Generating optimized configurable business process models in scenarios subject to uncertainty

ContextThe quality of business process models (i.e., software artifacts that capture the relations between the organizational units of a business) is essential for enhancing the management of business processes. However, such modeling is typically carried out manually. This is already challenging and time consuming when (1) input uncertainty exists, (2) activities are related, and (3) resource allocation has to be considered. When including optimization requirements regarding flexibility and robustness it becomes even more complicated potentially resulting into non-optimized models, errors, and lack of flexibility.ObjectiveTo facilitate the human work and to improve the resulting models in scenarios subject to uncertainty, we propose a software-supported approach for automatically creating configurable business process models from declarative specifications considering all the aforementioned requirements.MethodFirst, the scenario is modeled through a declarative language which allows the analysts to specify its variability and uncertainty. Thereafter, a set of optimized enactment plans (each one representing a potential execution alternative) are generated from such a model considering the input uncertainty. Finally, to deal with this uncertainty during run-time, a flexible configurable business process model is created from these plans.ResultsTo validate the proposed approach, we conduct a case study based on a real business which is subject to uncertainty. Results indicate that our approach improves the actual performance of the business and that the generated models support most of the uncertainty inherent to the business.ConclusionsThe proposed approach automatically selects the best part of the variability of a declarative specification. Unlike existing approaches, our approach considers input uncertainty, the optimization of multiple objective functions, as well as the resource and the control-flow perspectives. However, our approach also presents a few limitations: (1) it is focused on the control-flow and the data perspective is only partially addressed and (2) model attributes need to be estimated.     

Generating instance models from meta models

Meta modeling is a wide-spread technique to define visual languages, with the UML being the most prominent one. Despite several advantages of meta modeling such as ease of use, the meta modeling approach has one disadvantage: it is not constructive, i.e., it does not offer a direct means of generating instances of the language. This disadvantage poses a severe limitation for certain applications. For example, when developing model transformations, it is desirable to have enough valid instance models available for large-scale testing. Producing such a large set by hand is tedious. In the related problem of compiler testing, a string grammar together with a simple generation algorithm is typically used to produce words of the language automatically. In this paper, we introduce instance-generating graph grammars for creating instances of meta models, thereby overcoming the main deficit of the meta modeling approach for defining languages.

基于UML活动图生成功能测试线索

测试自动化是提高软件测试效率的重要途径。基于UML模型的面向对象软件测试是当前研究的热点。这些研究大都是类或集成测试,对于如何自动生成较为完整、合理的系统测试用例较少。在总结研究现状的基础上,以应用举例的方式提出一种从描述系统用例问顺序依赖关系的活动图和用例实现的活动图中获取系统功能测试线索的方法。     

Generating systems from multiple sketched models

Diagrams are often used to model complex systems: in many cases several different types of diagrams are used to model different aspects of the system. These diagrams, perhaps from multiple stakeholders of different specialties, must be combined to achieve a full abstract representation of the system. Many CAD tools offer multi-diagram integration; however, sketch-based diagramming tools are yet to tackle this difficult integration problem. We extend the diagram sketching tool InkKit to combine software engineering sketches of different types. Our extensions support software design processes by providing a sketch-based approach that allows the iterative creation of multiple outputs interacting with one another from the inter-linked models. We demonstrate that InkKit can generate a functional system consisting of a user interface with processes to submit and retrieve data from a database from sketched user interfaces designs and sketched entity relationship diagrams.     

基于UML活动图及混合遗传算法的测试场景生成

有效降低测试成本是软件测试优化的重要研究问题。将遗传算法引入到软件测试中,对生成测试场景提供了必要的动力,然而遗传算法局域搜索能力差,在进化后期搜索效率低,导致算法比较费时。基于UML活动图提出了混合遗传算法生成测试场景的方法,该方法结合遗传算法和爬山法,有效地加快了测试场景的生成速度。为了避免局部性问题,在算法每次进行爬山操作之前调用种群生成函数。实验结果表明,与简单的遗传算法相比,混合遗传算法不仅有效地解决了局部性问题,而且较大地提高了生成测试场景的效率,降低了软件测试成本。     

Generating relevant models

Manthey and Bry's model generation approach to theorem proving for FOPC has been greeted with considerable interest. Unfortunately the original presentation of the technique can become arbitrarily inefficient when applied to problems whose statements contain large amounts of irrelevant information. We show how to avoid these problems whilst retaining nearly all the advantages of the basic approach.     

Generating parametric models of tubes from laser scans

We present an automatic method for computing an accurate parametric model of a piecewise defined pipe surface, consisting of cylinder and torus segments, from an unorganized point set. Our main contributions are reconstruction of the spine curve of a pipe surface from surface samples, and approximation of the spine curve by G¹ continuous circular arcs and line segments. Our algorithm accurately outputs the parametric data required for bending machines to create the reconstructed tube.     

Approach to behavior scenarios debugging

The paper presents two approaches to debugging of application model behavior scenarios: semi-automatic and automatic. The first approach allows the user to automate the process of finding a place in a concrete symbolic behavioral scenario that caused an error. The second approach allows to find together with places the cause of multiple errors in some set of generated behavior scenarios in a single analysis cycle.     

Generating valid grammar-based test inputs by means of genetic programming and annotated grammars

Automated generation of system level tests for grammar based systems requires the generation of complex and highly structured inputs, which must typically satisfy some formal grammar. In our previous work, we showed that genetic programming combined with probabilities learned from corpora gives significantly better results over the baseline (random) strategy. In this work, we extend our previous work by introducing grammar annotations as an alternative to learned probabilities, to be used when finding and preparing the corpus required for learning is not affordable. Experimental results carried out on six grammar based systems of varying levels of complexity show that grammar annotations produce a higher number of valid sentences and achieve similar levels of coverage and fault detection as learned probabilities.     

Performance analysis of security aspects by weaving scenarios extracted from UML models

Aspect-oriented modeling (AOM) allows software designers to describe features that address pervasive concerns separately as aspects, and to systematically incorporate the features into a design model using model composition techniques. The goal of this paper is to analyze the performance effects of different security features that may be represented as aspect models. This is part of a larger research effort to integrate methodologies and tools for the analysis of security and performance properties early in the software development process. In this paper, we describe an extension to the AOM approach that provides support for performance analysis. We use the performance analysis techniques developed previously in the PUMA project, which take as input UML models annotated with the standard UML Profile for Schedulability, Performance and Time (SPT), and transform them first into Core Scenario Model (CSM), and then into different performance models. The composition of the aspects with the primary (base) model is performed at the CSM level. A new formal definition of CSM properties and operations is described as a foundation for scenario-based weaving. The proposed approach is illustrated with an example that utilizes two standards, TPC-W and SSL.     

Generating requirements from systems models using patterns: a case study

Academic research has produced many model-based specification and analysis techniques, however, most organisations continue to document requirements as textual statements. To help bridge this gap between academic research and requirements practice, this paper reports an extension to the RESCUE process in which patterns for generating requirements statements from i* system models were manually applied to i* models developed for a complex air traffic control system. The paper reports the results of this application and describes them with examples, the benefits of the approach to the project, and ongoing research to implement these patterns in the REDEPEND modelling tool to make requirements engineers more productive. We review similar work on requirements modelling and expression, and compare our work to it to demonstrate the proposed advance in the state of the art. Finally the paper discusses future uses of requirements generation from model patterns in RESCUE.     

Generating heterogeneous executable specifications in SystemC from UML/MARTE models

Modeling and analysis of real-time embedded system is becoming an important area of research nowadays. In this context, the UML/MARTE profile has been introduced to support the specification, design, and verification stages in the development process. It provides a wide set of facilities to capture the information required in the refinement steps throughout the design flow. To carry out the actions involved in these design steps, MARTE-based tools and methodologies are required. This paper presents a methodology to automatically generate SystemC heterogeneous executable specifications from generic MARTE models. To generate these specifications, the information included in the MARTE models is extracted to discover the system structure and hierarchy. A subset of the concurrency and communication features of the MARTE profile is used for this purpose. Then, automatic generation of the executable specification is possible. The code implementing the corresponding behavior can be easily integrated into the executable model. This design methodology proposes a refinement flow in order to perform the design steps before deciding the final system implementation.     

Generating topological structures for surface models

Rapid prototyping has imposed new requirements on the processing of CAD models. To manufacture an object directly, the model must correspond to a real object and thus represent a closed volume. Its boundary must be continuous and closed, and no cracks or improper intersections are allowed. CAD models cannot always meet these requirements, especially when they are constructed by a surface modeler. The algorithm discussed analyzes surface models and generates a topological structure for them that meets rapid prototyping requirements for a closed volume with a continuous, closed boundary     

On compliance checking for clausal constraints in annotated process models

Compliance management is important in several industry sectors where there is a high incidence of regulatory control. It must be ensured that business practices, as reflected in business processes, comply with the rules. Such compliance checks are challenging due to (1) the different life cycles of rules and processes, and (2) their disparate representations. (1) requires retrospective checking of process models. To address (2), we herein devise a framework where processes are annotated to capture the semantics of task execution, and compliance is checked against a set of constraints posing restrictions on the desirable process states. Each constraint is a clause, i.e., a disjunction of literals. If a process can reach a state that falsifies all literals of one of the constraints, then that constraint is violated in that state, and indicates non-compliance. Naively, such compliance can be checked by enumerating all reachable states. Since long waiting times are undesirable, it is important to develop efficient (low-order polynomial time) algorithms that (a) perform exact compliance checking for restricted cases, or (b) perform approximate compliance checking for more general cases. Herein, we observe that methods of both kinds can be defined as a natural extension of our earlier work on semantic business process validation. We devise one method of type (a), and we devise two methods of type (b); both are based on similar restrictions to the processes, where the restrictions made by methods (b) are a subset of those made by method (a). The approximate methods each guarantee either of soundness (finding only non-compliances) or completeness (finding all non-compliances). We describe how one can trace the state evolution back to the process activities which caused the (potential) non-compliance, and hence provide the user with an error diagnosis.     

Diagnosis from scenarios

Diagnosis of a system consists in providing explanations to a supervisor from a partial observation of the system and a model of possible executions. This paper proposes a partial order diagnosis algorithm that recovers sets of scenarios which correspond to a given observation. Systems are modeled using High-level Message Sequence Charts (HMSCs), and the diagnosis is given as a new HMSC, which behaviors are all explanations of the partial observation. The main difficulty is that some actions of the monitored system are unobservable but may still induce some causal ordering among observed events. We first give an offline centralized diagnosis algorithm, then we discuss a decentralized version of this algorithm. We then give an online diagnosis algorithm, and define syntactic criteria under which the memory used can be bounded. This allows us to give a complete diagnosis framework for infinite state systems, with a strong emphasis on concurrency and causal ordering in behaviors. The last contribution of the paper is an application of diagnosis techniques to a security problem called anomaly detection. Anomaly detection consists in comparing what occurs in the system with usual/expected behaviors, and raising an alarm when some unusual behavior (meaning a potential attack) occurs.     

Generating efficient dynamical models for microelectromechanicalsystems from a few finite-element simulation runs

In this paper, we demonstrate how efficient low-order dynamical models for micromechanical devices can be constructed using data from a few runs of fully meshed but slow numerical models such as those created by the finite-element method (FEM). These reduced-order macromodels are generated by extracting global basis functions from the fully meshed model runs in order to parameterize solutions with far fewer degrees of freedom. The macromodels may be used for subsequent simulations of the time-dependent behavior of nonlinear devices in order to rapidly explore the design space of the device. As an example, the method is used to capture the behavior of a pressure sensor based on the pull-in time of an electrostatically actuated microbeam, including the effects of squeeze-film damping due to ambient air under the beam. Results show that the reduced-order model decreases simulation time by at least a factor of 37 with less than 2% error. More complicated simulation problems show significantly higher speedup factors. The simulations also show good agreement with experimental data     

基于隐马尔可夫模型的入侵场景构建

提出了一种基于隐马尔可夫模型的入侵场景构建方法,实现自动地从大量低级的入侵检测告警信息中构建出更高层次的入侵场景的目的。为了简化处理过程,对数据流采用两次抽象描述和一次回溯处理过程完成对入侵场景的构建,在DARPA2000测试数据集上的实验表明该方法是有效的。     

Fault-tree models of accident scenarios of RoPax vessels

Ro-Ro vessels for cargo and passengers (RoPax) are a relatively new concept that has proven to be popular in the Mediterranean region and is becoming more widespread in Northern Europe. Due to its design characteristics and amount of passengers, although less than a regular passenger liner, accidents with RoPax vessels have far reaching consequences both for economical and for human life. The objective of this paper is to identify hazards related to casualties of RoPax vessels. The terminal casualty events chosen are related to accident and incident statistics for this type of vessel. This paper focuses on the identification of the basic events that can lead to an accident and the performance requirements. The hazard identification is carried out as the first step of a Formal Safety Assessment (FSA) and the modelling of the relation between the relevant events is made using Fault Tree Analysis (FTA). The conclusions of this study are recommendations to the later steps of FSA rather than for decision making (Step 5 of FSA). These recommendations will be focused on the possible design shortcomings identified during the analysis by fault trees throughout cut sets. Also the role that human factors have is analysed through a sensitivity analysis where it is shown that their influence is higher for groundings and collisions where an increase of the initial probability leads to the change of almost 90% of the accident occurrence.     

Generating assembly features onto split solid models

A large model can be split into smaller components where by assembly features can be created and attached onto the components so that they can be reassembled to form the original model. The assembly features may function as positioning or interlocking purposes depending on the mating requirement. This paper describes a method for creating assembly features onto the solid components automatically. The main idea of the method is to construct spatial rectangular assembly cells inside the original model. This is done by ray tracing the tool surface that is used to split the model, provided that there is no undercut on the split surface along the assembly direction. The spatial cells represent solid regions in which assembly features can be attached. Different kinds of assembly features can be mapped to the spatial cells, which are then attached to the split components. The split surface can be planar, quadrics or higher order freeform surfaces, thus allowing a high degree of flexibility in creating the assembly feature shapes.