服务端对WCF数据举例说明

到这里服务端的代码就全部列举出来了。当然本文中介绍的是元数据同步，而相应的SyncProvider实现是
通过MySimpleSyncProvider.cs文件提供的， #t#

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当然为了不让我的某些错误理解影响大家阅读源码，这里直接将相应的英文注释也放在这里。　publicclassMySyncProvider:KnowledgeSyncProvider,IChangeDataRetriever,INotifyingChangeApplierTarget

1. {  
2. //Thenameofthemetadatastorecustomcolumnthatisusedtosaveatimestampoflastchangeonan  
3. //iteminthemetadatastoresowecandochangedetection.  
4. conststringTIMESTAMP_COLUMNNAME="timestamp";  
5. //Thisisoursampleinmemorydatastorewhichforsimplicty,storessetsofstringname-ProcessChangeBatchpairs  
6. //referencedbyidentifiersofthetype'Guid'  
7. MySimpleDataStore_store;  
8. //UsetheSyncFramework'soptionalmetadatastoretotrackversioninformation  
9. SqlMetadataStore_metadataStore=null;//表示通过使用轻型数据库存储元数据来实现的元数据存储区。  
10. ReplicaMetadata_metadata=null;//提供对元数据存储区中的副本元数据和项元数据的访问。ReplicaMetadata还对删除检测和用于实现同步提供程序方法的帮助器提供服务  
11. privatestring_name=null;  
12. privatestring_folderPath=null;  
13. privatestring_replicaMetadataFile=null;  
14. privatestring_replicaIdFile=null;  
15. //Theprovider'suniqueidentifier  
16. SyncId_replicaId=null;  
17. SyncIdFormatGroup_idFormats=null;  
18. SyncSessionContext_currentSessionContext=null;  
19. //Constructadatastorebyprovidinganamefortheendpoint(replica)and  
20. //afiletowhichwe'llpersistthesyncmetadata(file)  
21. publicMySyncProvider(stringfolderPath,stringname)  
22. {  
23. namename=name;  
24. folderPathfolderPath=folderPath;  
25. replicaMetadataFile=_folderPath.ToString()+""+_name.ToString()+".Metadata";  
26. replicaIdFile=_folderPath.ToString()+""+_name.ToString()+".Replicaid";  
27. SetItemIdFormatandReplicaIdFormatforusingGuidids.  
28. idFormats=newSyncIdFormatGroup();  
29. idFormats.ItemIdFormat.IsVariableLength=false;  
30. idFormats.ItemIdFormat.Length=16;  
31. idFormats.ReplicaIdFormat.IsVariableLength=false;  
32. idFormats.ReplicaIdFormat.Length=16;  
33. }  
34. publicSyncIdReplicaId  
35. {  
36. get  
37. {  
38. if(_replicaId==null)  
39. {  
40. replicaId=GetReplicaIdFromFile(_replicaIdFile);  
41. }  
42. return_replicaId;  
43. }  
44. }  
45. #regionMetadataStoreRelatedMethods  
46. privatevoidInitializeMetadataStore()  
47. {  
48. Valuesforaddingacustomfieldtothemetadatastore  
49. Listfields=newList();  
50. SyncIdid=ReplicaId;  
51. Createoropenthemetadatastore,initializingitwiththeidformatswe'llusetoreferenceouritemsandendpoints  
52. if(!File.Exists(_replicaMetadataFile))  
53. {  
54. fields.Add(newFieldSchema(TIMESTAMP_COLUMNNAME,typeof(System.UInt64)));  
55. //创建一个具有指定名称和位置的元数据存储区文件，然后返回表示该文件的元数据存储区对象。  
56. _metadataStore=SqlMetadataStore.CreateStore(_replicaMetadataFile);  
57. //在元数据存储区创建和初始化副本的元数据，并返回一个用于访问该副本元数据的副本元数据对象。  
58. _metadata=_metadataStore.InitializeReplicaMetadata(_idFormats,//提供程序的ID格式架构  
59. replicaId,//与此元数据相关联的副本ID  
60. fields,//每个元数据项的自定义元数据字段的架构信息集合。如果不存在自定义元数据字段，则可为null引用  
61. null/*Noindexestocreate*/);//可用于更有效地查找元数据存储区中的项的索引架构列表。如果不存在自定义索引，则可以是null引用  
62. }  
63. else  
64. {  
65. _metadataStore=SqlMetadataStore.OpenStore(_replicaMetadataFile);//打开现有的元数据存储区文件，并返回表示该文件的元数据存储区对象  
66. _metadata=_metadataStore.GetReplicaMetadata(_idFormats,_replicaId);//获取用于访问元数据存储区中的副本元数据的副本元数据对象。  
67. }  
68. }  
69. privatevoidCloseMetadataStore()  
70. {  
71. metadataStore.Dispose();  
72. metadataStore=null;  
73. }  
74. //Updatethemetadatastorewithchangesthathaveoccuredonthedatastoresincethelasttimeitwasupdated.  
75. publicvoidUpdateMetadataStoreWithLocalChanges()  
76. {  
77. SyncVersionnewVersion=newSyncVersion(0,_metadata.GetNextTickCount());  
78. metadata.DeleteDetector.MarkAllItemsUnreported();  
79. foreach(Guididin_store.Ids)  
80. {  
81. ItemDatadata=_store.Get(id);  
82. ItemMetadataitem=null;  
83. //Lookupanitem'smetadatabyitsID  
84. item=_metadata.FindItemMetadataById(newSyncId(id));  
85. if(null==item)  
86. {  
87. Newitem,musthavebeencreatedsincethatlasttimethemetadatawasupdated.  
88. Createtheitemmetadatarequiredforsync(givingitaSyncIDandaversion,definedtobeaDWORDandaULONGLONG  
89. Forcreates,simplyprovidetherelativereplicaID(0)andthetickcountfortheprovider(everincreasing)  
90. item=_metadata.CreateItemMetadata(newSyncId(id),newVersion);  
91. item.ChangeVersion=newVersion;  
92. SaveItemMetadata(item,data.TimeStamp);  
93. }  
94. else  
95. {  
96. if(data.TimeStamp>item.GetUInt64Field(TIMESTAMP_COLUMNNAME))//theitemhaschangedsincethelastsyncoperation.  
97. {  
98. //ChangedItem,thisitemhaschangedsincethelasttimethemetadatawasupdated.  
99. //Assignanewversionbysimplystating"who"modifiedthisitem(0=local/me)and"when"(tickcountforthestore)  
100. item.ChangeVersion=newVersion;  
101. SaveItemMetadata(item,data.TimeStamp);  
102. }  
103. else  
104. {  
105. //Unchangeditem,nothinghaschangessojustmarkitaslivesothatthemetadataknowsithasnotbeendeleted.  
106. _metadata.DeleteDetector.ReportLiveItemById(newSyncId(id));  
107. }  
108. }  
109. }  
110. Nowgobackthroughtheitemsthatarenolongerinthestoreandmarkthemasdeletedinthemetadata.　  
111. Thissetstheitemasatombstone.  
112. foreach(ItemMetadataitemin_metadata.DeleteDetector.FindUnreportedItems())  
113. {  
114. item.MarkAsDeleted(newVersion);  
115. SaveItemMetadata(item,0);//settimestampto0fortombstones  
116. }  
117. }  
118. privatevoidSaveItemMetadata(ItemMetadataitem,ulongtimeStamp)  
119. {  
120. item.SetCustomField(TIMESTAMP_COLUMNNAME,timeStamp);  
121. SaveItemMetadata(item);  
122. }  
123. privatevoidSaveItemMetadata(ItemMetadataitem)  
124. {  
125. metadata.SaveItemMetadata(item);  
126. }  
127. //MethodforcleaninguptombstonesolderthanacertainTimeSpan  
128. publicvoidCleanupTombstones(TimeSpantimespan)  
129. {  
130. InitializeMetadataStore();  
131. metadataStore.BeginTransaction();//对元数据存储区启动显式事务  
132. metadata.CleanupDeletedItems(timespan);  
133. metadataStore.CommitTransaction();//提交已对元数据存储区启动的显式事务  
134. CloseMetadataStore();  
135. }  
136. #endregionMetadataStoreRelatedMethods  
137. #regionKnowledgeSyncProviderOverrides  
138. //BeginSessioniscalledatthebeginningofeachsyncoperation.　Doinitializationhere.　Forexampleupdate  
139. //metadataifitwasnotupdatedastheactualdatawaschanged.  
140. publicoverridevoidBeginSession(SyncProviderPositionposition,SyncSessionContextsyncSessionContext)  
141. {  
142. BeginSession();  
143. currentSessionContext=syncSessionContext;  
144. }  
145. //EndSessioniscalledafterthesyncoperationiscompleted.　Cleanuphappenshere.  
146. publicoverridevoidEndSession(SyncSessionContextsyncSessionContext)  
147. {  
148. EndSession();  
149. }  
150. //Simplyaskthemetadatastoretocomputemychangebatchforme,providingthebatchsizeandtheknowledgeoftheotherendpoint!  
151. //Theengineisaskingforthelistofchangesthatthedestinationproviderdoesnotknowabout.  
152. //SyncKnowledge:表示副本所具有的有关自己项存储区的知识。  
153. //此类型的所有公共静态（在VisualBasic中共享）成员都是线程安全的。不保证任何实例成员的线程安全。  
154. publicoverrideChangeBatchGetChangeBatch(uintbatchSize,SyncKnowledgedestinationKnowledge,outobjectchangeDataRetriever)  
155. {  
156. ChangeBatchbatch=_metadata.GetChangeBatch(batchSize,destinationKnowledge);  
157. changeDataRetriever=this;//thisiswherethetransfermechanism/protocolwouldgo.Foraninmemoryprovider,thisissufficient  
158. returnbatch;  
159. }  
160. //ThisisonlycalledwhentheenginehasdetectedthatthedestinationisoutofdateduetoTombstonecleanup.  
161. publicoverrideFullEnumerationChangeBatchGetFullEnumerationChangeBatch(uintbatchSize,SyncIdlowerEnumerationBound,SyncKnowledgeknowledgeForDataRetrieval,outobjectchangeDataRetriever)  
162. {  
163. FullEnumerationChangeBatchbatch=_metadata.GetFullEnumerationChangeBatch(batchSize,lowerEnumerationBound,knowledgeForDataRetrieval);  
164. changeDataRetriever=this;//thisiswherethetransfermechanism/protocolwouldgo.Foraninmemoryprovider,thisissufficient  
165. returnbatch;  
166. }  
167. //指定batchSize为10，以及相应的知识  
168. publicoverridevoidGetSyncBatchParameters(outuintbatchSize,outSyncKnowledgeknowledge)  
169. {  
170. batchSize=10;  
171. knowledge=_metadata.GetKnowledge();  
172. }  
173. //应用修改  
174. publicoverridevoidProcessChangeBatch(ConflictResolutionPolicyresolutionPolicy,ChangeBatchsourceChanges,  
175. objectchangeDataRetriever,SyncCallbackssyncCallback,SyncSessionStatisticssessionStatistics)  
176. {  
177. metadataStore.BeginTransaction();  
178. 从原数据存储中获得取得本地所有修改  
179. IEnumerablelocalChanges=_metadata.GetLocalVersions(sourceChanges);  
180. Createachangeapplierobjecttomakechangeapplicationeasier(maketheenginecallme  
181. whenitneedsdataandwhenIshouldsavedata)  
182. NotifyingChangeApplierchangeApplier=newNotifyingChangeApplier(_idFormats);  
183. changeApplier.ApplyChanges(resolutionPolicy,sourceChanges,changeDataRetrieverasIChangeDataRetriever,localChanges,_metadata.GetKnowledge(),  
184. _metadata.GetForgottenKnowledge(),this,_currentSessionContext,syncCallback);  
185. metadataStore.CommitTransaction();  
186. }  
187. //Iffullenumerationisneededbecause　thisproviderisoutofdateduetotombstonecleanup,thenthismethodwillbecalledbytheengine.  
188. publicoverridevoidProcessFullEnumerationChangeBatch(ConflictResolutionPolicyresolutionPolicy,FullEnumerationChangeBatchsourceChanges,objectchangeDataRetriever,SyncCallbackssyncCallback,SyncSessionStatisticssessionStatistics)  
189. {  
190. metadataStore.BeginTransaction();  
191. Getallmylocalchangeversionsfromthemetadatastore  
192. IEnumerablelocalChanges=_metadata.GetFullEnumerationLocalVersions(sourceChanges);  
193. Createachangeapplierobjecttomakechangeapplicationeasier(maketheenginecallme  
194. whenitneedsdataandwhenIshouldsavedata)  
195. NotifyingChangeApplierchangeApplier=newNotifyingChangeApplier(_idFormats);  
196. changeApplier.ApplyFullEnumerationChanges(resolutionPolicy,sourceChanges,changeDataRetrieverasIChangeDataRetriever,localChanges,_metadata.GetKnowledge(),  
197. _metadata.GetForgottenKnowledge(),this,_currentSessionContext,syncCallback);  
198. metadataStore.CommitTransaction();  
199. }

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