Structure of the WBEM Server

The components of the WBEM server are illustrated in Figure 4.4. The WBEM server is a broker between various independent elements: primarily the WBEM clients and listeners which represent the operators or higher-level management systems and the providers which interact directly with the actual hardware or software being managed.

Figure 4.4: WBEM Server Architecture

The heart of the WBEM server is the CIM Object Manager (CIMOM), which uses information stored in a model in the repository to direct commands and responses between the WBEM clients, providers, and listeners. The CIMOM provides interfaces to:

• A repository, in which an abstract model of the device's managed characteristics (hardware, software, and services) are stored. I describe how to build such a model in Chapter 5.

• Providers, which act as drivers and interface between the abstract world of the model and the messy characteristics of real hardware and software. The providers supply the intelligence to translate an abstract request ("return the state of the fan") into a specific command ("read the top two bits of register 17 in the integrated circuit at address OxFFFF6638 and convert the result in accordance with the following mapping, etc."). Providers are discussed in detail in Chapter 11.

• Clients, able to interact with the CIMOM to manipulate the model as requested by an operator. Clients may exist on the device being managed, on the operator's workstation, or on some other device; see Chapter 13.

• Listeners, which receive information about events and alarms that have occurred in the managed device and about which an operator has expressed interest.

• Security plug-ins, which typically interface to external authentication services to authenticate users and operators.