We describe a data structure and algorithms based on segment trees. They are used to manage different versions of a document and to reconstruct the version which was valid at a given time in the past or to get the most recent version. Difficulties arise because it is not known when a version will be replaced by a newer one. Thus unbounded time intervals are to be handled. The data structure also supports the retrieval of the history of a document.

The need for change of direction in Software Engineering has been suggested in severalresources [Power of Models]. In recent years many organizations have focused on ModelDriven Engineering (MDE) as an approach to application design and implementation.Model Driven Architecture (MDA) was introduced by Object Management Group (OMG) in2001 in support of MDE. Models are the basic elements in MDE. The focus on MDE is onthe concept of “Everything is a model”. So far several languages, tools and platforms havebeen created for MDE.In particular, models can be developed in a distributed environment, thus once they mergetogether, conflicts and inconsistencies should be detected in a convenient way to bereconciled (automatically by software or manually by developers). This project is based onprevious works that define difference and conflict metamodels of a source model. In thisreport, we introduce the benefits of versioning systems in MDE framework. A conflictmetamodel that is generated from the input metamodel and the architecture for detectingconflicts are represented. The proposed approach is metamodel independent that meansconflict metalmodel is created for any input model which conforms to Kernel Meta MetaModel (KM3). The concept of used conflict model can be also changed regardless ofmodels. The extended idea for conflicts detection, the presented architecture for modelcode management and the tools that can detect conflicts of concurrent models can help toimprove MDE in model code management. For this report, some implementation in Eclipseplatform has been rendered while some future works are suggested. / University of L'Aquila, Project group in Moedling with Alfonso Pierantonio

To improve quality of software systems, change-based fault prediction and scope-bounded checking have been used to predict or detect faults during software development. In fault prediction, changes to program source code, such as added lines or deleted lines, are used to predict potential faults. In fault detection, scope-bounded checking of programs is an effective technique for finding subtle faults. The central idea is to check all program executions up to a given bound. The technique takes two basic forms: scope-bounded static checking, where all bounded executions of a program are transformed into a formula that represents the violation of a correctness property and any solution to the formula represents a counterexample; or scope-bounded testing where a program is tested against all (small) inputs up to a given bound on the input size. Although the accuracies of change-based fault prediction and scope-bounded checking have been evaluated with experiments, both of them have effectiveness and efficiency limitations. Previous change-based fault predictions only consider the code modified by a change while ignoring the code impacted by a change. Scope-bounded testing only concerns the correctness specifications, and the internal structure of a program is ignored. Although scope-bounded static checking considers the internal structure of programs, formulae translated from structurally complex programs might choke the backend analyzer and fail to give a result within a reasonable time. To improve effectiveness and efficiency of these approaches, we introduce local semantic analysis into change-based fault prediction and scope-bounded checking. We use data-flow analysis to disclose internal dependencies within a program. Based on these dependencies, we identify code segments impacted by a change and apply fault prediction metrics on impacted code. Empirical studies with real data showed that semantic analysis is effective and efficient in predicting faults in large-size changes or short-interval changes. While generating inputs for scope-bounded testing, we use control-flow to guide test generation so that code coverage can be achieved with minimal tests. To increase the scalability of scope-bounded checking, we split a bounded program into smaller sub-programs according to data-flow and control-flow analysis. Thus the problem of scope-bounded checking for the given program reduces to several sub-problems, where each sub-problem requires the constraint solver to check a less complex formula, thereby likely reducing the solver’s overall workload. Experimental results show that our approach provides significant speed-ups over the traditional approach. / text

<p>The need for change of direction in Software Engineering has been suggested in severalresources [Power of Models]. In recent years many organizations have focused on ModelDriven Engineering (MDE) as an approach to application design and implementation.Model Driven Architecture (MDA) was introduced by Object Management Group (OMG) in2001 in support of MDE. Models are the basic elements in MDE. The focus on MDE is onthe concept of “Everything is a model”. So far several languages, tools and platforms havebeen created for MDE.In particular, models can be developed in a distributed environment, thus once they mergetogether, conflicts and inconsistencies should be detected in a convenient way to bereconciled (automatically by software or manually by developers). This project is based onprevious works that define difference and conflict metamodels of a source model. In thisreport, we introduce the benefits of versioning systems in MDE framework. A conflictmetamodel that is generated from the input metamodel and the architecture for detectingconflicts are represented. The proposed approach is metamodel independent that meansconflict metalmodel is created for any input model which conforms to Kernel Meta MetaModel (KM3). The concept of used conflict model can be also changed regardless ofmodels. The extended idea for conflicts detection, the presented architecture for modelcode management and the tools that can detect conflicts of concurrent models can help toimprove MDE in model code management. For this report, some implementation in Eclipseplatform has been rendered while some future works are suggested.</p> / University of L'Aquila, Project group in Moedling with Alfonso Pierantonio