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Advanced Phonebook Data Management Using Xydra and RDF

Explore the capabilities of Xydra for managing phonebook data with RDF. This robust API facilitates storing, retrieving, and synchronizing complex data types, including strings, integers, and more, while maintaining access control and versioning. Users can interact with a structured phonebook system featuring advanced features like event handling, snapshot management, and asynchronous I/O processing. Ideal for developers looking to leverage Semantic Web technologies in their applications. Learn how to optimize storage and manage information effectively with Xydra.

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Advanced Phonebook Data Management Using Xydra and RDF

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  1. Xydra Graphics

  2. XAddress main/phonebook/john/phone XID XID XID XID XValue XBooleanListValue, XBooleanValue, XByteListValue, XCollectionValue<E>, XDoubleListValue, XDoubleValue, XID, XIDListValue, XidOrVariable, XIDSetValue, XIDSortedSetValue, XIntegerListValue, XIntegerValue, XListValue<E>, XLongListValue, XLongValue, XNumberListValue<T>, XNumberValue, XSetValue<E>, XStringListValue, XStringSetValue, XStringValue, main XRepository phonebook XModel john XObject phone 123-456 XField XValue XField XValue … XField XValue … XObject … XField XValue XModel XObject XField XValue

  3. XydraandtheSemantic Web Xydrais well-suitedtostoreand manage RDF data NamedGraph Subject Property Object main XRepository phonebook XModel john XObject phone 123-456 XField XValue Semantic Web Xydra URI Xaddress (externalreferences) / XID (internalreferences) BlankNode -- LanguageTaggedLiteral -- DatatypedLiteralXydravalues (BooleanValue, LongValue, StringValue, ..) PlainLiteralStringValue

  4. Xydraand XML main XRepository phonebook XModel john XObject phone 123-456 XField XValue <?xmlversion="1.0" encoding="UTF-8"?> <main> <phonebook> <john> <phone> <long>123-456</long> </phone> </john> </phonebook> </main> XID namingrulesensurestringscanbeusedas valid XML elementnames Values areserialised in a self-describingand extensible form

  5. Xydra Store API These twoallowstatesynchronisationbetweenseveralrepositores Observechanges Request change Read currentstate Persistence, Access controlVersioning, Transactions, Persistenceforgroups, members, rights Computeaccessrights

  6. Xydra Store API Serializable Event Observechange Command Request change • Repository/Model/Object/FieldSnapshot • Read currentstate • getChildren/getValue • getRevision • VersionedStore • Persistence, Versioning, Transactions, Access control • getSnapshot • executeCommand • getEventsSince • AccessRightsManager • Nestedgroups, hierarchicalrights, computeaccessrights • hasAccess • AccessRightsStore • Stores groups, members, rights • get/changeGroups • get/changeMembers • get/changeAccessDefinition

  7. Blocking I/O Thereforethe Store API isdesignedwithasync in mind • VersionedStore • Snapshot getSnapshot( Xaddressaddress, longrev) Async I/O • AsyncVersionedStore • voidgetSnapshot( Xaddressaddress, longrev, Callback< Snapshot> ) Sync Async Async Sync Easy towrap Nonsense

  8. Implementationsfor different Platforms • GaeStore • Persistence on GAE datastore • Parallel transactionmanagement via ChangeEntites • Snapshots via memcache/datastore • Custom accesspersistence on datastore Memory-Store Persistenceonly in memory HTML5-Store (planned) Persistence via HTML5 or Google GearsorSQLite CsvFile-Store (planned) Persistence in CSV file(s) XydraAsync Store API Command/Event/SnapshotGroup/Member/Access AppEngine (GAE) Browser/JavaScript (GWT) Desktop Java Desktop Java

  9. For all platforms Xydra Core API Xydra Tools • Repository API • Event listener • Forwards all incomingchangesto registered eventlisteners • Familiarchangeoperations (add/removechild, get/setvalue), on theflytranslatedintocommandsto an in-memoryXydrastoreimplementation • Checks accessrightsalready on clientside • Based on a local, partial copyofaccessrightsdatabase • Undo • Byexecuting anti-commands • SynchronisationManager • synchronisestatebetween a Store and a SyncableStore XydraAsync Store API Command/Event/SnapshotGroup/Member/Access SyncableMemory-Store Persistenceonly in memory Sync via SynchronisationManager

  10. REST API Implementsasyncpersistence API REST Async Client Java methodcallsin the same VM XML over HTTP XydraAsync Store API Command/Event/SnapshotGroup/Member/Access XydraAsync StoreImplementation REST Server

  11. Error Handling Whatcan happen with an applicationcommandissuestotheAsync Store API? Error source OK SafeCommandFailed e.g. for a SafeCommandtherevisionnumbersdontmatchexpectations Sync CommandFailed e.g. operation on deletedentity Access Forbidden i.e. actorhasnopermissionto do this Timeout Noresponse. Network down? Server gone? Network IllegalArgument The requestfromtheclientisill-formed Client Server RuntimeError e.g. thedatabase just crashed, AppEngine ran out ofquota

  12. Synchronisation Advanced Synchronisation: Oneclientwithseveral persistent stores • 4 localevents not yetcommitted • 3 events in syncfromstore Store 2 XModel XChangeLog Syncable 1 XModel XChangeLog • 2 localevents not yetcommitted • 4 events in syncfromstore Store 1 XModel XChangeLog • 5 events in history • Store hasnoknowledgewhosyncedwhat Syncable 2

  13. Xydrasourcecodeprojects in SVN • xydra-gae • Code for Google AppEngine: • GaeStore • (GaeRestClient) • xydra-java • Code forplain Java • JavaRestClient • JavaFileStore • xydra-gwt • Code for Google Web Toolkit: • GwtRestClient Runs-on-GAE Runs-on-GWT Depends-on xydra-server Code sharedby REST Server implementations • xydra-core • Core API (blocking): • - Event listeners, • Store API: (async) • executeCommand • getSnapshot • Syncable Store API (blocking) • - TBD xydra-client Code sharedby REST Client implementations Runs-on-GAE Runs-on-GWT Runs-on-GAE Runs-on-GWT Runs-on-GAE

  14. Xydra Core implementation plan Real-World Application doSomething(…, Callback ); Core API Very easy touse API Register eventlisteners TODO: Add nice API fortransactions Impl Delegatesto a SyncableStoreandmaintainsstateofthemostrecentXmodel SyncableStore API TBD: Extendsoruses Store API Callback Usedforsynchronisation Store API MemoryStore

  15. Store Implementation Plan Interceptand check accessrights. If ok, delegate. AccessRightsManager uses Group & RightPersistence API G&R Implementation Delegatingto a Xydra Store AllowAllStoreimplemention with trivial allow-all accessrights AllowAllStoreimplemention with trivial allow-all accessrights Repository State Access Rights

  16. AllowAll Store implementation plan ForeachXModel: ChangeLog Event 0 Event 1 Event 2 … ModelSnapshotCache Map: revNr ModelSnapshot Map: ObjectID  ObjectSnapshotCache ObjectSnapshotCache Map: revNr ObjectSnapshot ObjectSnapshotCache Map: revNr ObjectSnapshot ObjectSnapshotCache Map: revNr ObjectSnapshot ObjectSnapshotCache Map: revNr ObjectSnapshot

  17. ARM datamodelling • Design goals: • Handle ca. 1 Mio. users • Each in 10 groups • Ofwhich 5 indirect Model „actors“ objectIdfieldIdvalue groupId „hasMember“ XIDSetactors actorIdhasPasswordHashXstring Thistriggers: actorIdhasGroupsXIDSetallTransitiveGroups (actorId, hasGroups,*) isread-only enc( XID x): If null  „_N“ elsex.replaceAll(„_“,“__“) // use „_.“ asseparator enc( Xaddress a):enc(a.repo)+“._“+enc(a.model)+“._“+enc(a.obj)+“._“+enc(a.field) Foreach model ‚xxx‘ in mainrepo: Model xxx objectIdfieldIdvalue actorIDenc(xaddress )+“_.“+enc(rightID) Xboolean RightIdsaredefinedtomean: READ, WRITE, ADMIN

  18. ARM architecture grantAccess(…), denyAccess(..) createGroup(), addUserToGroup(..),… AccessWrapper GroupWrapper Model xxx Noredundancy Model „actors“ Noredundancy Access Rights Manager Repository Interpret writeoperations, In-memoryindexes (whichmight also bepersisted) ActorXaddressRight Index0 0 0 - 0 0 1 - 0 1 0 XR 0 1 1 XR 1 0 0 AR (redundant to AXR?) 1 0 1 AR (redundant to AXR?) 1 1 0 AXR 1 1 1 AXR Index Model „actors“Read-only Persistent Model „actors“ Persistent Model „xxx“

  19. Xydra Data Modelling Clear model vs. Query efficienye.g. use a numberoffieldIdsas a fast setof XIDs Nice OO API vs. Efficientbatchoperations ThatswhywemadetheXydraStore API so ugly Desired: A fast wayto check iftherehadbeen ANY changes in thedatastore.

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