Extended portal: violating the assignment rule and enforcing the single parent rule

  • Authors:
  • Pablo Basanta-Val;Marisol García-Valls;Iria Estevez-Ayres;Carlos Delgado-Kloos

  • Affiliations:
  • Universidad Carlos III de Madrid, Avda. de la Universidad, Leganés (Madrid) Spain;Universidad Carlos III de Madrid, Avda. de la Universidad, Leganés (Madrid) Spain;Universidad Carlos III de Madrid, Avda. de la Universidad, Leganés (Madrid) Spain;Universidad Carlos III de Madrid, Avda. de la Universidad, Leganés (Madrid) Spain

  • Venue:
  • JTRES '06 Proceedings of the 4th international workshop on Java technologies for real-time and embedded systems
  • Year:
  • 2006

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Abstract

One of the main drawbacks of programming with the RTSJ (The Real-time Specification for Java) is probably its special model of references. The restrictions imposed by the assignment and single parent rules constrains the programming model in such a way that it is sometimes more difficult to use than the Java one. The community has faced this problem producing a special and new set of programming paradigms and patterns, designed to be used in collaboration with the region-based model; this enhances the range of application that may be constructed with it. However, the current version of RTSJ does not have general mechanisms that enable to perform safe violations of the assignment rule in an easy way.In this paper, we address this issue by introducing a new extension named extended portal. This extension (that has an interface that is very close to the current RTSJ portals) introduces mechanisms that allow a safe violation of the assignment rules, providing also an easy navigation mechanism for accessing the creation context of an object. Using this extension, the programmer can have access to a forbidden reference in two steps, reducing the complexity from Θ (n) of the current portals to Θ (1) of the extended ones. The work is mainly concentrated on the justification of the utility and feasibility of the extension. To clarify this idea, an example that illustrates the drawbacks of the current portals and the benefits of the extended ones is described. Also, a Java interface and a set of low level changes required at the implementation level are explained.