs.chap10:service=Scheduler">
<attribute name="StartAtStartup">true</attribute>
<attribute name="SchedulableClass">org.jboss.chap10.ex2.ExSchedulable</attribute>
<attribute name="SchedulableArguments">TheName,123456789</attribute>
<attribute name="SchedulableArgumentTypes">java.lang.String,long</attribute>
<attribute name="InitialStartDate">NOW</attribute>
<attribute name="SchedulePeriod">60000</attribute>
<attribute name="InitialRepetitions">-1</attribute>
</mbean>
</server> The SchedulableClass org.jboss.chap10.ex2.ExSchedulable example class is given below.
package org.jboss.chap10.ex2;
import java.util.Date;
import org.jboss.varia.scheduler.Schedulable;
import org.apache.log4j.Logger;
/**
* A simple Schedulable example.
* @author Scott.Stark@jboss.org
* @version $Revision: 1.5 $
*/
public class ExSchedulable implements Schedulable
{
private static final Logger log = Logger.getLogger(ExSchedulable.class);
private String name;
private long value;
public ExSchedulable(String name, long value)
{
this.name = name;
this.value = value;
log.info("ctor, name: " + name + ", value: " + value);
}
public void perform(Date now, long remainingRepetitions)
{
log.info("perform, now: " + now +
", remainingRepetitions: " + remainingRepetitions +
", name: " + name + ", value: " + value);
}
}Deploy the timer SAR by running:
[examples]$ ant -Dchap=chap10 -Dex=2 run-example
The server console shows the following which includes the first two timer invocations, separated by 60 seconds:
21:09:27,716 INFO [ExSchedulable] ctor, name: TheName, value: 123456789 21:09:28,925 INFO [ExSchedulable] perform, now: Mon Dec 20 21:09:28 CST 2004, remainingRepetitions: -1, name: TheName, value: 123456789 21:10:28,899 INFO [ExSchedulable] perform, now: Mon Dec 20 21:10:28 CST 2004, remainingRepetitions: -1, name: TheName, value: 123456789 21:11:28,897 INFO [ExSchedulable] perform, now: Mon Dec 20 21:11:28 CST 2004, remainingRepetitions: -1, name: TheName, value: 123456789
The Log4jService MBean configures the Apache log4j system. JBoss uses the log4j framework as its internal logging API.
ConfigurationURL: The URL for the log4j configuration file. This can refer to either a XML document parsed by the org.apache.log4j.xml.DOMConfigurator or a Java properties file parsed by the org.apache.log4j.PropertyConfigurator. The type of the file is determined by the URL content type, or if this is null, the file extension. The default setting of resource:log4j.xml refers to the conf/log4j.xml file of the active server configuration file set.
RefreshPeriod: The time in seconds between checks for changes in the log4 configuration specified by the ConfigurationURL attribute. The default value is 60 seconds.
CatchSystemErr: This boolean flag if true, indicates if the System.err stream should be redirected onto a log4j category called STDERR. The default is true.
CatchSystemOut: This boolean flag if true, indicates if the System.out stream should be redirected onto a log4j category called STDOUT. The default is true.
Log4jQuietMode: This boolean flag if true, sets the org.apache.log4j.helpers.LogLog.setQuiteMode. As of log4j1.2.8 this needs to be set to avoid a possible deadlock on exception at the appender level. See bug#696819.
The WebService MBean provides dynamic class loading for RMI access to the server EJBs. The configurable attributes for the service are as follows:
Port: the WebService listening port number. A port of 0 will use any available port.
Host: Set the name of the public interface to use for the host portion of the RMI codebase URL.
BindAddress: the specific address the WebService listens on. This can be used on a multi-homed host for a java.net.ServerSocket that will only accept connect requests to one of its addresses.
Backlog: The maximum queue length for incoming connection indications (a request to connect) is set to the backlog parameter. If a connection indication arrives when the queue is full, the connection is refused.
DownloadServerClasses: A flag indicating if the server should attempt to download classes from thread context class loader when a request arrives that does not have a class loader key prefix.