Adl-Tabatabai, A., Langdale, G., Lucco, S., Wahbe, R., "Efficient and languageindependent mobile programs," Proceedings of the SIGPLAN `96 Conference on Programming Language Design and Implementation, pp. 127-36, May 1996.  Home/Search   Document Not in Database   Summary   Related Articles   Check

....Facile [39] implements a hybrid approach that allows the transmission of both an architecture independent representation and a machine code representation for the same agent. Acharya et al. 1] characterize systems according to the entity that initiates the transmission of code. Omniware [2], Safe TCL, and Java allow programs to download code from a remote site and execute it locally. Avalon Common Lisp, REV, NCL [21] and Obliq allow programs to send code to a remote site, and receive the results of the subsequent computation. Finally, Agent TCL [27] Emerald [66] Mole [67] Aglets ....

Adl-Tabatabai, A., Langdale, G., Lucco, S., Wahbe, R., "Efficient and languageindependent mobile programs," Proceedings of the SIGPLAN `96 Conference on Programming Language Design and Implementation, pp. 127-36, May 1996.

....within the sandbox. 7 The instructions that restrict memory references can be added by the compiler, by a post processing tool, or at extension load time. The results of Wahbe et al. show a run time overhead of five to ten percent. A follow on to this work was the Omniware Portable Code system [Adl Tabatabai96]. The Omniware compiler generates portable code for an abstract virtual machine (OmniVM) which is translated to native fault isolated code at runtime. Along with the source language independence provided by software fault isolation techniques, the Omniware system also offers targetindependent ....

Adl-Tabatabi A., Langdale, G., Lucco. S., Wahbe, R., "Efficient and LanguageIndependent Mobile Programs," Proceedings of the 1996 Conference on Programming Language Design and Implementation, pp. 127--136, Philadelphia, PA (May 1996).

....the foreign heap is updated. The same write barrier is used to prevent the passing of illegal cross heap references. If the reference that would be created by a write is illegal, a segmentation violation error is thrown. The use of a write barrier is similar to the use of write checks in Omniware [2]. Although it may seem odd to use another protection mechanism (software fault isolation) in a type safe system, the motivation is resource management, not memory safety. Finally, to improve the use of the JVM s memory as a whole, K0 does not reserve non overlapping, contiguous memory regions for ....

A.-R. Adl-Tabatabai, G. Langdale, S. Lucco, and R. Wahbe. Efficient and language-independent mobile programs. In Proc. ACM SIGPLAN '96 Conf. on Programming Language Design and Implementation (PLDI), pages 127--136, May 1996.

.... the virtual machines essentially taking advantage of the 80 20 rule (20 of the code takes 80 of the execution time) Since the Romer study, a number of efforts have concentrated on improving the performance of Java, incorporating many of the techniques from traditional compiler optimization [Adl Tabatabai96], and there are now commercial products that claim parity between the performance of Java and the corresponding C code [Mangione98] Another advantage to Java over more traditional systems languages such as C or C is that the stronger typing and lack of pointers make Java code easier to ....

....code provided by the user. The downside is that this requires access to the original source code and depends heavily on maintenance of the compiler infrastructure. Software Fault Isolation (SFI) provides a way to sandbox object code and perform safety checks efficiently. Early measurements [Adl Tabatabai96] indicate that this can be done with 10 20 runtime overhead for sim 31 ple safety checks, without access to the original source code. Proof Carrying Code (PCC) takes a different approach and moves the burden of ensuring safety to the original compiler of the code. The system requires that each ....

Adl-Tabatabai, A., Langdale, G., Lucco, S. and Wahbe, R. "Efficient and Language-Independent Mobile Programs" PLDI, May 1996.

....increases in network connectivity, emergence of standard Internet protocols and the evolution of the World Wide Web towards an embedded object model have fostered mobile code. Systems based on mobile code, such as virtual machines like Java [Lindholm Yellin96] Inferno [Inferno] and OmniWare [Adl Tabatabai et al. 96] and embedded object systems like ActiveX [Brockshmidt 94] inherently require that clients fetch applications over the network prior to their execution. In such systems, the time spent transferring application code is a significant source of user perceived delays for typical applications, ....

Adl-Tabatabai, A., Langdale, G., Lucco, S. and Wahbe, R. "Efficient and LanguageIndependent Mobile Programs." In Conference on Programming Language Design and Implementation, May, 1996, p. 127-136.

....the program of the agent is compiled into machine code, forcing the access control mechanism is not straightforward. Inspecting whether the machine code is subject to the access control mechanism is difficult and a few techniques to address this problem has been developed. For example, sandboxing [6, 1] enables to isolate an agent in a fault domain implemented by software. Otherwise, the server has to give up forcing the access control mechanism, and thus accept only the agents digitally signed to guarantee that they are not malicious. 2.3 Protection from malicious servers The last criterion ....

Adl-Tabatabai, A., G. Langdale, S. Lucco, and R. Wahbe, "Efficient and Language-independent Mobile Programs," in Proc. of Conf. on Programming Language Design and Implementation, pp. 127--136, May 1996.

....languages. Most languages are based on rather traditional concepts, enhanced by a few constructs for process migration from one host to another. Well known implementations of mobile code languages are Telescript [10] Java [11] Aglets [12] Javelin [13] Agent Tcl [14] Sumatra [15] Omniware [16], Obliq [17] ML [18] TACOMA [19] and Ara [20] Most current platforms do not cover all aspects of mobility, but concentrate on single aspects, like the mobility of data and code, the concurrency of mobile system components, or the relocation of mobile devices. A truly integrated approach ....

A. Adl-Tabatabai, G. Langdale, S. Lucco, and R. Wahbe, "Efficient and language-independent mobile programs," in Proceedings of the ACM SIGPLAN'96 Conference on Programming Language Design and Implementation, pp. 127-- 136, ACM, May 1996.

.... to evolve separately from one another without causing undefined function errors [8, 15, 25] Dynamically linked libraries partition a program into parts that can be built and changed separately [33] And mobile agent systems transfer runnable code between active entities in a distributed system [1, 2, 7, 18, 19, 29, 35]. However, these approaches alone are inappropriate for heterogeneous distributed object computing systems. Each requires a single common source language (Java, Kali Scheme, Erlang, and mobile agents) computer architecture (COM) or software environment (dynamic linking) Furthermore, with COM ....

Adl-Tabatabai, A., Langdale, G., Lucco, S., Wahbe, R., "Efficient and language-independent mobile programs," Proceedings of the SIGPLAN `96 Conference on Programming Language Design and Implementation, pp. 127-36, May 1996.

....written in lava to the testing of Java virtual machines. We show that production grammars, expressed in a suitable language, can be used to automatically create, and reason about, complex test cases from concise, well structured specifications. Modern virtual machines [Lindholm Yellin 99, Inferno, Adl Tabatabai et al. 96] such as Java, have emerged in recent years as generic and ubiquitous components in extensible applications. Virtual machines can now be found in hypertext systems [Berners Lee et al. 96] web servers [SunJWS] databases [Oracle] desktop applications, and consumer devices such as cellphones ....

Adl-Tabatabai, A., Langdale, G., Lucco, S. and Wahbe, R. "Efficient and Language -Independent Mobile Programs." In Conference on Programming Language Design and Implementation, May 1996, p. 127-136.

....easier to develop and port. Last, the application codes do not need to be altered even when the language processor is changed from an interpreter to a JIT compiler. An interesting research issue for the JIT compiler approach is to maintain safety with lowoverhead even after compilation. Omniware [12, 1] solves this issue by using the SFI technique described in Section 3.1. Acknowledgment The author thanks Jan Vitek for his useful comments on the draft of the paper. ....

A. Adl-Tabatabai, G. Langdale, S. Lucco, and R. Wahbe. Efficient and languageindependent mobile programs. In Proc. of ACM Conf. on Programming Language Design and Implementation, pages 127--136, May 1996.

....a modern RISC processor) Their tool was targeted for the MIPS and Alpha processors. A follow on to that work is the Omniware Portable Code system. The Omniware compiler generates portable code for an abstract virtual machine (OmniVM) which is translated to native fault isolated code at runtime [Adl96]. Along with the source language independence provided by software fault isolation techniques, the Omniware system also offers target independent portable code. Omniware was developed by Colusa Software, which has been acquired by Microsoft. The future availability of Omniware as a product is not ....

....benchmarks with MiSFIT, using write call and read write call protection. The performance of the MiSFIT protected code relative to native code is reported in Table 2, along with Omniware Pentium performance numbers for the same tests. The Omniware numbers were obtained from recently published work [Adl96]. Although it is unlikely that anyone would want to load a SPEC benchmark into a database server or web browser, these results give a feeling for the overhead imposed by MiSFIT on typical code. To conservatively estimate the overhead imposed by MiSFIT, our results include only time spent at user ....

Adl-Tabatabai, A., Langdale, G., Lucco, S., Wahbe, R., "Efficient and Language-Independent Mobile Programs," PLDI `96, 127-136 (1996).

....the usual problems for the authors as they attempt to produce an optimising C compiler. Nonetheless, they have managed to achieve good speed ups over a set of ordinarily compiled C programs, ranging from 1.2 to 1.8 times as fast. The Omniware Virtual Machine produced by Adl Tabatabai et al. (Adl Tabatabai et al. 1996) is an abstract RISC that runs mobile programs sent to it across a network. The Omniware Virtual Machine has been designed so that code generation for it by compilers is easy, and the subsequent translation of this code to that of a modern processor is fast and efficient. Initially, the aim was to ....

Adl-Tabatabai, A., Langdale, G., Lucco, S., & Wahbe, R. 1996 (May). Efficient and language-independent mobile programs. Pages 127--136 of: Proceedings of the 1996 ACM conference on programming language design and implementation.

....a monolithic architecture, scales well with increasing numbers of clients, and does not entail high overhead. 1. Introduction Virtual machines (VMs) have evolved significantly in the last two decades and may soon serve as a widely available network computing platform [Lindholm Yellin96, Inferno, Adl Tabatabai et al. 96] They are particularly well suited for network computing because they offer a uniform programming model, work on a wide range of systems, and provide a variety of high level services not supported by native architectures and general purpose operating systems. Modern virtual machines offer ....

Adl-Tabatabai, A., Langdale, G., Lucco, S. and Wahbe, R. "Efficient and LanguageIndependent Mobile Programs." In Conference on Programming Language Design and Implementation, May, 1996, p. 127-136.

.... mobile code is used with various different meanings in the literature. Just to take three examples, let us cite: ffl The term mobile code describes any program that can be shipped unchanged to a heterogeneous collection of processors and executed with identical semantics on each processor [ATLLW96] ffl . mobile code, an approach where programs are considered as documents, and should therefore be accessible, transmitted and displayed (i.e. evaluated) as any other document [Rou96b] ffl Mobile agents are code containing objects that may be transimitted between communicating ....

....independent abstract machine retains all the language independence of the operating system solution, but does not have the portability problems. In the simplest version, the protection boundaries are enforced by an interpreter, performing all the needed checks at run time. In the Omniware model [ATLLW96] the overhead of interpretation is eliminated through software fault isolation (SFI) Code for the Omniware abstract machine is translated almost directly into native machine code, but all memory accesses are translated to code that checks for accesses outside a given boundary. The self certified ....

A. Adl-Tabatabai, G. Langdale, S. Lucco, and Robert Wahbe. Efficient and language-independent mobile programs. In Proceedings of the SIGPLAN '96 Conference on Programming Language Design and Implementation, 1996.

....by off loading responsibility from the interpreter: the instruction set and its approved usage are designed to reduce operand validation per executed instruction. Work at the University of Arizona and elsewhere seeks to further boost efficiency through the use of compilation techniques. Omniware [10] (object code) x X X Omniware portable object code depends on software based fault isolation (SFI) to enforce safety efficiently. It prescribes a set of rules that instruction sequences must adhere to, e.g. restrictions on how address arithmetic is performed. In conjunction with run time support, ....

Adl-Tabatabai, A., et al. Efficient and Language-Independent Mobile Programs. in ACM SIGPLAN Conference on Programming Language Design and Implementation (PLDI '96). 1996. Philadelphia, PA: ACM.

....autonomous systems is security. This is still an open problem and is an active area of research. It will be interesting to develop mobile object systems based on our technology. For example, if we combine our technology with mobile code techniques such as Java byte code [17] and OmniCode [1], the combination would enable native code objects to roam over the world in order to accomplish a given task. ....

A. Adl-Tabatabai, G. Langdale, S. Lucco, and R. Wahbe. Efficient and language-independent mobile programs. In Proc. of ACM Conf. on Programming Language Design and Implementations, pages 127--136, May 1996.

....a complex security model to the programmer [20] and does not support programs written in more common scripting languages. Research in safe programming languages is an important enabling technology for agent systems. The Safe Tcl and Java languages also offer restricted environments. Sandboxing [2] is an alternative to Python s restricted execution environment. Java has also been proposed as a language for agent programming, but the language itself does not provide necessary support services for agents. Using Java applets involve many of the same security concerns as agents [7] Several ....

A.-R. Adl-Tabatabai, G. Langdale, S. Lucco, and R. Wahbe. Efficient and language-independent mobile programs. In Proceedings of the ACM SIGPLAN '96 Conference on Programming Language Design and Implementation (PLDI), pages 127--136, May 1996.

....remote Just In Time compilation performance; but we overlap transfer with execution. 3 Non Strict Execution for Java To study the benefits of non strict execution we require a platform for mobile programs. Our methods can potentially be applied to any mobile program system (e.g. Omniware [1] or ActiveX [4] but we choose to use Java because of its widespread use and built in support for mobile programs. In this section we describe non strict execution and its implications for Java. Java is an object oriented language that enables remote execution by providing a platform independent ....

A. Adl-Tabatabai, G. Langdale, S. Lucco, and R. Wahbe. Efficient and language-independent mobile programs. In Programming Language Design and Implementation, May 1996.

....The JIT compiler must therefore generate extra conditionals in the inner loop of vector code. There are techniques for guaranteeing valid indices without requiring these extra conditionals, such as performing loop bounds analysis or exploiting virtual memory mechanisms for protection purposes [1], but to our knowledge these optimizations are not performed by any current JIT compiler. Note that we were unable to measure any extra compilation overhead incurred by the JIT compiler; this null result can probably be attributed entirely to the poor resolution of the PC clock. Finally, the JDK ....

A. Adl-Tabatabai, G. Langdale, S. Lucco, and R. Wahbe. Efficient and language-independent mobile programs. Technical Report CMU-CS-95-204, School of Computer Science, Carnegie Mellon University, October 1995.

....initial results for this work show overheads of roughly five percent to ten percent. A follow on to that work is the Omniware Portable Code system. The Omniware compiler generates portable code for an abstract virtual machine (OmniVM) which is translated to native fault isolated code at runtime [Adl96]. Along with the source language independence provided by software fault isolation techniques, the Omniware system also offers target independent portable code. Silver has developed a version of gcc which generates software fault isolated code for the DEC Alpha processor [Silver96] Most of the ....

Adl-Tabatabai, A., Langdale, G., Lucco, S., Wahbe, R., "Efficient and Language-Independent Mobile Programs," PLDI `96, Philadelphia, PA, 127136, May 1996.

.... portions of the interpreted program into native code, or by compiling to host machine level during load time or through binary translation, thereby eliminating the fetch decode overhead altogether [Bell 73, Klint 81, Deutsch Schiffman 84, Andrews Sand 92, Sites et al. 92, Cmelik Keppel 94, Adl Tabatabai et al. 96, Afzal et al. 96, Wilkinson 96] These optimizations will have varying degrees of success, depending on the interpreter and interpreted program. We therefore believe that efforts to build specialized hardware for interpreters may be premature; the greatest advance will come as the designers of ....

Adl-Tabatabai, A., Langdale, G., Lucco, S., and Wahbe, R. Efficient and Language-Independent Mobile Programs. In Proceedings of the 1996 ACM Symposium on Programming Languages Design and Implementation, pages 127--136, May 1996.

....requirements to make judicious decisions about placement of computation and data. Many systems provide some form of support for program mobility. The simplest form of support is the ability to download code and execute it to completion at a single site as provided by systems like Omniware [4], Safe TCL [7] Java [13] Other systems like Avalon [11] NCL [12] REV [17] and Obliq [10] allow programs in execution to initiate computation on remote nodes and wait for their completion. The most sophisticated support is provided by systems like Agent TCL [14] Emerald [16] Mole [22] Aglets ....

....our initial experience with a prototypical application that combines and composes weather images from multiple geographically distributed sources. In this paper, we assume that the reader is familiar with mobile code languages. For introduction to mobile code languages and mobility mechanisms, see [4, 7, 10, 11, 12, 13, 14, 15, 16, 20, 17, 22, 24]. 2 Design constraints In this section, we discuss the language design constraints that arise from the desire to be resource aware and the use of mobility as a mechanism to adapt to changes in resource availability. We discuss the requirements of awareness, agility and authority and the ....

A. Adl-Tabatabai, G. Langdale, S. Lucco, and R. Wahbe. Efficient and Language-Independent Mobile Programs. In Proceedings of the SIGPLAN'96 Conference on Programming Language Design and Implementation, pages 127--36, May 1996.

....and scalability than monolithic virtual machines where all components reside on all clients. 1. Introduction Virtual machines have evolved significantly in the last two decades to emerge as the prevailing network computing platform. Modern virtual machines [Lindholm Yellin96, Inferno, Adl Tabatabai et al. 96] offer much more sophisticated services compared to their predecessors [IBMVM86] Today s virtual machines (VMs) provide safety guarantees, dynamic extensibility, on the fly compilation, configurable security policies, and resource management facilities. Research trends indicate that these ....

Adl-Tabatabai, A., Langdale, G., Lucco, S. and Wahbe, R. "Efficient and LanguageIndependent Mobile Programs." PLDI, May, 1996, p. 127-136.

....of our nested process architecture is a well defined subset of the x86 architecture, allowing all processes to run with no instruction emulation on x86 machines. However, other processor architectures could be used just as easily, including purely emulation based instruction sets such as Omniware [2] or Java bytecode [25] The only restriction is that application processes must only use the subset of the instruction set that satisfies the properties described in Section 3; otherwise they may not function properly in virtualized environments. The instructions compilers produce generally ....

A. Adl-Tabatabai, G. Langdale, S. Lucco, and R. Wahbe. Efficient and Language-Independent Mobile Programs. In Proc. ACM SIGPLAN Symp. on Programming Language Design and Implementation,

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A. Adl-Tabatabai, G. Langdale, S. Lucco, and R. Wahbe. Efficient and Language-Independent Mobile Programs. Conference on Programming Language Design and Implementation, p. 127--136, Philadelphia, PA, May 1996.

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