Objects generally do not exist separately in i-doit but are in relation to each other. The servers are contained in racks, admins maintain servers, an operating system with software is running on a server ... In this article we will elaborate on the basic concepts of object relations.
Objects can be in various types of relations. To provide clarification each relation receives a type. Many pre-defined types of relations are already supplied by i-doit in the default installation. A listing of all these types can be found at Administration → CMDB Settings → Relation types.
|Relation title||Description from the point of view of the master object||Description from the point of view of the slave object|
|Administration service||is administration instance for ||is managed by |
|Assigned cards||has card ||is card of|
|Backup||saves||saved by |
|Chassis||includes||is inserted to|
|Cluster memberships ||is member of ||has member |
|Cluster service assignment||is host for on ||runs on |
|Connectors||is connected to ||is connected with |
|Contact assignment (administrates) ||administrates||is administered by |
|Contact assignment (uses)||uses||is used by |
|Contract assignment ||is contract of ||has contract assignment |
|DBMS||administrates||is configured in |
|Database access ||is used by ||has database access |
|Database gateway ||has database gateway to ||is database gateway |
|Database instance ||is host for ||runs on |
|Database links ||has database link to ||is database link of |
|Dependency||has dependency to ||depends on |
|FC port ||supplies network ||network is supplied by |
|Files||has file assignment to ||is file for |
|Group memberships ||is member of ||has member |
|Headquarter (Organization) ||is headquarter of ||is branch of |
|Host address ||supplies network ||network is supplied by |
|Interface||has dependency to ||depends on |
|Layer 2 Transport ||transports Layer 2 Net ||is transported by |
|Location||is location of ||is located at |
|Logical devices (Client) ||is connected to ||is connected with |
|Logical location||is logical unit of||is assigned to|
|Network connections ||is connected to ||is connected with |
|Operating system ||has operating system ||is installed on |
|Organization (Organization)||has member ||belongs to |
|Organization (Persons) ||has member ||belongs to |
|Person group memberships ||has member ||is member of |
|Ports||supplies network ||network is supplied by |
|Power consumer ||supplies power to ||obtains power from |
|Remote Management Controller ||is remotely managed by ||is management controller of |
|Replication partner ||is Replication partner of ||has Replication partner |
|SOA-Component||is SOA component of ||has SOA component |
|SOA-Stacks||has SOA Stack ||is SOA Stack of |
|Service assignment ||is host for ||runs on |
|Service component ||is Service component of ||has Service component |
|Share Access||share is used by ||has share access to |
|Software assignment ||is running ||runs on |
|Stacking||is stack for ||is stacked with|
|VRRP||has VRRP member ||is VRRP member of |
|Virtual host ||is administration instance for ||is managed by |
|Virtual machine ||is host for ||runs on |
Below the list of relation types a new type can be created using the Add new value button. If you wish to use this relation in a custom category, you have to define it as "Implicit".
Already documented object relations are listed in Extras → CMDB → Relations according to their respective type. When you click on All in the navigation tree to the left, all object relations are loaded regardless of their type. With large IT documentations it may take a while to load the list.
When creating a relation between two objects, a third object of the type Relations is created in the background. The object title of this object consists of the object title of the master object, followed by the description and the object title of the slave object.
|Master object||Description of the relation||Slave object|
|PDU-HQ-Intern-01-A||supplies power ||ESX1|
The relation object is required to save characteristics of the relation as attributes. This includes:
- Relation type: see above
- Weighting: see below
- Service (optional): The object relation can be directly assigned to a service.
As it is already obvious, an object relation consists of a master and a slave object. This is a weighted relation. The slave object is dependent on the master object.
The direction of the relation (which object is the master and which one is the slave) has consequences for the CMDB explorer. Object relations are displayed recursively either upwards or downwards in the tree view. Master objects are below the slave objects in the standard profile.
License requirements for objects
Relation objects do not require a license.
Relations to other objects are gathered in the Relations category per object. This category is assigned to each object type in a fixed way and can be opened via the arrows icon.
Implicit versus Explicit Relations#
Relations do not only have different types (see above) but they are also being created implicitly or explicitly. Implicit relations originate from categories. If the Location category is edited, for example, and an object which is higher in the hierarchy is selected in the Location attribute, then the implicit relation of the type Location will be created automatically in the background. This implicit relation is also shown in the Relations category at Extras → CMDB → Relations → Locations.
If you want to build a relation between two objects independent of the categories and their attributes, an explicit relation will be created. This explicit relation is created in the Relations category. The object where you are during that moment is pre-selected as Object 1. The object with which Object 1 is to be put into a relation has to be selected under Object 2. You also have to choose the direction between the two objects. Dependency is selected as the default relation type, as it is already set as explicit at Administration → CMDB Settings → Relation types. But you can also easily define a new explicit relation and use it immediately. This can be carried out via the slips-icon, similar to the procedure with Dialog+ fields.
When creating a new explicit relation type, the type and the descriptions can be defined from the corresponding object views.
Implicit or explicit?
So what is better: Should you use implicit or explicit relations? The answer is: implicit relations. Categories and attributes are central elements for structuring the IT documentation. Users document in categories and that is also where users look for information. Therefore it is better to document unspecific relations of the type Dependency explicitly in a category in which implicit and explicit relations are varied. Both possibilities can be evaluated, but only the implicit relations are transparent.
Each relation receives a weighting, as already mentioned above. The weighting is specified as attribute in the relation object. Values between 1 and 10 are possible as weighting. They express how dependent the slave object is on the master object. 1 means very important, while 10 means unimportant. 5 is the golden mean, it stands for important and represents the default value.
Example: A power supply receives its power from an UPS, so the weighting could be 1 (very important) as the power supply could not function without a usable UPS. However, if a node fails within the web cluster, other nodes take on its job. This means that the dependency to higher-level services is not as strong and could lie somewhere between 5 (important) and 10 (unimportant).
The Analysis module uses this weighting in combination with services and Network Monitoring to evaluate which services are affected by malfunctions.
Besides the direction-based relations with master and slave objects there exist also parallel relations in i-doit. The parallel relations also set two objects in relation to each other, however, without expressing a dependency on each other.
Example: When a web cluster with multiple nodes is documented in i-doit, the nodes act independently of each other. Only the functioning of the cluster depends on all nodes. The Cluster members category (or the mirrored category Cluster memberships) creates parallel object relations between the cluster members in the background.
A listing of all parallel relations can be found at Extras → CMDB → Relations → Parallel relations. They cannot be created by the user but are created implicitly and automatically in the background.
Object Relation in a Custom Category#
Object relations can be documented in custom categories. You need to distinguish between two field types:
- Object-Browser: No relation object is created. The relation to be documented here between two objects is not listed in the Relations category and the CMDB explorer does not process these relations.
- Object-Relation: Here only an implicit relation type can be given as Addition. Explicit relations are not shown.
Object browser or object relation?
As for implicit and explicit relations the same question arises: Which field type is better? Here the answer is clear as well: The Object-Relation has additional uses and should therefore be preferred to the Object-Browser.