Towards Object-Centric Time-Traveling Debuggers

International audienceObject-centric debugging aims at facilitating the debugging of object-oriented programs by focusing debugging operations on specific objects. This technique is tedious to use because developers have to manually find objects to debug, which is not straightforward. Time-traveling debuggers allows developers to explore executions back and forth in time. It has been shown that time-traveling features effectively facilitate debugging and program understanding. We propose to combine these techniques to benefit from both of them to debug objectoriented programs. Time-travel navigation could help finding and remembering objects by providing means to explore executions back and forth. Object-centric debugging could extend time-traveling debugging with object-centric exploration features. These techniques have never been combined, and the challenges and benefits of such combination have never been explored. We present SeekerOC, a time-traveling debugger prototype which provides object-centric debugging support. To combine both techniques, we use Time-Traveling Queries, a query system to automatically explore executions. We discuss the expected benefits of this combination, and we argue that exploring object-centric time-traveling debugging will open new research perspectives towards more effective debugging techniques and tools for object-oriented systems

Object-Centric Reflection: Unifying Reflection and Bringing It Back to Objects

Reflective applications are able to query and manipulate the structure and behavior of a running system. This is essential for highly dynamic software that needs to interact with objects whose structure and behavior are not known when the application is written. Software analysis tools, like debuggers, are a typical example. Oddly, although reflection essentially concerns run-time entities, reflective applications tend to focus on static abstractions, like classes and methods, rather than objects. This is phenomenon we call the object paradox, which makes developers less effective by drawing their attention away from run-time objects. To counteract this phenomenon, we propose a purely object-centric approach to reflection. Reflective mechanisms provide object-specific capabilities as another feature. Object-centric reflection proposes to turn this around and put object-specific capabilities as the central reflection mechanism. This change in the reflection architecture allows a unification of various reflection mechanisms and a solution to the object paradox. We introduce Bifr\"ost, an object-centric reflective system based on first-class meta-objects. Through a series of practical examples we demonstrate how object-centric reflection mitigates the object paradox by avoiding the need to reflect on static abstractions. We survey existing approaches to reflection to establish key requirements in the domain, and we show that an object-centric approach simplifies the meta-level and allows a unification of the reflection field. We demonstrate how development itself is enhanced with this new approach: talents are dynamically composable units of reuse, and object-centric debugging prevents the object paradox when debugging. We also demonstrate how software analysis is benefited by object-centric reflection with Chameleon, a framework for building object-centric analysis tools and MetaSpy, a domain-specific profile

Reflection as a Tool to Debug Objects

International audienceIn this paper, we share our experience with using reflection as a systematic tool to build advanced debuggers. We illustrate the usage and combination of reflection techniques for the implementation of object-centric debugging. Objectcentric debugging is a technique for object-oriented systems that scopes debugging operations to specific objects. The implementation of this technique is not straightforward, as there are, to the best of our knowledge, no description in the literature about how to build such debugger. We describe an implementation of object-centric breakpoints. We built these breakpoints with Pharo, a highly reflective system, based on the combination of different classical reflection techniques: proxy, anonymous subclasses, and sub-method partial behavioral reflection. Because this implementation is based on common reflective techniques, it is applicable to other reflective languages and systems for which a set of identified primitives are available

Sindarin: A Versatile Scripting API for the Pharo Debugger

International audienceDebugging is one of the most important and time consuming activities in software maintenance, yet mainstream debuggers are not well-adapted to several debugging scenarios. This has led to the research of new techniques covering specific families of complex bugs. Notably, recent research proposes to empower developers with scripting DSLs, plugin-based and moldable debuggers. However, these solutions are tailored to specific use-cases, or too costly for one-time-use scenarios. In this paper we argue that exposing a debugging scripting interface in mainstream debuggers helps in solving many challenging debugging scenarios. For this purpose, we present Sindarin, a scripting API that eases the expression and automation of different strategies developers pursue during their debugging sessions. Sindarin provides a GDB-like API, augmented with AST-bytecode-source code mappings and object-centric capabilities. To demonstrate the versatility of Sindarin, we reproduce several advanced breakpoints and non-trivial debugging mechanisms from the literature

Two ways to Grid: the contribution of Open Grid Services Architecture (OGSA) mechanisms to service-centric and resource-centric lifecycles

Service Oriented Architectures (SOAs) support service lifecycle tasks, including Development, Deployment, Discovery and Use. We observe that there are two disparate ways to use Grid SOAs such as the Open Grid Services Architecture (OGSA) as exemplified in the Globus Toolkit (GT3/4). One is a traditional enterprise SOA use where end-user services are developed, deployed and resourced behind firewalls, for use by external consumers: a service-centric (or ‘first-order’) approach. The other supports end-user development, deployment, and resourcing of applications across organizations via the use of execution and resource management services: A Resource-centric (or ‘second-order’) approach. We analyze and compare the two approaches using a combination of empirical experiments and an architectural evaluation methodology (scenario, mechanism, and quality attributes) to reveal common and distinct strengths and weaknesses. The impact of potential improvements (which are likely to be manifested by GT4) is estimated, and opportunities for alternative architectures and technologies explored. We conclude by investigating if the two approaches can be converged or combined, and if they are compatible on shared resources

A methodology for the capture and analysis of hybrid data: a case study of program debugging

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