Basic Concepts
The goal of the OGIT (Open Graph of IT) Ontology Framework is to build an open semantic representation of all IT and its interactions with business processes and people for providing a foundation for computational evaluation. The resulting knowledge graph allows to interconnect various IT entities in the IT Operations and IT Management space. While previous approaches like the IBM Common Data Model (CDM) required too much details and did not allow any ambiguity and incorrectness, the Open Graph of IT ontology allows varying levels of detail and can easily consume real world data with all its inaccuracies and redundancies.
The ontology structure is designed for growth both in depth as well as in breadth. It encourages re-use and agreement on best practices but it also leaves room to use data without the need to a priori agree on a common semantics .
This document provides a high-level overview of the core ideas of OGIT. For more technical depth, please refer to the ontology details document.
OGIT is an ontology that serves as a reference model for entities in the IT landscape and relationships between entities. It is comparable to the schema.org effort that provides schemas for structured data on the internet. In OGIT there are three types of elements:
- Entities represent concepts (nodes in the graph),
- Verbs are binary relations (edges) between two Entities and describe something an Entity does to or with another,
- Attributes are binary relations (edges) between an Entity and a scalar value, such as a string or an integer.
All Entities, Verbs and Attributes are uniquely identified by URIs.
The ontology is divided into 5 layers of abstraction, as shown in the following diagram:
Basically, the innermost layer contains generic concepts, such as Device, while the outermost layer contains user-specific extensions. This separation exists not only for the sake of clarity of the schema, but also to determine who is responsible for changes to certain parts of the ontology. While the innermost layer is governed rigorously, anyone can make changes in the outermost layer. The following sections describe the layers in more detail.
The SGO is the most generic level of OGIT and is the only layer maintained by the Ontology Board. Concepts that are described in the SGO are not specific to one domain, but are broadly usable.
An NTO contains concepts of a certain domain. The differentiation between SGO and NTO is made to allow subject matter experts to deal with NTO definitions while strategic experts deal with the definition of the big picture.
Examples for NTOs:
- Automation
- Business Process
- Cost
- Service Management
Each of these attribute sections describes attributes to be used with a node type that was defined in the SGO or an NTO.
Each node well-defined by SGO and NTO ontologies will have a set of attributes that is specific to this unique type of node. The SNRA defines the minimal required attribute set. The SNRA are always included and are mandatory, so the syntax will be checked and tools will only work properly if the SNRA definition is followed.
Each well-defined node type can have a number of attributes that have proven useful. If these attribute suggestions are followed, then the reuse and effectiveness of platform resources (e.g., knowledge in automation, architectural benchmarks) are maximized. SNBA can be understood as “optional” attributes.
The Free attribute space in every node is used by applications, users and organizations to add data structured according to their own needs, concepts and ideas. Data stored here uses the mechanisms of OGIT, but is not easily reusable by other users. When similar or equivalent attributes are employed by multiple users, they may be moved up one layer into the SNBA section to be published and discussed in a platform-wide distribution.