Runtime Support for Type-Safe Dynamic Java Classes

Abstract

Modern software must evolve in response to changing conditions. In the most widely used programming environments, code is static and cannot change at runtime. This poses problems for applications, that have limited down-time. More support is needed for dynamic evolution. In this paper we present an approach for supporting dynamic evolution of Java programs. In this approach, Java programs can evolve by changing their components, namely classes, during their execution. Changes in a class lead to changes in the its instances, thereby allowing evolution of both code and state. The approach promotes compatibility with existing Java applications, and maintains the security and type safety controls imposed by Java's dynamic linking mechanism. Experimental analyses of our implementation indicate that the implementation imposes a moderate performance penalty relative to the unmodified virtual machine. This work is supported by the Defense Advanced Research Project Agency (DARPA) and Rome Laboratory, Air Force Materiel Command, USAF, under agreement number F30602-97-1-0221. The U.S. Government is authorized to reproduce and distribute reprints for Governmental purposes notwithstanding any copyright annotation thereon. The views and conclusions contained herein are those of the authors and should not be interpreted as necessarily representing the official policies or endorsements, either expressed or implied, of the Defense Advanced Research Project Agency (DARPA), Rome Laboratory, or the U.S. Government. Report Documentation PageForm Public reporting burden for the collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden, to Washington Headquarters Services, Directorate for Information Operations and Reports, 1215 Jefferson Davis Highway, Suite 1204, Arlington VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to a penalty for failing to comply with a collection of information if it does not display a currently valid OMB control number. Modern software must evolve in response to changing conditions. In the most widely used programming environments, code is static and cannot change at runtime. This poses problems for applications, that have limited down-time. More support is needed for dynamic evolution. In this paper we present an approach for supporting dynamic evolution of Java programs. In this approach, Java programs can evolve by changing their components, namely classes, during their execution. Changes in a class lead to changes in the its instances, thereby allowing evolution of both code and state. The approach promotes compatibility with existing Java applications, and maintains the security and typ...

On Correctness of Dynamic Protocol Update

“…Dynamic ML [22] enables type-safe module replacement at runtime; changes can include the alternation of abstract types at updatetime, and the addition (and possibly removal) of module definitions via garbagecollection. Dynamic Java classes [12] offer type safety preservation but compromise portability by modifying the Java Virtual Machine; also, class replacement is not synchronized with threads using old code.…”

Flexible and Efficient In-Vivo Enhancement for Grid Applications

“…Bialek et al's system [6] also rewrites the updated software at the source or bytecode levels to enable its dynamic updates; however, instead of replacing classes using HotSwap, which is a standard JVM facility, their approach globally renames classes. Several approaches [17,15,11] have introduced custom virtual machines to support dynamic updates of Java applications. These approaches, however, require installing a custom JVM, which may have limited functionality and interoperability.…”

The Ariel Distributed Programming Project: Secure Execution of Mobile Programs

“…The details regarding this work can be found in [9,10]. While much of our work here was done to support a dynamic access control model, we believe that dynamic JVM can be used to several additional purposes, including runtime optimization, runtime code distribution and update, and hot updates.…”