Recent Advances in Mobile Middleware for Wireless Systems and Services

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Jiko kaifukugata operetingu shisutemu kochiku furemu waku

制度:新 ; 報告番号:甲2786号 ; 学位の種類:博士(工学) ; 授与年月日:2009/2/25 ; 早大学位記番号:新500

Unit Test Virtualization with VMVM

Testing large software packages can become very time intensive. To address this problem, researchers have investigated techniques such as Test Suite Minimization. Test Suite Minimization reduces the number of tests in a suite by removing tests that appear redundant, at the risk of reducing fault-finding ability since it can be difficult to identify which tests are truly redundant. We take a completely different approach to solving the same problem of long running test suites by instead reducing the time needed to execute each test, an approach that we call Unit Test Virtualization. We describe the empirical analysis that we performed to ground our approach and provide an implementation of Unit Test Virtualization targeting Java applications. We evaluated our implementation, VMVM, using 20 real-world Java applications and found that it reduces test suite execution time by up to 97 percent (on average, 62 percent) when compared to traditional unit test execution. We also compared VMVM to a well known Test Suite Minimization technique, finding the reduction provided by VMVM to be four times greater, while still executing every test with no loss of fault-finding ability

Safe Class and Data Evolution in Large and Long-Lived Java Applications

There is a growing class of applications implemented in object-oriented languages that are large and complex, that exploit object persistence, and need to run uninterrupted for long periods of time. Development and maintenance of such applications can present challenges in the following interrelated areas: consistent and scalable evolution of persistent data and code, optimal build management, and runtime changes to applications. The research presented in this thesis addresses the above issues. Since Java is becoming increasingly popular platform for implementing large and long-lived applications, it was chosen for experiments. The first part of the research was undertaken in the context of the PJama system, an orthogonally persistent platform for Java. A technology that supports persistent class and object evolution for this platform was designed, built and evaluated. This technology integrates build management, persistent class evolution, and support for several forms of eager conversion of persistent objects. Research in build management for Java has resulted in the creation of a generally applicable, compiler-independent smart recompilation technology, which can be re-used in a Java IDE, or as a standalone Java-specific utility similar to make. The technology for eager object conversion that we developed allows the developers to perform arbitrarily complex changes to persistent objects and their collections. A high level of developer's control over the conversion process was achieved in part due to introduction of a mechanism for dynamic renaming of old class versions. This mechanism was implemented using minor non-standard extensions to the Java language. However, we also demonstrate how to achieve nearly the same results without modifying the language specification. In this form, we believe, our technology can be largely re-used with practically any persistent object solution for Java. The second part of this research was undertaken using as an implementation platform the HotSpot Java Virtual Machine (JVM), which is currently Sun's main production JVM. A technology was developed that allows the engineers to redefine classes on-the-fly in the running VM. Our main focus was on the runtime evolution of server-type applications, though we also address modification of applications running in the debugger. Unlike the only other similar system for Java known to us, our technology supports redefinition of classes that have methods currently active. Several policies for handling such methods have been proposed, one of them is currently operational, another one is in the experimental stage. We also propose to re-use the runtime evolution technology for dynamic fine-grain profiling of applications

DSpace 5.x Documentation

DSpace is an open source software platform that enables organisations to: - capture and describe digital material using a submission workflow module, or a variety of programmatic ingest options - distribute an organisation's digital assets over the web through a search and retrieval system - preserve digital assets over the long term This system documentation includes a functional overview of the system, which is a good introduction to the capabilities of the system, and should be readable by non-technical folk. Everyone should read this section first because it introduces some terminology used throughout the rest of the documentation. For people actually running a DSpace service, there is an installation guide, and sections on configuration and the directory structure. Finally, for those interested in the details of how DSpace works, and those potentially interested in modifying the code for their own purposes, there is a detailed architecture and design section.DSpace is an open source software platform that enables organisations to: - capture and describe digital material using a submission workflow module, or a variety of programmatic ingest options - distribute an organisation's digital assets over the web through a search and retrieval system - preserve digital assets over the long term This system documentation includes a functional overview of the system, which is a good introduction to the capabilities of the system, and should be readable by non-technical folk. Everyone should read this section first because it introduces some terminology used throughout the rest of the documentation. For people actually running a DSpace service, there is an installation guide, and sections on configuration and the directory structure. Finally, for those interested in the details of how DSpace works, and those potentially interested in modifying the code for their own purposes, there is a detailed architecture and design section

Implementation and evaluation of a mobile Android application for auditory stimulation of chronic tinnitus patients

Tinnitus is a common symptom where the affected person perceives a sound without an external source. To support the development of new therapies a tinnitus tracking platform, including mobile applications, was developed at Ulm University in cooperation with the tinnitus research initiative. In the future, these mobile applications should be extended to include a simple game that requires the user to concentrate on an auditory stimulation, distracting them from their tinnitus. This is accomplished by using localization of an audio source as a game mechanic. The measurement of the offset between the position the user guessed for an audio source and its actual location could also serves as an additional data point. In this thesis an application for the Android operating system is designed that implements such a game and serves as a proof of concept. Since the Android API does not include the capability for positional audio, a separate audio API based on OpenAL was created as part of this thesis. This API as well as the framework developed to implement the game are designed to be reusable for future, similar projects. The game concept was also evaluated in a study using the demonstration application

Making Software More Reliable by Uncovering Hidden Dependencies

As software grows in size and complexity, it also becomes more interdependent. Multiple internal components often share state and data. Whether these dependencies are intentional or not, we have found that their mismanagement often poses several challenges to testing. This thesis seeks to make it easier to create reliable software by making testing more efficient and more effective through explicit knowledge of these hidden dependencies. The first problem that this thesis addresses, reducing testing time, directly impacts the day-to-day work of every software developer. The frequency with which code can be built (compiled, tested, and package) directly impacts the productivity of developers: longer build times mean a longer wait before determining if a change to the application being build was successful. We have discovered that in the case of some languages, such as Java, the vast majority of build time is spent running tests. Therefore, it's incredibly important to focus on approaches to accelerating testing, while simultaneously making sure that we do not inadvertently cause tests to erratically fail (i.e. become flaky). Typical techniques for accelerating tests (like running only a subset of them, or running them in parallel) often can't be applied soundly, since there may be hidden dependencies between tests. While we might think that each test should be independent (i.e. that a test's outcome isn't influenced by the execution of another test), we and others have found many examples in real software projects where tests truly have these dependencies: some tests require others to run first, or else their outcome will change. Previous work has shown that these dependencies are often complicated, unintentional, and hidden from developers. We have built several systems, VMVM and ElectricTest, that detect different sorts of dependencies between tests and use that information to soundly reduce testing time by several orders of magnitude. In our first approach, Unit Test Virtualization, we reduce the overhead of isolating each unit test with a lightweight, virtualization-like container, preventing these dependencies from manifesting. Our realization of Unit Test Virtualization for Java, VMVM eliminates the need to run each test in its own process, reducing test suite execution time by an average of 62% in our evaluation (compared to execution time when running each test in its own process). However, not all test suites isolate their tests: in some, dependencies are allowed to occur between tests. In these cases, common test acceleration techniques such as test selection or test parallelization are unsound in the absence of dependency information. When dependencies go unnoticed, tests can unexpectedly fail when executed out of order, causing unreliable builds. Our second approach, ElectricTest, soundly identifies data dependencies between test cases, allowing for sound test acceleration. To enable more broad use of general dependency information for testing and other analyses, we created Phosphor, the first and only portable and performant dynamic taint tracking system for the JVM. Dynamic taint tracking is a form of data flow analysis that applies labels to variables, and tracks all other variables derived from those tagged variables, propagating those tags. Taint tracking has many applications to software engineering and software testing, and in addition to our own work, researchers across the world are using Phosphor to build their own systems. Towards making testing more effective, we also created Pebbles, which makes it easy for developers to specify data-related test oracles on mobile devices by thinking in terms of high level objects such as emails, notes or pictures