A methodology for string resolution

In this paper we present a methodology, not a tool. We present this methodology with the intent that it be adopted, on a case by case basis, by each of the existing tools in EPICS. In presenting this methodology, we describe each of its two components in detail and conclude with an example depicting how the methodology can be used across a pair of tools. The task of any control system is to provide access to the various components of the machine being controlled, for example, the Advanced Photon Source (APS). By access, we mean the ability to monitor the machine`s status (reading) as well as the ability to explicitly change its status (writing). The Experimental Physics and Industrial Control System (EPICS) is a set of tools, designed to act in concert, that allows one to construct a control system. EPICS provides the ability to construct a control system that allows reading and writing access to the machine. It does this through the notion of databases. Each of the components of the APS that is accessed by the control system is represented in EPICS by a set of named database records. Once this abstraction is made, from physical device to named database records, the process of monitoring and changing the state of that device becomes the simple process of reading and writing information from and to its associated named records

BURT: back up and restore tool

BURT is just one of the tools in the Experimental Physics Industrial Control System (EPICS). In this document we address the problem of backing up and restoring sets of values in databases whose values are continuously changing. In doing so, we present the Back Up and Restore Tool (BURT). In this presentation we provide a theoretical framework that defines the problem and lays the foundation for its solution. BURT is a tool designed and implemented with respect to that theoretical framework. It is not necessary for users of BURT to have an understanding of that framework. It was included in this document only for the purpose of completeness. BURT`s basic purpose is to back up sets of values so that they can be later restored. Each time a back up is requested, a new ASCII file is generated. Further, the data values are stored as ASCII strings and therefore not compressed. Both of these facts conspire against BURT as a candidate for an archiver. Users who need an archiver should use a different tool, the Archiver

EZCA primer

This document provides a quick introduction to EZCA, a library that was designed to provide an easy to use interface to Channel Access (CA). As such, this document is not a user`s manual, where a more detailed explanation of EZCA can be found. In short, this document is designed to get users to a state where they can be writing EZCA code as quickly as possible. It is not a document that answers all EZCA questions

A framework for back-up and restore under the Experimental Physics and Industrial Control System

EPICS is a system that allows one to design and implement a controls system. At its foundation, i.e., the level closest to the devices being controlled, are autonomous computers, each called an Input/Output Controller or IOC. In EPICS, devices controlled by an IOC are represented by software entities called process variables. All devices are monitored/controlled by reading/writing values from/to their associated process variables. Under this schema, distributing processing over a number of IOCs and representing devices with process variables, there are a variety of ways one can view or group the information in the control system. Two of the more common groupings are by IOC (location) and by devices (function). Simply stated, the authors require a system capable of restoring the state of the machine, in their case the Advanced Photon Source, to a known desired state from somewhere in the past. To that end, they propose a framework which describes a system that periodically records and preserves the values of key process variables so that later on, those values can be written to the machine in an attempt to restore it to that same state. One of the more powerful notions that must be preserved in any system that solves this problem is the independence between the specification of what is monitored and the specification of what is written. In other words, grouping process variables for monitoring must be kept independent of the number of different ways to group process variables (e.g., by IOC, by device, etc.) when they are written

Identifying Logical Homogeneous Clusters for Efficient Wide-area Communications

Recently, many works focus on the implementation of collective communication operations adapted to wide area computational systems, like computational Grids or global-computing. Due to the inherently heterogeneity of such environments, most works separate "clusters" in different hierarchy levels. to better model the communication. However, in our opinion, such works do not give enough attention to the delimitation of such clusters, as they normally use the locality or the IP subnet from the machines to delimit a cluster without verifying the "homogeneity" of such clusters. In this paper, we describe a strategy to gather network information from different local-area networks and to construct "logical homogeneous clusters", better suited to the performance modelling.Comment: http://www.springerlink.com/index/TTJJL61R1EXDLCM

Links in a distributed database: Theory and implementation

This document addresses the problem of extending database links across Input/Output Controller (IOC) boundaries. It lays a foundation by reviewing the current system and proposing an implementation specification designed to guide all work in this area. The document also describes an implementation that is less ambitious than our formally stated proposal, one that does not extend the reach of all database links across IOC boundaries. Specifically, it introduces an implementation of input and output links and comments on that overall implementation. We include a set of manual pages describing each of the new functions the implementation provides

MGF: A Grid-Enabled MPI Library with a Delegation Mechanism to Improve Collective Operations

Abstract. The success of Grid technologies depends on the ability of libraries and tools to hide the heterogeneous complexity of Grid systems. MPI-based programming libraries can make this environment more accessible to developers with parallel programming skills. In this paper we present MGF, an MPI library which extends the existing MPICH-G2. MGF aims are: to allow parallel MPI applications to be executed on Grids without source code modifications; to give programmers a detailed view of the execution system network topology; to use the most efficient channel available for point-to-point communications and finally, to improve collective operations efficiency introducing a delegation mechanism