TOGAF TRM ("CRIB NOTES")

What are Reference Models used for ?  

There are two main purposes behind the Reference Models : 

•  to establish a taxonomy shared by all participants in the architecture and engineering processes 
• to establish the complete map of the architecture domain 

Shared taxonomy. Establishing an « official » taxonomy for IT assets is not a trivial task. Endless hours are spent in the most innefficient way because of misunderstandings among the participants in the development processes. Even seemingly simple terms such as « CPU » can generate confusion. There several kinds of CPU’s and in a virtualized environment what is a CPU may not be clear.

Moreover, a taxonomy should take into account the established names in the organization, for lowering resistance and avoiding a costly « reeducation process ». Hence, it takes some effort. The pay-off is not easy to measure, as it comes under the form of saved time in future meetings and the avoindance of awkward situations generated by misunderstandings.

The complete map. The reference model provides the « big picture » of the domain. Typically, each participant in the development processes is deeply concerned with the tasks and challenges that direct depend on him, at the same time he is oblivious to the rest of areas. If the IT landscape is compared to a city, each participant is concerned only about his neighborhood. The reference model facilitates the architecture team to argue with the stakeholders going beyond their immediate concerns.

TOGAF Technical Reference Model (TRM)  

The TOGAF Technical Reference Model (TRM) is an architecture of generic services and functions that provides a foundation on which more specific architectures and architectural components can be built.

Any TRM has two components : 

• A taxonomy (which provides a coherent description of the components and conceptual structure of the information systems) 
• The TRM graphic (which provides a visual representation of the model)

The TRM is expected to be customized for each organization.

The TRM can be used as a taxonomy to develop a Standards Information Base (SIB).

TOGAF TRM is organized in three major entities (Application Software, Application Platform and Communications Infrastructure) connected by two interfaces (Application Platform Interface and Communications Infrastructure Interface).

The figure reproduced below depicts the TOGAF Technical Reference Model.

TOGAF TRM

Application software

This entity encompasses Business Applications and Infrastructure Applications.  

Business Applications 

Implement business processes for a particular enterprise or vertical industry. This section of the model identifies all of the application components used in the organization.

A few examples :

• Patiente record management (in the Medical industry)   
• Inventory management (in Retail) 
• Geological data modeling (in Petroleum)  
• Vehicle tracking (in Logistics)  

Infrastructure Applications 

Provide general purpose business functionality, based on infrastructure services. They typically have the following characteristics :

• Widespread availability as COTS software means that it is uneconomic to consider custom implementation.   
• User interaction is an important part of the application’s function. 
• Implementations are based on infrastructure services. 
• Implementations may include significant extensions beyond that needed to use the underlying infrastructure services.  
• Interoperability is a strong requirement.  

A few examples :

• Groupware services 
• Spreadsheets 
• Document editing and presentation 
• System and network management applications    
• Software engineering tools  

Application platform 

The Application Platform identifies and provides structure to the set of technical services that are required for supporting the business and infrastructure applications. It is the green area in the above diagram. The technical service groups are :

• Graphics and image
• Data management
• Data interchange
• User interface
• International operations
• Location and directory
• Transaction processing
• Security
• Software engineering
• System and network management
• Operating systems services
• Network services

Additional groups or some regrouping might be adopted in an organization.

An additional purpose of the TRM is to avoid too much heterogeneity. Ideally, each service should be provided by a single component, what makes asset management much more efficient.

Application platform interface

The Application Platform Interface (API) specifies a complete interface between the Application Software and the underlying Application Platform.

The goal is to achieve full application portability.

  

Communications infrastructure 

The Communications Infrastructure provides the services to interconnect systems. It deals with the complex world of networks and the physical Communications Infrastructure, including switches, service providers, and the physical transmission media. Currently, Internet typically plays a role in this domain.

Communications infrastructure interface

The Communications Infrastructure Interface is the interface between the Application Platform and the Communications Infrastr ucture.

The goal is to achieve full interoperability.  

Qualities 

There is a set of attributes or qualities that are applicable across all TRM components. For example, for the management service to be effective, manageability must be a pervasive quality of all platform services, applications, and Communications Infrastructure services.

Taxonomy of Service Qualities

The service qualities presently identified in the TRM taxonomy are:

• Availability (the degree to which something is available for use), including:
• Manageability 
• Serviceability 
• Performance 
• Reliability 
• Recoverability 
• Locatability  

• Assurance, including:
• Security 
• Integrity 
• Credibility   

• Usability, or ease-of-operation by users, including:
• International Operation  

• Adaptability, including:
• Interoperability 
• Scalability 
• Portability  
• Extensibility  

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