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18th Annual conference on object-oriented programming, systems, languages and applications (oopsla 2003)

作者： Fähndrich, M Rustan, K Leino, M Microsoft Res Redmond WA 98052 USA

Distinguishing non-null references from possibly-null references at the type level can detect null-related errors in object-oriented programs at compile-time. This paper gives a proposal for retrofitting a language such as C# or Java with non-null types. It addresses the central complications that arise in constructors, where declared non-null fields may not yet have been initialized, but the partially constructed object is already accessible. The paper reports experience with an implementation for annotating and checking null-related properties in C# programs.

关键词： C# Java null references type system non-null types

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HydroJ: object-oriented pattern matching for evolvable distributed systems

HydroJ: Object-oriented pattern matching for evolvable distr...

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18th Annual conference on object-oriented programming, systems, languages and applications (oopsla 2003)

作者： Lee, K LaMarca, A Chambers, C Univ Washington Seattle WA 98195 USA Intel Res Seattle WA USA

In an evolving software system, components must be able to change independently while remaining compatible with their peers. One obstacle to independent evolution is the brittle parameter problem: the ability of two components to communicate can depend on a number of inessential details of the types, structure, and/or contents of the values communicated. If these details change, then the components can no longer communicate, even if the essential parts of the message remain unaffected. We present HydroJ, an extension of Java that addresses this problem. In HydroJ, components communicate using self-describing, semi-structured messages, and programmers use pattern matching to define the handling of messages. This design stems from two central ideas: first, that self-describing messages reduce dependence on inessential message format details;and second, that object-oriented pattern matching naturally focuses on the essential information in a message and is insensitive to inessential information. We have developed these ideas in the context of Rain, a distributed, heterogeneous messaging system for ubiquitous computing. To evaluate the design, we have constructed a prototype HydroJ compiler, implemented some Rain services in HydroJ, studied the evolution of an existing Rain service over time, and formalized HydroJ's key features in a core language.

关键词： languages pattern matching dynamic dispatch XML semi-structured data software evolution object-oriented programming distributed systems ubiquitous computing HydroJ

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Lazy modular upgrades in persistent object stores

Lazy modular upgrades in persistent object stores

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18th Annual conference on object-oriented programming, systems, languages and applications (oopsla 2003)

作者： Boyapati, C Liskov, B Shrira, L Moh, CH Richman, S MIT Comp Sci & Artificial Intelligence Lab Cambridge MA 02139 USA

Persistent object stores require a way to automatically upgrade persistent objects, to change their code and storage representation. Automatic upgrades are a challenge for such systems. Upgrades must be performed in a way that is efficient both in space and time, and that does not stop application access to the store. In addition, however, the approach must be modular: it must allow programmers to reason locally about the correctness of their upgrades similar to the way they would reason about regular code. This paper provides solutions to both problems. The paper first defines upgrade modularity conditions that any upgrade system must satisfy to support local reasoning about upgrades. The paper then describes a new approach for executing upgrades efficiently while satisfying the upgrade modularity conditions. The approach exploits object encapsulation properties in a novel way. The paper also describes a prototype implementation and shows that our upgrade system imposes only a small overhead on application performance.

关键词： software upgrades presistent objects ownership types

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MJ: A rational module system for Java and its applications

MJ: A rational module system for Java and its applications

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18th Annual conference on object-oriented programming, systems, languages and applications (oopsla 2003)

作者： Corwin, J Bacon, DF Grove, D Murthy, C IBM

While Java provides many software engineering benefits, it lacks a coherent module system and instead provides only packages (which are primarily a name space mechanism) and classloaders (which are very low-level). As a result, large Java applications suffer from unexpected interactions between independent components, require complex CLASSPATH definitions, and are often extremely complex to install and maintain. We have implemented a module system for Java called MJ that is implemented with class loaders, but provides a much higher-level interface. High-level properties can be specified in a module definition and are enforced by the module system as new modules are loaded. To experimentally validate the ability of MJ to properly handle the complex module interrelationships found in large Java server systems, we replaced the classloader mechanisms of Apache Tomcat 4.1.18 [27] with 30 MJ modules. The modified Tomcat is functionally identical to the original, but requires no CLASS PATH definitions, and will operate correctly even if user code loads a different version of a module used by Tomcat, such as the Xerces XML parser [31]. Furthermore, by making a small change to the Java core libraries enabled by MJ, we obtained a 30% performance improvement in a servlet microbenchmark.

关键词： Java modularity components language design

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object equality profiling

Object equality profiling

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18th Annual conference on object-oriented programming, systems, languages and applications (oopsla 2003)

作者： Marinov, D O'Callahan, R MIT Comp Sci Lab Cambridge MA 02139 USA IBM Corp Div Res TJ Watson Res Ctr Yorktown Hts NY 10598 USA

We present object Equality Profiling (OEP), a new technique for helping programmers discover optimization opportunities in programs. OEP discovers opportunities for replacing a set of equivalent object instances with a single representative object. Such a set represents an opportunity for automatically or manually applying optimizations such as hash consing, heap compression, lazy allocation, object caching, invariant hoisting, and more. To evaluate OEP, we implemented a tool to help programmers reduce the memory usage of Java programs. Our tool performs a dynamic analysis that records all the objects created during a particular program run. The tool partitions the objects into equivalence classes, and uses collected timing information to determine when elements of an equivalence class could have been safely collapsed into a single representative object without affecting the behavior of that program run. We report the results of applying this tool to benchmarks, including two widely used Web application servers. Many benchmarks exhibit significant amounts of object equivalence, and in most benchmarks our profiler identifies optimization opportunities clustered around a small number of allocation sites. We present a case study of using our profiler to find simple manual optimizations that reduce the average space used by live objects in two SpecJVM benchmarks by 47% and 38% respectively.

关键词： object equality object mergeability profiling profile-guided optimization space savings Java language

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17th ACM conference on object-oriented programming, systems, languages, and applications

17th ACM Conference on Object-Oriented Programming, Systems,...

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17th ACM conference on object-Orientated programming systems, languages, and applications

The proceedings contains 25 papers. Topics discussed include storage management, components and composition, languages, optimizations, static analysis, scalability, computational tools and aspects.

关键词： object oriented programming

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Implementing distribution and persistence aspects with AspectJ

Implementing distribution and persistence aspects with Aspec...

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17th Meeting on object-oriented programming, systems, languages and applications (oopsla 2002)

作者： Soares, S Laureano, E Borba, P Univ Fed Pernambuco Informat Ctr Recife PE Brazil Catholic Univ Pernambuco Informat & Stat Dept Recife PE Brazil

This paper reports our experience using AspectJ, a general-purpose aspect-oriented extension to Java, to implement distribution and persistence aspects in a web-based information system. This system was originally implemented in Java and restructured with AspectJ. Our main contribution is to show that AspectJ is useful for implementing several persistence and distribution concerns in the application considered, and other similar applications. We have also identified a few drawbacks in the language and suggest some minor modifications that could significantly improve similar implementations. Despite the drawbacks, we argue that the AspectJ implementation is superior to the pure Java implementation. Some of the aspects implemented in our experiment are abstract and constitute a simple aspect framework. The other aspects are application specific but we suggest that different implementations might follow the same aspect pattern. The framework and the pattern allow us to propose architecture-specific guidelines that provide practical advice for both restructuring and implementing certain kinds of persistent and distributed applications with AspectJ.

关键词： languages standardization experimentation aspect-oriented programming separation of concerns AspectJ distributed programming object persistence

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Workflow enactment with continuation and future objects

Workflow enactment with continuation and future objects

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17th ACM conference on object-Orientated programming systems, languages, and applications

作者： Manolescu, Dragos A.

An increasing number of software developers are turning to workflow to separate the logic and the control aspects in their applications, thus making them more amenable to change. However, in spite of recent efforts lo standardize and provide reusable workflow components, many developers build their own. This is a challenging endeavor and involves solving problems which seem incompatible with the object paradigm and current object-oriented programming languages. In the context of an object-oriented workflow framework, this paper demonstrates a novel approach that resolves this impedance mismatch with techniques drawn from programming language theory. This successful cross-pollination narrows the gap between the results of decades of research in programming languages and developers working hard to cope with change.

关键词： object oriented programming

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ARK: an object(ive) view of extensible minimal languages for system configuration

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INFORMATION AND SOFTWARE TECHNOLOGY 2002年第4期44卷 259-268页

作者： Holgate, M Partain, W Univ Glasgow Dept Comp Sci Arusha Project Glasgow G12 8RZ Lanark Scotland

This paper presents ARK, a minimal, XML-based configuration language and framework for our particular problem domain: UNIX System Administration. The language allows the capture of poorly structured configuration data and code fragments written in various programming languages, while the ARK engine is responsible for interpreting the XML and allowing applications to query data and invoke code fragments. The paper discusses the need for a minimal, simple approach, and provides examples which illustrate the use of the prototype-based model supported by the language. The ARK framework is currently being used to manage several academic and industrial UNIX installations. (C) 2002 Elsevier Science B.V. All rights reserved.

关键词： XML configuration framework system administration prototype-based language

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Institutions: integrating objects, XML and databases

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INFORMATION AND SOFTWARE TECHNOLOGY 2002年第4期44卷 207-216页

作者： Alagic, S Univ So Maine Dept Comp Sci Portland ME 04104 USA

A general model theory based on institutions is proposed as a formal framework for investigating typed object-oriented, XML and other data models equipped with integrity constraints. A major challenge in developing such a unified model theory is in the requirement that it must be able to handle major structural differences between the targeted models as well as the significant differences in the logic bases of their associated constraint languages. A distinctive feature of this model theory is that it is transformation-oriented. It is based on structural transformations within a particular category of models or across different categories with a fundamental requirement that the associated constraints are managed in such a way that the database integrity is preserved. (C) 2002 Elsevier Science B.V. All rights reserved.

关键词： object-oriented XML data models institutions transformations integrity constraints

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