Multiparty Session Actors

Actor coordination armoured with a suitable protocol description language has been a pressing problem in the actors community. We study the applicability of multiparty session type (MPST) protocols for verification of actor programs. We incorporate sessions to actors by introducing minimum additions to the model such as the notion of actor roles and protocol mailbox. The framework uses Scribble, which is a protocol description language based on multiparty session types. Our programming model supports actor-like syntax and runtime verification mechanism guaranteeing type-safety and progress of the communicating entities. An actor can implement multiple roles in a similar way as an object can implement multiple interfaces. Multiple roles allow for inter-concurrency in a single actor still preserving its progress property. We demonstrate our framework by designing and implementing a session actor library in Python and its runtime verification mechanism.Comment: In Proceedings PLACES 2014, arXiv:1406.331

Risk Objectivism and Risk Subjectivism: When Are Risks Real

Typically, those who discuss Risk management envision a two-step process wherein, first, Risk is more or less objectively appraised and, second, the acceptability of those Risks is subjectively evaluated. This paper questions the philosophical foundations of that approach

CAN Fieldbus Communication in the CSP-based CT Library

In closed-loop control systems several realworld entities are simultaneously communicated to through a multitude of spatially distributed sensors and actuators. This intrinsic parallelism and complexity motivates implementing control software in the form of concurrent processes deployed on distributed hardware architectures. A CSP based occam-like architecture seems to be the most convenient for such a purpose. Many, often conflicting, requirements make design and implementation of distributed real-time control systems an extremely difficult task. The scope of this paper is limited to achieving safe and real-time communication over a CAN fieldbus for an\ud existing CSP-based framework

The U.S. Postal Service War on Private Mailboxes and Privacy Rights

On March 25, 1999, neatly concealed in an obscure and seemingly minor "Procedure Revision," the U.S. Postal Service announced its intent to execute Postal Bulletin 21994. In an alleged attempt to combat mail fraud, the Postal Service required that by June 24, 1999, all commercial mail-receiving agencies (CMRAs) that offer rental of private mailboxes should have collected from their customers confidential information that the Postal Service itself is not allowed to collect. Furthermore, starting as early as October 24, 1999, the USPS will deliver mail only to the private boxes addressed in a particular format that will be unfamiliar to many senders. Those new requirements violate the privacy regulations that cover the Postal Service. The USPS plans to make available to the public confidential information about any private box holder who uses the box for business with the public. However, access to such information could actually facilitate criminal activity. Moreover, the Postal Service also plans to apply these new regulations to executive suites.In addition, because it is impossible for box holders to know everyone who might have their private box address on file, many otherwise deliverable pieces of mail will be returned to the sender, marked "address unknown." Finally, the new regulations will foist enormous costs on some 1.5 million to 2.5 million private mailbox holders, which include many of the country's smallest businesses. CMRAs will also incur expenses, not only of compliance with and notification to box holders of the new regulations but also of lost business. A conservative estimate of the direct costs alone of the new regulations could approach $1 billion

Supporting Mentors

Providing support to the match is critical for success in all programs, whether they are school-based, institution-based, or community-based. Depending upon program characteristics and available resources, the details of ongoing support may vary. This packet helps programs develop and implement strategies that support mentors, help them build trusting relationships with their mentees and, ultimately, contribute to positive outcomes for youth. The materials include checklists to help guide planning and a list of additional resources

Stacking classifiers for anti-spam filtering of e-mail

We evaluate empirically a scheme for combining classifiers, known as stacked generalization, in the context of anti-spam filtering, a novel cost-sensitive application of text categorization. Unsolicited commercial e-mail, or "spam", floods mailboxes, causing frustration, wasting bandwidth, and exposing minors to unsuitable content. Using a public corpus, we show that stacking can improve the efficiency of automatically induced anti-spam filters, and that such filters can be used in real-life applications

Campus Update: October 1993 v. 5, no. 8

Monthly newsletter of the BU Medical Campu