Learning about the common data model - Documentation for BMC CMDB 19.11

Examples

Simple server with an operating system

The diagram on the right represents a server. A server is represented in the CDM with a CI. BMC_ComputerSystem CIs have attributes that give more details about themselves. Each attribute has a name and a value. In the diagram, BMC_ComputerSystem has many attributes. However, for purpose of illustration, only two are shown in the diagram:

The Name attribute of BMC_ComputerSystem is always set to the fully qualified domain name (FQDN) of the host, if that is available. If the FQDN isn't available, alternative values are used. For more information about these values, see  CDM Mapping for Host .

In the diagram, the top box represents the operating system running on the server. Operating systems are represented by a BMC_OperatingSystem CI that has many attributes. However, for purpose of illustration only Name and OSType are shown here. All CIs have a Name attribute and it is usually populated with something that usefully identifies the CI.

The two CIs, BMC_ComputerSystem and BMC_OperatingSystem, are connected by a line that represents a relationship between them. BMC_HostedSystemComponents relationship connects both these CIs. Relationships, like CIs, have attributes. As explained earlier, directionality of relationships helps identify the source and destination. In this example, BMC_ComputerSystem is the source and BMC_OperatingSystem is the destination.

For more information about the CI classes and attributes, refer to the BMC Helix CMDB CDM Help file in PDFs and videos (Login required).  

Two servers with a dependency

If there are two servers to model, then two BMC_ComputerSystem CIs are used to model them. The following diagram shows two servers that have a dependency on one another:

The original server, along with its operating system (Windows), is shown on the left. Another server, with Linux as its operating system is shown on the right. Each BMC_ComputerSystem CI has a relationship with its respective BMC_OperatingSystem CI, just like in the case of a simple server. However, in this case the two BMC_ComputerSystem CIs have certain kind of dependency between them and are related using BMC_Dependency relationship.

The two BMC_ComputerSystem CIs are both of the same class. You don't really need to worry too much about the distinction, but for those that are interested, a class is an abstract concept that represents what it means to be a certain type of CI. For example, the BMC_ComputerSystem class represents what it means to be a server. It doesn't represent any particular server; instead, it says that all servers have names and manufacturers. CIs represent actual servers.