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Triple Space Computing (TSC) has been proposed as communication and coordination paradigm based on the convergence of spacebased computing and the Semantic Web. It acts as a global virtual shared space like middleware to enable communication and coordination of semantic data based on the principle of publish and read. This paper presents an overview of the work in progress under Austrian FIT-IT funded TSC project (http:==tsc.deri.at). It presents the evolution of the TSC framework, overall architecture and its usage by Semantic Web Services.

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For constantly changing businesses, it is essential that the underlying software architecture is capable of managing agile business processes and meeting future business needs. Decoupling between applications and services in distributed systems is addressed by e.g., service-oriented architectures. On the other hand, applications and its underlying middleware are still tightly coupled with respect to the middleware's architectural style. As a result of the tight coupling middleware adaptations introduced due to e.g., new business requirements can affect the application as well. In this paper we propose the concept of space-based architecture (SBA), that allows decoupling distributed applications with respect to the underlying middleware architecture by combining the characteristics and properties of state-of-the-art middleware architectural styles captured in a simple API. The benefit of our approach is minimal application adaptations in case of changing the underlying middleware architectural style, which allows for more efficient realization of new business requirements.

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Space-based computing middleware offers a data driven style for the coordination of processes. The interaction requirements between these processes can be complex, and the template matching coordination law of the Linda and JavaSpaces model is not sufficient. Moreover, the usage should not be limited to a single platform. Several authors have proposed coordination extensions, but besides the suggestion to use XML or RDF based query facilities, a formalization of a general and extensible space-based coordination model has not yet been realized. In this paper we present the algebraic data structures and the coordination model based on a navigational query language for the extensible virtual shared memory architecture, and show how they can be adapted to support arbitrary coordination laws by the introduction of user-definable matchmaker and selector functions. The platform independence is achieved through a language independent communication protocol. The formal specification of the data model is the necessary basis for this protocol.

Usability is an important quality attribute for APIs. To create APIs with good usability, appropriate measurement methods are needed. But currently available methods are cost-and time-expensive and the results are not objective and therefore hard to quantify. API design guidelines give a good overview about important usability factors, but lack a scientific basis. When looking at scientific API usability studies, only a very small area of API design has been researched yet. Existing results don't give enough basis for a good API usability measurement method.In this paper we identify influencing usability factors for the two most common concepts of APIs: classes and methods. We therefore conduct a study with 20 programmers and 2 different API variants and evaluate how differences between the APIs influence usability when instantiating classes and calling methods. The results build a basis for API usability measurement methods and should help design more usable APIs.

Semantic technologies promise to solve challenging problems of current enterprise information systems, e.g., the integration of heterogeneous information clients and the evaluation of complex data dependencies. As many of these problems also apply to coordination applications, recent research initiatives have proposed to integrate coordination models with semantic technology. In this paper, we present such an integrated coordination model which combines logic-based reasoning with a reliable semantic subscription mechanism. We present a formal definition of the model's behavioral semantics and investigate the added value of using semantic technologies. Finally, we draw first conclusions about the practical applicability of the proposed approach based on performance benchmarks of a prototype implementation.