Abstract In recent years, multi-level modeling has become more and more popular. It is mainly due to the fact that multi-level modeling aims to reduce or even totally eliminate any accidental complexity inadvertently created as by-product in traditional model design. Moreover, besides reducing model complexity, multi-level modeling also improves on general comprehension of models. The key enablers of multi-level modeling are the concepts of clabjects and deep instantiation. The latter is often governed by the potency notion, of which many different interpretations and variations emerged over the years. However, there exist also some approaches that disregard the potency notion. Thus, multi-level modeling approaches tend to take advantage of different theoretical and practical backgrounds. In this paper, we propose a unifying framework, the Multi-Level Modeling Playground (MLMP), which is a validating modeling environment for multi-level modeling research. The MLMP environment is based on our multi-layer modeling framework (the Dynamic Multi-Layer Algebra), which provides useful mechanisms to validate different multi-level modeling constructs. Since beyond the structure also the well-formedness rules of the modeling constructs can be specified, our proposed MLMP environment delivers several practical benefits: i) well-formedness is always verified, ii) multi-level constructs can be experimented with independently of any concrete tool chains, and iii) relationships (i.e., correlations or exclusions) between different multi-level constructs can be easily investigated in practice. Also, the capability of the environment is demonstrated via complete examples inspired by state-of-the-art research literature.

Bad Smells are certain suboptimal structures or patterns in software. They can cause maintenance issues and hinder understandability. Therefore, it is essential to avoid Bad Smells in software. While the topic is well researched in other fields, it is still an open issue in industrial automation. In this work, we are taking a step towards closing that gap and propose a catalog of IEC 61499 Bad Smells.

In recent years, a wide range of tools and methodologies have been introduced in the field of multi-level meta-modeling. One of the newest approaches is the Dynamic Multi-Layer Algebra (DMLA). DMLA incorporates a fully self-modeled textual operation language (DMLAScript) over its tuple-based model entity representation. This textual language provides effective and complex features when editing models. On the other hand, the language supports the precise injective mapping of the multi-layers. However, such complexity comes at a price. Using DMLAScript can be difficult in practice for users who are only familiar with the classical, object-oriented way of thinking, and are not confident with the multi-level approach. In this paper, we introduce the concepts of a new language above DMLAScript, which supports the more effective manipulation of concrete domain models by taking advantage of the particular process of multi-level modeling within DMLA. Although the approach is technically bound to DMLA, the concepts discussed in the paper are of general use.