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Helping Programmers Improve the Energy Efficiency of Source Code (Abstract/Poster), Pereira, Rui, Carção Tiago, Couto Marco, Cunha Jácome, Fernandes João P., and Saraiva João , Proceedings of the 39th International Conference on Software Engineering (ICSE 2017), Buenos Aires, Argentina, (2017) paper.pdfpostera3.pdf
The Influence of the Java Collection Framework on Overall Energy Consumption, Pereira, Rui, Couto Marco, Saraiva João, Cunha Jácome, and Fernandes João P. , 5th International Workshop on Green and Sustainable Software (ICSE 2016), 15-21, p.–, (2016) Abstractgreens.pdf

This paper presents a detailed study of the energy consumption of the different Java Collection Framework (JFC) implementations. For each method of an implementation in this framework, we present its energy consumption when handling different amounts of data. Knowing the greenest methods for each implementation, we present an energy optimization approach for Java programs: based on calls to JFC methods in the source code of a program, we select the greenest implementation. Finally, we present preliminary results of optimizing a set of Java programs where we obtained 6.2% energy savings.

User-Friendly Spreadsheet Querying: An Empirical Study, Pereira, Rui, Saraiva João, Cunha Jácome, and Fernandes João P. , 31st Annual ACM Symposium on Applied Computing (SAC'16), Smart Human Computer Interaction Track, Poster Paper, Pisa, Italy, (2016) sac-hci16.pdf
Energy Efficiency across Programming Languages: How Do Energy, Time, and Memory Relate?, Pereira, Rui, Couto Marco, Ribeiro Francisco, Rua Rui, Cunha Jácome, Fernandes João P., and Saraiva João , 10th ACM SIGPLAN International Conference on Software Language Engineering (SLE’17), 23-24 October, Vancouver, Canada, (2017) paper.pdf
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Towards Systematic Spreadsheet Construction Processes (Abstract/Poster), Mendes, Jorge, Cunha Jácome, Duarte Francisco, Engels Gregor, Saraiva João, and Sauer Stefan , Proceedings of the 39th International Conference on Software Engineering (ICSE 2017), Buenos Aires, Argentina, (2017) paper.pdfposter.pdf
Systematic Spreadsheet Construction Processes, Mendes, Jorge, Cunha Jácome, Duarte Francisco, Engels Gregor, Saraiva João, and Sauer Stefan , IEEE Symposium on Visual Languages and Human-Centric Computing (VL/HCC), 11-14 Oct., Raleigh, North Carolina, USA, (2017) paper.pdf
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Watch out for that tree! A Tutorial on Shortcut Deforestation, Fernandes, João P., Cunha Jácome, Pardo Alberto, and Saraiva João , 2015 Central European Functional Programming School, Revised Selected Papers, (2016) cefp15.pdf
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Querying Model-Driven Spreadsheets, Cunha, Jácome, Fernandes João Paulo, Mendes Jorge, Pereira Rui, and Saraiva João , Proceedings of the 2013 IEEE Symposium on Visual Languages and Human-Centric Computing, Washington, DC, USA, p.83–86, (2013) Abstractvlhcc2013-query.pdf

Spreadsheets are being used with many different purposes that range from toy applications to complete information systems. In any of these cases, they are often used as data repositories that can grow significantly. As the amount of data grows, it also becomes more difficult to extract concrete information out of them. This paper focuses on the problem of spreadsheet querying. In particular, we propose an expressive and composable technique where intuitive queries can be defined. Our approach builds on a model-driven spreadsheet development environment, and queries are expressed referencing entities in the model of a spreadsheet instead of in its actual data. Finally, the system that we have implemented relies on Google's query function for spreadsheets.

A Quality Model for Spreadsheets, Cunha, Jácome, Fernandes João Paulo, Peixoto Christophe, and Saraiva João , Proceedings of the 8th International Conference on the Quality of Information and Communications Technology, Quality in ICT Evolution Track, p.231–236, (2012) Abstractquatic2012.pdf

In this paper we present a quality model for spreadsheets, based on the ISO/IEC 9126 standard that defines a generic quality model for software. To each of the software characteristics defined in the ISO/IEC 9126, we associate an equivalent spreadsheet characteristic. Then, we propose a set of spreadsheet specific metrics to assess the quality of a spreadsheet in each of the defined characteristics. In order to obtain the normal distribution of expected values for a spreadsheet in each of the metrics that we propose, we have executed them against all spreadsheets in the large and widely used EUSES spreadsheet corpus. Then, we quantify each characteristic of our quality model after computing the values of our metrics, and we define quality scores for the different ranges of values. Finally, to automate the atribution of a quality score to a given spreadsheet, according to our quality model, we have integrated the computation of the metrics it includes in both a batch and a web-based tool.

Automatically Inferring Models from Spreadsheets, Cunha, Jácome, Erwig Martin, Mendes Jorge, and Saraiva João , Automated Software Engineering (ASE), Volume 23, Issue 3, p.361-392, (2016) Abstractase14.pdfWebsite

Many errors in spreadsheet formulas can be avoided if spreadsheets are built automatically from higher-level models that can encode and enforce consistency constraints in the generated spreadsheets. Employing this strategy for legacy spreadsheets is difficult, because the model has to be reverse engineered from an existing spreadsheet and existing data must be transferred into the new model-generated spreadsheet. We have developed and implemented a technique that automatically infers relational schemas from spreadsheets. This technique uses particularities from the spreadsheet realm to create better schemas. We have evaluated this technique in two ways: First, we have demonstrated its applicability by using it on a set of real-world spreadsheets. Second, we have run an empirical study with users. The study has shown that the results produced by our technique are comparable to the ones developed by experts starting from the same (legacy) spreadsheet data. Although relational schemas are very useful to model data, they do not fit well spreadsheets as they do not allow to express layout. Thus, we have also introduced a mapping between relational schemas and ClassSheets. A ClassSheet controls further changes to the spreadsheet and safeguards it against a large class of formula errors. The developed tool is a contribution to spreadsheet (reverse) engineering, because it fills an important gap and allows a promising design method (ClassSheets) to be applied to a huge collection of legacy spreadsheets with minimal effort.

Embedding, Evolution, and Validation of Spreadsheet Models in Spreadsheet Systems, Cunha, Jácome, Fernandes João P., Mendes Jorge, and Saraiva João , IEEE Transactions on Software Engineering, Volume 41, Issue 3, p.241-263, (2014) Abstracttse14.pdfWebsite

This paper proposes and validates a model-driven software engineering technique for spreadsheets. The technique that we envision builds on the embedding of spreadsheet models under a widely used spreadsheet system. This means that we enable the creation and evolution of spreadsheet models under a spreadsheet system. More precisely, we embed ClassSheets, a visual language with a syntax similar to the one offered by common spreadsheets, that was created with the aim of specifying spreadsheets. Our embedding allows models and their conforming instances to be developed under the same environment. In practice, this convenient environment enhances evolution steps at the model level while the corresponding instance is automatically co-evolved. Finally, we have designed and conducted an empirical study with human users in order to assess our technique in production environments. The results of this study are promising and suggest that productivity gains are realizable under our model-driven spreadsheet development setting.

Extension and Implementation of ClassSheet Models, Cunha, Jácome, Fernandes João Paulo, Mendes Jorge, and Saraiva João , Proceedings of the 2012 IEEE Symposium on Visual Languages and Human-Centric Computing, Washington, DC, USA, p.19–22, (2012) Abstractvlhcc12.pdf

n this paper we explore the use of models in the context of spreadsheet engineering. We review a successful spreadsheet modeling language, whose semantics we further extend. With this extension we bring spreadsheet models closer to the business models of spreadsheets themselves. An addon for a widely used spreadsheet system, providing bidirectional model-driven spreadsheet development, was also improved to include the proposed model extension.

HaExcel: A Model-Based Spreadsheet Evolution System (Poster), Cunha, Jácome, Fernandes João Paulo, Mendes Jorge, and Saraiva João , 2011 IEEE Symposium on Visual Languages and Human-Centric Computing, September, (2011) Abstractposter.vlhcc11.png

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SmellSheet Detective: A Tool for Detecting Bad Smells in Spreadsheets, Cunha, Jácome, Fernandes João Paulo, Mendes Jorge, Martins Pedro, and Saraiva João , Proceedings of the 2012 IEEE Symposium on Visual Languages and Human-Centric Computing, Washington, DC, USA, p.243–244, (2012) Abstractvlhcc12-td.pdf

This tool demo paper presents SmellSheet Detective: a tool for automatically detecting bad smells in spreadsheets. We have defined a catalog of bad smells in spreadsheet data which was fully implemented in a reusable library for the manipulation of spreadsheets. This library is the building block of the SmellSheet Detective tool, that has been used to detect smells in large, real-world spreadsheet within the EUSES corpus, in order to validate and evolve our bad smells catalog.

Model-Based Spreadsheet Engineering, Cunha, Jácome , March, (2011) Abstractthesis.pdf

Spreadsheets can be viewed as programming languages for non-professional programmers. These so-called ``end-user'' programmers vastly outnumber professional programmers creating millions of new spreadsheets every year. As a programming language, spreadsheets lack support for abstraction, testing, encapsulation, or structured programming. As a result, and as numerous studies have shown, the high rate of production is accompanied by an alarming high rate of errors. Some studies report that up to 90% of real-world spreadsheets contain errors. After their initial creation, many spreadsheets turn out to be used for storing and processing increasing amounts of data and supporting increasing numbers of users over long periods of time, making them complicated systems. An emerging solution to handle the complex and evolving software systems is Model-driven Engineering (MDE). To consider models as first class entities and any software artifact as a model or a model element is one of the basic principles of MDE. We adopted some techniques from MDE to solve spreadsheet problems. Most spreadsheets (if not all) lack a proper specification or a model. Using reverse engineering techniques we are able to derive various models from legacy spreadsheets. We use functional dependencies (a formalism that allow us to define how some column values depend on other column values) as building blocks for these models. Models can be used for several spreadsheet improvements, namely refactoring, safe evolution, migration or even generation of edit assistance. The techniques presented in this work are available under the framework HAEXCEL that we developed. It is composed of online and batch tools, reusable HASKELL libraries and OpenOffice.org extensions. A study with several end-users was organized to survey the impact of the techniques we designed. The results of this study indicate that the models can bring great benefits to spreadsheet engineering helping users to commit less errors and to work faster.

Embedding and Evolution of Spreadsheet Models in Spreadsheet Systems, Cunha, Jácome, Fernandes João Paulo, Mendes Jorge, and Saraiva João , Proceedings of the 2011 IEEE Symposium on Visual Languages and Human-Centric Computing, Washington, DC, USA, p.186–201, (2011) Abstractvlhcc11.pdf

This paper describes the embedding of ClassSheet models in spreadsheet systems. ClassSheet models are well-known and describe the business logic of spreadsheet data. We embed this domain specific model representation on the (general purpose) spreadsheet system it models. By defining such an embedding, we provide end users a model-driven engineering spreadsheet developing environment. End users can interact with both the model and the spreadsheet data in the same environment. Moreover, we use advanced techniques to evolve spreadsheets and models and to have them synchronized. In this paper we present our work on extending a widely used spreadsheet system with such a model-driven spreadsheet engineering environment.

Evaluating Refactorings for Spreadsheet Models, Cunha, Jácome, Fernandes João Paulo, Mendes Jorge, Pereira Rui, Saraiva João Alexandre, and Martins Pedro , Journal of Systems and Software, Volume 118, p.234-250, (2016) Abstractmain.pdf

Software refactoring is a well-known technique that provides transformations on software artifacts with the aim of improving their overall quality.

In the past, we have proposed a catalog of refactoring for spreadsheet models expressed in the ClassSheets modeling language, which allows us to specify the business logic of a spreadsheet in an object-oriented fashion.

Reasoning about spreadsheets at the model level enhances a model-driven spreadsheet environment where a ClassSheet model and its conforming instance (the spreadsheet data) automatically co-evolves after a refactoring is applied at the model level. Our motivation for such research was to improve the model and its conforming instance: the spreadsheet data.

In this paper we define such refactorings using previously proposed evolution steps for models and instances.

We also present an empirical study we designed and conducted in order to confirm our original intuition that these refactorings have a positive impact on end-user productivity, both in terms of effectiveness and efficiency.

The results are presented not only in terms of productivity changes between refactored and non-refactored scenarios, but also in terms of overall user satisfaction, relevance, and experience.

In almost all cases the refactorings indeed improved end-users productivity. Moreover, in most cases users were more engaged with the refactored version of the spreadsheets they worked with.

Refactoring meets Model-Driven Spreadsheet Evolution, Cunha, Jácome, Fernandes João Paulo, Martins Pedro, Pereira Rui, and Saraiva João , Proceedings of the 9th International Conference on the Quality of Information and Communications Technology, Quality in Model Driven Engineering Track, p.196–201, (2014) Abstractquatic14.pdf

Software refactoring is a well-known technique that provides transformations on software artifacts with the aim of improving their overall quality. In this paper we present a set of refactorings for ClassSheets, a modeling language that allows to specify the business logic of a spreadsheet in an object-oriented fashion. The set of refactorings that we propose allows us to improve the quality of these spreadsheet models. Moreover, it is implemented in a setting that guarantees that all model refactorings are automatically carried to all the corresponding (spreadsheet) instances, thus providing an automatic evolution of the data so it is always synchronized with the model.

Embedding Model-Driven Spreadsheet Queries in Spreadsheet Systems, Cunha, Jácome, Fernandes João Paulo, Mendes Jorge, Pereira Rui, and Saraiva João , Proceedings of the 2014 IEEE Symposium on Visual Languages and Human-Centric Computing, Washington, DC, USA, p.151-154, (2014) Abstractvlhcc14.pdf

Spreadsheets are widely used not only to define mathematical expressions, but also to store large and complex data. To query such data is usually a difficult task to perform, usually for end user. In this work we embed the textual query language in the model-driven spreadsheet environment as a spreadsheet itself. The result is an expressive and powerful query environment that has knowledge of the business logic defined by the spreadsheet data (the spreadsheet model) to guide end users constructing correct queries.

Embedding, Evolution, and Validation of Spreadsheet Models in Spreadsheet Systems, Cunha, Jácome, Fernandes João P., Mendes Jorge, and Saraiva João , Number TR-HASLab:01:2014, (2014) Abstracttr_embedding.pdf

This paper proposes and validates a model-driven software engineering technique for spreadsheets. The technique that we envision builds on the embedding of spreadsheet models under a widely used spreadsheet system, so that models and their conforming instances are developed under the same environment. In practice, this convenient environment enhances evolution steps at the model level while the corresponding instance is automatically co-evolved. Finally, we have designed and conducted an empirical study with human users in order to assess our technique in production environments. The results of this study are promising and suggest that productivity gains are realizable under our model-driven spreadsheet development setting.

Type-Safe Evolution of Spreadsheets, Cunha, Jácome, Visser Joost, Alves Tiago, and Saraiva João , Number DI-CCTC-10-09, (2010) Abstracttr_evolution.pdf

Spreadsheets are notoriously error-prone. To help avoid the introduction of errors when changing spreadsheets, models that capture the structure and inter-dependencies of spreadsheets at a conceptual level have been proposed. Thus, spreadsheet evolution can be made safe within the confines of a model. As in any other model/instance setting, evolution may not only require changes at the instance level but also at the model level. When model changes are required, the safety of instance evolution can not be guarded by the model alone. Coupled transformation of models and instances are supported by the 2LT platform and have been applied for transformation of algebraic datatypes, XML schemas, and relational database models. We have extended 2LT to spreadsheet evolution. We have designed an appropriate representation of spreadsheet models, including the fundamental notions of formulæ, references, and blocks of cells. For these models and their instances, we have designed coupled transformation rules that cover specific spreadsheet evolution steps, such as extraction of a block of cells into a separate sheet or insertion of columns in all occurrences of a repeated block of cells. Each model-level transformation rule is coupled with instance level migration rules from the source to the target model and vice versa. These coupled rules can be composed to create compound transformations at the model level that induce compound transformations at the instance level. With this approach, spreadsheet evolution can be made safe, even when model changes are involved.

Model-Based Programming Environments for Spreadsheets, Cunha, Jácome, Saraiva João, and Visser Joost , Programming Languages, Volume 7554, p.117–133, (2012) Abstractsblp12.pdf

Although spreadsheets can be seen as a flexible programming environment, they lack some of the concepts of regular programming languages, such as structured data types. This can lead the user to edit the spreadsheet in a wrong way and perhaps cause corrupt or redundant data. We devised a method for extraction of a relational model from a spreadsheet and the subsequent embedding of the model back into the spreadsheet to create a model-based spreadsheet programming environment. The extraction algorithm is specific for spreadsheets since it considers particularities such as layout and column arrangement. The extracted model is used to generate formulas and visual elements that are then embedded in the spreadsheet helping the user to edit data in a correct way. We present preliminary experimental results from applying our approach to a sample of spreadsheets from the EUSES Spreadsheet Corpus.

Discovery-Based Edit Assistance for Spreadsheets, Cunha, Jácome, Saraiva João, and Visser Joost , Proceedings of the 2009 IEEE Symposium on Visual Languages and Human-Centric Computing (VL/HCC), Washington, DC, USA, p.233–237, (2009) Abstractvl-hcc09.pdf

Spreadsheets can be viewed as a highly flexible end-users programming environment which enjoys wide-spread adoption. But spreadsheets lack many of the structured programming concepts of regular programming paradigms. In particular, the lack of data structures in spreadsheets may lead spreadsheet users to cause redundancy, loss, or corruption of data during edit actions. In this paper, we demonstrate how implicit structural properties of spreadsheet data can be exploited to offer edit assistance to spreadsheet users. Our approach is based on the discovery of functional dependencies among data items which allow automatic reconstruction of a relational database schema. From this schema, new formulas and visual objects are embedded into the spreadsheet to offer features for auto-completion, guarded deletion, and controlled insertion. Schema discovery and spreadsheet enhancement are carried out automatically in the background and do not disturb normal user experience.

MDSheet: A Framework for Model-driven Spreadsheet Engineering, Cunha, Jácome, Fernandes João Paulo, Mendes Jorge, and Saraiva João , Proceedings of the 34rd International Conference on Software Engineering, p.1395–1398, (2012) Abstracticse12_tooldemo.pdf

n this paper, we present MDSHEET, a framework for the embedding, evolution and inference of spreadsheet models. This framework offers a model-driven software development mechanism for spreadsheet users.

A Bidirectional Model-driven Spreadsheet Environment (Poster/Abstract), Cunha, Jácome, Fernandes João Paulo, Mendes Jorge, and Saraiva João , Proceedings of the 34rd International Conference on Software Engineering, p.1443–1444, (2012) Abstractabstract.pdfposter.pdf

n this extended abstract we present a bidirectional model-driven framework to develop spreadsheets. By being model driven, our approach allows to evolve a spreadsheet model and automatically have the data co-evolved. The bidirectional component achieves precisely the inverse, that is, to evolve the data and automatically obtain a new model to which the data conforms.