Web services can be broadly classified into two types, namely effect providing (EP) services and data providing (DP) services. In this work, we address DP service composition problem that intends to satisfy user preference specified at the instance level, namely the expected occurrence. We first use the query rewriting method to identify a composition of service types that satisfies user¡¦s requirement and employ Bayesian Network model to express the causal relationship between exchange variables of DP service types. Service selection is then conducted by computing the posterior probability in the Bayesian Network. We conduct experiments to show that our proposed Bayesian Network-based method outperforms the other baseline methods in terms of execution success rate and data quality. It also has reasonable execution time.

This thesis, studies automated methods to achieve web service advertisement and discovery, and presents efficient search and matching techniques based on OWL-S. In the proposed system, the service discovery and matchmaking is performed via a centralized peer-to-peer web service repository. The repository has the ability to run on a software cloud, which improves the availability and scalability of the service discovery. The service advertisement is done semi-automatically on the client side, with an automatic WSDL to OWL-S conversion, and manual service description annotation. An OWL-S based unified ontology -Suggested Upper Merged Ontology- is used during annotation, to enhance semantic matching abilities of the system. The service advertisement and availability are continuously monitored on the client side to improve the accuracy of the query results. User-agents generate query specification using the system ontology, to provide semantic unification between the client and the system during service discovery. Query matching is performed via complex Hilbert Spaces composed of conceptual planes and categorical similarities for each web service. User preferences following the service queries are monitored and used to improve the service match scores in the long run.

A semantic model oriented transformation mechanism is developed for the centralization of intra-enterprise data integration. Such a mechanism is especially crucial in the banking domain which is selected in this study. A new domain ontology is constructed to provide basis for annotations. A bottom-up approach is preferred for semantic annotations to utilize existing web service definitions. Transformations between syntactic web service XML responses and semantic model concepts are defined in transformation files. Transformation files are stored and executed in a separate central transformation repository to enhance abstraction and reusability. An RDF-Store is implemented to store transformed RDF data. Inference power of semantic model is exposed by executing semantic queries in the RDF-Store.

This research combines the methodology proposed in Axiomatic Design Theory (ADT) with a service oriented decomposition approach for systematic development of Service Oriented Architecture compliant systems. A previous study had applied ADT to component oriented development where simultaneous specification and decomposition of models related to requirements, design, product domain, and components were supported. Recently, Web services have gained popularity and they became a more desired alternative to components. This research sets the foundation for service-oriented modeling and development with ADT support through enhancing the component oriented work conducted before. The goal is to be able to consider customer needs viewed in the domain context, together with the requirements and design so that efficient development can take place based on existing Web services. The system under development is viewed as a hierarchy of process models where leaf-level processes correspond to Web services.

The recent development of the service-oriented architecture (SOA) has provided an opportunity to apply this new technology to support model management. This is particularly critical when more and more decision models are delivered as web services. A web-services-based approach to model management is useful in providing effective decision support. When a decision model is implemented as a web service, it is called a model-based web service. In model management, selecting a proper model-based web service is an important issue. Most current research on selecting such web service relies on matching inputs and outputs of the model, which is oversimplified. The incorporation of more semantic knowledge may be necessary to make the selection of model-based web services more effective. In this research, we propose a new mechanism that represents the semantics associated with a problem and then use the similarity of semantic information between a new problem description and existing web services to find the most suitable web services for solving the new problem. The paper defines the concept of entity similarity, attribute similarity, and functional similarity for problem matching. The web service that has the highest similarity is chosen as a base for constructing the new web services. The identified mapping is converted into BPEL4WS codes for utilizing the web services. To verify the feasibility of the proposed method, a prototype system has been implemented in JAVA.

<p>Arbetet har gjorts åt Saab Security Systems i Växjö. Syftet med arbetet har varit att ta fram ett generellt distribuerat informationssystem som ska användas för informationsspridning på en flygplats. Från Saabs sida är målet med att införa ett nytt informationssystem att få en generell standard för hur informationsspridning ska gå till. På det nya informationssystemet ställs krav på flexibilitet, att det ska vara utbyggningsbart, att det ska finnas möjlighet att ansluta nya aktörer samt att det ska vara en tjänstebaserad arkitektur. Den övergripande frågställningen för arbetet har varit som följer.</p><p>Kan tjänstabaserad arkitektur vara en lösning för hur information kan överföras på ett säkert sätt mellan flygklubbarna och flygledartornet?</p><p>Under arbetets gång har en teoretisk studie gjorts där fem olika mellanprogram jämförts utifrån transport av information, tjänstebeskrivning, tjänsteregistrering och upptäckt samt säkerhet. Jämförelsen hade fokus på flexibilitet och visade att Jini, CORBA och Web Services var de bästa lösningarna. Dessa tre mellanprogram jämfördes sedan ur ett säkerhetsperspektiv.</p><p>Det som studerades var vilka lösningar som finns för integritet, attestering och verifiering. Dessutom testades hur kommunikation med de tre olika mellanprogrammen fungerar genom en brandvägg.</p><p>Efter den teoretiska genomgången samt testerna med brandväggen så valdes Web Services för den implementation som skulle utföras. Jag valde Web Services eftersom det var det mellanprogram som fungerade bäst vid kommunikation genom en brandvägg.</p><p>Implementationen som utförts inom ramarna för examensarbetet är en applikation för att möjliggöra för flygklubbar att boka tid för start vid Göteborg City Airport och skulle visa på konceptet för informationssystemet och den säkerhet som behövs.</p><p>Arbetet med olika tjänstebaserade lösningar visar att detta sätt att bygga ett informationssystem för flygplatsen lämpar sig väl. Flexibilitet vad gäller möjligheten att koppla upp sig mot systemet från olika plattformar krävs då det finns många aktörer och detta är SOA en lösning på. Det är även en viktig aspekt att det finns möjlighet för de säkerhetslösningar som anses nödvändiga.</p><p>Testningen av systemet visade att dessa säkerhetslösningar fungerade för implementationen av tidsbokningstjänsten.</p>

Interoperability between heterogeneous software systems is an important issue to increase software reusability in the software industry. Many methods are proposed to implement interoperable systems using distributed computing infrastructures such as CORBA, HLA and SOA. Those infrastructures can provide communication channels between software systems with heterogeneous environments. SOA (Service Oriented Architecture) provides a more flexible approach to interoperability than do the others because it provides platform independence and employs platform-neutral message passing with Simple Object Access Protocol (SOAP) to communicate between a service and a client.The main contribution of this study is to design and implement an interoperable DEVS simulation environment using the SOA concept and a new construct called the DEVS namespace. The interoperable DEVS environment consists of a DEVS simulator service and an associated integrator. The DEVS simulator service provides both simulator level and model level interoperability. Moreover, using the DEVS namespace, DEVS simulator services can be interoperable with any services using the same message types.To demonstrate the utility of the proposed environment, we describe various applications of the interoperable DEVS simulation environment. The applications are drawn from real world development of automated testing environments for military information system interoperability. A radar track generation and display federation and a model negotiation web service illustrated the ability of the proposed middleware to work across platforms and languages. Its ability to support higher level semantic interoperability will be demonstrated in a testing service that can deploy model agents to provide coordinated observation of web requests of participants in simulated distributed scenarios.

Grids are collaborative distributed Internet systems characterized by large scale, heterogeneity, lack of central control, multiple autonomous administrative domains, unreliable components and frequent dynamic change. In such systems, it is desirable to maintain and query dynamic and timely information about active participants such as services, resources and user communities. The web services vision promises that programs are made more flexible, adaptive and powerful by querying Internet databases (registries) at runtime in order to discover information and network attached building blocks, enabling the assembly of distributed higher-level components. In support of this vision, we introduce the Web Service Discovery Architecture (WSDA), we introduce the hyper registry, which is a centralized database node for discovery of dynamic distributed content. It supports XQueries over a tuple set from a dynamic XML data model.

Paskutiniu metu duomenų centrai teikia skirtingas tinklo, informacijos talpinimo, terminalinių serverių ir kitas paslaugas. Paslaugų kokybė priklauso ne tik nuo specifikuojamų SLA parametrų, bet ir nuo vartotojo poreikių. Taigi buvo sudaryta duomenų centrų paslaugų įvertinimo metodika, skirta palyginti paslaugų kokybę tiek vartotojams, tiek ir paslaugų teikėjams. Siūloma taikyti serverių bei tinklo sujungimų rezervacijas, norint užtikrinti aukštą paslaugų pateikiamumą. Dvi populiariausios duomenų centrų paslaugos buvo ištirtos: „thin-client“ (terminalinių serverių) architektūra, ir Web paslaugos. Web paslaugos kokybės įvertinimo bandymai buvo atlikti, norint parodyti, kad WRT kokybės parametras yra labiau informatyvus nei įprasti duomenų perdavimo tinklo parametrai. „Thin-client“ architektūros analizė parodė, kad ji gali būti naudojama LAN ir WAN tinkluose, ir gali būti labai ekonomiškai naudinga. Tinklo ir serverių resursų stebėjimas turi būti vykdomas, norint teikti aukštos kokybės paslaugas - taigi duomenų centrų paslaugų teikėjai privalo naudoti reikiamą aparatūrinę ir programinę įrangą periodiškiems matavimams atlikti, bei saugoti ir apdoroti gautus rezultatus. / Nowadays datacenters provide different network, hosting, terminal desktop and other services, and it has become very important to be able to evaluate the quality of these services. SLA (Service Level Agreement) metrics define the quality of service, but it also depends on the needs of the particular user. So the evaluation methodology was created in order to compare the quality of services, both: for the user, and for the datacenter service provider. A service provider has to implement the server architecture with network connection and server redundancy in order to assure high service availability. Two most popular datacenter services were analyzed: “thin-client” architecture and web services. The web service quality evaluation experiments have been made to show that web oriented performance metric "Web Response Time" (WRT) is more informative for web service quality assurance, comparing to the traditional latency and loss metrics in the network environment. “Thin-client” architecture analysis show that it can be used both in LAN and WAN networks, and it can be economically useful to outsource IT systems to datacenters by using this technology. Network and server resource performance monitoring has to be done in order to supply high quality services - so datacenter service providers have to use monitoring hardware and software to make periodical measurements and collect, store and process the results.

As the use of Web expands, Web Service is gradually becoming the basic system infrastructure. However, as it matures and a large number of Web Service becomes available, the focus will shift from service development to service management. One key component in management systems is monitoring. The growing complexity of Web Service platforms and their dynamically varying workloads make manually monitoring them a demanding task. Therefore monitoring tools are required to support the management efforts. Our approach, Web Service Monitoring System (WSMS), utilizes Autonomic Computing technology to monitor Web Service for an automated manager. WSMS correlates lower level events into a meaningful diagnosed symptom which provides higher level information for problem determination. It also gains the ability to take autonomic actions and solve the original problem using corrective actions. In this thesis, a complete design of WSMS is presented along with a practical implementation showing viability and proof of concept of WSMS. / Thesis (Master, Computing) -- Queen's University, 2008-11-12 16:20:13.738