Information and Monitoring The European DataGrid Project Team

EU DataGrid: Information and Monitoring 2 Contents u Grid Information Systems u GMA and R-GMA u Tools and APIs

EU DataGrid: Information and Monitoring 3 Features of a grid information system u Provides information on both: n The Grid itself s Mainly for the middleware packages s The user may query it to understand the status of the Grid n Grid applications s For users u Flexible infrastructure n Able to cope with nodes in a distributed environment with an unreliable network n Dynamic addition and deletion of information producers n Security system able to address the access to information at a fine level of granularity n Allow new data types to be defined n Scaleable n Good performance n Standards based

EU DataGrid: Information and Monitoring 4 GMA u From GGF u Very simple model u Does not define: n Data model n Data transfer mechanism n Registry implementation Producer Consumer Registry Store location Lookup location execute or stream

EU DataGrid: Information and Monitoring 5 R-GMA u Use the GMA from GGF u A relational implementation n Powerful data model and query language s All data modelled as tables s SQL can express most queries in one expression u Applied to both information and monitoring u Creates impression that you have one RDBMS per VO Producer Consumer Registry Store location Lookup location execute or stream

EU DataGrid: Information and Monitoring 6 Relational Data Model in R-GMA u Not a general distributed RDBMS system, but a way to use the relational model in a distributed environment where global consistency is not important u Producers announce:SQL “CREATE TABLE” publish:SQL “INSERT” u Consumers collect:SQL “SELECT” u Some producers, the Registry and Schema make use of RDBMS as appropriate – but what is central is the relational model u All R-GMA tuples are time-stamped

EU DataGrid: Information and Monitoring 7 Example: 2 tables u Service u ServiceStatus URIVARCHAR(255) URI to contact the service VOVARCHAR(50) Where info should be published – or an empty string to indicate all typeVARCHAR(50)Type of service Contact VARCHAR(50)The of a human being to complain to siteVARCHAR(50) Domain name of site hosting the service secure VARCHAR(1)‘y’ or ‘n‘ - indicates whether or not this is a secure service majorVersionINTVersion of protocol not implementation minorVersionINTVersion of protocol not implementation patchVersionINTVersion of protocol not implementation URIVARCHAR(255) URI to contact the service statusINTstatus code. 0 means the service is up. messageVARCHAR(255)Message corresponding to status code

EU DataGrid: Information and Monitoring 8 SQL example 1 u SELECT DISTINCT type FROM Service | type | | GridFTP | | GRIS | | RFIO | | R-GMA.ResilientStreamProducerService | | R-GMA.ArchiverService | | R-GMA.StreamProducerService | | R-GMA.CanonicalProducerService | | R-GMA.DBProducerService | | R-GMA.LatestProducerService | | GIN | | R-GMA.RegistryService | | R-GMA.SchemaService | | R-GMA.BrowserService | | GOUT | | edg-netmon | | edg-iperf | | edg-udpmon | | myproxy | | edg-pinger | Rows in set

EU DataGrid: Information and Monitoring 9 SQL Example 2 SELECT Service.site, ServiceStatus.status, ServiceStatus.message, Service.URI FROM Service,ServiceStatus WHERE Service.URI = ServiceStatus.URI AND ServiceStatus.status <> 0 AND Service.Type = 'GIN' | site | status | message | URI | | nikhef.nl | 2 | Gin is stopped | | | nikhef.nl | 2 | Gin is stopped | | | nikhef.nl | 2 | Gin is stopped | | Rows in set

EU DataGrid: Information and Monitoring 10 Data Transfer: Producer  Consumer u Consumer can issue one-off queries n Similar to normal database query u Consumer can also start a continuous query n Requests all data published which matches the query s As new data matching the query is produced it is streamed to the Consumer s Can be seen as an alert mechanism s Remember that all tuples carry a time-stamp

EU DataGrid: Information and Monitoring 11 3 Kinds of Query Tuple StreamProducer DataBaseProducer LatestProducer Tuple Continuous Queries History Query Latest Queries Tuple insertselect

EU DataGrid: Information and Monitoring 12 Producers u StreamProducer – Supports Continuous Queries n In memory data structure n Can define minimum retention period u DataBaseProducer – Supports History Queries n Information not lost n Supports joins n Clean up strategy u LatestProducer – Supports Latest Queries n As DataBaseProducer but n Just holds the latest information for any “primaryish” key u CanonicalProducer – Supports anything n Offers “anything” as relations n User has to write code to handle SQL etc.

EU DataGrid: Information and Monitoring 13 Registry and Schema u Registry has two main tables: n Producer s Table name s Predicate s Location n Consumer s Query s Location u Schema holds description of tables n Column names and types of each table u Registry predicate defines subset of “global” table Producer Consumer Registry Store location Lookup location execute or stream Schema Store table description

EU DataGrid: Information and Monitoring 14 Contributions to the “global” table CPULoad (Global Schema) CountrySiteFacilityLoadTimestamp CPULoad (Producer 3) CHCERNATLAS CHCERNCDF CPULoad (Producer 1) UKRALCDF UKRALATLAS CPULoad (Producer 2) UKGLACDF UKGLAALICE WHERE country = ’UK’ AND site = ’RAL’ WHERE country = ’CH’ AND site = ’CERN’ CPULoad (Global Schema) CountrySiteFacilityLoadTimestamp UKRALCDF UKRALATLAS CPULoad (Global Schema) CountrySiteFacilityLoadTimestamp UKRALCDF UKRALATLAS UKGLACDF UKGLAALICE CPULoad (Global Schema) CountrySiteFacilityLoadTimestamp UKRALCDF UKRALATLAS UKGLACDF UKGLAALICE CHCERNALICE CHCERNCDF

EU DataGrid: Information and Monitoring 15 Mediator u Queries posed against a virtual data base u The Mediator must: n find the right Producers n combine information from them u Hidden component – but vital to R-GMA u Will eventually support full distributed queries but for now will only merge information: n from multiple producers for queries on one table n or over multiple tables from one producer

EU DataGrid: Information and Monitoring 16 Queries over “global” table – merging streams CPULoad (Consumer) CountrySiteFacilityLoadTimestamp CPULoad (Producer 3) CHCERNATLAS CHCERNCDF CPULoad (Producer 1) UKRALCDF UKRALATLAS CPULoad (Producer 2) UKGLACDF UKGLAALICE CPULoad (Consumer) CountrySiteFacilityLoadTimestamp UKRALCDF UKRALATLAS CPULoad (Consumer) CountrySiteFacilityLoadTimestamp UKRALCDF UKRALATLAS UKGLACDF UKGLAALICE Mediator handles merging information from multiple producers for queries on one table SELECT * from CPULoad WHERE country = ’UK’

EU DataGrid: Information and Monitoring 17 Service/ServiceStatus (Latest Producer) Queries over “global” table – joining tables Service URIVOtype ContactsitesecuremajorVersionminorVersionpatchVersion ServiceStatus URIupmessage gppse01ySE is running gppse02nSE ERROR 101 lxshare0404ySE is running Service/ServiceStatus (Consumer) URI Contact SELECT Service.URI Service. Contact from Service S, ServiceStatus SS WHERE (S.URI= SS.URI and SS.up=‘n’) Service/ServiceStatus (Consumer) URI Contact gppse02n

EU DataGrid: Information and Monitoring 18 Archiver (Re-publisher) u It is a combined Consumer-Producer n Follows the GMA concept but packaged for ease of use u You just have to tell it what to collect and it does so on your behalf u Re-publishes to any kind of “Insertable” (i.e. not to the CanonicalProducer) n Can support joins if archiving to a DataBaseProducer or a LatestProducer

EU DataGrid: Information and Monitoring 19 Topologies u Normally publish via SP u Archivers instantiated with a Producer and a Predicate n Often no predicate u Must avoid cycles in the graph A DBP A SP A HP SP

EU DataGrid: Information and Monitoring 20 GIN and GOUT (Gadget IN and Gadget OUT) R-GMA Consumers LDAP InfoProvider GIN LDAP Server LDAP InfoProvider Stream Producer GIN Consumer (CE) Consumer (SE) Consumer (SiteInfo) RDBMS Latest Producer GOUT ConsumerA PI Archiver Stream Producer R-GMA GLUE Schema

EU DataGrid: Information and Monitoring 21 Ranglia u R-GMA meets Ganglia u A CanonicalProducer is used to interface Ganglia u Allows R-GMA queries to be made to Ganglia n Not yet released

EU DataGrid: Information and Monitoring 22 R-GMA Tools u R-GMA Browser n Application dynamically generating web pages n Supports pre-defined and user-defined queries u R-GMA CLI (edg-rgma) n Command Line Interface (similar to MySQL) n Supports single query and interactive modes n Can perform simple operations with Consumers, Producers and Archivers u R-GMA packaged SQL (edg-rgma-util) n e.g. edg-rgma-util contacts: s Command: SELECT siteName, sysAdminContact, userSupportContact, siteSecurityContact FROM SiteInfo

EU DataGrid: Information and Monitoring 23

EU DataGrid: Information and Monitoring 24 edg-rgma u show tables u describe ServiceStatus u show producers of ServiceStatus u latest select * from ServiceStatus u old continuous select * from ServiceStatus

EU DataGrid: Information and Monitoring 25 edg-rgma – Example $> edg-rgma rgma> stream declare userTable rgma> stream minret 0.2 rgma> stream INSERT into userTable (userId, aString, aReal, anInt) values ('fisher', 'hello', 3.162, 21) rgma> timeout 0.3 rgma> old continuous SELECT * from userTable | userId | aString | aReal | anInt | MeasurementDate | MeasurementTime | | fisher | hello | | 21 | | 11:06:01 | Rows in set

EU DataGrid: Information and Monitoring 26 APIs u Exist in Java, C++, C, Python and Perl u C, Python and Perl follow an object based style reflecting the Java and C++ APIs Java myProducer = new StreamProducer(); C++ myProducer= new edg::info::StreamProducer(); C myProducer = StreamProducer_new(); Perl $myProducer = edg_rgma_perl::StreamProducer_new(); Python myProducer = edg_rgma_python.StreamProducer_new() or myProducer = rgma.StreamProducer()

EU DataGrid: Information and Monitoring 27 Some Times… u TerminationInterval n Period by which the producer must re-announce its existence s If it fails to do so it will be removed from the registry s Default is 20 minutes s Don’t set it too short s Don’t set it too long u RetentionPeriod n Period for which the published data will remain available, even after the Producer has been closed s Default is 0

EU DataGrid: Information and Monitoring 28 C++ Producer - Example #include … #include "info/StreamProducer.hh" int main(int argc, char* args[]) { if (argc != 2) { std::cout << "One argument must be specified\n" << std::endl; exit(1); } try { edg::info::StreamProducer myProducer; std::string astring = std::string("WHERE (userId = '") + std::string(args[1]) + std::string("')"); std::cout << "Predicate: " << astring << std::endl; myProducer.declareTable("userTable", astring); myProducer.setTerminationInterval(edg::info::TimeInterval(1200)); myProducer.setMinRetentionPeriod(edg::info::TimeInterval(600)); astring = std::string("INSERT INTO userTable (userId, aString, aReal, anInt) VALUES ('") + std::string(args[1]) + std::string("', 'C++ producer', , 42)"); std::cout << astring << std::endl; myProducer.insert(astring); } catch (edg::info::RGMAException& e) { std::cout << "Exception " << e.what() << std::endl; }

EU DataGrid: Information and Monitoring 29 C++ Consumer - Example #include … #include "info/Consumer.hh" #include "info/ResultSet.hh" int main(){ try { edg::info::Consumer myConsumer("SELECT * FROM userTable“, edg::info::Consumer::LATEST); edg::info::TimeInterval Timeout(60); myConsumer.start(Timeout); while(myConsumer.isExecuting()){ sleep(1); } if(myConsumer.hasAborted()){ std::printf("Consumer query timed-out\n"); } edg::info::ResultSet resultSet = myConsumer.popIfPossible(); if (resultSet) { std::printf("ResultSet: %s\n", resultSet.toString().c_str()); } } catch (edg::info::RGMAException& e) { std::printf("Exception: %s\n", e.what()); }

EU DataGrid: Information and Monitoring 30 Summary u R-GMA n is suitable for Information and Monitoring n is a relational implementation of the GGF’s GMA n has different Producer types n mediator creates the impression of a single RDBMS n has authentication using grid certificates n has been integrated with Ganglia n has an API available in multiple languages

EU DataGrid: Information and Monitoring 31 Further Information u Information and Monitoring Services n u R-GMA n