scholarly journals Contrasting Malicious Applets by Modifying the Java Virtual Machine

Author(s):  
Vincenzo Ciaschini ◽  
Roberto Gorrieri
2014 ◽  
Vol 11 (1) ◽  
pp. 47-68 ◽  
Author(s):  
Patricia Conde ◽  
Francisco Ortin

Java 7 has included the new invokedynamic opcode in the Java virtual machine. This new instruction allows the user to define method linkage at runtime. Once the link is established, the virtual machine performs its common optimizations, providing better runtime performance than reflection. However, this feature has not been offered at the abstraction level of the Java programming language. Since the functionality of the new opcode is not provided as a library, the existing languages in the Java platform can only use it at the assembly level. For this reason, we have developed the JINDY library that offers invokedynamic to any programming language in the Java platform. JINDY supports three modes of use, establishing a trade-off between runtime performance and flexibility. A runtime performance and memory consumption evaluation is presented. We analyze the efficiency of JINDY compared to reflection, the MethodHandle class in Java 7 and the Dynalink library. The memory and performance costs compared to the invokedynamic opcode are also measured.


Author(s):  
King Tin Lam ◽  
Cho-Li Wang

Web application servers, being today’s enterprise application backbone, have warranted a wealth of J2EE-based clustering technologies. Most of them however need complex configurations and excessive programming effort to retrofit applications for cluster-aware execution. This chapter proposes a clustering approach based on distributed Java virtual machine (DJVM). A DJVM is a collection of extended JVMs that enables parallel execution of a multithreaded Java application over a cluster. A DJVM achieves transparent clustering and resource virtualization, extolling the virtue of single-system-image (SSI). The authors evaluate this approach through porting Apache Tomcat to their JESSICA2 DJVM and identify scalability issues arising from fine-grain object sharing coupled with intensive synchronizations among distributed threads. By leveraging relaxed cache coherence protocols, we are able to conquer the scalability barriers and harness the power of our DJVM’s global object space design to significantly outstrip existing clustering techniques for cache-centric web applications.


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