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Förslaget inkom 2007-08-16

An agent-based environment for discovery and composition of simulation components

Master degree thesis opportunity at FOI for one or two master students

*Component-based development*
Utilization of pre-existing components when developing complex software systems is increasingly applied within the software industry. This strategy assures quality and robustness of the systems and has also the potential for reduction of cost related to the development process. Component-based software development has also been a long-term goal within the modelling & simulation (M&S) community to increase reuse and availability of simulation models.

However, composing sub-models in order to build new models raise the non-trivial issue of composability. Composability is the capability to select and assemble reusable simulation components in various combinations into simulation systems to meet user requirements. There are two types of composability, syntactic and semantic. Syntactic composability is concerned with the compatibility of implementation details, such as parameter passing mechanisms, external data accesses, and timing mechanisms. It is the question of whether a set of components can be combined. Semantic composability, on the other hand, is concerned with whether the models that make up the composed simulation system can be composed and remain valid.

The HLA (High Level Architecture) [1] is a standard for distributed simulations often applied within the Defence community. An RTI (Run-Time Infrastructure) implements the HLA standard, providing services to inter-connect distributed simulation components. Simulations based on the HLA are referred to as federations, whereas the individual components of a federation are called federates.

The concept of BOMs (Base Object Models) [3] has been identified within HLA as a potential facilitator for HLA object model construction and providing reusable model components used for the rapid construction and modification of federates and federations. The main objective is to provide a mechanism for facilitating interoperability, reuse, and composability.

The Simulation Reference Markup Language (SRML) is a markup language based on XML that was developed by the World Wide Web Consortium with support from the Boeing company. It is an XML application that can describe the behaviour for distributed simulation models, and its runtime environment is software that is capable of executing those models [2]. The SRML language was developed with a number of goals, among them being a flexible reference standard for representing simulations with enough expressive power to model most anything for the purpose of simulation.

*Web Services*
Web Services (WS) extends the current Web from a distributed source of information to a distributed source of services. According to IBM, Web Services are self-contained, modular applications, accessible via the Web through open standard languages, which provide a set of functionalities to businesses or individuals.
A Web service is a software system identified by a URI, whose public interfaces and bindings are defined and described using XML. Its definition can be discovered by other software systems. These systems may then interact with the Web service in a manner prescribed by its definition, using XML-based messages conveyed by Internet protocols [4].
One of the biggest challenges regarding WS is developing automatic or semi-automatic techniques for discovery and composition of those services. Various techniques and approaches have been presented by different researchers. The main goal of these techniques is to provide automatic ways to discover and reason about combination of services. They often apply software synthesis and composition methods to WS composition, which first of all requires a compiler that is able to translate the web service description language, e.g. WSDL, into formal logic or other formal component description language, a synthesis mechanism which automatically selects, adapts and composes Web S


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