Session types and contracts are two formalisms used to study clientserver protocols. In this paper we study the relationship between them. The main result is the existence of a fully abstract model of session types; this model is based on a natural interpretation of these types into a subset of contracts.

Abstract. Session types are used to describe and structure interactions between independent processes in distributed systems. Higher-order types are needed in order to properly structure delegation of responsibility between processes. In this paper we show that higher-order web-service contracts can be used to provide a fully-abstract model of recursive higher-order session types. The model is set-theoretic, in the sense that the meaning of a contract is given in terms of the set of contracts with which it complies. A crucial step in the proof of full-abstraction is showing that every contract has at least one other contract with which it complies.

Abstract. Session types are a type formalism used to describe communication protocols over private session channels. Each participant in a binary session owns one endpoint of a session channel. A key notion is that of duality: the endpoints of a session channel should have dual session types in order to guarantee communication safety. Duality relations have been independently defined in different ways and different works, without considering their effect on the type system. In this paper we systematically study the existing duality relations and some new ones, and compare them in order to understand their expressiveness. The outcome is that those relations are split into two groups, one related to the naïve inductive duality, and the other related to a notion of mutual compliance, which we borrow from the literature on contracts for web-services.

Purpose -The aim of this study is to investigate both the path taken by companies in order to survive in a competitive environment and the factors that have favoured or limited their development. Design/methodology/approach -The study was carried out using a retrospective approach. Empirical evidence was gathered using a descriptive survey and data collected during previous research programs involving 100 SMEs located in the Veneto region (Italy). Findings -The findings show that a lack of organizational capabilities is one of the main factors limiting development in SMEs. The companies investigated appear to follow similar paths and performance measurement systems (PMS) could play a key role as a potential driver of managerial development in SMEs.Research limitations/implications -The study refers solely to Italian SMEs located in the Veneto region. Conclusions on the role played by PMS as a system for supporting development were based on a theoretical study; an ad hoc empirical study would be useful for further investigation of this topic. Practical implications -The study emphasizes the important role played by organizational capability for favouring the competitiveness and survival of SMEs. The study indicated that in SMEs managerial developments usually come later, following changes in strategy. Firms could prevent managerial crisis by implementing managerial systems. Originality/value -Traditionally the growth of SMEs is measured by turnover and number of employees. This study highlights the importance of investigating not only quantitative, but also qualitative growth to analyse development in SMEs. PMS is presented as a key managerial system that can support qualitative growth and promote the competitiveness of SMEs.

Web services are one of the most widely used technologies for service oriented computing. In particular, they support client-server protocols whose specifications are written in XML languages as such as WSCL or WSDL. Notwithstanding the wide adoption of web services, it is not yet clear which formalism should be used to reason about the protocols they support. Session types and contracts are two formalisms used to study client-server protocols, both promoted as good formal methods for web services. In this paper we study the relationship between contracts and session types. The main result is the existence of a fully abstract model of session types; this model is based on a natural interpretation of these types into a subset of contracts.

Abstract. In the standard testing theory of DeNicola-Hennessy one process is considered to be a refinement of another if every test guaranteed by the former is also guaranteed by the latter. In the domain of web services this has been recast, with processes viewed as servers and tests as clients. In this way the standard refinement preorder between servers is determined by their ability to satisfy clients.But in this setting there is also a natural refinement preorder between clients, determined by their ability to be satisfied by servers. In more general settings where there is no distinction between clients and servers, but all processes are peers, there is a further refinement preorder based on the mutual satisfaction of peers.We give a uniform account of these three preorders. In particular we give two characterisations. The first is behavioural, in terms of traces and ready sets. The second, for finite processes, is equational.

No abstract

PurposeLiterature and practice highlight the need to stimulate processes of qualitative growth in SMEs. The aim of the research presented in this paper is to identify a type of benchmarking and a benchmarking tool which can support the qualitative growth of these companies.Design/methodology/approachDuring the study, literature review and empirical research had been carried out and further information was gathered by means of workshops and interviews to experts. Finally, the achieved results were tested on a sample of eight Italian SMEs.FindingsApproaches to benchmarking were reviewed and classified; synthetic benchmarking based on managerial practices was chosen as the most appropriate approach to stimulate improvement and qualitative growth in SMEs; moreover a tool for synthetic benchmarking on managerial practices tool was developed.Practical implicationsThe research has practical implication; it provides SMEs with adequate tool and methodology able to support the development of management system. The tool is able to allow SMEs to learn best managerial practices, assess itself with respect to these practices and at the same time understand what must be done to carry out improvement.Originality/valueThe developed tool has a general validity, it does not consider particular situation, but if some codified practices are not applicable to a specific company, it is possible to rule out these practices without compromising the effectives of the tool.