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Middleware

Overview

The SACCOM project (“Soft Actuation over Cooperating Objects Middleware”) aims to interface the POBICOS platform on the Guildford Smart Campus testbed in order to perform two experiments: the POBICOS middleware experiment and the Soft-Actuation experiment [1].

The POBICOS proxy is the POBICOS middleware run as a process on a typical PC, on top of a host OS (usually Linux). The middleware code executed by the proxy is identical (at the source code level) to that running on a native WSAN POBICOS node. The proxy exposes one “legacy node” to the application layer. The legacy node paired with its POBICOS proxy act together as a fully operational POBICOS node, capable of running POBICOS applications and of interacting with the physical environment via sensors and actuators. The POBICOS proxy includes a TinyOS hardware resources emulation layer; this makes it possible to use the same TinyOS-based POBICOS code for the proxy and the native POBICOS node. The Linux operating system, for which the emulation layer has been created, provides services used to implement functionalities available in physical TinyOS motes. For example, the inter-proxy communication is emulated using TCP/IP. Multiple proxies run concurrently on a single PC; together they expose a multi-node legacy network. Jointly, the POBICOS proxies, as well as a number of infrastructural services, form a centralized runtime system called the POBICOS Proxy Environment (PPE). PPE preserves the original POBICOS programming model and API; applications developed for the native, mote-based, wireless sensor/actuator POBICOS network can run on PPE. The POBICOS application is composed of so-called micro-agents (or simply – agents). The micro-agents of a given application are organized in a tree. Accordingly, one can talk about parent and child agents, as well as the root agent. A micro-agent uses the POBICOS API by invoking instructions and receives events. For example, some instructions and events make it possible for agents to communicate, by exchanging messages (an agent communicates only with its parent and children). Other instructions and events refer to (represent) the hosting node’s sensors and actuators. At runtime, micro-agents are hosted by POBICOS nodes (in the case of PPE – proxies). Usually, an application is spread over multiple nodes (proxies). A POBICOS proxy itself does not have any sensors or actuators directly available; instead it uses the sub-POBICOS protocol to access sensors and actuators of the underlying legacy node. For this to be possible, the legacy node must run an implementation of the sub-POBICOS protocol; a node exposing its sensors and actuators via this protocol is referred to as a sub-POBICOS node (SPN).

The described POBICOS architecture is reported in Figure below.

Attach:pobicos.png Δ

References

[1] SACCOM D1.3 Final Report on Experimentation and Potential Improvements: Jarosław Domaszewicz,Tomasz Tajmajer,Aleksander Pruszkowski,Jolanta Kowal,Sławomir Kula,Spyros Lalis,Manos Koutsoubelias,Nasos Grigoropoulos,Kostas Lekkas

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Page last modified on July 16, 2013, at 11:41 AM