JMX Tutorial


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JMX Tutorial

  1. 1. JMX Tutorial Christophe Ebro JMX Specification Lead Sun Microsystems, Inc. christophe.ebro@sun.co1 2 Objectives Contents Understand the JMX Specification • Introduction • 3 level architecture • Architecture • Instrumentation via MBeans • Instrumentation Specification • Different kinds of MBeans • Server Specification • Client Server architecture • Client Server services3 4 What is the JMX? Benefits • Enables Java applications to be managed Java Management Extension without heavy investment It consists of – Little impact on Java application design • An architecture • Provides scaleable management • Design patterns architecture • Java APIs – Component architecture, pick and choose components • Services for application and network • Integrates existing management solutions management – Can be managed via multiple protocols, e.g. SNMP, WBEM, HTTP – Information model independent5 6 • Leverages existing standard Java 1
  2. 2. JMX: 3 Level Architecture JMX Architecture Instrumentation Server Distributed Services Level Level Level The JMX architecture defines three levels: Object 1 JMX-compliant (MBean) Management • Instrumentation Level Connector C Application – How to instrument managed resources Object 2 (MBean) Server Services (as MBeans) • Server Level Protocol Adaptor Web Browser SNMP/CMIP Client – How managed resources are managed via the Server Services Proprietary (as MBeans) management server Management Connector Application • Distributed Services Level MBean server Server Java Virtual Machine – How distributed clients and management C JMX Client applications access and interact with servers and C the managed resources in the servers7 8 Contents Basic Goal • Introduction In a running Java application, we would like to be able to: • Architecture • Manage existing Java objects: • Instrumentation Specification – get an attribute value • Server Specification Object 1 – change an attribute value Object 2 – invoke an operation • Add new Java objects: Object 3 – using existing Java classes – using new classes from an arbitrary location Object 4 • And do all this from a9 10 remote location Definitions Contents • Client: Application controlling servers by • Introduction submitting requests, activating new • Architecture services, etc ... – Instrumentation Level • Server: Application making local resources – Server Level available remotely and providing one or more services – Distributed Services Level • MBean server: Registry for MBeans in the • Instrumentation Specification server • Server Specification • MBean: Managed bean. Java class implementing a management interface and representing a resource to be managed or11 monitored 12 2
  3. 3. Instrumentation Level Instrumentation Level Instrumentation Server Distributed Services Level Level Level Object 1 JMX-compliant (MBean) Connector C Management Application • Provides management agent independence Object 2 • Specification for implementing JMX (MBean) Server Services (as MBeans) Protocol Web Browser manageable resources Adaptor SNMP/CMIP Client Server Services • Resource can be a service, device, user, ... (as MBeans) Proprietary Management etc. Connector Application MBean server Server Java Virtual Machine • Resource developed in Java or have Java C wrapper JMX Client C13 14 Components of the MBean (1) Instrumentation Level Object 1 (MBean) Connector • MBeans Object 2 Server Services (MBean) (as MBeans) Protocol – Defines how resources are instrumented using Adaptor MBeans Server Services (as MBeans) Connector – MBean instrumentation allows the resource to be Mbean server Server Java Virtual Machine manageable through JMX-compliant agents • Notification Model • An MBean exposes the management – MBeans and other JMX components may emit interface of the managed resource/object notifications • The management interface is the set of • MBean Metadata Classes information and controls that a15 – Describes the MBeans management interface for 16 management application uses to operate on management agents and management the resource MBean (2) Four Types of MBeans • Standard MBeans • An MBean exposes the management interface – Simplest to design and implement as: – Management interface described by method names, like getState, setState, reset – Attributes which may be accessed • Dynamic MBeans – Operations which may be invoked – Must implement DynamicMBean interface – Notifications which may be emitted (optional) – Expose management interface at runtime for greater – Constructors for the MBeans Java class flexibility via generic methods, like getAttribute, setAttribute, invoke • An MBean follows design patterns • Model MBeans are dynamic MBeans – The way an attribute or operation to be exposed – Self contained, self described, configurable at runtime has to be declared – Generic MBean class for dynamic instrumentation of resources • An MBean must be registered in the MBean server to be visible remotely • Open MBeans are dynamic MBeans17 18 • An MBean does not know about its MBean – Basic data types only for universal manageability 3
  4. 4. Notification Model MBean Metadata Classes • JMX defines a generic notification model • MBean server (server level) has to provide – Based on Java event model MBean metadata • Notification can be emitted by: • Classes that describe the management – MBean instances interface of an MBean – MBean server • There are metadata classes for attributes, • JMX defines operations, notifications, and constructors – Notification objects • Metadata include name, description, – Broadcaster interface for notification senders attribute type, operation parameter types, ... – Listener interface for notification listeners etc. • Distribution of notification for remote • Different types of MBeans extend metadata management applications not in JMX 1.0 classes to provide additional information19 20 May be provided by JMX implementations Contents Server Level Instrumentation Server Distributed Services • Introduction Level Level Level • Architecture Object 1 JMX-compliant (MBean) C Management Connector – Instrumentation Level Application Object 2 – Server Level (MBean) Server Services (as MBeans) Protocol Web Browser – Distributed Services Level Adaptor SNMP/CMIP Client Server Services • Instrumentation Specification (as MBeans) Proprietary Management Application • Server Specification MBean server Connector Server Java Virtual Machine C JMX Client C21 22 Server Level MBean Server (1) • Specification for implementing servers Object 1 (MBean) Connector • Servers directly control resources and make Object 2 Server Services them available to remote management (MBean) (as MBeans) Protocol Adaptor applications Server Services (as MBeans) Connector • JMX server consists of: MBean server Server Java Virtual Machine – MBean server – Server services • The MBean server is a registry of objects which are exposed to management operations in a server • Implemented by developers of management – Only registered MBeans can be managed from systems outside the servers JVM – Independent of semantics of JMX manageable • The MBean server only exposes an MBeans resources or management application management interface (not the MBeans direct23 24 reference) 4
  5. 5. MBean Server (2) Server Services • Also provides standardized interface for accessing MBeans within the same JVM Object 1 (MBean) Connector • MBeans can be instantiated and registered by: Object 2 (MBean) Server Services (as MBeans) Protocol – Another MBean Adaptor – The management server itself Server Services (as MBeans) Connector MBean server – A remote management application (through Server Java Virtual Machine distributed services) • Each registered MBean is assigned a unique name, • Objects that perform management operations on the usually user-defined MBeans registered in the MBean server • Only these names are used by server/client – Provides management intelligence inside the applications to identify the MBeans server • Relies on protocol adaptors and connectors to make – Server services are also MBeans25 26 server accessible from outside servers JVM JMX 1.0 Server Services Contents • M-Let dynamic class loading service • Introduction retrieves and instantiates new classes from • Architecture arbitrary network locations – Instrumentation Level • Monitors observe MBean attribute value and – Server Level emit notifications for several types of changes in the target – Distributed Services Level • Timers provide scheduling based on a one- • Instrumentation Specification time alarm clock or repeated, periodic • Server Specification notification • Relation service defines associations between MBeans and enforces the27 cardinality of the relation based on 28 Distributed Services Level Distributed Services Level Instrumentation Agent Distributed Services Level Level Level • Outside scope of JMX 1.0 Object 1 JMX-compliant • Defines distribution mechanism (MBean) C Management Connector Application – Connectors Object 2 (MBean) Server Services – Protocol Adaptors (as MBeans) Protocol Web Browser Adaptor SNMP/CMIP Client – Proxies Server Services (as MBeans) Proprietary • Specifies interfaces for JMX clients Management MBean server Connector Application • Defines management interfaces and Server Java Virtual Machine components that operate on servers or C hierarchies of servers JMX Client C29 30 5
  6. 6. Connector (1) Connector (2) JMX-Compliant Management • Provides remote access to MBean Application Object 1 attributes and operations (MBean) Connector Connector Object 2 Client Virtual Machine (MBean) • Provides remote instantiation, MBean Server registration and de-registration of Server Java Virtual Machine MBeans • Composed of a client part and a server • Propagates MBean and MBean server part, the connector connects a JMX client notifications to the client application application with an MBean server • Client part provides a protocol-independent API to access the remote MBean server31 • Tunnels management operations over a 32 specific protocol (RMI HTTP ) Protocol Adaptor Connectors and Protocol Not Shown Object 1 HTML Browser, Adaptors HTTPS IIOP (JMX IIOP JSR) Client API (MBean) Protocol SNMP Client, Object 2 Adaptor etc... Java (MBean) Application RMI MBean Server Server Java Virtual Machine RMI Java Application HTTP HTTP Object 1 • Only has a server part, on the server (MBean) Object 2 HTML Browser: • Creates a view of the MBeans through a (MBean) HTML HotJava, Netscape, ... given protocol and information model SNMP SNMP Client: SNM, SEM, MBean Server JDMK, ... Server Java Virtual Machine33 34 Proxy MBean Development Process • The proxy MBean provides an image of an MBean as a stub object on the client side Main Steps • Operations performed on the proxy MBean are • Instrument managed resources propagated to the MBean • Notifications emitted by the MBean are propagated • Instantiate MBeans in a JMX server to the proxy MBean • Test MBeans • The proxy is generated from an MBean MBeans Proxy MBeans • Develop the client application (optional) Object 1 Object 1 Connector Object 2 Object 2 Client Java Virtual Machine MBean Server35 Server Java Virtual Machine 36 6
  7. 7. Problems solved by JMX (1) Problems solved by JMX (2) Open the design of new Java applications Make an existing Java application manageable • Design the new application such that it • The existing application can be modified so includes an MBean server that – Remote access for management operations is – It creates an MBean server and a connector or a free protocol adaptor – The application will be extensible dynamically – It registers the objects that need to be managed • Develop servers for a variety of purposes • Requirement: registered objects must be – System Management/Monitoring instrumented as MBeans – Network Management/Monitoring – This requirement is light37 38 – Application Management/Monitoring – It does not break existing design or force the Advantages of this Solution Contents • Protocol independent • Introduction • Information model independent • Architecture • Light requirements on software design: – An MBean only needs to implement a • Instrumentation management interface – An MBean does not need to be aware of JMX Specification servers and agents – Standard MBean – An MBean does not need to know anything about – Dynamic MBean communication with the outside world – MBean Metadata • Scalability and flexibility – Notification Model – By registering and unregistering MBeans the Java application can include only what it needs at the – Model MBean time it needs it • Server Specification39 40 – New protocol adaptors (with new protocols) can Instrumentation MBean Requirements • Defined by the JMX Instrumentation Spec • MBean must be a public concrete Java class • Must follow specified • Must implement one of two types of MBean interfaces – Design patterns – Standard MBean interface – Implement MBean interfaces – Management interface is static, i.e. determined from • MBean enable management by any JMX methods defined in the MBeans interface servers – Depends on design patterns and introspection – DynamicMBean interface • An MBean can be created from an already – Management interface is generic and determined existing Java object or from scratch indirectly through method calls – Generic get, set, and invoke methods • Developers decide • Optional NotificationBroadcaster interface – Granularity of MBeans41 42 How to wrap legacy code 7
  8. 8. Terminology Choice of MBean Interfaces • An attribute is a field or property of a JMX manageable resource exposed via an • Choice of standard MBean or dynamic MBeans management interface MBean interface determines how MBean will be developed, not how it will be managed • An operation is an action that a JMX manageable resource makes available to • JMX server provides abstraction to manage management applications exposed via an both types of instrumentation transparently MBeans management interface • Management applications handle them in a • A method refers to a Java method or similar manner function43 44 Contents Standard MBeans • Introduction • Implement Java interface named after the class • Architecture – Name of MBean interface is formed by • Instrumentation Specification adding MBean suffix to class name – Standard MBean • Standard MBean interface lists the attributes – Dynamic MBean and operations exposed to management MyClassMBea – MBean Metadata n • Impose very little constraint on the MBean – Notification Model class design Implements getFoo() – Model MBean MyClass • Server Specification getFoo() setFoo()45 46 Lexical design patterns for Lexical Design Patterns: Example public interface SimpleStandardMBean { methods public String getState() ; • An attribute is deduced from the public void setState(String s) ; public Integer getNbChanges() ; existence of a get and/or set method: } public void reset() ; public class SimpleStandard implements SimpleStandardMBean { public String getState() { Attribute State public MyType getMyAttribute(); return state; } Type String public void setState(String s) { Access read-write public void setMyAttribute(MyType value); state = s; nbChanges++; Attribute } NbChanges public Integer getNbChanges() { Type Integer • Any other method is considered to be } return new Integer(nbChanges); Access read-only an operation: public void reset() { state = "initial state"; reset is an manageable nbChanges = 0; operation nbResets++; } public void reset(); public Integer getNbResets() { NbResets is not a return new Integer(nbResets); manageable public MyResult myOperation(MyType arg); } attribute private String state = "initial state";47 48 private int nbChanges = 0; private int nbResets = 0; 8
  9. 9. Contents Which MBean • Introduction Standard MBean • Suitable when structure of management data is • Architecture well-defined in advance • Instrumentation Specification • Determine structure at compile time – Standard MBean • Provide quick and easy way to instrument – Dynamic MBean manageable resources – MBean Metadata Dynamic MBean – Notification Model • Suitable when structure of management data is – Model MBean likely to evolve often over time • Server Specification • Can determine structure dynamically at run-time • Provide adaptability and more elaborate49 50 management capabilities Dynamic MBeans DynamicMBean Interface Management Interface • Implement DynamicMBean interface «Interface» DynamicMBean • Provide generic get, set, invoke methods getMBeanInfo(): M BeanInfo getAttribute( attribute:String:)Object • Describe their management interface at getAttributes( attributes:String[]:)AttributeList runtime (by means of MBeanInfo) DynamicMBea setAttribute( attribute:Attribute )void : n setAttributes( attributes:AttributeList: ) ttributeList A getAttribute() invoke( actionName:String, Implements setAttribute() params:Object[], invoke() ... signature:String[] ): Object MyClass51 52 Dynamic MBean: Example (1) Dynamic MBean: Example (2) Definition of a dynamic MBean with: • one read-write attribute State • one read-only attribute NbChanges • one reset operation public AttributeList getAttributes(String[] attributes) { // Checks if "State" and/or "NbChanges" is in the list. public class SimpleDynamic implements DynamicMBean { // Calls getAttribute. public SimpleDynamic() { } // Creates MBeanAttributeInfo for "State" and "NbChanges" public void setAttributes(AttributeList attribute) { // Creates MBeanOperationInfo for "reset" // Checks if "State" is in the list. } // Calls setAttribute. public MBeanInfo getMBeanInfo() { } // Creates a MBeanInfo with the name "SimpleDynamic" and the public Object invoke(String opName, Object[] args, // MBeanAttributeInfo and MBeanOperationInfo String[] signature) { } // Checks the operation is "reset", public Object getAttribute(String attribute) { // with the correct signature (no args). // Checks if the requested attribute is "State" or "NbChanges" // Perform reset // Returns the attribute value. } } ... public void setAttribute(Attribute attribute) { } // Checks if attribute is "State" and if argument // is a String. Sets the value of the attribute.53 } 54 9
  10. 10. getAttribute method invoke method public Object getAttribute(String attributeName) public Object invoke(String operationName, throws AttributeNotFoundException, Object params[], MBeanException, String signature[]) ReflectionException { throws MBeanException, // Check attributeName is not null to avoid ReflectionException { // NullPointerException later on // Check operationName is not null to avoid if (attributeName == null) { // NullPointerException later on throw new RuntimeOperationsException( if (operationName == null) { new IllegalArgumentException(...), ...); throw new RuntimeOperationsException( } new IllegalArgumentException(...), ...); // Check for a recognized attribute_name and } // call the corresponding getter // Check for a recognized operation name and call the if (attributeName.equals("State")) { // corresponding operation return getState(); if (operationName.equals("reset")){ } reset(); if (attributeName.equals("NbChanges")) { return null; return getNbChanges(); } else { } // unrecognized operation name: // If attributeName has not been recognized throw throw new ReflectionException( // an AttributeNotFoundException new NoSuchMethodException(operationName), ...); throw(new AttributeNotFoundException(...)); } } }55 56 Contents MBean Metadata Classes MBeanInfo • Introduction getClassName(): String getNotifications() MBeanNotificationInfo[] : getAttributes() MBeanAttributeInfo[] : • Architecture getConstructors(): MBeanConstructorInfo[] MBeanFeatureInfo getOperations(): MBeanOperationInfo[] getName(): String getDescription(): String getDescription() String : • Instrumentation Specification 0..* 0..* MBeanOperationInfo MBeanNotificationInfo – Standard MBean UNKNOWN:int {frozen} getNotifT ypes() String[] : ACTION: int {frozen} – Dynamic MBean INFO: int {frozen} 0..* ACTION_INFO: int {frozen} MBeanAttributeInfo – MBean Metadata getReturnType(): String getSignature(): MBeanParameterInfo[] getImpact(): int getT ype(): String isReadable(): boolean isWritable(): boolean – Inheritance Pattern 0..* isIs(): boolean MBeanConstructorInfo – Notification Model getSignature(): MBeanParameterInfo[] 0..* 0..* – Model MBean MBeanParameterInfo getT ype(): String • Server Specification57 58 Behavior of Dynamic MBeans Contents • Coherence • Introduction – Developer must ensure that advertised • Architecture management interface (via getMBeanInfo) is accurately mapped to internal implementation • Instrumentation Specification – MBean server does not test or validate the self- – Standard MBean description of a dynamic MBean – Dynamic MBean • Dynamics – MBean Metadata – The management interface of an MBean should – Inheritance Pattern be applicable throughout the lifetime of the MBean – Notification Model – Model MBean – getMBeanInfo should return the same MBeanInfo during the lifetime of the dynamic • Server Specification59 MBean 60 10
  11. 11. Notification Model Notification Class • Notifications are instances of Notification – Can be used directly or may be subclassed • A Notification object contains the following Notification Source fields: implements – An event source references the notification source NotificationBroadcaster (from java.util.EventObject superclass) Notification – A notification type is a string used to characterize a Object generic notification object Notification Consumer is an instance of – A sequence number is a serial number identifying an implements Notification NotificationListener class notification instance within the context of a notification broadcaster – A time stamp indicates when the notification was generated – A message containing a string which could be an61 62 explanation of the notification for display to the user U d t i df th d t th tifi ti NotificationListener Interface NotificationFilter Interface • Must be implemented by all MBeans expecting to receive notifications void handleNotification( • A notification filter object is provided by the listener Notification notification, when the listener registers for notifications with the Object handback) broadcaster • Invoked by notification broadcaster MBean when it emits a • boolean isNotificationEnabled(Notification n) notification Invoked by notification broadcaster before it emits a notification • A single notification handler receives all notifications from all potential broadcasters • Listeners rely on a filter to screen notifications – All notifications are characterized by notification type string • An object can be both a • Handback object NotificationListener and – The object that the listener provides when the listener registers for notifications with the notification broadcaster NotificationFilter – Stored by notification broadcaster and returned unchanged with63 each notification 64 NotificationBroadcaster Send Notification Semantics Interface • MBeanNotificationInfo[] getNotificationInfo() Provides the description of all notifications this broadcaster emits For each notification • void addNotificationListener( For each (listener, filter, handback) NotificationListener listener, If filter.isNotificationEnabled(notification)then NotificationFilter filter, listener.handleNotification(notification,handback) Object handback) EndIf EndFor Used by listener to register for notifications EndFor (listener, filter, handback) tuple stored Key is (listener, handback) • void removeNotificationListener( NotificationListener listener, Object handback) Remove (listener, filter, handback) tuple65 66 11
  12. 12. Contents Model MBean (1) • Introduction Target Resource Java Object • Architecture Model MBean behavior driven by • Instrumentation Specification Target Resource descriptors Java Object – Standard MBean Model MBean behavior driven by – Dynamic MBean descriptors – MBean Metadata – Inheritance Pattern Target Resource – Notification Model RMI/CORBA/EJB Object – Model MBean • Server Specification67 68 Model MBean (2) Interaction with Managed Resources A model MBean is a generic, configurable • Resource obtains access to MBean server dynamic MBean • Resource invokes MBean server to create new or •Concrete model MBean classes provided in find existing model MBeans conjunction with the JMX server • Resource configures model MBeans by – JMX server must provide RequiredModelMBean manipulating the model MBean descriptors •Configured via descriptors • Get attribute invoked on a model MBean •Descriptors contains dynamic, extensible, and – Model MBean has caching mechanism for attributes configuration behavior information which includes: – Return cached values or delegate invocation to resource object – Persistence policies, value caching policies, logging policies – Mapping from MBean attributes and operations to methods • Operation invoked on a model MBean on underlaying Java object(s) – delegate to managed resource object getAttribute("myApplStatus") • Managed resource sends notifications by invoking69 ==> myAppl.statusChecker() 70 sendNotifi ation method of model MBean Contents Server Specification • Introduction Object 1 • Architecture (MBean) Connector Object 2 Server Services • Instrumentation Specification (MBean) (as MBeans) Protocol Adaptor • Server Specification Server Services (as MBeans) Connector MBean server – MBean Server Server Java Virtual Machine – M-Let Service – Monitor Service MBean server Server services – Timer Service • MBean registry • Dynamic class loading • All management • Monitoring – Relation Service operations go through • Timer MBean server • Relation71 72 12
  13. 13. ObjectName Class Object Name Pattern Matching • Consists of two parts • Used in queries to identify target objects to Domain name limit scope of query – Provides for name spaces within a JMX server • Domain name or for a more global management solution * matches any character sequence, including empty – MBean server can provide default domain ? matches any one single character Key Property List • Key property list – Unordered list of property-value pairs * wildcard for key properties, – Used to assign unique names within a domain replaces any number of key properties – Must contain at least one key property • Examples • String representation MyDomain:description=printer,type=ink *:* all objects in MBean server [domainName]:property=value[,property=value]* :* all objects of the default domain73 74 ??Domain:* all objects in MyDomain Canonical name: key properties sorted in lexical *Domain:* all objects in domain ending with Domain Foundation Classes Contents • ObjectInstance class • Introduction – Contains • Architecture – Class name • Instrumentation Specification – ObjectName – Equality test with another ObjectInstance • Server Specification – Returned when an MBean is created and is used – MBean Server subsequently for querying – M-Let Service • Attribute class – Monitor Service – represents single attribute-value pair – Timer Service • AttributeList class – Relation Service75 – represents a list of attribute-value pair 76 MBeanServerFactory MBeanServer Interface (1) Class • Object creation methods: createMBean instantiates and registers an MBean • Only has static methods to instantiate – Create new MBean server instances instantiates an MBean but does not register MBean • MBean server referenced by domain name deserialize – Find MBean server instances byte array in context of MBean class loader – Release MBean server reference • MBean registration methods: registerMBean unregisterMBean isRegistered77 78 13
  14. 14. MBeanServer Interface (2) Query Methods • MBean proxy methods: Takes two arguments: ObjectName and QueryExp getMBeanInfo • Object name provides scope of query getAttribute getAttributes setAttribute setAttributes – Object name pattern matching selects MBeans on invoke which query expression will be applied addNotificationListener • Query expression operates on MBean attributes removeNotificationListener – Applies to a single MBean • Query method: – Use Query class to build QueryExp queryMBeans(ObjectName n,QueryExp q) QueryExp exp = returns Set of ObjectInstances Query.and( Query.between(Query.attr("age"), queryNames(ObjectName n,Query q) Query.value(20), return Set of ObjectNames Query.value(30)), Query.match(Query.attr("name"),79 • Read-only attributes: 80 Query.value("G*ling")) ) Contents Server Service MBeans • Introduction My MBeans • Architecture • Instrumentation Specification JMX • Agent Specification M-Let Service MBeans – MBean Server Monitor – M-Let Service Timer – Monitor Service – Timer Service Relation – Relation Service • Conclusion81 82 M-Let Service Contents • Introduction • MBeans can be Object obtained from a • Architecture 1 Object 2 remote JAR file • Instrumentation Specification Object 3 Object 4 • Server Specification http://soft.eng/mybean.html – MBean Server <MLET – M-Let Service CODE=object4.class ARCHIVE=mybean.jar M-Let NAME="test:name=object4"> </MLET> – Monitor Service CLASSPATH – Timer Service http://soft.eng/mybean.jar – Relation Service classes/ ass object3.class classes/ object4.class83 ass 84 14
  15. 15. Monitor Service Counter Monitor Illustration • A monitor MBean observes an attribute of another MBean at regular interval specified by the granularity period Threshold Threshold Threshold Threshold Notif Notif Notif Notif • The derived gauge is either granularity period modulus – the exact value, or threshold – the difference between two consecutive values threshold • A MonitorNotification is sent when the offset attribute value crosses a level or threshold, threshold or string value changes threshold threshold • There are several types of monitors: – Counter Monitor85 – Gauge Monitor 86 String Monitor Gauge Monitor Illustration String Monitor Illustration High Low High Match Differ Match Notif Notif Notif Notif Notif Notif granularity period granularity period HighThreshold LowThreshold "XYZ" "YYY" "XXXX" "XYZ" "XYZ"87 88 Contents Timer Service • Introduction " Enables notifications to be sent to all • Architecture registered listeners – At a specified date • Instrumentation Specification – Starting at a specified date and repeating • Server Specification several times, at regular time intervals – MBean Server " addNotification – M-Let Service " removeNotification – Monitor Service " SendPastNotification attribute – Timer Service – If true, send past notifications when timer re- started and update to the next notification date – Relation Service – if false, update past notification dates to next89 90 notification date but dont send past notifications 15
  16. 16. Contents Relation Service • Introduction • Used to define logical relations between MBeans • Architecture • Act as a repository for relation types and • Instrumentation Specification relations • Server Specification • To create relation between MBeans: – MBean Server – Create a new relation type, or use existing one – M-Let Service – Create a relation from this relation Type – Monitor Service – ---> will associate MBeans to this relation – Timer Service • Provides a set of operations to get – Relation Service information about relations and related91 92 MBeans Relation Service Example Maintaining Consistency (1) • Only registered MBeans can participate in relations – Relation service operates only on object names • Create relations between the Owner and its – Provides object names in response to queries Books in a Personal Library • Consistency checks when – Relation type is created e.g. role information inconsistent Relation Type – Relation is created Personal Library e.g. does not confirm to relation type or object name does not exist – Role values (MBeans in role) are updated • Removal semantics 1..1 0..* – Remove relation type removes all relation of relation type Role 1 Role 2 – Remove relation does not de-register MBeans Owner Book – De-register an MBean removes the MBean from all role values93 94 – PurgeFlag attribute and purgeRelations method Maintaining Consistency (2) Useful Links • Common use is to maintain consistency when an JMX MBean is de-registered • Home page (Specification, RI, and related JSRs) – Trigger code execution when a relation has been updated or deleted due to an MBean de-registration • Email archives – For example, to trigger code execution when resources are unplugged or removed Sun JDMK • Only guarantees that an MBean satisfies its role • Home page – Cannot define how many relations an MBean may appear in • Email archives IBM Tivoli JMX • AdventNet Agent Toolkit • 96 16
  17. 17. 97 17