Architecture frameworks and architecture description languages
In systems and software engineering, the notion of architecture framework dates back to the 1970s [6, 44]. The motivation for the definition of the term (3.6) and its specification (in 6.1) in this International Standard is to provide a means of defining existing and future architecture frameworks in a uniform manner to promote sharing of information about systems, architectures and techniques for architecture description, inter-working to enable improved understanding, and interoperability between architecture communities who are using different conceptual foundations. The uniform definition of architecture viewpoints and coordinated collections of such viewpoints can promote reuse of tools and techniques to the communities using these frameworks.
The specification of architecture framework is intended to establish the relationships between an architecture framework and other concepts in this International Standard (illustrated in figures 2 and 4). Architecture frameworks often include additional content, prescriptions and relationships, such as process requirements, life cycle connections, and documentation formats, not defined by this International Standard, but potential future areas of standardization.
The term architecture description language (ADL) has been in use since the 1990s in the software, systems and enterprise architecture communities. Within the conceptual model of this International Standard, an architecture description language is any language for use in an architecture description. Therefore an ADL can be used by one or more viewpoints to frame identified system concerns within an architecture description.
Early ADLs included Rapide (Stanford) [25], Wright (CMU) [43], and Darwin (Imperial College). ADLs focused on structural concerns: large-scale system organization expressed in terms of components, connectors and configurations and varying support for framing behavioral concerns. More recently, "wide-spectrum" ADLs have been developed which support a wider range of concerns. These include Architecture Analysis & Description Language (AADL) [37], SysML [31], and ArchiMate [40]. EXAMPLES 1 and 2 describe two contemporary ADLs with reference to their relationship to the conceptual model defined in this International Standard.
EXAMPLE 1 ArchiMate organizes ADs into several layers of concerns: Business, Application and Technology (or Infrastructure); several aspects of concerns within each of those layers: Structural, Behavioral and Informational aspects, and defines eighteen basic viewpoints for these. Each viewpoint is defined via its own metamodel, relating that viewpoint o others, and specifying, the stakeholders, concerns, purpose, layers and aspects.
EXAMPLE 2 The Systems Modeling Language (SysML) is built upon UML. SysML defines several types of diagrams: Activity, Sequence, State Machine, Use Case, Block Definition, Internal Block, Package, Parametric, and Requirement diagrams. In the terms of this International Standard, each SysML diagram type is a model kind. SysML provides firstclass constructs for Stakeholders, Concerns, Views and Viewpoints so that users can create new viewpoints in
accordance with this International Standard. Like an architecture framework, an ADL frames a specific set of concerns for an audience of stakeholders, by defining one or more model kinds together with any associated analysis methods or tools. Similar to an architecture framework or architecture viewpoint, an ADL is a reusable resource---it is not limited in use to an individual system or architecture description.