Towards Model History Analysis Using Modeling Deltas.

The evolving complex software models are designed and maintained by a team of designers using collaborative modeling tools with a support of version control. Collaborative modeling tools provide a teamwork of several designers on a shared modeling artifact, whereas model version control is used to store, manage and handle the histories of that model. During the evolution and maintenance process of models, model designers feel a need for history analysis feature for tracing and comprehending the change history of a complete model or its particular artifacts. In order to analyze the histories or trace a particular element of an evolving model, designers need to determine answers to several questions such as (1) How often does an element change? (2) When is an element created? (3) When is an element deleted? (4) Which elements are constantly changing? (5) How does the history of an element look like? (6) How was the state of a whole model in earlier versions? (7) What are the differences between any two versions of a model? etc. These analysis questionnaires are also partly defined in [3]. For answering these questions, the change histories of modeling artifacts have to be identified and stored in appropriate ways for further analysis and manipulation. To this end, this paper presents early status of history visualization to model history analysis using modeling deltas. The differences between subsequent model versions are represented in difference documents, also referred to as Modeling Deltas [2]. Modeling Deltas are executable sequence of modification operations which transform a model from one state to another. Modeling deltas represent information about the whole history of a model. Thus, modeling deltas are essential for building and developing various services and components for version control, history analysis and collaborative applications on top of them. It is quite essential to reuse and exploit the model differences in further analysis and manipulations i.e. only difference representation is useless if difference information is not reusable. The general Delta Operations Language (DOL), meta-model generic and operation-based approach is introduced in [2] to model difference representations. Conceptually, DOL is a set of domain-specific languages for model difference representation in terms of operations. A specific DOL for a specific modeling language is derived from the meta-model of a modeling language. A specific DOL is fully capable of representing model differences conforming the given metamodel in terms of DOL operations. Only changed elements between model versions are identified and represented in Modeling Deltas. Each modeling delta consists of the semantic differences between subsequent model versions. DOL-based modeling delta representation is applied to model history analysis in this paper. The remainder of the paper is structured as follows: Section 2 gives a motivating example of DOL-based difference representation. Model history analysis using modeling deltas is discussed in Section 3. Section 4 draws some conclusions.