Abstract

Abstract
Today E-Government institutions face a lot of challenges related to the quality and effectiveness of the services they provide. In most cases, their users are more demanding, imposing new ways of acting and dealing with their needs, requesting often expeditious and effective attendance. Independently for their nature, we believe that such pertinent characteristics begin to be sustained immediately as we start to study and model E-Government processes. Modeling and simulation are useful tools on the assurance of the availability of E-Government services in many aspects, contributing significantly to improve processes implementation, ranging from their inception to their final software application roll-up and maintenance. In this paper we studied the use of YAWL - a work flowing language - for modeling E-Government processes, showing through a real world application case how it can help us in the construction of effective models that may be used as a basis for understanding and building the correspondent software applications.

Abstract
Model synchronization plays an important role in modeldriven software development. Bidirectional model transformation approaches provide techniques for developers to specify the bidirectional relationship between source and target models, while keeping related models synchronized for free. Since models of interest are usually not in a one-to-one correspondence, this synchronization process is inherently ambiguous. Nevertheless, existing bidirectional model transformation tools focus mainly on enforcing consistency and provide developers only limited control over how models are synchronized, solving the latent ambiguity via default strategies whose behavior is unclear to developers. In this paper, we propose a novel approach in which developers write update programs that succinctly describe how a target model can be used to update a source model, such that the bidirectional behavior is fully determined. The new approach mitigates the unpredictability of existing solutions, by enabling a finer and more transparent control of what a bidirectional transformation does, and suggests a research direction for building more robust bidirectional model transformation tools. Copyright © 2014 ACM.

Abstract
A bidirectional transformation consists of pairs of transformations-a forward transformation get produces a target view from a source, while a putback transformation put puts back modifications on the view to the source-satisfying sensible roundtrip properties. Existing bidirectional approaches are get-based in that one writes (an artifact resembling) a forward transformation and a corresponding backward transformation can be automatically derived. However, the unavoidable ambiguity that stems from the underspecification of put often leads to unpredictable bidirectional behavior, making it hard to solve nontrivial practical synchronization problems with existing bidirectional transformation approaches. Theoretically, this ambiguity problem could be solved by writing put directly and deriving get, but differently from programming with get it is easy to write invalid put functions. An open challenge is how to check whether the definition of a putback transformation is valid, while guaranteeing that the corresponding unique get exists. In this paper, we propose, as far as we are aware, the first safe language for supporting putback-based bidirectional programming. The key to our approach is a simple but powerful language for describing primitive putback transformations. We show that validity of putback transformations in this language is decidable and can be automatically checked. A particularly elegant and strong aspect of our design is that we can simply reuse and apply standard results for treeless functions and tree transducers in the specification of our checking algorithms. © 2014 Springer International Publishing Switzerland.

Abstract
Bidirectional transformations, in particular lenses, are programs with a forward get transformation and a backward putback transformation that keep source and view data types synchronized. Several bidirectional programming languages exist to aid programmers in writing a (sort of) forward transformation, and deriving a backward transformation for free. However, the maintainability offered by such languages comes at the cost of expressiveness and (more importantly) predictability because the ambiguity of synchronization -handled by the putback transformation- is solved by default strategies over which programmers have little control. In this paper, we argue that controlling such ambiguity is essential for bidirectional transformations and propose a novel language in which programmers write a (sort of) putback transformation, and get the unique get transformation for free. Like traditional bidirectional languages, our put-oriented language allows reasoning about the correctness of defined transformations from the properties of their building blocks. But it allows programmers to describe the behavior of a bidirectional transformation much more precisely, while retaining the maintainability of writing a single program. We demonstrate the practical power of the new approach through a series of examples, ranging from simple ones that illustrate traditional lenses to complex ones for which our putback-based approach is central to specifying nontrivial update strategies. Categories and Subject Descriptors D.1.1 [Programming Techniques]: Applicative (Functional) Programming; D.3.1 [Programming Languages]: Formal Definitions and Theory; F.3.2 [Logics and Meanings of Programs]: Semantics of Programming Languages-Algebraic approaches to semantics.

Abstract
Different XML formats are widely used for data exchange and processing, being often necessary to mutually convert between them. Standard XML transformation languages, like XSLT or XQuery, are unsatisfactory for this purpose since they require writing a separate transformation for each direction. Existing bidirectional transformation languages mean to cover this gap, by allowing programmers to write a single program that denotes both transformations. However, they often 1) induce a more cumbersome programming style than their traditionally unidirectional relatives, to establish the link between source and target formats, and 2) offer limited configurability, by making implicit assumptions about how modifications to both formats should be translated that may not be easy to predict. This paper proposes a bidirectional XML update language called BIFLUX (BIdirectional FunctionaL Updates for XML), inspired by the FLUX XML update language. Our language adopts a novel bidirectional programming by update paradigm, where a program succinctly and precisely describes how to update a source document with a target document, in an intuitive way, such that there is a unique "inverse" source query for each update program. BIFLUX extends FLUX with bidirectional actions that describe the connection between source and target formats. We introduce a core BIFLUX language, with a clear and well-behaved bidirectional semantics and a decidable static type system based on regular expression types.