The conceptualization of a configurable multi-party multi-message request-reply conversation

Organizations, to function effectively and expand their boundaries, require a deep insight into both process orchestration and choreography of cross-organization business processes. The set of requirements for service interactions is significant, and has not yet been sufficiently refined. Service Interaction Patterns studies by Barros et al. demonstrate this point. However, they overlook some important aspects of service interaction of bilateral and multilateral nature. Furthermore, the definition of these patterns are not precise due to the absence of a formal semantics. In this paper, we analyze and present a set of patterns formed around the subset of patterns documented by Barros et al. concerned with Request-Reply interactions, and extend these ideas to cover multiple parties and multiple messages. We concentrate on the interaction between multiple parties, and analyze issues of a non-guaranteed response and different aspects of message handling. We propose one configurable, formally defined, conceptual model to describe and analyze options and variants of request-reply patterns. Furthermore, we propose a graphical notation to depict every pattern variant, and formalize the semantics by means of Coloured Petri Nets. In addition, we apply this pattern family to evaluate WS-BPEL v2.0 and check how selected pattern variants can be operationalized in Oracle BPEL PM

A General Framework for Architecture Composability

Architectures depict design principles: paradigms that can be understood by all, allow thinking on a higher plane and avoiding low-level mistakes. They provide means for ensuring correctness by construction by enforcing global properties characterizing the coordination between components. An architecture can be considered as an operator A that, applied to a set of components B, builds a composite component A(B) meeting a characteristic property Φ. Architecture composability is a basic and common problem faced by system designers. In this paper, we propose a formal and general framework for architecture composability based on an associative, commutative and idempotent architecture composition operator ⊕. The main result is that if two architectures A1 and A2 enforce respectively safety properties Φ1 and Φ2 , the architecture A1 ⊕ A2 enforces the property Φ1 ∧ Φ2 , that is both properties are preserved by architecture composition. We also establish preservation of liveness properties by architecture composition. The presented results are illustrated by a running example and a case study

A Semantic Framework for Architecture Modelling

Architectures are common means for organising coordination between components in order to build complex systems and to make them manageable. They allow thinking on a higher plane and avoiding low-level mistakes. Architectures provide means for ensuring correctness-by-construction by enforcing global properties characterising the coordination between components. In this work, we consider the following questions of architecture modelling: 1) how to model architectures; 2) how to compose them if several properties enforced by different architectures are required; 3) how to specify architectures styles that generalise the notion of architectures and represent families of architectures satisfying the same property. An architecture can be considered as an operator that, applied to a set of components, builds a composite component meeting a characteristic property. The underlying concepts of components and their interaction originate from the BIP framework. This thesis is structured in two parts. In the first part, we study the expressiveness of glue operators in the BIP framework. We provide results for classical BIP glue and for several modifications obtained by relaxing the constraints imposed on priority models. We also study an alternative semantics of BIP glue based on the offer predicate. It meets fundamental properties required from component-based frameworks, namely compositionality, incrementality, flattening and modularity. We provide the comparison with the classical BIP semantics and the algorithm for the synthesis of connectors from the interaction logic used to describe coordination constraints. In the second part, we define architectures and propose an architecture composition operator. We study their properties and prove that the composition operator preserves safety properties of its operands. The alternative glue semantics presented in the first part of the thesis allows to extend architectures with priorities. For the specification of architecture styles, we propose configuration logics. We provide a sound and complete axiomatisation of the propositional configuration logic as well as decision procedures for checking that an architecture satisfies a given logical specification. To allow genericity of specifications, we study higher-order extensions of the propositional configuration logic. We illustrate with examples the specification of various architecture styles. We provide an experimental evaluation using the Maude rewriting system to implement the decision procedure for configuration logics. Additionally, we study the relation between the architecture composition operator and the composition of configuration logic formulas

Graphs and Graph Transformations for Object-Oriented and Service-Oriented Systems

Theories of graphs and graph transformations form an important part of the mathematical foundations of computing, and have been applied in a wide range of areas from the design and analysis of algorithms to the formalization of various computer systems and programs. In this thesis, we study how graphs and graph transformations can be used to model the static structure and dynamic behavior of object-orientated and service-oriented systems. Our work is mainly motivated by the difficulty in understanding and reasoning about objectorientated and service-oriented programs, which have more sophisticated features compared with traditional procedural programs. We show that the use of graphs and graphs transformations provides both an intuitive visualization and a formal representation of object-orientated and serviceoriented programs with these features, improving people’s understanding of the execution states and behaviors of these programs. We provide a graph-based type system, operational semantics and refinement calculus for an object-oriented language. In this framework, we define class structures and execution states of oo programs as directed and labeled graphs, called class graphs and state graphs, respectively. The type system checks whether a program is well-typed based on its class graph, while the operational semantics defines each step of program execution as a simple graph transformations between state graphs. We show the operational semantics is type-safe in that the execution of a well-typed program does not “go wrong”. Based on the operational semantics, we study the notion of structure refinement of oo programs as graph transformations between their class graphs. We provide a few groups of refinement rules for various purposes such as class expansion and polymorphism elimination and prove their soundness and relative completeness. We also propose a graph-based representation of service-oriented systems specified in a serviceoriented process calculus. In this framework, we define states of service-oriented systems as hier- archical graphs that naturally capture the hierarchical nature of service structures. For this, we exploit a suitable graph algebra and set up a hierarchical graph model, in which graph transformations are studied following the well-known Double-Pushout approach. Based on this model, we provide a graph transformation system with a few sets of graph transformation rules for various purposes such as process copy and process reduction. We prove that the graph transformation system is sound and complete with respect to the reduction semantics of the calculus

Proceedings of the 2nd Int'l Workshop on Enterprise Modelling and Information Systems Architectures - Concepts and Applications (EMISA'07)

The 2nd International Workshop on “Enterprise Modelling and Information Systems Architectures – Concepts and Applications” (EMISA’07) addresses all aspects relevant for enterprise modelling as well as for designing enterprise architectures in general and information systems architectures in particular. It was jointly organized by the GI Special Interest Group on Modelling Business Information Systems (GI-SIG MoBIS) and the GI Special Interest Group on Design Methods for Information Systems (GI-SIG EMISA). -- These proceedings feature a selection of 15 high quality contributions from academia and practice on enterprise architecture models, business processes management, information systems engineering, and other important issues in enterprise modelling and information systems architectures

Formalizing Service Interactions

Cross-organizational business processes are gaining increased attention these days, especially with the service oriented architecture (SOA) as a realization for business process management (BPM). In SOA, interaction agreements between business partners are defined as choreographies containing common interaction patterns. However, complex interactions are difficult to specify, basically because a formal, common standard supporting all interaction patterns is missing. This paper motivates the use of the π-calculus for formally representing service interaction patterns.

M.: Formalizing Service Interactions

Abstract. Cross-organizational business processes are gaining increased attention these days, especially with the service oriented architecture (SOA) as a realization for business process management (BPM). In SOA, interaction agreements between business partners are defined as choreographies containing common interaction patterns. However, complex interactions are difficult to specify, basically because a formal, common standard supporting all interaction patterns is missing. This paper takes the next steps by investigating formal representations of service interaction patterns in π-calculus and Petri nets. Since dynamic routing based on mobility is a central aspect of choreographies we argue that π-calculus is better suited for formalizing service interactions than place/transition and colored Petri nets.