Both expert and novice software developers frequently access software development resources available on the Web in order to lookup or learn new APIs, tools and techniques. Software quality is affected negatively when developers fail to find high-quality information relevant to their problem. While there is a substantial amount of freely available resources that can be accessed online, some of the available resources contain information that suffers from error proneness, copyright infringement, security concerns, and incompatible versions. Use of such toxic information can have a strong negative effect on developer’s efficacy. This dissertation focuses specifically on software tutorials, aiming to automatically evaluate the quality of such documents available on the Web. In order to achieve this goal, we present two contributions: 1) scalable detection of duplicated code snippets; 2) automatic identification of valid version ranges. Software tutorials consist of a combination of source code snippets and natural language text. The code snippets in a tutorial can originate from different sources, perhaps carrying stringent licensing requirements or known security vulnerabilities. Developers, typically unaware of this, can reuse these code snippets in their project. First, in this thesis, we present our work on a Web-scale code clone search technique that is able to detect duplicate code snippets between large scale document and source code corpora in order to trace toxic code snippets. As software libraries and APIs evolve over time, existing software development tutorials can become outdated. It is difficult for software developers and especially novices to determine the expected version of the software implicit in a specific tutorial in order to decide whether the tutorial is applicable to their software development environment. To overcome this challenge, in this thesis we present a novel technique for automatic identification of the valid version range of software development tutorials on the Web.

Die vorliegende Arbeit befasst sich mit verschiedenen Aspekten der hp-FEM. Insbesondere werden hierbei folgende Punkte genauer untersucht: 1. Das effiziente Aufstellen der Steifigkeitsmatrix auf Referenzelementen, die keine Tensorproduktstruktur besitzen. 2. Eine lokale Konvergenzbetrachtung für die randkonzentrierte hp-FEM. 3. Ein Multilevel-Löser für die randkonzentrierte hp-FEM. 4. Eine Strategie für hp-Adaptivität.

In this paper, we consider domain decomposition preconditioners for a system of linear algebraic equations arising from the <i>p</i>-version of the fem. We propose several multi-level preconditioners for the Dirichlet problems in the sub-domains in two and three dimensions. It is proved that the condition number of the preconditioned system is bounded by a constant independent of the polynomial degree. The proof uses interpretations of the <i>p</i>-version element stiffness matrix and mass matrix on [-1,1] as <i>h</i>-version stiffness matrix and weighted mass matrix. The analysis requires wavelet methods.

We describe a data structure and algorithms based on segment trees. They are used to manage different versions of a document and to reconstruct the version which was valid at a given time in the past or to get the most recent version. Difficulties arise because it is not known when a version will be replaced by a newer one. Thus unbounded time intervals are to be handled. The data structure also supports the retrieval of the history of a document.

Modern agile software development methods allow to continuously evolve software systems by easily adding new features, fixing bugs, and adapting the software to changing requirements and conditions while it is continuously used by the users. A major obstacle in the agile evolution is the underlying database that persists the software system’s data from day one on. Hence, evolving the database schema requires to evolve the existing data accordingly—at this point, the currently established solutions are very expensive and error-prone and far from agile. In this thesis, we present InVerDa, a multi-schema-version database system to facilitate agile database development. Multi-schema-version database systems provide multiple schema versions within the same database, where each schema version itself behaves like a regular single-schema database. Creating new schema versions is very simple to provide the desired agility for database development. All created schema versions can co-exist and write operations are immediately propagated between schema versions with a best-effort strategy. Developers do not have to implement the propagation logic of data accesses between schema versions by hand, but InVerDa automatically generates it. To facilitate multi-schema-version database systems, we equip developers with a relational complete and bidirectional database evolution language (BiDEL) that allows to easily evolve existing schema versions to new ones. BiDEL allows to express the evolution of both the schema and the data both forwards and backwards in intuitive and consistent operations; the BiDEL evolution scripts are orders of magnitude shorter than implementing the same behavior with standard SQL and are even less likely to be erroneous, since they describe a developer’s intention of the evolution exclusively on the level of tables without further technical details. Having the developers’ intentions explicitly given in the BiDEL scripts further allows to create a new schema version by merging already existing ones. Having multiple co-existing schema versions in one database raises the need for a sophisticated physical materialization. Multi-schema-version database systems provide full data independence, hence the database administrator can choose a feasible materialization, whereby the multi-schema-version database system internally ensures that no data is lost. The search space of possible materializations can grow exponentially with the number of schema versions. Therefore, we present an adviser that releases the database administrator from diving into the complex performance characteristics of multi-schema-version database systems and merely proposes an optimized materialization for a given workload within seconds. Optimized materializations have shown to improve the performance for a given workload by orders of magnitude. We formally guarantee data independence for multi-schema-version database systems. To this end, we show that every single schema version behaves like a regular single-schema database independent of the chosen physical materialization. This important guarantee allows to easily evolve and access the database in agile software development—all the important features of relational databases, such as transaction guarantees, are preserved. To the best of our knowledge, we are the first to realize such a multi-schema-version database system that allows agile evolution of production databases with full support of co-existing schema versions and formally guaranteed data independence.

Technological advances have allowed to collect and store large volumes of data over the years. Besides, it is significant that today's applications have high performance and can analyze these large datasets effectively. Today, it remains a challenge for data mining to make its algorithms and applications equally efficient in the need of increasing data size and dimensionality [1]. To achieve this goal, many applications rely on parallelism, because it is an area that allows the reduction of cost depending on the execution time of the algorithms because it takes advantage of the characteristics of current computer architectures to run several processes concurrently [2]. This paper proposes a parallel version of the FuzzyPred algorithm based on the amount of data that can be processed within each of the processing threads, synchronously and independently.

WordPress is a very widely used content management system that enables users to easier create websites. The popularity of WordPress has made it a prime target for attacks by hackers since a potential vulnerability would affect many targets. Vulnerabilities that can be utilised in an attack are referred to as exploits. Most exploits are only viable for a subset of all the version of the software that they target. The knowledge of which version of a content managements system a website is running is often not explicit or easy to determine. Attackers can potentially exploit a vulnerable website faster if the version is known, since this allows them to search for existing vulnerabilities and exploits, instead of trying to identify a new vulnerability. The purpose of this thesis is to investigate existing and alternate methods for detecting the version of WordPress on websites that are powered by it. The scope is limited to an analysis of existing tools and the suggested methods for version identification are limited to identification using unique values that are calculated from the contents of files. The suggested methods for version identification and the generation of the required data is implemented using Python 3, the programming language. We investigate the feasibility of version obfuscation, how discernible a version of WordPress is, and how to compare versions of WordPress. The thesis has proven the feasibility of version identification with a new perspective that delivers more accurate results than previous methods. Version obfuscation has also been proven to be very feasible without affecting the usability of the WordPress website. Furthermore, a method for discerning between two specific versions of WordPress is presented. All the results are in theory applicable to other software projects that are hosted and developed in the same way. This new area of research has much for security professionals and has room for future improvement.

Git is a distributed version control system that tracks changes to a project overtime and is used to save these changes. Today it is being used by millions of people and is becoming a demand on the job market. For this reason it has become important to learn the version control system. Learning Git however may be difficult for beginners and learning it through tutorials may not always be effective. Learning it through a serious educational game (SEG) may be more effective as a SEG can provide motivation and feedback which are two factors for successful learning. This study seeks to assess how effective a SEG is in teaching Git by looking at the amount of knowledge gained from playing a SEG. This study also seeks to assess how much participants learned Git using a tutorial compared to participants who used a serious educational game. From the results, the study found that the SEG expanded the understanding of Git. The study also found that there was no significant difference in the amount of understanding gained from the SEG and the tutorial.

Corrected and modernized (clefs, instruments) edition, very close to original and practical - but NOT SCIENTIFICALLY CRITICAL - this great version with full orchestra as in original dedicated to marriage of HRH Prince William of England and His Lady Catherine Middleton on 29th of April 2011. Derived from print, app. 1819, digital library, SLUB DRESDEN.

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