Why does WebSharingAppDemo-CEProviderEndToEnd sample still need a client db connection after scope creation to perform sync - microsoft-sync-framework

Question

I'm researching a way to build an n-tierd sync solution. From the WebSharingAppDemo-CEProviderEndToEnd sample it seems almost feasable however for some reason, the app will only sync if the client has a live SQL db connection. Can some one explain what I'm missing and how to sync without exposing SQL to the internet?
The problem I'm experiencing is that when I provide a Relational sync provider that has an open SQL connection from the client, then it works fine but when I provide a Relational sync provider that has a closed but configured connection string, as in the example, I get an error from the WCF stating that the server did not receive the batch file. So what am I doing wrong?
SqlConnectionStringBuilder builder = new SqlConnectionStringBuilder();
builder.DataSource = hostName;
builder.IntegratedSecurity = true;
builder.InitialCatalog = "mydbname";
builder.ConnectTimeout = 1;
provider.Connection = new SqlConnection(builder.ToString());
// provider.Connection.Open(); **** un-commenting this causes the code to work**
//create anew scope description and add the appropriate tables to this scope
DbSyncScopeDescription scopeDesc = new DbSyncScopeDescription(SyncUtils.ScopeName);
//class to be used to provision the scope defined above
SqlSyncScopeProvisioning serverConfig = new SqlSyncScopeProvisioning();
....
The error I get occurs in this part of the WCF code:
public SyncSessionStatistics ApplyChanges(ConflictResolutionPolicy resolutionPolicy, ChangeBatch sourceChanges, object changeData)
{
Log("ProcessChangeBatch: {0}", this.peerProvider.Connection.ConnectionString);
DbSyncContext dataRetriever = changeData as DbSyncContext;
if (dataRetriever != null && dataRetriever.IsDataBatched)
{
string remotePeerId = dataRetriever.MadeWithKnowledge.ReplicaId.ToString();
//Data is batched. The client should have uploaded this file to us prior to calling ApplyChanges.
//So look for it.
//The Id would be the DbSyncContext.BatchFileName which is just the batch file name without the complete path
string localBatchFileName = null;
if (!this.batchIdToFileMapper.TryGetValue(dataRetriever.BatchFileName, out localBatchFileName))
{
//Service has not received this file. Throw exception
throw new FaultException<WebSyncFaultException>(new WebSyncFaultException("No batch file uploaded for id " + dataRetriever.BatchFileName, null));
}
dataRetriever.BatchFileName = localBatchFileName;
}
Any ideas?

Answer 1

For the Batch file not available issue, remove the IsOneWay=true setting from IRelationalSyncContract.UploadBatchFile. When the Batch file size is big, ApplyChanges will be called even before fully completing the previous UploadBatchfile.
// Replace
[OperationContract(IsOneWay = true)]
// with
[OperationContract]
void UploadBatchFile(string batchFileid, byte[] batchFile, string remotePeer1

Answer 2

I suppose it's simply a stupid example. It exposes "some" technique but assumes you have to arrange it in proper order by yourself.
http://msdn.microsoft.com/en-us/library/cc807255.aspx