Capturing relationships between concepts in a domain is as important as capturing the concepts themselves. Modeling languages reflect this by providing connections with rich semantics, such as associations and links, thus providing a key advantage over approaches that support relationships with simple references only. While connections for two-level modeling (e.g. in the UML) have enjoyed a stable design for a considerable time, the same cannot be said for connections in multi-level modeling languages. As interest in multi-level modeling grows, it is important to provide a comprehensive design for connections that not only adheres to multi-level principles such as level-agnosticism and explicit level organization, but also supports deep characterization, i.e., the ability to specify level content beyond one level boundary. In this paper we propose a unifying conceptual model for connections whose expressiveness and scalability does not come at the cost of concept proliferation.

As the number and diversity of technologies involved in building enterprise systems continues to grow so does the importance of modeling tools that are able to present customized views of enterprise systems to different stakeholders according to their needs and skills. Moreover, since the range of required view types is continuously evolving, it must be possible to extend and enhance the languages and services offered by such tools on an ongoing basis. However, this can be difficult with today's modeling tools because the meta-models that define the languages, views and services they support are usually hardwired and thus not amenable to extension. In practice, therefore, various workarounds have to be used to extend a tool's underlying meta-model. Some of these are built into the implemented modeling standards (e.g. the UML profile, BPMN 2.0 and ArchiMate 2.0 extension mechanisms) while others have to be applied by complementary, external tools (e.g. model weaving). These techniques not only increase accidental complexity, they also reduce the ability of the modeling tool to ensure adherence to enterprise rules and constraints. In this paper we discuss the strengths and weaknesses of the various approaches for language extension and propose a modeling framework best able to support the main extension use-cases currently found in practice today.

Domain-Specific Modeling Languages (DSMLs) have received great attention in recent years and are expected to play a big role in the future of software engineering as processes become more view-centric. However, they are a “two-edged sword”. While they provide strong support for communication within communities, allowing experts to express themselves using concepts tailored to their exact needs, they are a poor vehicle for communication across communities because of their lack of common, transcending concepts. In contrast, General-Purpose Modeling Languages (GPMLs) have the opposite problem - they are poor at the former but good at the latter. The value of models in software engineering would therefore be significantly boosted if the advantages of DSMLs and GPMLs could be combined and models could be viewed in a domain-specific or general-purpose way depending on the needs of the user. In this paper we present an approach for achieving such a synergy based on the orthogonal classification architecture. In this architecture model elements have two classifiers: a linguistic one representing their “general-purpose” and an ontological one representing their “domain-specific” type. By associating visualization symbols with both classifiers it is possible to support two concrete syntaxes at the same time and allow the domain-specific and general-purpose notation to support each other - that is, to form a symbiotic relationship.