ArchiMate: Adding Value to TOGAF
The ArchiMate® enterprise architecture modeling language has been developed to provide a uniform representation for enterprise architecture descriptions1. It offers an integrated architectural approach that describes and visualizes the different architecture domains and their underlying relationships and dependencies. In a short time, ArchiMate has become the open standard for architecture modeling in the Netherlands. It was officially launched in April 2009 as an Open Group standard; since then, the international interest in ArchiMate has been growing rapidly. ArchiMate complements TOGAF2, the leading standard of The Open Group for developing enterprise architectures.
An Integrated Approach to Enterprise Architecture
Frameworks for enterprise architecture vary in the types of support that they offer. They may have, among others, any combination of the following ingredients:
- A process (“way of working”) for creating architectures; this may be accompanied by guidelines, techniques, and best practices.
- A set or classification of viewpoints.
- A language for describing architectures (defining concepts and relationships, but also a notation).
- The concept of a (virtual) architecture repository, possibly containing predefined architectural artifacts and (reference) models.
The core of TOGAF is a process called the Architecture Development Method (ADM). The ADM also describes viewpoints, techniques, and reference models, but not a complete language: the TOGAF Architecture Content Framework does identify relevant architecture building blocks, but it does not constitute a precisely defined language, nor does it provide a notation for these building blocks. ArchiMate also describes viewpoints, and in addition to this, it defines a well worked-out language, including a (graphical) notation. This language also provides a concrete visualization of the views identified in TOGAF.
TOGAF and ArchiMate share their view on the use of viewpoints and the concept of an underlying common repository of architectural artifacts and models; i.e., they have a firm common foundation. However, TOGAF and ArchiMate complement each other with respect to the definition of an architecture development process and the definition of an enterprise architecture modeling language. Together, they make up a complete, integrated approach for delivering enterprise architecture.
Creating Architecture Models with ArchiMate
Within TOGAF, ArchiMate is used primarily for the creation of architecture models. TOGAF distinguishes four architectures: the Business Architecture (created in Phase B of the ADM), the Application Architecture and Data Architecture (both part of the Information Systems Architecture, Phase C), and the Technology Architecture (Phase D). In all of these phases, baseline (“as is”) and target (“to be”) architectures are created. In Phase A (Architecture Vision) of the ADM, first global versions of these architectures are already sketched; for this, ArchiMate may also be suitable.
We illustrate the different architectures with a small example based on a fictitious insurance company. ArchiSurance is a merger of three previously independent companies: Home & Away for home and travel insurances, PRO-FIT for car insurances, and Legally Yours for legal aid insurances. The new company has a single front office and three separate back offices. ArchiSurance intends to rationalize its application portfolio, by integrating legacy applications with similar functionality from the old companies that are still in use.
The Business Architecture provides the context for system development trajectories, showing, among others, the main business processes, the actors (or roles) performing these processes, and the information (objects) exchanged between the processes. Figure 1 shows an example of a Business Architecture expressed in ArchiMate. We assume that the business architecture of ArchiSurance does not change in the application rationalization process.
The Application Architecture shows the applications or application components, their relationships, and their functionality. The functionality that the applications offer to their environment is modeled with services. The service concept plays a central role in ArchiMate, also in the Business Architecture and the Technology Architecture (although this is not shown in our example), and in particular as a linking pin between the different architectures.
The target Application Architecture of ArchiSurance replaces the legacy applications with a single back-office system and a single CRM system for the whole company.
In ArchiMate, separate views can be used to show the relationships between the different architectures. As an example of this, figure 2 shows how the services from the Application Architecture are used in the processes of the Business Architecture.
The Data Architecture shows the main data object used within the applications, as well as their relationships.
The Technology Architecture shows, among others, the devices and system software on which applications run, the networks connecting devices, and artifacts that form the physical implementation of application components or data objects.
In the target Technology Architecture, some of these application servers become redundant. However, to increase reliability and availability, an additional backup server is introduced.
An important step in Phases B, C, and D of the TOGAF ADM is a gap analysis, which reviews the differences between the baseline and target architectures. It shows which building blocks are carried over from baseline to target, which building blocks are new in the target architecture (which can be used as a basis to decide whether to buy or build these building blocks), and which elements have been eliminated from the baseline architecture (on purpose or accidentally; i.e., gap analysis can also be used as a mechanism for validation of the target architecture).
TOGAF suggests the use of a gap matrix as a technique for gap analysis. However, ArchiMate models also form a useful starting point for gap analysis, and the results can also be presented as an ArchiMate view.
ArchiMate Models to Guide the Implementation Trajectory
Phases E, F, and G of the TOGAF ADM deal with the implementation of the proposed target architecture.
In Phases E (Opportunities & Solutions) and F (Opportunities & Solutions), transition architectures are used to describe possible intermediary situations between baseline and target. Based on these transition architectures, implementation projects can be defined. Given the baseline and target Application Architecture of ArchiSurance, a transition architecture can be envisioned in which the two CRM applications have been replaced by a single application (but still with multiple back-office systems), or a transition architecture with a single back-office system (but still with two CRM applications).
In Phase G (Implementation Governance), formal ArchiMate models of the architectures can be used as a reference for architecture compliance reviews.
Summary and Conclusions
TOGAF is a leading enterprise architecture method of The Open Group. ArchiMate has recently been adopted as an Open Group standard for modeling enterprise architectures. TOGAF and ArchiMate share their view on the use of viewpoints and the concept of an underlying common repository of architectural artifacts and models; i.e., they have a firm common foundation. However, they complement each other with respect to the definition of an architecture development process and the definition of an enterprise architecture modeling language. ArchiMate provides a concrete visualization for the architectures and views proposed in TOGAF.
ArchiMate version 1.0 chiefly supports modeling of the architectures in Phases B, C, and D in the TOGAF ADM. (Note that the examples in this paper give an impression of the ArchiMate language, but do not show all the concepts. For a complete overview of the language, refer to ArchiMate® 1.0 Specification1.) The resulting models are used as input for the subsequent ADM phases. However, modeling concepts specifically aimed at the other phases—e.g., concepts for modeling principles, goals and requirements, or concepts to support migration planning—are still missing in the language. This observation points in a direction for possible language extensions in future versions of ArchiMate.
1. The Open Group, ArchiMate® 1.0 Specification, Van Haren Publishing, 2009. Also available on www.archimate.org.
2. The Open Group, TOGAF™ Version 9, Van Haren Publishing, 2009. Also available on www.togaf.org.
by Garry Doherty, a TOGAF product manager at The Open Group, Henk Jonkers, Marc Lankhorst, Erik Proper and Henry Franken