Although networked-based computational environments such as Linda-LAN provide parallel processing capability, performance is still a major concern. One critical factor that can hinder the performance of any parallel processing environment is the high cost of interprocess communication. The goal of this project is to increase the performance of C-Linda programs executed in the Linda-LAN environment. With the current two packet message passing scheme, a receiving process listens for a header packet to arrive on a socket connection. Once the header packet has been received, the process then reads the data packet that follows. Reading the data packet may cause the process to block since the data may not have arrived. By modifying the two packet scheme to use only a single packet, the potential for blocking is removed since the header and data packets are guaranteed to arrive at the same time. Hence, the time spent waiting for the data is nullified, thus producing an increase in performance. / Master of Science

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The aim of this study is to analyze the Django framework in terms of design patterns and architectural principles with emphasis on development of information systems. Based on a comparison of two real systems was identified basic general functionality, the systems commonly support. This analysis helped identify the strengths and weaknesses of the framework. These ensue from the application architecture and from weaknesses of some of its components. Based on these were derived requirements for library expansion and new application components. Problems that have arisen with the solution of the new application components within the specified requirements are theoretically analyzed and described their solutions with emphasis on the application of appropriate design patterns. The solution here appears the Observer design pattern in an environment different processes, access control entries (pessimistic and optimistic locking) and a database schema in an incremental approach to the development of an information system. Implemented components were used to program information system in a team, which demonstrates the overall suitability of this framework for use in the development of information systems.

With the substantial growth of cloud computing over the past decade, microservices has gained significant popularity in the industry as a new architectural pattern. It promises a cloud-native architecture that breaks large applications into a collection of small, independent, and distributed packages. Since microservices-based applications are distributed, one of the key challenges when designing an application is the choice of mechanism by which services communicate with each other. There are several approaches for implementing Interprocess communication (IPC) in microservices, and each comes with different advantages and trade-offs. While theoretical and informal comparison exists between them, this thesis has taken an experimental approach to compare and contrast common forms of IPC communications. In this the- sis, IPC methods have been categorized into Synchronous and Asynchronous categories. The Synchronous type consists of REST API and Google gRPC, while the Asynchronous type is using a message broker known as RabbitMQ. Further, a collection of microservices for an e-commerce scenario has been designed and developed using all the three IPC methods. A load test has been executed against each model to obtain quantitative data related to Performance Efficiency, and Availability of every method. Developing the same set of functionalities using different IPC methods has offered a qualitative data related to Scalability, and Complexity of each IPC model. The evaluation of the experiment indicates that, although there is no universal IPC solution that can be applied in all cases, Asynchronous IPC patterns shall be the preferred option when designing the system. Nevertheless, the findings of this work also suggest there exist scenarios where Synchronous patterns can be more suitable. / Med den kraftiga tillväxten av molntjänster under det senaste decenniet har mikrotjänster fått en betydande popularitet i branschen som ett nytt arkitektoniskt mönster. Det erbjuder en moln-baserad arkitektur som delar stora applikationer i en samling små, oberoende och distribuerade paket. Eftersom microservicebaserade applikationer distribueras och körs på olika maskiner, är en av de viktigaste utmaningarna när man utformar en applikation valet av mekanism med vilken tjänster kommunicerar med varandra. Det finns flera metoder för att implementera Interprocess-kommunikation (IPC) i mikrotjänster och var och en har olika fördelar och nackdelar. Medan det finns teoretisk och in- formell jämförelse mellan dem, har denna avhandling tagit ett experimentellt synsätt för att jämföra och kontrastera vanliga former av IPC-kommunikation. I denna avhandling har IPC-metoder kategoriserats i synkrona och asynkrona kategorier. Den synkrona typen består av REST API och Google gRPC, medan asynkron typ använder en meddelandemäklare känd som RabbitMQ. Dessutom har en samling mikroservice för ett e-handelsscenario utformats och utvecklats med alla de tre olika IPC-metoderna. Ett lasttest har utförts mot var- je modell för att erhålla kvantitativa data relaterade till prestandaeffektivitet, och tillgänglighet för varje metod. Att utveckla samma uppsättning funktionaliteter med olika IPC-metoder har erbjudit en kvalitativ data relaterad till skalbarhet och komplexitet för varje IPC-modell. Utvärderingen av experimentet indikerar att även om det inte finns någon universell IPC-lösning som kan tillämpas i alla fall, ska asynkrona IPC-mönster vara det föredragna alternativet vid utformningen av systemet. Ändå tyder resultaten från detta arbete också på att det finns scenarier där synkrona mönster är mer lämpliga.

The future of computing lies with distributed systems, i.e. a network of workstations controlled by a modern distributed operating system. By supporting load balancing and parallel execution, the overall performance of a distributed system can be improved dramatically. Process migration, the act of moving a running process from a highly loaded machine to a lightly loaded machine, could be used to support load balancing, parallel execution, reliability etc. This thesis identifies the problems past process migration facilities have had and determines the possible differing strategies that can be used to resolve these problems. The result of this analysis has led to a new design philosophy. This philosophy requires the design of a process migration facility and the design of an operating system to be conducted in parallel. Modern distributed operating systems follow the microkernel and client/server paradigms. Applying these design paradigms, in conjunction with the requirements of both process migration and a distributed operating system, results in a system where each resource is controlled by a separate server process. However, a process is a complex resource composed of simple resources such as data structures, an address space and communication state. For this reason, a process migration facility does not directly migrate the resources of a process. Instead, it requests the appropriate servers to transfer the resources. This novel solution yields a modular, high performance facility that is easy to create, debug and maintain. Furthermore, the design easily incorporates providing multiple migration strategies. In order to verify the validity of this design, a process migration facility was developed and tested within RHODOS (ResearcH Oriented Distributed Operating System). RHODOS is a modern microkernel and client/server based distributed operating system. In RHODOS, a process is composed of at least three separate resources: process state - maintained by a process manager, address space - maintained by a memory manager and communication state - maintained by an InterProcess Communication Manager (IPCM). The RHODOS multiple strategy migration manager utilises the services of the process, memory and IPC Managers to migrate the resources of a process. Performance testing of this facility indicates that this design is as fast or better than existing systems which use faster hardware. Furthermore, by studying the results of the performance test ing, the conditions under which a particular strategy should be employed have been identified. This thesis also addresses heterogeneous process migration. The current trend is to have islands of homogeneous workstations amid a sea of heterogeneity. From this situation and the current literature on the topic, heterogeneous process migration can be seen as too inefficient for general use. Instead, only homogeneous workstations should be used for process migration. This implies a need to locate homogeneous workstations. Entities called traders, which store and disseminate knowledge about the resources of several workstations, should be used to provide resource discovery. Resource discovery will enable the detection of homogeneous workstations to which processes can be migrated.

The software that operates mobile and embedded devices, the embedded operating system, has evolved to adapt from the traditional desktop environment, where processing horsepower and energy supply are abundant, to the challenging resource-starved embedded environment. The embedded environment presents the software with some difficult constraints when compared to the typical desktop environment: slower hardware, smaller memory size, and a limited battery life. Different embedded OSs tackle these constraints in different ways. We survey two of the more popular embedded OSs: Linux and Windows CE. To reveal their strengths and weaknesses, we examine and compare each of the OS’s process management and scheduler, interrupt handling, memory management, synchronization mechanisms and interprocess communication, and power management. / text

In this Doktorarbeit the Lattice Boltzmann scheme, a heuristic method for the simulation of flows in complicated boundaries, is investigated. Its theory is renewed by emphasizing the entropy maximization principle, and new means for the modelling of geometries (including moving boundaries) and the visual representation of evoluting flows are presented. An object oriented implemen- tation is given with communication between objects realized by an interpreter object and communication from outside realized via interprocess communica- tion. Within the new theoretical apprach the applicability of existing Lattice Boltzmann schemes to model thermal flows for arbitrary temperatures is reex- amined. / In dieser Doktorarbeit wird das Gitter-Boltzmann-Schema, eine heuristische Methode fuer die Simulation von Stroemungen innerhalb komplexer Raender, untersucht. Die zugrundeliegende Theorie wird unter neuen Gesichtspunkten, insbesondere dem Prinzip der Entropiemaximierung, betrachtet. Des weiteren werden neuartige Methoden fuer die Modellierung der Geometrie (einschl. beweglicher Raender) und der visuellen Darstellung aufgezeigt. Eine objektorientierte Implementierung wird vorgestellt, wobei die Kommunikation zwischen den Objekten über Interpreter-Objekte und die Kommunikation mit der Aussenwelt ueber Interprozess-Kommunikation gehandhabt wird. Mit dem neuen theoretischen Ansatz wird die Gueltigkeit bestehender Gitter-Boltzmann-Schemata fuer die Anwendung auf Stroemungen mit nicht konstanter Temperatur untersucht.

Main goal of this thesis is to create forex automated trading system with possibility to add trading strategies as modules and implementation of trading strategy module based on neural networks. Created trading system is composed of client part for MetaTrader 4 trading platform and server GUI application. Trading strategy modules are implemented as dynamic libraries. Proposed trading strategy uses multilayer neural networks for prediction of direction of 45 minute moving average of close prices in one hour time horizon. Neural networks were able to find relationship between inputs and output and predict drop or growth with success rate higher than 50%. In live demo trading, strategy displayed itself as profitable for currency pair EUR/USD, but it was losing for currency pair GBP/USD. In tests with historical data from year 2014, strategy was profitable for currency pair EUR/USD in case of trading in direction of long-term trend. In case of trading against direction of trend for pair EUR/USD and in case of trading in direction and against direction of trend for pair GBP/USD, strategy was losing.

In this Doktorarbeit the Lattice Boltzmann scheme, a heuristic method for the simulation of flows in complicated boundaries, is investigated. Its theory is renewed by emphasizing the entropy maximization principle, and new means for the modelling of geometries (including moving boundaries) and the visual representation of evoluting flows are presented. An object oriented implemen- tation is given with communication between objects realized by an interpreter object and communication from outside realized via interprocess communica- tion. Within the new theoretical apprach the applicability of existing Lattice Boltzmann schemes to model thermal flows for arbitrary temperatures is reex- amined. / In dieser Doktorarbeit wird das Gitter-Boltzmann-Schema, eine heuristische Methode fuer die Simulation von Stroemungen innerhalb komplexer Raender, untersucht. Die zugrundeliegende Theorie wird unter neuen Gesichtspunkten, insbesondere dem Prinzip der Entropiemaximierung, betrachtet. Des weiteren werden neuartige Methoden fuer die Modellierung der Geometrie (einschl. beweglicher Raender) und der visuellen Darstellung aufgezeigt. Eine objektorientierte Implementierung wird vorgestellt, wobei die Kommunikation zwischen den Objekten über Interpreter-Objekte und die Kommunikation mit der Aussenwelt ueber Interprozess-Kommunikation gehandhabt wird. Mit dem neuen theoretischen Ansatz wird die Gueltigkeit bestehender Gitter-Boltzmann-Schemata fuer die Anwendung auf Stroemungen mit nicht konstanter Temperatur untersucht.