This thesis presents a framework design and implementation that enables run-time selection of different remote call mechanisms. In order to implement an extendable and modular system with run-time upgrading facility, a plug-in framework design is used. Since such a design requires enhanced usage of run-time facilities of the programming language that is used to implement the framework, in this study Java is selected because of its reflection and dynamic class loading facilities. A sample usage of this framework is enabling an application to distribute its tasks over a network using a suitable distributed object technology (DOT). In this work, CORBA, RMI and Java Sockets are the sample DOT plug-ins. A series of performance evaluations of these DOTs are presented to establish a baseline for choosing a suitable DOT for the application domain that uses this framework.

Data Distribution Service (DDS) specification defines an API for Data-Centric Publish-Subscribe (DCPS) model to achieve efficient data distribution in distributed computing environments. Lack of definition of interoperability architecture in DDS specification obstructs data distribution between different and heterogeneous DDS implementations. In this thesis, DDS is implemented as a CORBA service to achieve interoperability and a QoS policy is proposed for faster data distribution with CORBA features.

<p>This work address the adding, removing and upgrading of network elements in a computer network at run-time. This is already accomplished by Sun Microsystems Jini architecture, but we have investigated if it is possible to create a maintenance system that can handle this, using CORBA. We also want the manual intervention to be minimal. We have discovered that it is possible to create such a system, using CORBA, and that this solution also can handle upgrading a network element at run-time. This report outlines the design of this system, realizing automatic run-time network maintenance.</p>

<p>Development of distributed real-time applications, in contrast to best effort applications, traditionally have been a slow process due to the lack of available standards, and the fact that no commercial off the shelf (COTS) distributed object computing (DOC) middleware supporting real-time requirements have been available to use, in order to speed up the development process without sacrificing any quality.</p><p>Standards and DOC middlewares are now emerging that are addressing key requirements of real-time systems, predictability and efficiency, and therefore, new possibilities such as component decomposition of real-time systems arises.</p><p>A number of component decomposed architectures of the distributed active real-time database system DeeDS is described and discussed, along with a discussion on the most suitable DOC middleware. DeeDS is suitable for this project since it supports hard real-time requirements and is distributed. The DOC middlewares that are addressed in this project are OMG's Real-Time CORBA, Sun's Enterprise JavaBeans, and Microsoft's COM/DCOM. The discussion to determine the most suitable DOC middleware focuses on real-time requirements, platform support, and whether implementations of these middlewares are available.</p>

<p>The business pressures which companies and organisations encounter are steadily growing. They continuously have to improve their efficiency to keep up with these new developments. One very important aspect in doing so is the reinforced adoption of computer based information systems. This paper focuses on a computer based system which is able to automate everyday business communication between distributed team members.</p><p>Reliable and confidential message delivery, event notification, the integration of different end devices (mobile phones, PCs etc.) and the message transport across different networks (wireless, wired) have been allocated as the main system requirements. Based on these requirements the performance of two middleware technologies, namely CORBA and Web services, has been compared. The result of this comparison was that both technologies are suited to use for implementing such a system but both too, have strengths and weaknesses in achieving the stated requirements.</p><p>CORBA for example, due to several supporting, already included services, allows the programmer to concentrate on the application development itself and use these services to ensure reliable and confidential message transmission. Additionally, CORBA is very efficient in using the bandwidth of the underlying communication network, but makes higher demands to the memory space available on clients. This is critical, if clients are mobile devices with limited resources.</p><p>Web service technology is much more modest than CORBA with respect to the client side memory space, but message transmission requires much more bandwidth. Further one there are no built-in security and reliability services available for Web services, like there are for CORBA. Hence it is up the application programmer to manually implement these features; however he has not necessarily develop everything from scratch but can resort to already existing specifications, still having the freedom of developing specially tailored features.</p><p>In short could be stated that CORBA is more consequential and consistent and WS technology is more adjustable and flexible.</p>

<p>The Swedish field of digital X-ray imaging has since several years relied heavily on distributed information systems and digital storage containers. </p><p>To ensure accurate and safe radiological reporting, Swedish software-firm eCare AB delivers a system called Feedback—the first and only quality assurance IT support product of its kind. This thesis covers several aspects of the design and implementation of future versions of this software platform. </p><p>The focus lies on distributed directory services and models for secure and robust data propagation in TCP/IP networks. For data propagation, a new application, InfoBroker, has been designed and implemented to facilitate integration between Feedback and other medical IT support systems. The directory services, introduced in this thesis as the Feedback Directory Services, have been designed on the architectural level. A combination of CORBA and Java Enterprise Edition is suggested as the implementation platform.</p>

<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>

<p>The aim of this work is to design an experiment, where client-server systems can be compared. They belong to the group of systems that are called component systems. Client-server systems are difficult to compare, because they are complex. The client-server systems are documented in different ways. Notations in the implementation of them are in different ways. There is a large difference in the communication between the client and server. The architectures between the client-server systems differ also, but they are not totally different. Therefore it is possible to construct an experiment for comparing them. Client-server systems that will be compared are Java RMI, Web Services, CORBA, and Enterprise JavaBeans. We are going to use Java as the programming language. Some of these systems, for example CORBA, can be implemented in other languages. The designed experiment is among other things going to answer how long time is needed to implement a specific application, how fast a specific client-server system is, and how long time is spent for learning about a specific system.</p>

Die Common Object Request Broker Architecture (CORBA) der Object Management Group (OMG) bietet die Chance, nicht nur eine Plattform fuer neue verteilte Anwendungen zu sein, sondern erlaubt es auch, bestehende Anwendungen und Altsoftware hersteller- und systemuebergreifend zu integrieren. Diese Eigenschaft hebt CORBA von anderen Programmierplattformen ab und gibt CORBA das Potential, eine aussichtsreiche Basis fuer kuenftige Anwendungssysteme zu sein. Das Ziel dieser Studienarbeit besteht darin, die Umsetzbarkeit verschiedener Interaktionsarten in CORBA zu untersuchen und an Beispielen praktisch auszuprobieren. Moegliche Ablaufformen aus der Literatur, aus den Systemen DCE und MPI und anhand eigener Ueberlegungen werden im ersten Teil dieser Arbeit systematisch zusammengefasst. Danach folgt eine ausfuerliche Behandlung der Architektur von CORBA und der hier moeglichen Ablaufformen und Interaktionsszenarien. Abschliessend werden acht verschiedene Versionen eines einfachen verteilten Woerterbuches vorgestellt, um einige der in CORBA realisierten Konzepte am praktischen Beispiel zu verdeutlichen. Als CORBA-Plattform stand Orbix-MT 2.0.1 (multi-threaded) der Firma IONA Technologies Ltd. unter Solaris 2.x zur Verfuegung.

Schaffung einer stabilen, erweiterbaren und skalierbaren Infrastruktur für die Bereitstellung von Diensten im Umfeld von Bibliotheken und ähnlichen wissensanbietenden Einrichtungen unter Verwendung von XML-RPC und Python.