MDSplus Tom Fredian MIT 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 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 button popup menu Command Window Icons for Node 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? – –