Java Dynamic Management Kit 3.2 Programming Guide | ||||
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An access control list (ACL) defines access rights to managers or proxy servers that access agents through the SNMP adaptor. Rights are based on the IP address of the host or proxy machine of the manager. If the ACL does not exist when the agents are started, all managers are granted access through the SNMP adaptor. Information on each machine together with its access rights are stored in an ACL.
An action is a public method of an m-bean that is intended to be invoked remotely. Public methods in an m-bean that are not actions are intended to be invoked only by other local m-beans.
An activation service is a service that is able to control the execution of m-beans that implement the com.sun.jaw.reference.agent.services.ActivatableIf interface.
An adaptor connects the framework to external applications. It provides a view through a specific protocol of m-beans instantiated and registered with the framework.
The base agent is a container in which m-beans are instantiated and run. A base agent consists of a framework that is initialized with the base services and at least one adaptor.
The base services are the services that the framework requires to be able to function. They are supplied as separate components and can be rewritten, enabling you to customize the framework. The base services are the repository service, the metadata service, the filtering service, and the relationship service.
The bootstrap service simplifies the distribution of new releases of an application (agent or manager) from a central server. It is a standalone Java program that enables you to load an application from a remote .jar file. To obtain a new version of an application, run the bootstrap service on the system that requires the application. Information on the application is contained in an m-let text file. You specify the URL of the m-let text file when you run the bootstrap service.
A client bean, or c-bean, is a stub object that represents a remote m-bean to a manager developed with the adaptor client API. Like an m-bean, a c-bean is a JavaBeans component. The manager accesses an m-bean by performing operations on the c-bean, which are propagated to the m-bean. Events emitted by the m-bean are propagated to the c-bean. A c-bean is generated from its m-bean by using the mogen compiler.
The class loader enables a Java Dynamic Management agent to obtain Java classes that are not already loaded into its framework. When an agent requests that such a class be instantiated, it is loaded by the class loader. The Java classes must be present on a machine on which the class and library server is running.
The class and library server serves classes and libraries to the class loader and the library loader. It works in conjunction with the RMI class loader provided with the Java Dynamic Management Kit. The supplied server runs as a standalone Java program but is implemented as an m-bean. This enables it to be integrated with a Java Dynamic Management agent and managed through the adaptorMO interface.
The filtering service selects m-beans to be the subject of a management operation. Selection is based on the presence and values of specific attributes. For example, a filter could select all the m-beans for which the value of the attribute color is red.
The framework (core management framework) is a registry for objects in an agent.
Properties are always accessed by method calls on the object that owns them. For readable properties, there is a getter method to read the property value.
An agent consists of a base agent and the m-beans instantiated during the lifetime of the base agent.
The job tool provides a graphical representation of the m-beans registered with an agent. It is a debugging tool that enables you to preview an m-bean under development by instantiating and performing operations on the m-bean instance. It is a simple Java manager.
The launcher service enables all Java Dynamic Management applications running on a single machine to share the same base agent. It also enables you to load new applications into a base agent that is already running. The launcher service uses the m-let service for loading the m-beans and other resources that make up an application.
The library loader loads native libraries into the framework. A native library is loaded whenever a new m-bean class that includes native code is loaded.
A managed bean, or m-bean, is a Java object that can be registered with the framework. An m-bean conforms to design patterns derived from the JavaBeans component model and additional design patterns specific to the m-bean model. The additional patterns are defined to ease the interaction between objects and the framework.
The management applet or m-let service enables an agent to obtain m-beans from a remote .jar file. The agent does this by loading an m-let text file, which specifies information on the m-beans to be obtained. The information on each m-bean is specified in a single instance of a tag, called the MLET tag. The location of the m-let text file is specified by a URL. The agent creates an instance of each m-bean specified in the m-let file when the file is loaded.
The mibgen compiler generates skeletal m-beans and a Java file containing the "SNMP view" of the bean. This is referred to as metadata. Metadata files do not need to be modified. For metadata files, the Meta suffix is added.
The metadata service supplies an agent with the properties and actions supported by an m-bean.
The mibgen compiler takes as input a set of SNMP MIBs and generates skeletal m-beans that implement the MIBs. MIBs can be expressed using SNMPv1 or SNMPv2 syntax.
The MLET tag specifies an m-bean to be obtained by the m-let service. The syntax of the MLET tag is similar to the syntax of the APPLET HTML tag.
The mogen compiler takes the compiled Java class of an m-bean and generates the Java interface and Java stubs of a c-bean. The Java stubs consist of Java source code that implements the interface. To develop a Java manager with code generated by mogen, you use the adaptorMO interface. This makes sure that the behavior of the stubs is the same on any adaptor client, provided that it also implements the adaptorMO interface.
An object name uniquely identifies an m-bean within a framework. Management applications use object names to identify the m-beans on which to perform management operations. If you do not specify the object name explicitly, the Java Dynamic Management Kit assigns a default object name to the object.
The repository service stores m-beans that are registered with the framework as normal Java objects. For an m-bean, the repository service stores and retrieves the m-bean attribute values and the association between the m-bean and its object name. An M-bean can only be managed if it is registered with an object name in the repository.
The search key enables unique names to be assigned to instances of the same class. A search key consists of one or more attribute-value pairs that do not have to correspond to a property within the m-bean.
Properties are always accessed by method calls on the object that owns them. For writable properties, there is a setter method to allow the property value to be updated.
A singleton is an m-bean without a search key. Only one instance of such a class is permitted within the domain.
A skeletal m-bean is generated by the mibgen compiler for each group defined in the MIB. These skeletal m-beans are initialized with default values for the different MIB variables but need to be completed by adding implementation-specific code (access methods).
Signed jar files are .jar files that have been signed using the javakey security tool. Using a security manager that allows only classes from such a file to be downloaded ensures that only classes from a trusted source are downloaded over a network.
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Starting and Stopping the Base Agent in the Windows NT Environment |