Chapter 3: WBEM and Other Management Systems

As you read this chapter, remember the two types of fool: the one who says, "because it's old, it's good" and the one who says, "because it's new, it's better."

WBEM and CIM

WBEM is perhaps the most misleading title since "Miss Universe." I believe that only terrestrial competitors have ever taken part in the Miss Universe competition and I spend a measurable part of my life explaining to colleagues that WBEM has nothing to do with the World Wide Web ^[1] and can be applied to the management of systems unrelated to enterprises (meaning companies). Much of my work is with carriers , the owners of long-distance telecommunications networks. Such networks have to meet stringent availability requirements and, within this world, "enterprise grade" is contrasted with "carrier grade," the enterprise epithet implying lower quality.

The M in WBEM, meaning management, may also be misleading; it refers to the management of devices and services rather than people, e.g., setting up voice mail for a particular subscriber, intercepting alarms from storage devices, tracing a fault in the address scheme of a Local Area Network, installing a new version of a word processing package on everyone's computer within an enterprise, and so on.

WBEM is the product of the DMTF and this group might therefore be the definitive source on what WBEM constitutes . In a slide presentation in June 2000 on the role of the DMTF, Winston Bumpus, the DMTF President, explicitly said this role was desktop systems, enterprise networks, and E-business infrastructure, and this is indeed the current emphasis.

Perhaps my main criticism of the DMTF is that it has set its sights too low. As I hope I demonstrate implicitly, the WBEM architecture, language, and models are very close to being ready for the higher-quality carrier domain. I discuss my only reservation in my answer to Frequently Asked Question 28 on page 149.

Having said what WBEM is not, I should now say what it is. WBEM encompasses the architecture and technologies for device, network, and service management. It emerged in the mid to late 1990s as a means of managing desktop computers, and in the late 1990s it started to evolve into a more general-purpose management tool.

The two major management standards in use in networks today are SNMP, primarily used for data (IP) networks, and TMN, which has traditionally been used in the backbone telecommunications networks. The rise of data networking and the convergence of data and voice networks mean that these two systems are now colliding in some networks, generally introducing SNMP management into the backbone rather than TMN into the enterprise. WBEM can be seen as a way of upgrading and ultimately replacing both.

The key differences between WBEM and the more traditional management standards such as TMN and SNMP are the available modelling constructs and WBEM's clear separation of the interface used to access information from the model of the device being managed.

SNMP has a very simple modelling language, allowing objects to be defined and interrelated through a "contains" hierarchy. Apart from its ability to construct two-dimensional tables, there is no other way to associate and combine items.

In contrast, both TMN and CIM have sophisticated object-oriented structures supporting concepts such as inheritance, classes, and polymorphism. Among other advantages, such as more intuitive modelling, these techniques allow much larger models to be built without them becoming unwieldy.

WBEM comprises a set of standardised technologies (see Figure 3.1) that include:

• CIM: A data modelling process and language (known as Managed Object Format ( mof )). CIM also includes a number of standard models ( schemata ) for systems, applications, networks, devices, and other common components , expressed in the mof language; see Table 3.1. This standardisation enables applications from different developers on different platforms to describe management data in a standard way so that it may be shared among a variety of management applications.

  Table 3.1: CIM Common Models

  Model	Contents	Reference
  Applications	Software products and applications and their deployment and monitoring	-
  Database	A database and the database service (as in RFC1697)	-
  Device	Configuration and state information for hardware	-
  Event	Events and alarms	Page 151
  Interop	Management of the WBEM server itself	Page 250
  Metrics	Information measured in a system and the handling of it	-
  Network	Networks and network protocols (OSPF, BGP, etc)	Page 100
  Physical	Inventory and asset management	_
  Policy	Rules and associated actions	Page 107
  Support	Interaction of support models for different equipment	-
  System	The combined action of several components working together as a system	Page 99
  User	The location, identity, and authority of different users	Page 114

  
  Figure 3.1: WBEM Components

• A standardised architecture for hierarchical management systems including the definition of a WBEM server (see Figure 4.4) and its interfaces. I describe this architecture in detail in Chapter 4; suffice it to say here that the WBEM server acts as a broker between the operators' workstations and the complex systems under their management.

• xmlCIM, an encoding specification, for encoding commands and responses which can be used to represent WBEM entities:

  • The definition of XML elements in Document Type Definition (DTD).

  • The representation of CIM in XML Specification.

• HTTP access, the HTTP encapsulation (CIM-XML), the transport mechanisms for carrying commands and responses across a network, including the "CIM Operations over HTTP" and the anticipated "CIM over SOAP" (Simple Object Access Protocol, as standardised by the W3C, the World-Wide Web Consortium) specifications.

^[1] Except that it borrows one protocol: HTTP.