The advancement in ubiquitous computing requires more effort to cope with contextual changes in the environment and to adapt to these changes in regular and efficient ways. A context model and context-awareness are proposed to provide a model of the contextual information and to describe its impact on individual behaviour of system’s components and on rules and relationships which control their interactions. This paper extends the Web service migration framework which provides software support for services migrating between potential service providers in service-oriented architecture according to the contextual changes. The extension utilises ontology-based context modelling in OWL/RDF and reasoning by means Jena reasoners and rules to make necessary migration decisions.

All customers today seek easy access to a wide range of information of products and services, which are in particular available online. It is therefore especially important that an enterprise can establish relationships with consumers at each stage of their life cycle, also in the virtual space. The available computer systems must be used more widely by the company management for the purpose of improving the customer service. This study aims to present the state-of-the-art online tools which, if appropriately selected and used, enable to build relations with customers and to manage them.

Nowadays, companies have to handle large amounts of data every day (e.g. employee data, reports, statements). These data are usually unstructured or semi-structured; they do not have a consistent format, since they come from various sources. As a solution, the Semantic Web provides a common data format, which helps integrate the heterogeneous data. In the industry, in order to be efficient and to remain competitive, it is crucial to have quick, easy, and reliable access to your data from anywhere. In this paper, we introduce a client-server system, which enables browsing of semantic data with smartphones and tablets running Android operating system. The users can access their data using predefined views. These views determine which parts of the data a user can see, and how to present them in the client application. Each user can have different access privileges to different views, so each employee can have a level of access suitable to his status.

We built formal definition of the NoSQL document-oriented data model. Two formal data models were built. The first data model is based on sets and second one is based on multisets (bags). The special relations called subdocument and subrecord were introduced. It is proven that those relations are preorder. Also general results about the cofinal relation on the sets are given.

More and more companies decide to deploy their new or existing applications at cloud computing providers. A few of the most important forces driving this process are the scalability, business agility and mobility offered by the cloud environments. A number of issues, however, tend to inhibit the adoption of cloud based systems, e.g. security, compliance, vendor lock-in, or inconsistent performance. This paper focuses on the performance questions of a web application implemented on Java platform, deployed at the servers of Amazon Web Services, which is considered one of the dominant cloud providers currently. We present the results of a load testing that investigates the throughput and response time of the application on two different types of instances (Micro and Small) with different computing power and price. We quantify the effect on the user-perceived performance when choosing either of these instance types.

We describe new approach for algorithmization of the chain-like structures’ dynamics. The main underlying idea of our approach is the sequentialization of the moves. The resulting algorithm enables efficient sampling of vast state spaces related to considered phenomena. In our simulation experiments the algorithm appeared to be much faster than other algorithms known from literature. Therefore it enables researchers to study complex models of such systems as biomolecules or artificial polymers. In this paper we perform simulation study of interrelations between various parameters specifying different movement characteristics. Also the impact of these parameters on the time taken to cover a given distance along a given trajectory in the motion space is analyzed.

It is often useful to expose an Application Programming Interface (API) as a scripting language when developing complex applications, especially when many teams are working on the same product. This allows for a solid separation of concerns and enables rapid development using the scripting language. However, to expose an API might involve huge amount of effort and a common problem with these scripting languages is their type-unsafe nature which can easily result in issues that are hard to debug. Our solution is to generate an interpreter from a functional API utilizing C++ meta-programming techniques. The generated script language is type safe. Using our libraries it takes minimal effort to generate an interpreter from such an API. We also present a case study with a widely used EDSL. This method also turned out to be a more general solution to several other problems, including providing type-safe auto-completion support for the interpreted language or implementing a plug-in system that enables fast prototyping while remaining type-safe.

Detection of the statically linked code is one of the important steps in a process of decompilation. It restricts a code, which can be skipped by the decompiler. Type annotations provide an additional information about the number, types, and suitable names for arguments and return values of recognized functions in recognized statically linked code. This is important for generation of calls for these functions. The detection is based on the generic signatures, which are created from the static libraries. The signatures are composed of the first bytes of library modules, CRC codes, module sizes, public symbols, and optionally tail bits or references. A tree structure of signature improves performance by decreasing a count of compared bytes. Generic approach of detection is achieved by an usage of a common object file format. The process is not restricted on specific architecture or file format. However, there are situations when a conflict in the detection can be resolved only by an analysis in the decompiler. Impact of signature usage is verified by the tests with the decompiler.

In software development testing plays the most important role to discover bugs and to verify that the product meets its requirements. This paper focuses on programs written in C++ programming language and analyses two important testing methods, the Decision Coverage and the more strict Modified Condition / Decision Coverage. We examine how the program characteristics – lines of code, McCabe metric, the number of the arguments in the decisions, deepness of the nested block – affect the number of necessary test cases of these testing methods. Choosing test methods is always a compromise between the code correctness and the available resources. Less strict ones require fewer test cases and consume less resources, however, they may discover fewer errors. Our results may help to chose between Decision Coverage and Modified Condition / Decision coverage.

Reference types are very useful structures enabling handling with dynamic memory. In this paper we extend categorical model of type system with reference data type. We illustrate our approach on simple functional programming language T-NBL extended with reference type. After constructing parametric algebraic specification we construct categorical model of reference type and we show how our results can be implemented in functional programming language Ocaml.

The main object of research in this paper is extension of Floyd-Hoare logic on partial pre- and postconditions. Compositionnominative approach is used to define this extension. According to this approach semantics of extended logic is represented by algebras of partial quasiary mappings. Operations of these algebras are called compositions. Semantics of Floyd-Hoare triples (assertions) is formalized with the help of a special monotone composition. Preimage predicate transformer composition – a counterpart of the weakest precondition – is also defined. Sound modifications of inference systems with added constraints are presented. Properties of extensional and intensional completeness of such inference systems are studied.

There is a common task in web applications when the content of a database table or the result of a query has to be listed on the client side. In traditional implementation the requested amount of data needed for the page is queried and created on the server and is sent to the client. Then, at every interaction a new http request is sent to the server and the database layer generates a new data set to be displayed. Modern web applications can rely on the higher computing power of the client computers. Therefore state-of-the-art applications can transfer more data to the client where data are handled in an array and frontend Javascript executes filtering, sorting, and paging. This approach saves server capacities and omits the network communication lag; at the same time the user interface becomes faster and more responsive. A backend-frontend solution would be useful that distributes the computational tasks according to the available resources on the client side. As the data processing capability is not universal to all clients, benchmark logic has to be applied to adjust client specific data limit.

A GI=M=1-type queueing system with finite buffer capacity and AQM-type packet dropping is investigated. Even when the buffer is not saturated an incoming packet can be dropped (lost) with probability dependent on the instanteneous queue size. The system of integral equations for time-dependent queue-size distribution conditioned by the number of packets present in the system initially is built using the embedded Markov chain approach. The solution of the corresponding system written for Laplace transforms is found using the linear algebra. Numerical examples, in which different-type dropping functions are investigated in some network-motivated traffic scenarios, are attached as well.