Claudio de la Riva

Visualizing software release histories: the use of color and third dimension

The data regarding the components of a software system consists of a large amount of information such as version history, number of lines, defect density, and complexity measures. The ability to quickly grasp a comprehensive view of the evolution and dependencies of such information is the key to making informed decisions about future developments of the system. Managers usually make such decision based only on expert judgement. For help in making such decisions, we can turn to the evolution history of large software systems, which contain a wealth of hidden information. Traditionally, this information is passed on through anecdotes without any supporting analytical data. This paper reports on our attempts to make such information more concrete through information visualization techniques. We present a three-dimensional visual representation for examining a systems software release history. The structure of the system is displayed by 2D or 3D graphs. The historical information is displayed by using time as the third dimension. Colors are used for displaying module properties and their historical changes in the system. A supporting software tool enables not only visualization but also navigation in the 3D space to change the viewpoint, to browse system information, to find interesting patterns and to discover previously unknown relationships among system components.

Symphony: view-driven software architecture reconstruction

Authentic descriptions of a software architecture are required as a reliable foundation for any but trivial changes to a system. Far too often, architecture descriptions of existing systems are out of sync with the implementation. If they are, they must be reconstructed. There are many existing techniques for reconstructing individual architecture views, but no information about how to select views for reconstruction, or about process aspects of architecture reconstruction in general. In this paper we describe view-driven process for reconstructing software architecture that fills this gap. To describe Symphony, we present and compare different case studies, thus serving a secondary goal of sharing real-life reconstruction experience. The Symphony process incorporates the state of the practice, where reconstruction is problem-driven and uses a rich set of architecture views. Symphony provides a common framework for reporting reconstruction experiences and for comparing reconstruction approaches. Finally, it is a vehicle for exposing and demarcating research problems in software architecture reconstruction.

Mutating database queries

A set of mutation operators for SQL queries that retrieve information from a database is developed and tested against a set of queries drawn from the NIST SQL Conformance Test Suite. The mutation operators cover a wide spectrum of SQL features, including the handling of null values. Additional experiments are performed to explore whether the cost of executing mutants can be reduced using selective mutation or the test suite size can be reduced by using an appropriate ordering of the mutants. The SQL mutation approach can be helpful in assessing the adequacy of database test cases and their development, and as a tool for systematically injecting faults in order to compare different database testing techniques.

Combining static and dynamic views for architecture reconstruction

Static analysis aims at recovering the structure of a software system, while dynamic analysis focuses on its run time behaviour. We propose a technique for combining the analysis of static and dynamic architectural information to support the task of architecture reconstruction. The approach emphasises the correct choice of architecturally significant concepts for the reconstruction process and relies on abstraction techniques for their manipulation. The technique allows the software architect to create a set of architectural views valuable for the architecture description of the system. To support our technique, we outline an environment that relies on hierarchical typed directed graphs to show the systems structure and message sequence charts for its behaviour. The main features of the environment are: visualisation of static and dynamic views, synchronisation of abstractions performed on the views, scripting support and management of the use cases. The approach and the environment are demonstrated with an example.

Reverse architecting: an industrial experience report

Reverse architecting is a flavour of reverse engineering that concerns the extraction of software architecture models from the system implementation. This paper presents experience in recovering the architecture of an embedded software system developed in Nokia. It outlines the reverse architecting approach, discusses its application on the case study and presents usage scenarios of the extracted information.

Constraint-based test database generation for SQL queries

Populating test databases with meaningful test data is a difficult task as it involves generating data for many joined tables that must be diverse enough to be able to reveal faults and small enough to make the testing process efficient. This paper proposes an approach for the automatic generation of a test database for a set of SQL queries using a test criterion specifically tailored for the SQL language (SQLFpc). Given as input a schema database and a set of test requirements derived from the application of the test criterion to the target queries, the approach returns a database instance which satisfies the test requirements. Both the schema and the test requirements are modeled in the Alloy language, after which the analyzer generates the test database. The approach is evaluated on a real case study and the results show its feasibility, generating a test database of reduced size with an elevated coverage and mutation score.

UML-based reverse engineering and model analysis approaches for software architecture maintenance

This paper proposes a UML-based software maintenance process. The process is guided by architectural descriptions and existing architectural models. The descriptions are given as variants of UML profiles describing the styles and rules relevant for a particular application domain. A reverse engineering subprocess, combining top-down and bottom-up reverse engineering activities, aims at constructing the architectural models. Resulting models are investigated in a model analysis subprocess. The models are checked against the profiles to find violations against the given architectural rules when maintaining and developing the subject system, and they are further analyzed using a set of UML model processing operations. The proposed approach is applied for maintaining a large-scale product platform architecture and real-life product-line products built on top of this platform. The model analysis results of the case study are discussed.

Architecture Recovery for Product Families

Software product families are rarely created right away but they emerge when a domain becomes mature enough to sustain their long-term investments. The typical pattern is to start with a small set of products to quickly enter a new market. As soon as the business proves to be successful new investments are directed to consolidating the software assets. The various products are migrated towards a flexible platform where the assets are shared and new products can be derived from. In order to create and maintain the platform, the organization needs to carry out several activities such as recovering the architectures of single products and product families, designing the reference architecture, isolating the variable parts, and generalizing software components. In this paper, we introduce a product family construction process that exploits related systems and product families, and we describe methods and tools used. We also present an approach for classifying platforms according to platform coverage and variation and describe three techniques to handle variability across single products and whole product families.

Designing Web-Based Mobile Services with REST

The Web is emerging as the favorite platform for delivering applications and services. The REST architectural style comprises the key principles behind its design and success. While REST is originally defined in the context of publishing hypermedia documents, it is becoming a popular method for implementing Web services as well. The goal of this paper is to explore the principles of the REST style for building mobile services and to address the mobile specific constraints. We present the design method that we have followed for building a basic photo storage service. Our preliminary evaluation confirms that REST is a flexible and extensible approach for building mobile services.

An open visualization toolkit for reverse architecting

Maintenance and evolution of complex software systems (such as large telecom embedded devices) involve activities such as reverse engineering (RE) and software visualization. Although several RE tools exist, we found their architecture hard to adapt to the domain specific requirements posed by our current practice in Nokia. We present an open architecture which allows easy prototyping of RE data exploration and visualization scenarios for a large range of domain models. We pay special attention to the visual and interactive requirements of the reverse engineering process. The article describes the basic architecture of our toolkit, compares it to the existing RE environments and present several visualizations taken from real cases.