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AbstractMost programming languages adopt static binding, but for distributed programming an exclusive reliance on static binding is too restrictive: dynamic binding is required in various guises, for example, when a marshalled value is received from the network, containing identifiers that must be rebound to local resources. Typically, it is provided only by ad hoc mechanisms that lack clean semantics. In this paper, we adopt a foundational approach, developing core dynamic rebinding mechanisms as extensions to the simply typed call-by-value ? calculus. To do so, we must first explore refinements of the call-by-value reduction strategy that delay instantiation, to ensure computations make use of the most recent versions of rebound definitions. We introduce redex-timeand destruct-timestrategies. The latter forms the basis for a ?marshcalculus that supports dynamic rebinding of marshalled values, while remaining as far as possible statically typed. We sketch an extension of ?marshwith concurrency and communication, giving examples showing how wrappers for encapsulating untrusted code can be expressed. Finally, we show that a high-level semantics for dynamic updating can also be based on the destruct-time strategy, defining a ?updatecalculus with simple primitives to provide type-safe updating of running code. We show how the ideas of this simple calculus extend to more real-world, module-level dynamic updating in the style of Erlang. We thereby establish primitives and a common semantic foundation for a variety of real-world dynamic rebinding requirements. [ABSTRACT FROM AUTHOR]

AbstractExisting languages provide good support for typeful programming of stand-alone programs. In a distributed system, however, there may be interaction between multiple instances of many distinct programs, sharing some (but not necessarily all) of their module structure, and with some instances rebuilt with new versions of certain modules as time goes on. In this paper, we discuss programming-language support for such systems, focussing on their typing and naming issues. We describe an experimental language, Acute, which extends an ML core to support distributed development, deployment, and execution, allowing type-safe interaction between separately built programs. The main features are (1) type-safe marshalling of arbitrary values; (2) type names that are generated (freshly and by hashing) to ensure that type equality tests suffice to protect the invariants of abstract types, across the entire distributed system; (3) expression-level names generated to ensure that name equality tests suffice for type safety of associated values, for example, values carried on named channels; (4) controlled dynamic rebinding of marshalled values to local resources; and (5) thunkification of threads and mutexes to support computation mobility. These features are a large part of what is needed for typeful distributed programming. They are a relatively lightweight extension of ML, should be efficiently implementable, and are expressive enough to enable a wide variety of distributed infrastructure layers to be written as simple library code above the byte-string network and persistent store APIs. This disentangles the language run-time from communication intricacies. This paper highlights the main design choices in Acute. It is supported by a full language definition (of typing, compilation, and operational semantics), by a prototype implementation, and by example distribution libraries. [ABSTRACT FROM AUTHOR]

Purpose - The purpose of this paper is to introduce a straightforward, practical model of employability that will allow the concept to be explained easily and that can be used as a framework for working with students to develop their employability. Design/methodology/approach - The model was developed from existing research into employability issues and the experience of the authors. The various elements of employability included in the model are discussed and their inclusion justified on the basis of existing research. Findings - The model sets out exactly what is meant by employability, in clear and simple terms, and the model suggests directions for interaction between the various elements. Research limitations/implications - The relationships between and the interaction of the elements within the model remain theoretical. Further research to test the model is planned and will be reported on at a later date. Practical implications - The model can be used to explain the concept of employability to those new to the subject, and particularly to students and their parents. It will be a useful tool for lecturers, personal tutors, careers advisors and any other practitioners involved in employability activities. It will also be used to develop a measurement tool for employability. Originality/value - This paper seeks to fill the gap between in-depth, scholarly and complex articles or books about employability and very simple descriptive articles. It will be of value to anybody with an interest in employability issues. [ABSTRACT FROM AUTHOR]