Analysis of WCF data instance by server
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PublicclassMySyncProvider:KnowledgeSyncProvider,IChangeDataRetriever,INotifyingChangeApplierTarget
{
/ / Thenameofthemetadatastorecustomcolumnthatisusedtosaveatimestampoflastchangeonan
/ / iteminthemetadatastoresowecandochangedetection.
ConststringTIMESTAMP_COLUMNNAME= "timestamp"
/ / Thisisoursampleinmemorydatastorewhichforsimplicty,storessetsofstringname-ProcessChangeBatchpairs
/ / referencedbyidentifiersofthetype'Guid'
MySimpleDataStore_store
/ / UsetheSyncFramework'soptionalmetadatastoretotrackversioninformation
SqlMetadataStore_metadataStore=null;// represents a metadata store implemented by using a lightweight database to store metadata.
ReplicaMetadata_metadata=null;// provides access to replica metadata and item metadata in the metadata store. ReplicaMetadata also provides services for deletion detection and helpers for implementing synchronization provider methods
Privatestring_name=null
Privatestring_folderPath=null
Privatestring_replicaMetadataFile=null
Privatestring_replicaIdFile=null
/ / Theprovider'suniqueidentifier
SyncId_replicaId=null
SyncIdFormatGroup_idFormats=null
SyncSessionContext_currentSessionContext=null
/ / Constructadatastorebyprovidinganamefortheendpoint (replica) and
/ / afiletowhichwe'llpersistthesyncmetadata (file)
PublicMySyncProvider (stringfolderPath,stringname)
{
Namename=name
FolderPathfolderPath=folderPath
ReplicaMetadataFile=_folderPath.ToString () + "+ _ name.ToString () +" .metadata "
ReplicaIdFile=_folderPath.ToString () + "+ _ name.ToString () +" .Replicaid "
SetItemIdFormatandReplicaIdFormatforusingGuidids.
IdFormats=newSyncIdFormatGroup ()
IdFormats.ItemIdFormat.IsVariableLength=false
IdFormats.ItemIdFormat.Length=16
IdFormats.ReplicaIdFormat.IsVariableLength=false
IdFormats.ReplicaIdFormat.Length=16
}
PublicSyncIdReplicaId
{
Get
{
If (_ replicaId==null)
{
ReplicaId=GetReplicaIdFromFile (_ replicaIdFile)
}
Return_replicaId
}
}
# regionMetadataStoreRelatedMethods
PrivatevoidInitializeMetadataStore ()
{
Valuesforaddingacustomfieldtothemetadatastore
Listfields=newList ()
SyncIdid=ReplicaId
Createoropenthemetadatastore,initializingitwiththeidformatswe'llusetoreferenceouritemsandendpoints
If (! File.Exists (_ replicaMetadataFile))
{
Fields.Add (newFieldSchema (TIMESTAMP_COLUMNNAME,typeof (System.UInt64)
/ / create a metadata store file with the specified name and location, and then return the metadata store object that represents the file.
_ metadataStore=SqlMetadataStore.CreateStore (_ replicaMetadataFile)
/ / create and initialize the copy of the metadata in the metadata store and return a copy metadata object that is used to access the copy metadata.
_ metadata=_metadataStore.InitializeReplicaMetadata (ID format schema of the _ idFormats,// provider
ReplicaId,// the copy ID associated with this metadata
Fields,// a collection of schema information for custom metadata fields for each metadata item. If there is no custom metadata field, it can be referenced for null
Null/*Noindexestocreate*/); / / A list of index schemas that can be used to find items in the metadata store more efficiently. If there is no custom index, it can be a null reference
}
Else
{
_ metadataStore=SqlMetadataStore.OpenStore (_ replicaMetadataFile); / / Open an existing metadata store file and return the metadata store object that represents the file
_ metadata=_metadataStore.GetReplicaMetadata (_ idFormats,_replicaId); / / gets the replica metadata object used to access the replica metadata in the metadata store.
}
}
PrivatevoidCloseMetadataStore ()
{
MetadataStore.Dispose ()
MetadataStore=null
}
/ / Updatethemetadatastorewithchangesthathaveoccuredonthedatastoresincethelasttimeitwasupdated.
PublicvoidUpdateMetadataStoreWithLocalChanges ()
{
SyncVersionnewVersion=newSyncVersion (0gramme metadata.GetNextTickCount ())
Metadata.DeleteDetector.MarkAllItemsUnreported ()
Foreach (Guididin_store.Ids)
{
ItemDatadata=_store.Get (id)
ItemMetadataitem=null
/ / Lookupanitem'smetadatabyitsID
Item=_metadata.FindItemMetadataById (newSyncId (id))
If (null==item)
{
Newitem,musthavebeencreatedsincethatlasttimethemetadatawasupdated.
Createtheitemmetadatarequiredforsync (givingitaSyncIDandaversion,definedtobeaDWORDandaULONGLONG
Forcreates,simplyprovidetherelativereplicaID (0) andthetickcountfortheprovider (everincreasing)
Item=_metadata.CreateItemMetadata (newSyncId (id), newVersion)
Item.ChangeVersion=newVersion
SaveItemMetadata (item,data.TimeStamp)
}
Else
{
If (data.TimeStamp > item.GetUInt64Field (TIMESTAMP_COLUMNNAME)) / / theitemhaschangedsincethelastsyncoperation.
{
/ / ChangedItem,thisitemhaschangedsincethelasttimethemetadatawasupdated.
/ / Assignanewversionbysimplystating "who" modifiedthisitem (0=local/me) and "when" (tickcountforthestore)
Item.ChangeVersion=newVersion
SaveItemMetadata (item,data.TimeStamp)
}
Else
{
/ / Unchangeditem,nothinghaschangessojustmarkitaslivesothatthemetadataknowsithasnotbeendeleted.
_ metadata.DeleteDetector.ReportLiveItemById (newSyncId (id))
}
}
}
Nowgobackthroughtheitemsthatarenolongerinthestoreandmarkthemasdeletedinthemetadata.
Thissetstheitemasatombstone.
Foreach (ItemMetadataitemin_metadata.DeleteDetector.FindUnreportedItems ())
{
Item.MarkAsDeleted (newVersion)
SaveItemMetadata (item,0); / / settimestampto0fortombstones
}
}
PrivatevoidSaveItemMetadata (ItemMetadataitem,ulongtimeStamp)
{
Item.SetCustomField (TIMESTAMP_COLUMNNAME,timeStamp)
SaveItemMetadata (item)
}
PrivatevoidSaveItemMetadata (ItemMetadataitem)
{
Metadata.SaveItemMetadata (item)
}
/ / MethodforcleaninguptombstonesolderthanacertainTimeSpan
PublicvoidCleanupTombstones (TimeSpantimespan)
{
InitializeMetadataStore ()
MetadataStore.BeginTransaction (); / / start an explicit transaction on the metadata store
Metadata.CleanupDeletedItems (timespan)
MetadataStore.CommitTransaction (); / / commit explicit transactions that have been initiated against the metadata store
CloseMetadataStore ()
}
# endregionMetadataStoreRelatedMethods
# regionKnowledgeSyncProviderOverrides
/ / BeginSessioniscalledatthebeginningofeachsyncoperation. Doinitializationhere. Forexampleupdate
/ / metadataifitwasnotupdatedastheactualdatawaschanged.
PublicoverridevoidBeginSession (SyncProviderPositionposition,SyncSessionContextsyncSessionContext)
{
BeginSession ()
CurrentSessionContext=syncSessionContext
}
/ / EndSessioniscalledafterthesyncoperationiscompleted. Cleanuphappenshere.
PublicoverridevoidEndSession (SyncSessionContextsyncSessionContext)
{
EndSession ()
}
/ / Simplyaskthemetadatastoretocomputemychangebatchforme,providingthebatchsizeandtheknowledgeoftheotherendpoint!
/ / Theengineisaskingforthelistofchangesthatthedestinationproviderdoesnotknowabout.
/ / SyncKnowledge: represents the knowledge that the copy has about its own item store.
/ / all public static (shared in VisualBasic) members of this type are thread safe. The thread safety of any instance member is not guaranteed.
PublicoverrideChangeBatchGetChangeBatch (uintbatchSize,SyncKnowledgedestinationKnowledge,outobjectchangeDataRetriever)
{
ChangeBatchbatch=_metadata.GetChangeBatch (batchSize,destinationKnowledge)
ChangeDataRetriever=this;//thisiswherethetransfermechanism/protocolwouldgo.Foraninmemoryprovider,thisissufficient
Returnbatch
}
/ / ThisisonlycalledwhentheenginehasdetectedthatthedestinationisoutofdateduetoTombstonecleanup.
PublicoverrideFullEnumerationChangeBatchGetFullEnumerationChangeBatch (uintbatchSize,SyncIdlowerEnumerationBound,SyncKnowledgeknowledgeForDataRetrieval,outobjectchangeDataRetriever)
{
FullEnumerationChangeBatchbatch=_metadata.GetFullEnumerationChangeBatch (batchSize,lowerEnumerationBound,knowledgeForDataRetrieval)
ChangeDataRetriever=this;//thisiswherethetransfermechanism/protocolwouldgo.Foraninmemoryprovider,thisissufficient
Returnbatch
}
/ / specify a batchSize of 10 and the corresponding knowledge
PublicoverridevoidGetSyncBatchParameters (outuintbatchSize,outSyncKnowledgeknowledge)
{
BatchSize=10
Knowledge=_metadata.GetKnowledge ()
}
/ / apply modification
PublicoverridevoidProcessChangeBatch (ConflictResolutionPolicyresolutionPolicy,ChangeBatchsourceChanges
ObjectchangeDataRetriever,SyncCallbackssyncCallback,SyncSessionStatisticssessionStatistics)
{
MetadataStore.BeginTransaction ()
Get all local modifications from the original data store
IEnumerablelocalChanges=_metadata.GetLocalVersions (sourceChanges)
Createachangeapplierobjecttomakechangeapplicationeasier (maketheenginecallme
WhenitneedsdataandwhenIshouldsavedata)
NotifyingChangeApplierchangeApplier=newNotifyingChangeApplier (_ idFormats)
ChangeApplier.ApplyChanges (resolutionPolicy,sourceChanges,changeDataRetrieverasIChangeDataRetriever,localChanges,_metadata.GetKnowledge ()
_ metadata.GetForgottenKnowledge (), this,_currentSessionContext,syncCallback)
MetadataStore.CommitTransaction ()
}
/ / Iffullenumerationisneededbecause thisproviderisoutofdateduetotombstonecleanup,thenthismethodwillbecalledbytheengine.
PublicoverridevoidProcessFullEnumerationChangeBatch (ConflictResolutionPolicyresolutionPolicy,FullEnumerationChangeBatchsourceChanges,objectchangeDataRetriever,SyncCallbackssyncCallback,SyncSessionStatisticssessionStatistics)
{
MetadataStore.BeginTransaction ()
Getallmylocalchangeversionsfromthemetadatastore
IEnumerablelocalChanges=_metadata.GetFullEnumerationLocalVersions (sourceChanges)
Createachangeapplierobjecttomakechangeapplicationeasier (maketheenginecallme
WhenitneedsdataandwhenIshouldsavedata)
NotifyingChangeApplierchangeApplier=newNotifyingChangeApplier (_ idFormats)
ChangeApplier.ApplyFullEnumerationChanges (resolutionPolicy,sourceChanges,changeDataRetrieverasIChangeDataRetriever,localChanges,_metadata.GetKnowledge ()
_ metadata.GetForgottenKnowledge (), this,_currentSessionContext,syncCallback)
MetadataStore.CommitTransaction ()
}
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