The Operations

The last part of the MBean view contains all of the operations exposed by the MBean. Each operation in the list is presented like a method signature: there is a return type, then a button with the operation name, and if applicable, a list of parameters, each with their type as well.

As with the table of attributes, the list of operations contains only those involving types that can be represented as strings. The return type must support the toString method and the type of each parameter must be one of basic data types supported by the HTML adaptor. For the complete list, see the Javadoc API of the HtmlAdaptorServer class.

Above each operation is a link to its description. Parameter names are also active links which pop up a window with a description text. Again, descriptions are only meaningful when provided by dynamic MBeans. The following figure shows some of the operations exposed by the HTML adaptor MBean and a description of the Start operation.

Figure 5-4 MBean Operations with a Description Dialog (Partial View)

We will not invoke any operations on this MBean until a brief explanation in "Instantiating and Managing MBeans".

To invoke an operation, you would fill in any and all parameter values in the corresponding text fields and then click the operation's button. The HTML adaptor would then display a page with the result of the operation: the return value if successful or the reason the operation was unsuccessful.