Vincenzo Deufemia

Design pattern recovery through visual language parsing and source code analysis

In this paper we propose an approach for recovering structural design patterns from object-oriented source code. The recovery process is organized in two phases. In the first phase, the design pattern instances are identified at a coarse-grained level by considering the design structure only and exploiting a parsing technique used for visual language recognition. Then, the identified candidate patterns are validated by a fine-grained source code analysis phase. The recognition process is supported by a tool, namely design pattern recovery environment, which allowed us to assess the retrieval effectiveness of the proposed approach on six public-domain programs and libraries.

A framework for modeling and implementing visual notations with applications to software engineering

We present a framework for modeling visual notations and for generating the corresponding visual programming environments. The framework can be used for modeling the diagrammatic notations of software development methodologies, and to generate visual programming environments with CASE tools functionalities. This is accomplished through an underlying modeling process based on the visual notation syntactic model of eXtended Positional Grammars (XPG, for short), and the associated parsing methodology, XpLR. In particular, the process requires the modeling of the basic elements (visual symbols) of a visual notation, their syntactic properties, the relations between them, the syntactic rules to formally define the set of feasible visual sentences, and a set of semantic routines performing additional checks and translation tasks. Such a process is completely supported by the VLDesk system, which enables the automatic generation of an editor for drawing visual sentences, as well as a processor for their recognition, parsing, and translation into other notations.The proposed framework also provides the basis for the definition of a meta-CASE technology. In fact, we can customize the generated visual programming environment in terms of the supported visual notation, its syntactic properties, and the translation rules. We have used this framework to model several diagrammatic notations used in software development methodologies, including those of the Unified Modeling Language.

Design pattern recovery by visual language parsing

We propose an object oriented (OO) design pattern recovery approach which makes use of a design pattern library, expressed in terms of visual grammars, and based on a visual language parsing technique. We also present a visual environment, which supports the pattern recognition process by automatically retrieving design patterns from imported UML class diagrams. The visual environment has been automatically generated through the VLDesk system, starting from a description of the design pattern grammar.

Improving Behavioral Design Pattern Detection through Model Checking

Recovering design pattern instances in a software system can help maintainers to understand its design and implementation. In this paper we present a fully automated design pattern recovery approach that analyzes the behavior of pattern instances both statically and dynamically. In particular, the proposed approach exploits model checking to statically verify the behavioral aspects of design pattern instances. To this end, we encode the properties defining the correct behavior of a pattern as LTL (Linear Temporal Logic) formulae and the sequence diagram representing the possible interaction traces among the objects involved in the candidate instances as PROMELA specifications. To verify whether the LTL properties are satisfied by the candidates we employ the SPIN model checking tool. The dynamic analysis of the pattern behavior is performed through a code instrumentation and monitoring phase applied on the candidate pattern instances. This phase allows us to obtain actual dynamic data during program execution, which is then used to verify its compliance to the pattern definition. The effectiveness of the proposed approach is shown by presenting and discussing the results obtained on JHotDraw and JRefactory.

An agent-based framework for sketched symbol interpretation

Recognizing hand-sketched symbols is a definitely complex problem. The input drawings are often intrinsically ambiguous, and require context to be interpreted in a correct way. Many existing sketch recognition systems avoid this problem by recognizing single segments or simple geometric shapes in a stroke. However, for a recognition system to be effective and precise, context must be exploited, and both the simplifications on the sketch features, and the constraints under which recognition may take place, must be reduced to the minimum. In this paper, we present an agent-based framework for sketched symbol interpretation that heavily exploits contextual information for ambiguity resolution. Agents manage the activity of low-level hand-drawn symbol recognizers, that may be heterogeneous for better adapting to the characteristics of each symbol to be recognized, and coordinate themselves in order to exchange contextual information, thus leading to an efficient and precise interpretation of sketches. We also present AgentSketch, a multi-domain sketch recognition system implemented according to the proposed framework. A first experimental evaluation has been performed on the domain of UML Use Case Diagrams to verify the effectiveness of the proposed approach.

Behavioral Pattern Identification through Visual Language Parsing and Code Instrumentation

In this paper we present a new technique able to recover behavioral design pattern instances which combines static analysis, based on visual language parsing, with dynamic analysis, based on source code instrumentation. In particular, the dynamic analysis is performed through the automatic instrumentation of the method calls involved in the candidate pattern instances identified during static analysis. The results obtained from a program monitoring activity are matched against the definitions of the pattern behaviors expressed in terms of monitoring grammars. We also present and discuss the results of a case study on JHotDraw 5.1 software library performed to assess the retrieval effectiveness of the proposed approach.

A Parsing Technique for Sketch Recognition Systems

Several disciplines require the support of computer-based tools for creating sketches during early design phases. Unfortunately, most computer programs cannot parse and semantically interpret handwritten sketches. In this paper, we present a framework for modeling sketch languages and for generating parsers to recognize them. The underlying parsing technique addresses the issues of stroke clustering and ambiguity resolution in sketches. We also present a workbench supporting the presented framework

Relaxed Functional Dependencies—A Survey of Approaches

Recently, there has been a renovated interest in functional dependencies due to the possibility of employing them in several advanced database operations, such as data cleaning, query relaxation, record matching, and so forth. In particular, the constraints defined for canonical functional dependencies have been relaxed to capture inconsistencies in real data, patterns of semantically related data, or semantic relationships in complex data types. In this paper, we have surveyed 35 of such functional dependencies, providing a classification criteria, motivating examples, and a systematic analysis of them.

Visual language implementation through standard compiler-compiler techniques

We present a technique for implementing visual language compilers through standard compiler generation platforms. The technique exploits eXtended Positional Grammars (XPGs, for short) for modeling the visual languages in a natural way, and uses a set of mapping rules to translate an XPG specification into a translation schema. This lets us generate visual language parsers through standard compiler-compiler techniques and tools like YACC. The generated parser accepts exactly the same set of visual sentences derivable through the application of XPG productions. The technique represents an important achievement, since it enables us to perform visual language compiler construction through standard compiler-compilers rather than specific compiler generation tools. This makes our approach particularly appealing, since compiler-compilers are widely used and rely on a well-founded theory. Moreover, the approach provides the basis for the unification of traditional textual language technologies and visual language compiler technologies.

A Two Phase Approach to Design Pattern Recovery

In this paper we present a two phase approach to the recovery of structural design pattern. In the first phase, the design pattern instances are identified at a course-grained level by considering the design structure only and using a visual language parsing technique. Then, the identified candidate patterns are validated by a fine-grained source code analysis phase. The latter phase is an enhancement of a previous approach developed by the authors aiming at improving the results of precision and time performances. The retrieval effectiveness of the approach is assessed by applying the recovery technique on four software systems