Mario Zagar

Ten tips to succeed in global software engineering education

The most effective setting for training in Global Software Engineering is to provide a distributed environment for students. In such an environment, students will meet challenges in recognizing problems first-hand. Teaching in a distributed environment is, however, very demanding, challenging and unpredictable compared to teaching in a local environment. Based on nine years of experience, in this paper we present the most important issues that should be taken into consideration to increase the probability of success in teaching a Global Software Engineering course.

Frequency domain analysis of B-spline interpolation

This paper describes B-spline interpolation and compares it with other reconstruction methods, especially in three-dimensional space. We first consider the B-spline bases in the terms of convolution in signal processing. The presented analysis requires careful usage of continuous and discrete representation of B-spline. Emphasis is given to the important difference between B-spline interpolation and approximation. The difference is shown through frequency domain analysis, so we derive frequency responses of the B-spline interpolation and approximation. We conclude by demonstrating the use of several reconstruction filters and appropriate gradient estimators in volume rendering. Exact reconstruction in volume visualization is very important in many industrial applications, such as material cavity control.

Network distributed file system in user space

File systems have traditionally been implemented in the operating systems kernel to ensure maximum possible speed and integration with the rest of the operating system, and this was true even for network file systems such as NFS. However, available CPU power on mainstream architectures continues to increase daily at a rate which is not closely followed by speed of computer network equipment. When considering development of network-distributed file systems today it becomes clear that speed improvements offered by pure kernel-side implementations are no longer significant given the bandwidth and latencies of computer networks. Recent efforts in enabling user-space file system implementations on free/open source Unix-like operating systems have made it possible to create a solution for distributing file system data over computer networks entirely in user-space. In this work we present such a solution

Rethinking Model Driven Development: analysis and opportunities

the trivially distributed file system

Internet of things cloud mediator platform

Application modeling is gaining its share as the next generation software development methodology. Model Driven Development (MDD) uses abstract models of software systems to yield concrete implementations. This process can be achieved in two fundamentally different ways: by generating end artifacts, or by applying model interpretation. Regardless of approach used, MDD still needs to surpass certain challenges to gain further appreciation among community. This paper classifies those challenges and proposes use of different methodologies which could enable simpler modeling solutions. Object Process Methodology (OPM) as software modeling tool is an adequate candidate yielding results in that direction.

A high performance memory database for web application caches

Internet of things (IoT) will connect a huge amount of devices to the Internet. There will also be many applications that will use the generated data to provide a service to end-user. This presents a problem in situations when the application owner is not the device owner. Application owner needs to find and contact the owners of the devices that provide the data he needs. When done by a human, this process lasts a long time and costs a lot of money. In this paper, we propose a middleware architecture that connects the appropriate devices and applications. It is based on software agents representing devices and applications negotiating between each other on the terms by which the data can be used.

Web-enabling cache daemon for complex data

This paper presents the architecture and characteristics of a memory database intended to be used as a cache engine for web applications. Primary goals of this database are speed and efficiency while running on SMP systems with several CPU cores (four and more). A secondary goal is the support for simple metadata structures associated with cached data that can aid in efficient use of the cache. Due to these goals, some data structures and algorithms normally associated with this field of computing needed to be adapted to the new environment.

Data marketplace for Internet of Things

One of the most common basic techniques for improving the performance of web applications is caching frequently accessed data in fast data stores, colloquially known as cache daemons. In this paper we present a cache daemon suitable for storing complex data while maintaining fine-grained control over data storage, retrieval and expiry. Data manipulation in this cache daemon is performed via standard SQL statements so we call it SQLcached. It is a practical, usable solution already implemented in several large Web sites.

Characteristics of multithreading models for high-performance IO driven network applications

The data generated by Internet of Things (IoT) devices is mostly owned by device owners and is often private in nature. There are however third parties that could benefit from using that data, and the challenge is in allowing them to access it under the conditions that data owners find acceptable. An opportunity presents itself to create a marketplace where device owners could sell that data and data consumers could buy it. Some properties of IoT data make it difficult to trade in traditional data markets. We hypothesise that it is possible to develop an efficient algorithm that responds to data consumers queries in a way that its budget constraints are respected and that device owners are compensated for the data they provide. In this paper we create a model of such a market, analyse its query performance, expected earnings of device owners and utility achieved by data consumers and conclude that data markets in IoT are a viable method of distributing generated measurements.

A hierarchical file system interface to datyabase-based content management application

In a technological landscape that is quickly moving toward dense multi-CPU and multi-core computer systems, where using multithreading is an increasingly popular application design decision, it is important to choose a proper model for distributing tasks across multiple threads that will result in the best efficiency for the application and the system as a whole. The work described in this paper creates, implements and evaluates various models of distributing tasks to CPU threads and investigates their characteristics for use in modern high-performance network servers. The results presented here comprise a roadmap of models for building multithreaded server applications for modern server hardware and Unix-like operating systems.