A Systematic Aspect-Oriented Refactoring and Testing Strategy, and its Application to JHotDraw

Aspect oriented programming aims at achieving better modularization for a system's crosscutting concerns in order to improve its key quality attributes, such as evolvability and reusability. Consequently, the adoption of aspect-oriented techniques in existing (legacy) software systems is of interest to remediate software aging. The refactoring of existing systems to employ aspect-orientation will be considerably eased by a systematic approach that will ensure a safe and consistent migration. In this paper, we propose a refactoring and testing strategy that supports such an approach and consider issues of behavior conservation and (incremental) integration of the aspect-oriented solution with the original system. The strategy is applied to the JHotDraw open source project and illustrated on a group of selected concerns. Finally, we abstract from the case study and present a number of generic refactorings which contribute to an incremental aspect-oriented refactoring process and associate particular types of crosscutting concerns to the model and features of the employed aspect language. The contributions of this paper are both in the area of supporting migration towards aspect-oriented solutions and supporting the development of aspect languages that are better suited for such migrations.Comment: 25 page

More order with less law: on contract enforcement, trust, and crowding

Most contracts, whether between voters and politicians or between house owners and contractors, are incomplete. “More law,” it typically is assumed, increases the likelihood of contract performance by increasing the probability of enforcement and/or the cost of breach. We examine a contractual relationship in which the first mover has to decide whether she wants to enter a contract without knowing whether the second mover will perform. We analyze how contract enforceability affects individual performance for exogenous preferences. Then we apply a dynamic model of preference adaptation and find that economic incentives have a nonmonotonic effect on behavior. Individuals perform a contract when enforcement is strong or weak but not with medium enforcement probabilities: Trustworthiness is “crowded in” with weak and “crowded out” with medium enforcement. In a laboratory experiment we test our model’s implications and find support for the crowding prediction. Our finding is in line with the recent work on the role of contract enforcement and trust in formerly Communist countries

The enforcement of child custody orders by contempt remedies

Family law statutes in every state govern the child-related issues that arise at the time of divorce. As a general rule, these statutes require the divorce courts to enter coercive orders that will govern the residential and decisionmaking aspects of post-divorce parent-child relationships. The laws in many states also set out the remedies, including civil and criminal contempt, available to enforce court-ordered parenting plans in the event of parental noncompliance. This area of statutory regulation, which touches the lives of millions of families every year, is in many ways sui generis. At the same time, the coercive nature of the court-ordered terms of post-divorce parenting plans, and the availability of enforcement by civil or criminal contempt remedies, place custody and visitation orders in a larger doctrinal context. This Article analyzed child custody and visitation laws against this backdrop of the law of injunctions and the law of contempt. The family law system assigns priority to the maintenance of established relationships between children and both of their parents following the parents' divorce. This priority leads to certain variations from the general model of injunctive remedies in many child custody cases. For example, divorce courts formulate the initial coercive parenting orders, which become immediately enforceable by contempt remedies upon violation by one parent, without making any determination of prior wrongdoing by either parent. Furthermore, the courts routinely enter coercive orders addressing the residential and decisionmaking aspects of post-divorce parenting, even though the anticipated period of judicial regulation is lengthy (until the children's ages of majority), and despite evidence of likely compliance problems. Finally, in the event of parental noncompliance, judicial enforcement via contempt remedies may involve the entry of orders that vary significantly from the classic contempt model, especially when the contempt remedy is civil rather than criminal in nature. Parenting plan orders typically set out specific responsibilities for both parents, to be performed over a period of years until the children become adults. The nature of these orders, involving recurring patterns of family behavior, and the importance of the interests that they seek to protect have shaped many of the family law doctrines discussed in this Article. These doctrines have molded the general law of injunctions to fit a unique legal context, the creation and enforcement of post-divorce custody orders

A Blockchain-based Approach for Data Accountability and Provenance Tracking

The recent approval of the General Data Protection Regulation (GDPR) imposes new data protection requirements on data controllers and processors with respect to the processing of European Union (EU) residents' data. These requirements consist of a single set of rules that have binding legal status and should be enforced in all EU member states. In light of these requirements, we propose in this paper the use of a blockchain-based approach to support data accountability and provenance tracking. Our approach relies on the use of publicly auditable contracts deployed in a blockchain that increase the transparency with respect to the access and usage of data. We identify and discuss three different models for our approach with different granularity and scalability requirements where contracts can be used to encode data usage policies and provenance tracking information in a privacy-friendly way. From these three models we designed, implemented, and evaluated a model where contracts are deployed by data subjects for each data controller, and a model where subjects join contracts deployed by data controllers in case they accept the data handling conditions. Our implementations show in practice the feasibility and limitations of contracts for the purposes identified in this paper

Taxi Licensing Follow-Up Study: Summary of Main Results

This paper presents the findings of a survey of taxi licensing policy in England and Wales in mid 1989. The survey acts partly as a follow-up study to earlier work reported earlier in this series (Toner 1989 WP 273) and partly as a vehicle for the assessment of a number of additional issues. These issues form the key to an understanding of the consequences to both consumers of taxi services and road users more generally of the decision to either retain or remove restrictions on entry to the hackney carriage trade. The results presented are purely corss-sectional in nature and do not include a treatment of the important issues of price and service effects. These topics will form the basis of further papers (see, for example Pells, (1990) WP 290 for initial findings on values of waiting time and price elasticities in the hackney market)