MDSplus

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MDSplus

• Tom Fredian
• MIT Plasma Science and Fusion Center

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What is MDSplus?

• Data Acquisition System
• Remote Data Access System
• Data Visualization and Analysis System
• Data available via fortan, c, c, java,
  idl,matlab, visual basic, labview, php, python
• Data Archival System

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History

• Designed and developed for use on Alcator C-Mod,
  RFX and ZTH between 1987-1991 to run on OpenVMS
  platform
• Remote data access from wide variety of platforms
  added 1994
• Ported to Unix/Windows 1999
• Added Globus Security Infrastructure 2002
• Based on X.509 identity certificates

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MDSplus is Widely used in the Fusion Community
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MDSplus Worldwide

• MDSplus currently installed at over 30
  experiments, fusion laboratories and
  universities.
• Most widely used tool for accessing fusion
  related data.
• Over 3000 downloads of the MDSplus software.

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MDSplus

• Data Acquisition
• MDSplus typically used in pulse mode
• DAQ Device support developed as needed
• Remote data access
• Simple efficient data access on the LAN
• Secure authenticated data access on the WAN
• Visualization Tools
• dwscope jScope
• IDL, MATLAB, python, PHP interfaces (and more)

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Data Storage

• The information about each pulse is stored in a
  hierarchical structure.
• Diagnostic / Data analysis setup
• Machine Control
• Task scheduling
• Raw and Analyzed results
• Calibration information
• Data longevity
• All of the data from a diagnostic is stored in an
  organized way.
• This provides a mechanism for the data from a
  diagnostic to be self descriptive.
• One set of tools can be used to operate on both
  data and setup information.
• Concurrent multi-user read and write

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Traverser
Icons for Node usage
Expandable Node
Right button popup menu
Command Window
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Complex Data types

• In addition to a wide selection of primitive data
  types (byte, word, long, float, double, complex,
  etc...) MDSPlus supports data types to store
  commonly used combinations of items.
• Signal (scaled data, raw data, dimension_0
  ,dimension_1 )
• Subscripting both arrays and signals
• With_units(item, units)
• Range - start end increment
• Action(dispatch, task)
• Dispatch(1, ident, phase, when, notify)
• etc

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Expressions
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Homogeneous Data Access Interface

• MdsConnect,hostport
• MdsOpen, tree, shot
• var MdsValue(expression ,args)
• MdsPut, name, expression ,args
• MdsClose , tree, shot
• MdsDisconnect

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Remote Access - details

• Types of client/server connections
• MdsConnect thin client
• One server process per client connection
• Server activated by inetd
• Expression evaluation done in server process ctx
• TreeOpen thick client
• One server process per client per tree host
• Server activated by inetd
• Expression evaluation done in client process ctx

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MDSplus Data Gateway

• MDSplus is sometimes used as a gateway to other
  data stores.
• Expression evaluation can call into local shared
  libraries to retrieve or put data.

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Secure WAN Access

• MDSplus network protocol (MDSIP) layered on top
  of Globus GSI using XIO
• X509 Credentials used to authenticate both client
  and server.
• Centralized management of access control via ROAM
  (Resource Oriented Authentication Manager)

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ROAM used to solve authorization problem

• Resource Oriented Authorization Manager (ROAM)
  provides a central location for authorization
  information
• Administrators other stakeholders can control
  access
• Users can request access

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ROAM data model is fundamental to a coherent
picture of authorization in the grid

• Oriented around resources codes, databases,
  entire sites

• If you have to sign a paper to get permission to
  use something, then its probably a resource
• Resources have associated permissions
• e.g. execute for a code, access for a site

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People interact with ROAM through a web page

• An interactive web page allows users and resource
  owners to request and grant permissions

• Less error-prone than editing text files
• No more grid-mapfiles!
• Can take the place of mdsip.hosts for MDSplus

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Potential use of MDSplus at FNAL

• Transfer of CERN control data to FNAL
• Push or pull data?
• Client application running at CERN gathering data
  and writing it securely to MDSplus data storage
  at FNAL
• MDSplus data server running at CERN with access
  to control data accessible securely via client at
  FNAL
• How much data? How often?
• MDSplus is currently pulse based. Not designed
  for trending data (yet).
• Extensions for long pulse/continuous data to be
  explored either via the Collaborative
  Technology SCIDAC proposal or ITER projects.
• What type/structure of data? How will it be
  accessed?

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Other topics (if time)

• Electronic Logbook (quick demo)
• MDSplus in action (C-Mod)
• 2GB/shot (uncompressed) 15 minute rep-rate
• 82,000 tree nodes in each data set (directories
  and files)
• Expressions examples for gateways

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Summary

• MDSplus used at most fusion research sites.
• Useful for handling some types of HEP data?
• Next Steps?
• http//www.mdsplus.org/
• http//www.fusiongrid.org/
• twf_at_psfc.mit.edu