Posted by kalali
on April 6, 2010 at 12:16 AM PDT
In this entry we discuss what Application Server Management Extension (AMX) and Java Management Extensions (JMX) are, how we can use them to develop custom administration, management and monitoring solutions for GlassFish v3. The article contains tens of diagrams and samples.
Manage, Administrate and Monitor GlassFish v3 using Application Server Management Extensions (AMX) & The Java Management Extensions (JMX)
Management is one of the most crucial parts of an application server set of functionalities. Development of the application which we deploy into the server happens once with minor development iteration during the software lifecycle, but the management is a lifetime task. One of the very powerful features of the GlassFish application server is the powerful administration and management channels that it provides for different level of administrators and developers whom want to extend the application server administration and management interfaces.
GlassFish as an application server capable or serving mission critical and large scale applications benefits from several administration channel including the CLI, web based administration console and finally the possibility to manage the application server by using standard Java management extension or the JMX.
Not only GlassFish fully expose its management functionalities as JMX MBeans but also it provides a very easier way to manage the application server using local objects which proxies JMX MBeans. These local objects are provided as AMX APIs which lift the need for learning JMX by administers and developers whom want to interact with the application server by code.
GlassFish provides very powerful monitoring APIs in term of AMX MBeans which let developers and administrators monitor any aspect of anything inside the application server using Java code without need to understand the JMX APIs or complexity of monitoring factors and statistics gathering. These monitoring APIs allows developers to monitor a bulk of Java EE functionalities together or just monitor or single attribute of a single configuration piece.
GlassFish self management capability is another powerful feature based on the AMX and JMX APIs to let administrators easily automate daily tasks which can consume a handful amount of time without automation. Self management can manage the application server dynamically by monitoring the application server in runtime and changing the application server configuration dynamically based on predefined rules.
1 Java Management eXtension (JMX)
JMX, native to Java platform, introduced to let Java developers have a standard and easy to learn and use way for managing and monitoring their Java applications and Java enabled devices. We as architects, designers and developers of Java applications which can be as small as an in house invoice management or as big as a running stock exchange system need a way to expose management of our developed software to other industry accepted management software and JMX is the answer to these need.
1.1 What is JMX?
JMX is a part of Java Standard edition and was present from early days of Java platform existence and seen many enhancements during Java platform evolution. The JMX related specifications define the architecture, design patterns, APIs, and services in the Java programming language for managing and monitoring applications and Java enabled devices.
Using the JMX technology, we can develop Java classes which perform the management and monitoring tasks and expose a set of their functionalities or attributes by means of an interface to which later on are exposed to JMX clients through specific JMX services. The objects which we use to perform and expose management functionalities are called Managed Beans or MBeans in brief.
In order for MBeans to be accessible to JMX clients, which will use them to perform management tasks or gathers monitoring data, they need to be registered in a registry which later on let our JMX client application to find and initialize them. This registry is one of the fundamental JMX services and called MBean Server.
Now that we have our MBeans registered with a registry, we should have a way to let clients communicate with the running application which registered the MBeans to execute our MBeans operations, this part of the system is called JMX connectors which let us communicate with the agent from a remote or local management station. The JMX connector and adapter API provides a two way converter which can transparently connect to JMX agent over different protocols and provides a standard way for management software to communicate with the JMX agents regardless of communication protocol.
1.2 JMX architecture
The JMX benefits from a layered architecture heavily based on the interfaces to provide independency between different layers in term of how each layer works and how the data and services are provided for each layer by its previous one.
We can divide the JMX architecture to three layers. Each layer only relay on its direct bottom layer and is not aware of its upper layer functionalities. These layers are: instrumentation, agent, and management layers. Each layer provides some services either for other layers, in-JVM clients or remote clients running in other JVMs. Figure 1 shows different layers of JMX architecture.
Figure 1 JMX layerd architecture and each layer components
This layer contains MBeans and the resources that MBeans are intended to manage. Any resource that has a Java object representative can be instrumented by MBeans. MBeans can change the value of object