Current trends in real-time systems identify java as a new alternative to develop both centralized and distributedreal-time systems. Many efforts have been devoted to develop the real-time Specification for java (RTS...
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Current trends in real-time systems identify java as a new alternative to develop both centralized and distributedreal-time systems. Many efforts have been devoted to develop the real-time Specification for java (RTSJ), and there is substantial ongoing activity to produce a straightforward and valuable distributedreal-time Specification for java (DRTSJ). The current paper provides a contribution to this latter activity defining, from different angles, a synchronous scheduling service aligned with principles of some popular real-time architectures. This service orchestrates the system in such a way that it provides end-to-end guarantees in the distributed transactions, guaranteeing their timely execution across the network and nodes. The service is described from two points of view: the system one, characterizing a portable model;and the programmer one, defining a distributed object-oriented implementation of a model based on real-time Remote Method Invocation (RTRMI). Finally, it also presents results of an implementation carried out to judge the efficiency of the service, offering a preliminary predictability and performance assessment of a distributed real-time java technology.
This article presents an approach to providing real-time support for java's Remote Method Invocation (RMI) and its integration with the RTSJ memory model in order to leave out garbage collection. A new construct f...
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This article presents an approach to providing real-time support for java's Remote Method Invocation (RMI) and its integration with the RTSJ memory model in order to leave out garbage collection. A new construct for remote objects, called No-heap Remote object (NhRo), is introduced. The use of a NhRo guarantees that memory required to perform a remote invocation (at the server side) does not use heap memory. Thus, the aim is to avoid garbage collection in the remote invocation process, improving predictability and memory isolation of distributedjava-based real-time applications. The article presents the bare model and the main programming patterns that are associated with the NhRo model. Sun RMI implementation has been modified to integrate the NhRo model in both static and dynamic environments.
More and more, the use of real-time distribution middlewares programmed with high-level languages like java is becoming of interest for industrial systems because this type of infrastructures reduce development effort...
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More and more, the use of real-time distribution middlewares programmed with high-level languages like java is becoming of interest for industrial systems because this type of infrastructures reduce development efforts required to both design and maintain complex networked applications. In that way towards having better development tools, this paper deals with the very specific issue of the asynchronism from the particular perspective of java's distributed technologies. It proposes and evaluates an extension to the java's Remote Method Invocation (RMI) with additional support for asynchronous remote invocations. Such a mechanism makes the transmission of some messages, typically those that do not require any confirmation from the server, much more efficient than synchronous communications, and consequently they optimize and speed up the performance of many industrial networked applications. In more detail, this paper concerns with the model itself and the set of changes it requires within their middleware programming interfaces and inside communication protocols to accommodate the proposed model. The proposal is supported by empirical evidences from a prototype developed as partial proof-of-concept.
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