MDSplus

Tom FredianMIT Plasma Science and Fusion Center

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

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

MDSplus is Widely used in the Fusion Community

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.

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)

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

Traverser

Right buttonpopup menu

CommandWindow

Icons forNode usage Expandable

Node

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…

Expressions

Homogeneous Data Access Interface

• MdsConnect,host[:port]

• MdsOpen, tree, shot

• var = MdsValue(expression [,args…])

• MdsPut, name, expression [,args…]

• MdsClose [, tree, shot]

• MdsDisconnect

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

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.

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)

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

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

• If you have to sign a paper to get permission to use something, then it’s probably a resource

• Resources have associated permissions– e.g. “execute” for a

code, “access” for a site

• Oriented around resources: codes, databases, entire sites

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

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?

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

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@psfc.mit.edu