Extending Compositional Message Sequence Graphs

We extend the formal developments for message sequence charts (MSCs) to support scenarios with lost and found messages. We define a notion of extended compositional message sequence charts (ECMSCs) which subsumes the notion of compositional message sequence charts in expressive power but additionally allows to define lost and found messages explicitly. As usual, ECMSCs might be combined by means of choice and repetition towards (extended) compositional message sequence graphs. We show that - despite extended expressive power - model checking of monadic second-order logic (MSO) for this framework remains to be decidable. The key technique to achieve our results is to use an extended notion for linearizations

Transcription and Translation Products of the Cytolysin Gene psm-mec on the Mobile Genetic Element SCCmec Regulate Staphylococcus aureus Virulence

The F region downstream of the mecI gene in the SCCmec element in hospital-associated methicillin-resistant Staphylococcus aureus (HA-MRSA) contains two bidirectionally overlapping open reading frames (ORFs), the fudoh ORF and the psm-mec ORF. The psm-mec ORF encodes a cytolysin, phenol-soluble modulin (PSM)-mec. Transformation of the F region into the Newman strain, which is a methicillin-sensitive S. aureus (MSSA) strain, or into the MW2 (USA400) and FRP3757 (USA300) strains, which are community-acquired MRSA (CA-MRSA) strains that lack the F region, attenuated their virulence in a mouse systemic infection model. Introducing the F region to these strains suppressed colony-spreading activity and PSMα production, and promoted biofilm formation. By producing mutations into the psm-mec ORF, we revealed that (i) both the transcription and translation products of the psm-mec ORF suppressed colony-spreading activity and promoted biofilm formation; and (ii) the transcription product of the psm-mec ORF, but not its translation product, decreased PSMα production. These findings suggest that both the psm-mec transcript, acting as a regulatory RNA, and the PSM-mec protein encoded by the gene on the mobile genetic element SCCmec regulate the virulence of Staphylococcus aureus

MSC and data: dynamic variables

The extension of the MSC language with more advanced data concepts is one of the current topics of discussion in teh MSC standardization community. A recent paper at the SAM98 workshop by two of the current authors treated the extension of MSC with static variables. Feasibility of an approach to parameterize the MSC language with a data language was shown. We have extended this research by studying the combination of MSC with a data language containing dynamic variables. Rather than giving a precise proposal of the way in which an actual data language must be added to the MSC language, we discuss options and problems. Choices have to bemade, for example, with respect to scope, use of variables, and the way of assigning variables. For some particular combination of the options mentioned above, we give a formal operationl semantics of the combined MSC?Data language. It is argued that the interface between the data language definition and the MSC language definition should be explicit

Bibliography

Introduction to the AI--Trader Project. http://www.vsb.informatik.uni-- frankfurt.de/projects/aitrader/, Computer Science Department, University of Frankfurt, 1995. [7] A. Puder and K. Romer. Using a Meta--Notation in a CORBA environment. In CORBA: Implementation, Use and Evaluation, ECOOP, Jyvaskyla, Finland, June 1997. [8] J.F. Sowa. Conceptual Structures, information processing mind and machine. Addison--Wesley Publishing Company, 1984. and include the output in your mail. Q: After creating Implementation Repository entries with imr create imr list does not show the newly created entries. What is going wrong? A: You must tell imr where micod is running, otherwise imr will create its own implementation repository which is destroyed when imr exits. You tell imr the location of the implementation repository by using the -ORBImplRepoAddr option, e.g.: micod-ORBIIOPAddr inet:jad

High-level Message Sequence Charts

syntax of HMSC A hierarchical graph is a mathematical structure that represents the information contents of an HMSC. The set HGid represents the set of all HMSC names. Obviously, this includes the names of BMSCs. Since we did not provide a formal graphical syntax for HMSC we cannot provide a formal mapping from HMSC to hierarchical graphs. However, the intuition is clear. A node in an HMSC contains a reference to another HMSC via its name. Definition 3.3.1 (Hierarchical graphs) A hierarchical graph is either a BMSC or a tuple #id, Nodes, Starts, Ends, Edges, l#, where . id # HGid is the name of the hierarchical graph; . Nodes, Starts, and Ends are pairwise disjoint sets of HMSC reference nodes, start nodes and end nodes respectively with Starts #= ?; . Edges # (Nodes # Starts) × (Nodes # Ends) is a set of edges. An edge (n, n # ) is denoted by n # n # ; . l : Nodes # HGid is a labeling function which associates to a node a reference to an HMSC by means of a..

Synchronous sequence charts in action

IWe identify a number of styles for using Interworkings (synchronous sequence charts), together with their roles in the context of the OSI reference model. We employ the wellknown ABP (alternating bit protocol) to see how Interworkings can and cannot be used. This experiment shows that the charts are attractive from an intuitive point of view, but when used in their purest form, lack sufficient expressive power. Some of the distinctions in style can be interpreted as distinct approaches to adding expressive power

A Hierarchy of Communication Models for Message Sequence Charts

In a Message Sequence Chart (MSC) the dynamical behaviour of a number of cooperating processes is depicted. An MSC defines a partial order on the communication events between these processes. This order determines the physical architecture needed for implementing the specified behaviour, such as a FIFO buffer between each of the processes. In a systematic way, we define 50 communication models for MSC and we define what it means for an MSC to be implementable by such a model. Some of these models turn out to be equivalent, in the sense that they implement the same class of MSCs. After analysing the notion of implementability, only ten models remain, for which we develop a hierarchy