User:HansvanDrunen/Sandbox

Organisations need to adapt increasingly fast and anticipate changing customer requirements and business goals. This need influences the entire chain of activities of a business, from the organisational structure to the network infrastructure. How can you control the impact of these changes? Architecture may be the answer. ArchiMate [1]is an integrated architectural approach that describes and visualises the different business domains and their relations. Using these integrated architectures aids stakeholders in assessing the impact of design choices and changes.

Architecture is a consistent whole of principles, methods and models that are used in the design and realisation of organisational structure, business processes, information systems, and infrastructure. However, these domains are not approached in an integrated way, which makes it difficult to judge the effects of proposed changes. Every domain speaks its own language, draws its own models, and uses its own techniques and tools. Communication and decision making across domains is seriously impaired.

ArchiMate provides this integration. ArchiMate is an architecture language and visualisation techniques that picture these domains and their relations. ArchiMate will provide the architect with instruments that support and improve the architecture process. ArchiMate has layered and service-oriented look on architectural models. The higher layers make use of services that are provided by the lower layers. Although, at an abstract level, the concepts that are used within each layer are similar, we define more concrete concepts that are specific for a certain layer. In this context, we distinguish three main layers: 1. The Business layer offers products and services to external customers, which are realised in the organisation by business processes performed by business actors. 2. The Application layer supports the business layer with application services which are realised by (software) applications. 3. The Technology layer offers infrastructural services (e.g., processing, storage and communication services) needed to run applications, realised by computer and communication hardware and system software. Each of these main layers can be further divided in sub-layers. For example, in the Business layer, the primary business processes realising the products of a company may make use of a layer of secondary (supporting) business processes; in the Application layer, the end-user applications may make use of generic services offered by supporting applications. On top of the Business layer, a separate Environment layer may be added, modelling the external customers that make use of the services of the organisation (although these may also be considered part of the Business layer). In line with service orientation, the most important relation between layers is formed by use relations, which show how the higher layers make use of the services of lower layers. However, a second type of link is formed by realisation relations: elements in lower layers may realise comparable elements in higher layers; e.g., a ‘data object’ (Application layer) may realise a ‘business object’ (Business layer); or an ‘artifact’ (Technology layer) may realise either a ‘data object’ or an ‘application component’ (Application layer). The general structure of models within the different layers is similar. The same types of concepts and relations are used, although their exact nature and granularity differ. First, we distinguish the structural or static aspect and the behavioural or dynamic aspect. Behavioural concepts are assigned to structural concepts, to show who or what displays the behaviour. In the example, role, interface and collaboration are assigned to business process, organisational service and business interaction, respectively. Second, we make a distinction between an external view and an internal view on systems. When looking at the behavioural aspect, these views reflect the principles of service orientation as introduced in the previous section. The service concept represents a unit of essential functionality that a system exposes to its environment. For the external users, only this external functionality, together with non-functional aspects such as the quality of service, costs etc., are relevant. If required, these can be specified in a contract or service level agreement. Services are accessible through interfaces, which constitute the external view on the structural aspect. Although for the external users only the external view is relevant, the design of organisations or systems and their internal operations and management also requires knowledge about the internal realisation of the services and interfaces. For this realisation, we make a distinction between behaviour that is performed by an individual structural element (e.g., actor, role component, etc.), or collective behaviour (interaction) that is performed by a collaboration of multiple structural elements. In addition to active structural elements (the business actors, application components and devices that display actual behaviour, i.e., the ‘subjects’ of activity), we also recognise passive structural elements, i.e., the objects on which behaviour is performed. In the domain of information-intensive organisations, which is the main focus of our language, these are usually information objects in the business layer and data objects in the application layer, but they may also be used to represent physical objects.