Symbolic Implementation of Connectors in BIP

BIP is a component framework for constructing systems by superposing three layers of modeling: Behavior, Interaction, and Priority. Behavior is represented by labeled transition systems communicating through ports. Interactions are sets of ports. A synchronization between components is possible through the interactions specified by a set of connectors. When several interactions are possible, priorities allow to restrict the non-determinism by choosing an interaction, which is maximal according to some given strict partial order. The BIP component framework has been implemented in a language and a tool-set. The execution of a BIP program is driven by a dedicated engine, which has access to the set of connectors and priority model of the program. A key performance issue is the computation of the set of possible interactions of the BIP program from a given state. Currently, the choice of the interaction to be executed involves a costly exploration of enumerative representations for connectors. This leads to a considerable overhead in execution times. In this paper, we propose a symbolic implementation of the execution model of BIP, which drastically reduces this overhead. The symbolic implementation is based on computing boolean representation for components, connectors, and priorities with an existing BDD package

Avoiding OCL specification pitfalls

This paper discusses about teaching software modeling by using OCL specifications, in the context in which the web represents the main source of information. The raise of the interest for models induced a higher need for clear and complete specifications. In case of models specified by means of MOF-based languages, adding OCL constraints proved to be an interesting answer to this need. Several OCL examples posted on web include hasty specifications, that are often dissuasive with respect to complementing models with OCL specification. OCL beginners, and not only, need to know how to avoid potential specification traps.Our proposal is based on a complete and unambiguous description of requirements, that represents the first step towards good OCL specifications. The work highlights several major aspects that need to be understood and complied with to produce meaningful and efficient OCL specifications. This approach was tested while teaching OCL at Babes-Bolyai University of Cluj-Napoca

I-Light Applications Workshop 2002 Proceedings

Editing for this document was provided by Gregory Moore and Craig A. Stewart.Indiana Governor Frank O'Bannon symbolically lit the fiber of the I-Light network on December 11, 2001. I-Light is a unique, high-speed fiber optic network connecting Indiana University Bloomington, Indiana University–Purdue University Indianapolis, and Purdue University West Lafayette with each other and with Abilene, the national high-speed Internet2 research and education network. This unique university-owned high speed network connects three of the Indiana's great research campuses. One year after the lighting of the network, we invited researchers from Indiana University and Purdue University to come together to discuss some of the research and instructional achievements that have been made possible in just one short year of the existence of I-Light. The results were dramatic: on December 4, 2002, more than 150 researchers gathered together in Indianapolis to discuss research and instructional breakthroughs made possible by I-Light.The I-Light Applications Workshop 2002 was sponsored by the Office of the Vice President for Information Technology and CIO, Indiana University; and the Office of the Vice President for Information Technology and CIO, Purdue University. I-Light was made possible by a special appropriation by the State of Indiana. The research described at the I-Light Applications Workshop has been supported by numerous grants from several sources, mentioned in the individual presentations included in this proceedings volume. Many of the scientific research projects discussed in this volume have been supported by the National Science Foundation and/or the National Institutes of Health. Some Purdue projects also received support from Indiana's 21st Century Fund. Multiple presentations featured work supported by the Lilly Endowment, Inc., through grants to Indiana University in support of the Pervasive Technology Laboratories and the Indiana Genomics Initiative, both at Indiana University. Purdue University projects received support from the National Science Foundation and the 21st Century Fund. Any opinions, findings and conclusions, or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the granting agencies

Exploiting replication in distributed systems

Techniques are examined for replicating data and execution in directly distributed systems: systems in which multiple processes interact directly with one another while continuously respecting constraints on their joint behavior. Directly distributed systems are often required to solve difficult problems, ranging from management of replicated data to dynamic reconfiguration in response to failures. It is shown that these problems reduce to more primitive, order-based consistency problems, which can be solved using primitives such as the reliable broadcast protocols. Moreover, given a system that implements reliable broadcast primitives, a flexible set of high-level tools can be provided for building a wide variety of directly distributed application programs

Layers of generality and types of generalization in pattern activities

Pattern generalization is considered one of the prominent routes for in-troducing students to algebra. However, not all generalizations are al-gebraic. In the use of pattern generalization as a route to algebra, we —teachers and educators— thus have to remain vigilant in order not to confound algebraic generalizations with other forms of dealing with the general. But how to distinguish between algebraic and non-algebraic generalizations? On epistemological and semiotic grounds, in this arti-cle I suggest a characterization of algebraic generalizations. This char-acterization helps to bring about a typology of algebraic and arithmetic generalizations. The typology is illustrated with classroom examples

Coordination of Dynamic Software Components with JavaBIP

JavaBIP allows the coordination of software components by clearly separating the functional and coordination aspects of the system behavior. JavaBIP implements the principles of the BIP component framework rooted in rigorous operational semantics. Recent work both on BIP and JavaBIP allows the coordination of static components defined prior to system deployment, i.e., the architecture of the coordinated system is fixed in terms of its component instances. Nevertheless, modern systems, often make use of components that can register and deregister dynamically during system execution. In this paper, we present an extension of JavaBIP that can handle this type of dynamicity. We use first-order interaction logic to define synchronization constraints based on component types. Additionally, we use directed graphs with edge coloring to model dependencies among components that determine the validity of an online system. We present the software architecture of our implementation, provide and discuss performance evaluation results.Comment: Technical report that accompanies the paper accepted at the 14th International Conference on Formal Aspects of Component Softwar

The Ekaterinburg Seminar "Algebraic Systems": 50 Years of Activities

The aim of the present article is to give a characterization of distinctive features of the scientic seminar founded and led by the author as well as to show the main sides of its activities during half a century