Hands-on experiments prepare students to deal with real-world problems and help to efficiently digest theoretical concepts and relate those to practical tasks. However, shortage of equipment, high costs, and the lack of human resources for laboratory maintenance and assistance decrease the implementation capacity of the hands-on training laboratories. At the same time, the Internet has become a common networking medium and is increasingly used to enhance education and training. In addition, experimental equipment at many sites is typically underutilized. Thus, remote laboratories accessible through the Internet can resolve cost and access constraints as they can be used at flexible times and from various locations. While many solutions have been proposed so far, this paper addresses an important issue of facilitating remote lab deployments by providing remote connectivity services to lab providers using a Relay Gateway Server architecture. A proof-of-concept solution is described which also includes other previously reported useful features. The system has been tested in engineering labs and student assessment is provided.

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SUMMARYThe semantics of the Java programming language require that the out-of-bounds array accesses be caught at runtime. In general, this requires dynamic checks at the time the array element is accessed. Some of these checks can be eliminated statically during just-in-time (JIT) compilation, but the most precise analyses are too expensive to run in JIT compilers. This paper presents a framework in which thorough static range analyses can be used safely during the less-performance-critical compilation of Java source into machine-independent mobile code. In this framework, the static analysis results are used to derive proofs that certain linear inequality constraints hold. These linear constraints and their proofs are then added to the mobile code as annotations. The annotation framework is designed so that proofs can be verified efficiently. This allows the JIT compiler to safely eliminate array bounds checks during compilation without an expensive runtime analysis. Experiments with a prototype system that can generate and verify these annotations demonstrate that this framework is more precise than prior work and that verification is efficient.

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