Connectors And Protocol Adaptors

Connectors and Protocol Adaptors allow agents to be accessed and managed by remote custom management applications. These applications could be outside the agent's Java Virtual Machine (JVM). This is illustrated in Figure 1-1 .

Connectors (referred to as adaptors in Java Dynamic Management Kit 3.x versions) connect the MBean server to management applications and enable MBeans to be instantiated and managed remotely. Every connector provides the same remote management interface, but through a different protocol, which allows remote management applications to connect to agents transparently through the network, regardless of the specific protocol. One or more connector clients can be connected to the MBean server, providing views through specific protocols of the MBeans instantiated and registered with the MBean server. The Java Dynamic Management Kit provides connectors for most major internet protocols (for example, HTTP/TCP, HTTP/SSL and RMI) .

A connector is composed of two parts:

• A connector server on the agent side.

• A connector client on the manager side.

The interface of the remote MBean server is implemented by the connector client. Connectors allow management applications to be ported onto a manager site, offering the same level of functionality at both the agent and manager side while ensuring seamless, transparent connectivity.

Protocol Adaptors only have a server component and provide connection between a remote management application and an agent, via a specific network protocol. From a manager side, you can view and manage all MBeans registered in the MBean server. This can be achieved by directly accessing the MBean server's interface through a given protocol. For example, a web browser accesses the HTML protocol adaptor directly and, therefore, a client of the HTML protocol adaptor is an HTML browser. Similarly, an SNMP manager accesses the SNMP adaptor directly. Therefore, a client of the SNMP adaptor is an SNMP manager.

In addition, the Java Dynamic Management Kit provides an SNMP toolkit that allows you to generate MBeans that support standard or proprietary MIB's, enabling new Java technology-based agents to be integrated into existing network infrastructures, including most SNMP-based management products.

Connectors and protocol adaptors enable management applications to:

• Find existing MBeans through their object names.

• Get or set attributes of existing MBean instances.

• Invoke operations on existing MBean instances.

• Instantiate an MBean and register the new MBean instance.

• Receive notifications from known MBeans (except through the HTML adaptor).

For an agent to be managed remotely, it must include at least one connector or protocol adaptor. However, an agent can include any number of connectors or protocol adaptors, enabling it to be managed remotely by many managers, through different protocols. Proxy MBeans, at the manager side, are used to perform management operations on the corresponding MBeans at the agent side. These MBeans are registered with the MBean server in a manner that is protocol-independent. You need to call the start method to start connectors and protocol adaptors. This allows you to specify the port number before you start them.