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Enhanced Directory Service

Enhanced Directory Service. Ralph Lange EPICS Collaboration Meeting October 11, 2009. It’s a Flat Channel Name World. All Channel Access clients need to know all channel names beforehand High Level Apps either need a full configuration or a framework-supplied directory

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Enhanced Directory Service

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  1. Enhanced Directory Service Ralph Lange EPICS Collaboration Meeting October 11, 2009

  2. It’s a Flat Channel Name World • All Channel Access clients need to know all channel names beforehand • High Level Apps either need a full configuration or a framework-supplied directory • Portable generic applications are restricted to simple tasks

  3. Idea: ChannelFinder Directory Service • Some background database • Contains Channel Names and theirProperties (list of Name/Value pairs) • May dump/load contents for persistence • Web Service • Matches property values andreturns a list of channels on GET • Creates/Updates entries on PUT/POST • Data format: XML or JSON

  4. Filling the Directory • IRMIS or other RDB systems Geographical, hierarchical, engineering,physics data • DB file parser (PV names, attributes) If you have a good naming convention • Control room applications ”Joe’s favorite channels”

  5. Querying the Directory Client connects in three steps: • Query Directory Service Specify expressions for property match Get list of channels • Query Nameserver Specify list of channels Get channels’ IOCs • Connect and subscribe

  6. Application Examples • Waterfall Plots • Scripts • Generic applications • Table-style panels • Archive clients

  7. Implementation Ideas ChannelFinder PoP implementation • Based on Java/Netbeans/JAXB/Glassfish/MySQL • Test database contains 150k channels w/ 7 properties each • Getting 2k channels w/ properties in ~0.1 sec • JPA classes create inefficient SQL for matching requests, will switch to JDBC or use in-memory table

  8. Implementation Ideas Nameserver Develop the JLab (now APS) nameserver to • Use a fast distributed network cache database (memcached) for persistence and redundancy • Do block requests to the database (i.e. not use PCAS) • Require minimal configuration • Separate IOC shutdown detection

  9. Project Status and Schedule • Currently in design phase • Work by Gabriele Carcassi, Don Dohan (IRMIS), Ralph Lange (Web Service), KunalSchroff (Apps) • Expected to be working summer 2010

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