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AMGA Metadata Services: examples and usage scenarios

AMGA Metadata Services: examples and usage scenarios. Tony Calanducci INFN Catania Itacuruca, 04-15 December 2006. Outline. AMGA Basics Metadata concepts and AMGA terminology Collection and Schema management Queries Command Line Tools and API

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AMGA Metadata Services: examples and usage scenarios

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  1. AMGA Metadata Services: examples and usage scenarios Tony Calanducci INFN Catania Itacuruca, 04-15 December 2006

  2. Outline • AMGA Basics • Metadata concepts and AMGA terminology • Collection and Schema management • Queries • Command Line Tools and API • Use AMGA to exchange data among running grid jobs • Secure access to metadata EGRIS-1

  3. Metadata concepts and terminology • Entries – Entities/Objects which we are attaching metadata to • Metadata - List of attributes (including their values) associated with entries • Schema – A set of attributes • Attribute – key/value pair • Type – The type (int, float, string,…) • Name/Key – The name of the attribute • Value - Value of an entry's attribute • Collection – A set of entries associated with a schema (AMGA Collection are hierarchical organized) • Analogy to the RDBMS world: think of collections as tables, attributes as columns, entries as rows EGRIS-1

  4. Example: Movie Trailers • Movie trailers files saved on Grid Storage Elements and registered into a LFC File Catalogue • We have a LFN (Logical File Name) per movie files • We want to add metadata to describe movie content. Possible schema: • Title -- varchar • Rutime -- int • Cast -- varchar • LFN -- varchar • AMGA will be the repository of the movies’ metadata EGRIS-1

  5. gMOD: grid Movie On Demand • gMOD provides a Video-On-Demand service • User chooses among a list of video and the chosen one is streamed in real time to the video client of the user’s workstation • For each movie a lot of details (Title, Runtime, Country, Release Date, Genre, Director, Case, Plot Outline) are stored and users can search a particular movie querying on one or more attributes • Two kind of users can interact with gMOD: TrailersManagers that can administer the db of movies (uploading new ones and attaching metadata to them); GILDA VO users (guest) can browse, search and choose a movie to be streamed. EGRIS-1

  6. gMOD under the hood • Built on top of gLite services: • Storage Elements, sited in different place, physically contain the movie files • LFC, the File Catalogue, keeps track in which Storage Element a particular movie is located • AMGA is the repository of the detailed information for each movie, and makes possible queries on them • The Virtual Organization Membership Service (VOMS) is used to assign the right role to the different users • The Workload Management System(WMS) is responsible to retrieve the chosen movie from the right Storage Element and stream it over the network down to the user’s desktop or laptop EGRIS-1

  7. CE WN WN WN LFC File Catalogue Metadata Catalogue gMOD interactions VOMS Storage Elements Genius Portal AMGA get Role User Workload Management System EGRIS-1

  8. gMOD screenshot gMOD is accesible through the Genius Portal (https://glite-tutor.ct.infn.it) EGRIS-1

  9. Accessing AMGA services from UI/WNs • Command Line Tools: • mdclient (interactive, like mysql & psql CLI) • mdcli (run one single command, useful into scripts) • APIs: • C++ • Java • Python/Perl/PHP • Client configuration file: • /opt/glite/etc/mdclient.config (default for all UI users) • $HOME/.mdclient.config (overrides the default one) • My suggestion, copy the default into $HOME/.mdclient.config and customize it • Useful options to set up: • Host = egris196.eela.ufrj.br • Login = NULL (or your AMGA username we’ve created: itacurucaXX) • UseSSL = require • AuthenticateWithCertificate = 1 • UseGridProxy = 1 EGRIS-1

  10. Accessing AMGA services from UI/WNs • Be sure you have a valid proxy • with VOMS extensions if you set up Login = NULL (authenticated as the gilda generic user….all VO users will see your entries) • if you set up Login = yourusername the VOMS extensions will not take into account (so do not care about them) • Start the AMGA client with • $ mdclient • Try • whoami • pwd • help • grp_member EGRIS-1

  11. AMGA Basic Commands(I) • Entries/Collection listing • dir • ls (ls -l) • Entries/Collection permissions • acl_show entry | collection • stat entry | collection • Collection and schema creation : • createdir collection_pathname • createdir /egris/yoursurname • cd collection_pathname) --- change the current collection • cd /egris/yoursurname • createdir trailers • cd trailers • addattr dir attr_name attr_type • addattr . Title varchar • addattr . Runtime int • addattr . Cast varchar • addattr . LFC varchar EGRIS-1

  12. AMGA Basic Commands (II) • Inspecting collection’s schema: • listrattr fullpath_collectioname • (listrattr /egris/yoursurname/trailers • Sequence managements: • they are used to create autoincremental IDs • sequence_create seq_name dir [increment] [start value] • sequence_create seq1 /egris/yoursurname/trailers • sequence_next seq_name • sequence_next /egris/yoursurname/trailers/seq1 • Entries creations: • addentries entry_name (attribute_name value)+ • cd /egris/yoursurname/trailers • addentry 1 Title 'Matrix' Runtime 110 Cast 'Keanu Reeves‘ LFN 'lfn:/grid/gilda/tony/matrix.mov‘ • addentry 2 Title 'Notting Hill' Runtime 99 Cast 'Julia Roberts, Hugh Grant' LFN 'lfn:/grid/gilda/tony/notting.mov‘ • addentry 3 Title 'Anger Management' Runtime 120 Cast 'Adam Sandlan, Jack Nicholson' LFN 'lfn:/grid/gilda/scardaci/anger.mov' EGRIS-1

  13. Other basic useful commands • Set/edit attributes values: • setattr entry (attribute value)+ • Get attributes values: • getattr pattern (attribute)+ • getattr /egris/yoursurname/trailers/ Title LFN • Removing attributes • removeattr dir attr_name • Removing entries • rm pattern EGRIS-1

  14. Making queries • AMGA provides a SQL-like selectattr statement: • selectattr attrs... condition • where: • attrs is a space-separated list of attributes with the following format: collection_name:attribute_name (ex.: /egris/yoursurname/trailers:Title) • condition rapresents one or more condition to select entries. Allowed operators are comparison operator (<,>,=), logical operator (and, or), various operator (like, limit), etc..There is support also for aggregator operator (count) and order clause. • ex: • selectattr /egris/yoursurname/trailers:Title .:LFN 'like(Title, "Anger%")' • selectattr /egris/yoursurname/trailers:Title .:LFN .:Cast 'like(Cast, "%ndle%") and Runtime > 80' EGRIS-1

  15. Updating attributes on condition • selectattr and setattr can be used to update entries attributes’ values • updateattr allows to do multiple updating on condition and ATOMICALLY • updateattr pattern attr expression [attr expression]... condition • ex: • getattr /egris/yoursurname/trailers/ Runtime >> 2 >> 99 >> 1 >> 111 >> 3 >> 121 • updateattr /egris/yoursurname/trailers/ Runtime Runtime+1 'Runtime > 100‘ • getattr /egris/yoursurname/trailers/ Runtime >> 2 >> 99 >> 1 >> 112 >> 3 >> 122 EGRIS-1

  16. Access AMGA from WNs with mdcli • All commands available through mdclient can be issued with mdcli <command>. This will: • connect to the AMGA server defined into mdclient.config • run the command • exit to the shell • Very useful in shell script (ex. the one running in the WN during job execution) • Ex: • ID=`mdcli sequence_next /egris/yoursurname/seq1` • mdcli addentry /egris/yoursurname/${ID} LFN \'${LFN}\' Analyzed 0 • LFN=`mdcli selectattr $AMGA_HOME:LFN \'$AMGA_HOME:FILE = ${ID}\'` • N.B.: If you need to use single quote, escape them with \ EGRIS-1

  17. Use AMGA to exchange data among running jobs • Suppose we have two sets of jobs: • Producers: they generate a file, store on a SE, register it onto the LFC File Catalogue assigning a LFN • Consumers: they will take a LFN, download the file and elaborate it • AMGA can be used to share the information generated by the Producers, it could act as a “bag-of-LFNs” (bag-of-task model) from which Consumers can fetch file for further elaboration EGRIS-1

  18. Producers-Consumers example • Set up of the collection containing the “tasks” • createdir /egris/youraccount/tasks • cd /egris/youraccount/tasks • addattr . LFN varchar(255) • addattr . Analyzed int • addattr . MagicNumber int • listattr . >> LFN >> varchar(255) >> Analyzed >> int >> MagicNumber >> int • sequence_create seq1 /egris/youraccount/tasks EGRIS-1

  19. Producers-Consumers example • Producers script excerpts: • #Produce your data and save it on the SE and reg on LFC • LFN=‘lfn:/grid/gilda/tony/bomdia.txt’ • ID=`mdcli sequence_next /egris/yourname/tasks/seq1` • mdcli addentry /egris/yourname/tasks/${ID} LFN \'${LFN}\' Analyzed 0 • Consumers script excerpts: • AMGA_HOME=/egris/yoursurname/tasks • ID=`mdcli selectattr$AMGA_HOME:FILE \'$AMGA_HOME:Analyzed = 0\' | head -1` • if [ $ID ]; then; echo “Task to be processed found“; else; exit 1; fi • MAGIC=`echo $RANDOM` • mdcli updateattr $AMGA_HOME/$ID Analyzed 1 MagicNumber $MAGIC \'Analyzed = 0\' • MAGIC2=`mdcli selectattr $AMGA_HOME:MagicNumber \'$AMGA_HOME:FILE = ${ID}\'` • if [ $MAGIC=$MAGIC2 ]; then LFN=`mdcli selectattr $AMGA_HOME:LFN \'$AMGA_HOME:FILE = ${ID}\'` • else; echo "Entry already processed by someone else“; exit 1; fi • lcg-cp -v --vo gilda $LFN file:$PWD/temp.dat • #Consume your data EGRIS-1

  20. Demo • Thanks to Fabio for the creations of the scripts!!! EGRIS-1

  21. Secure your metadata • AMGA allows to restrict access to a collection (or even to specific entries) using ACLs. This can be done thanks to the commands provided to manage groups of users. • Here there are some useful commands: • whoami -- Print the name of the current user • user_listcred user -- Lists all possible credentials of a user. Only root can inspect other's credentials. • grp_member -- Lists the groups a user belongs to • acl_show colletionpath -- Shows all access controls for a directory • grp_create groupname -- Creates a new group. The group created will have the following name owner:groupName • grp_adduser groupname user -- Adds a user to a group • grp_show groupname -- Lists the members of a group • acl_add directory group rights -- Adds a new access control to a directory granting a group certain rights • acl_remove directory group -- Removes an access control for a group from a directory EGRIS-1

  22. References • AMGA Project Homepage • http://amga.web.cern.ch/amga/ • AMGA 1.2.7 User Manual • http://amga.web.cern.ch/amga/downloads/amga-manual_1_2_7.pdf • Exercise documentation from ISSGC’06: • http://www.dma.unina.it/~murli/ISSGC06/glite/public_html/amga.html • http://www.dma.unina.it/~murli/ISSGC06/glite/public_html/summaryExercise.htm • AMGA GILDA Wiki pages: • https://grid.ct.infn.it/twiki/bin/view/GILDA/AMGAHandsOn • https://grid.ct.infn.it/twiki/bin/view/GILDA/AMGAAdv EGRIS-1

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