Mehrdad Sabetzadeh

Matching and Merging of Statecharts Specifications

Model Management addresses the problem of managing an evolving collection of models, by capturing the relationships between models and providing well-defined operators to manipulate them. In this paper, we describe two such operators for manipulating hierarchical Statecharts: Match, for finding correspondences between models, and Merge, for combining models with respect to known correspondences between them. Our Match operator is heuristic, making use of both static and behavioural properties of the models to improve the accuracy of matching. Our Merge operator preserves the hierarchical structure of the input models, and handles differences in behaviour through parameterization. In this way, we automatically construct merges that preserve the semantics of Statecharts models. We illustrate and evaluate our work by applying our operators to AT&T telecommunication features.

A manifesto for model merging

If a modeling task is distributed, it will frequently be necessary to merge models developed by different team members. Existing approaches to model merging make assumptions about the types of model to be merged, and the nature of the relationship between them. This makes it hard to compare approaches. In this paper, we present a manifesto for research on model merging. We propose a framework for comparing different approaches to merging, by treating merge as an algebraic operator over models and model relationships. We specify the algebraic properties of an idealized merge operator, as well as related operators such as match, diff, split, and slice. We then show how our framework can be used to compare existing approaches by applying it to two of our own research projects on model merging. We show how this analysis permits a detailed comparison of approaches, reveals the key features of each, and identifies weaknesses that require further research. Most importantly, the framework emphasizes the need to make explicit all assumptions about the relationships between models, and indeed to treat model relationships as first class objects.

View merging in the presence of incompleteness and inconsistency

View merging, also called view integration, is a key problem in conceptual modeling. Large models are often constructed and accessed by manipulating individual views, but it is important to be able to consolidate a set of views to gain a unified perspective, to understand interactions between views, or to perform various types of analysis. View merging is complicated by incompleteness and inconsistency: Stakeholders often have varying degrees of confidence about their statements. Their views capture different but overlapping aspects of a problem, and may have discrepancies over the terminology being used, the concepts being modeled, or how these concepts should be structured. Once views are merged, it is important to be able to trace the elements of the merged view back to their sources and to the merge assumptions related to them. In this paper, we present a framework for merging incomplete and inconsistent graph-based views. We introduce a formalism, called annotated graphs, with a built-in annotation scheme for modeling incompleteness and inconsistency. We show how structure-preserving maps can be employed to express the relationships between disparate views modeled as annotated graphs, and provide a general algorithm for merging views with arbitrary interconnections. We provide a systematic way to generate and represent the traceability information required for tracing the merged view elements back to their sources, and to the merge assumptions giving rise to the elements.

Consistency Checking of Conceptual Models via Model Merging

Requirements elicitation involves the construction of large sets of conceptual models. An important step in the analysis of these models is checking their consistency. Existing research largely focuses on checking consistency of individual models and of relationships between pairs of models. However, such strategy does not guarantee global consistency. In this paper, we propose a consistency checking approach that addresses this problem for homogeneous models. Given a set of models and a set of relationships between them, our approach works by first constructing a merged model and then verifying this model against the consistency constraints of interest. By keeping proper traceability information, consistency diagnostics obtained over the merge are projected back to the original models and their relationships. The paper also presents a set of reusable expressions for defining consistency constraints in conceptual modelling. We demonstrate the use of the developed expressions in the specification of consistency rules for class and ER diagrams, and i* goal models.

An algebraic framework for merging incomplete and inconsistent views

View merging, also called view integration, is a key problem in conceptual modeling. Large models are often constructed and accessed by manipulating individual views, but it is important to be able to consolidate a set of views to gain a unified perspective, to understand interactions between views, or to perform various types of end-to-end analysis. View merging is complicated by inconsistency of views. Once views are merged, it is useful to be able to trace the elements of the merged view back to their sources. In this paper, we propose a framework for merging incomplete and inconsistent graph-based views. We introduce a formalism, called annotated graphs, which incorporates a systematic annotation scheme capable of modeling incompleteness and inconsistency as well as providing a built-in mechanism for stakeholder traceability. We show how structure-preserving maps can capture the relationships between disparate views modeled as annotated graphs, and provide a general algorithm for merging views with arbitrary interconnections. We use the i* modeling language (Yu, 1997) as an example to demonstrate how our approach can be applied to existing graph-based modeling languages.

Analysis of inconsistency in graph-based viewpoints: a category-theoretical approach

Eliciting the requirements for a proposed system typically involves different stakeholders with different expertise, responsibilities, and perspectives. Viewpoints-based approaches have been proposed as a way to manage incomplete and inconsistent models gathered from multiple sources. In this paper, we propose a category-theoretical framework for the analysis of fuzzy viewpoints. Informally, a fuzzy viewpoint is graph in which the elements of a lattice are used to specify the amount of knowledge available about the details of nodes and edges. By defining an appropriate notion of morphism between fuzzy viewpoints, we construct categories of fuzzy viewpoints and prove that these categories are (finitely) complete. We then show how colimits can be employed to merge the viewpoints and detect the inconsistencies that arise independent of any particular choice of viewpoint semantics. We illustrate an application of the framework through a case-study showing how fuzzy viewpoints can serve as a requirements elicitation tool in reactive systems.

A Relationship-Driven Framework for Model Merging

A key problem in model-based development is merging a set of distributed models into a single seamless model. To merge a set of models, we need to know how they are related. In this position paper, we discuss the methodological aspects of describing the relationships between models. We argue that relationships between models should be treated as first-class artifacts in the merge problem and propose a general framework for model merging based on this argument. We illustrate the usefulness of our framework by instantiating it to the state-machine modelling domain and developing a flexible tool for merging state-machines.

An Eclipse-based tool framework for software model management

Software development involves the use of many models and Eclipse provides an ideal infrastructure for building tools to support the use of models. While there is a large selection of tools available for working with individual models, there is less support for working with collections of models, as for example, when a collection of models from different sources must be merged. We have identified the problem of working with collections of related models in software development as the Software Model Management (SMM) problem - a close cousin of the Model Management problem in the area of metadata management. In the course of building SMM tools to address particular scenarios, we have observed that they share common foundations both at the theoretical and implementation levels. In this paper, we describe the vision and initial development of a framework that implements these common foundations in order to facilitate and accelerate the development of Eclipse-based SMM tools.

Global consistency checking of distributed models with TReMer

We present TReMer+, a tool for consistency checking of distributed models (i.e., models developed by distributed teams). TReMer+ works by first constructing a merged model before checking consistency. This enables a flexible way of verifying global consistency properties that is not possible with other existing tools.

A category-theoretic approach to syntactic software merging

Software merging is a common and essential activity during the lifespan of large-scale software systems. Traditional textual merge techniques are inadequate for detecting syntactic merge conflicts. In this paper, we propose a domain-independent approach for syntactic software merging that exploits the graph-based structure(s) of programs. We use morphisms between fuzzy graphs to capture the relationships between the structural elements of the programs to be merged, and apply a truth ordering lattice to express inconsistencies and evolutionary properties as we compute the merge. We demonstrate the approach with a three-way consolidation merge in a commercial software system; in particular, we show how analyzing merged call structures can help developers gain a better understanding and control of software evolution.