我們知道Geodatabase的分散式資料庫可以線上也可以離線，而線上和離線的介面是不同的，這是因為兩者的操作過程不一樣，我們看一下兩者的區別：
線上
離線
通過這4張圖很清楚的說明了原理（其中每一種方式又分為區域網和網際網路）
重要的介面：
GeoDataServer 代表了一個資料庫的連線，這句話可能不好理解，但是通過程式碼，也許會明白：
public IGeoDataServer InitGeoDataServerFromFile(String path)
{
// Create the GeoDataServer and cast to the the IGeoDataServerInit interface.
IGeoDataServer geoDataServer = new GeoDataServerClass();
IGeoDataServerInit geoDataServerInit = (IGeoDataServerInit)geoDataServer;
geoDataServerInit.InitFromFile(@"C:\arcgis\ArcTutor\DatabaseServers\hazards.gdb");
return geoDataServer;
}
在離線方式下，我們的資料同步是通過匯入，匯出，而匯入，匯出這些方法由此介面提供，看下面的例子：
public void ExportReplicaDataChanges(IGeoDataServer sourceGDS, String replicaName,
String outputDirectory)
{
try
{
// Set the export options.
GDSExportOptions gdsExportOptions = new GDSExportOptions();
gdsExportOptions.ExportFormat = esriGDSExportFormat.esriGDSExportFormatXml;
gdsExportOptions.Compressed = true;
gdsExportOptions.BinaryGeometry = false;
// Export the data changes. Note: The replica must be in a Sending Data State.
IGDSData gdsData = sourceGDS.ExportReplicaDataChanges(replicaName,
gdsExportOptions, esriGDSTransportType.esriGDSTransportTypeUrl,
esriExportGenerationsOption.esriExportGenerationsAll, false);
// Force deletion of folder and contents if they exist.
if (Directory.Exists(outputDirectory))
{
Directory.Delete(outputDirectory, true);
}
// Create the output folder.
Directory.CreateDirectory(outputDirectory);
// Get the compressed data changes document from the URL to the local output directory.
if (gdsData.TransportType == esriGDSTransportType.esriGDSTransportTypeUrl)
{
string fileName = System.IO.Path.GetFileName(gdsData.URL);
string outputFileName = System.IO.Path.Combine(outputDirectory, fileName)
;
WebClient wc = new WebClient();
wc.DownloadFile(gdsData.URL, outputFileName);
wc.Dispose();
}
else
{
// The file has been embedded because there is no output directory set on ArcGIS Server.
Console.WriteLine("Server is not configured with a virtual directory.");
}
}
catch (COMException comExc)
{
throw new Exception(String.Format(
"Exporting data changes errored: {0}, Error Code: {1}", comExc.Message,
comExc.ErrorCode), comExc);
}
catch (Exception exc)
{
throw new Exception(String.Format("Exporting data changes errored: {0}",
exc.Message), exc);
}
}
而在線上方式下，用ReplicatonAgent介面
ReplicatonAgent 介面就是用來實現線上方式下的同步
public void SynchronizeReplica(IGeoDataServer parentGDS, IGeoDataServer childGDS,
String replicaName, esriReplicationAgentReconcilePolicy conflictPolicy,
esriReplicaSynchronizeDirection syncDirection, Boolean columnLevel)
{
try
{
// Iterate through the replicas of the parent geodata server.
IGPReplicas gpReplicas = parentGDS.Replicas;
IGPReplica parentReplica = null;
for (int i = 0; i < gpReplicas.Count; i++)
{
// See if the unqualified replica name matches the replicaName parameter.
IGPReplica currentReplica = gpReplicas.get_Element(i);
String currentReplicaName = currentReplica.Name;
int dotIndex = currentReplicaName.LastIndexOf(".") + 1;
String baseName = currentReplicaName.Substring(dotIndex,
currentReplicaName.Length - dotIndex);
if (baseName.ToLower() == replicaName.ToLower())
{
parentReplica = currentReplica;
break;
}
}
// Check to see if the parent replica was found.
if (parentReplica == null)
{
throw new ArgumentException(
"The requested replica could not be found on the parent GDS.");
}
// Iterate through the replica of the child geodata server.
gpReplicas = childGDS.Replicas;
IGPReplica childReplica = null;
for (int i = 0; i < gpReplicas.Count; i++)
{
// See if the unqualified replica name matches the replicaName parameter.
IGPReplica currentReplica = gpReplicas.get_Element(i);
String currentReplicaName = currentReplica.Name;
int dotIndex = currentReplicaName.LastIndexOf(".") + 1;
String baseName = currentReplicaName.Substring(dotIndex,
currentReplicaName.Length - dotIndex);
if (baseName.ToLower() == replicaName.ToLower())
{
childReplica = currentReplica;
break;
}
}
// Check to see if the child replica was found.
if (childReplica == null)
{
throw new ArgumentException(
"The requested replica could not be found on the child GDS.");
}
// Synchronize the replica.
IReplicationAgent replicationAgent = new ReplicationAgentClass();
replicationAgent.SynchronizeReplica(parentGDS, childGDS, parentReplica,
childReplica, conflictPolicy, syncDirection, columnLevel);
}
catch (COMException comExc)
{
throw new Exception(String.Format(
"Create replica errored: {0}, Error Code: {1}", comExc.Message,
comExc.ErrorCode), comExc);
}
catch (Exception exc)
{
throw new Exception(String.Format("Create replica errored: {0}", exc.Message)
, exc);
}