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using System;
using System.Collections.Concurrent;
using System.Collections.Generic;
using System.Linq;
using System.ServiceModel;
using System.ServiceModel.Discovery;
using System.Text;
using System.Xml;
namespace Rashim.RND.ManagedDiscovery.ServiceHost
{
// Implement DiscoveryProxy by extending the DiscoveryProxy class and overriding the abstract methods
[ServiceBehavior(InstanceContextMode = InstanceContextMode.Single, ConcurrencyMode = ConcurrencyMode.Multiple)]
public class DiscoveryProxyService : DiscoveryProxy
{
// Repository to store EndpointDiscoveryMetadata. A database or a flat file could also be used instead.
Dictionary<EndpointAddress, EndpointDiscoveryMetadata> onlineServices;
public DiscoveryProxyService()
{
this.onlineServices = new Dictionary<EndpointAddress, EndpointDiscoveryMetadata>();
}
// OnBeginOnlineAnnouncement method is called when a Hello message is received by the Proxy
protected override IAsyncResult OnBeginOnlineAnnouncement(DiscoveryMessageSequence messageSequence, EndpointDiscoveryMetadata endpointDiscoveryMetadata, AsyncCallback callback, object state)
{
this.AddOnlineService(endpointDiscoveryMetadata);
return new OnOnlineAnnouncementAsyncResult(callback, state);
}
protected override void OnEndOnlineAnnouncement(IAsyncResult result)
{
OnOnlineAnnouncementAsyncResult.End(result);
}
// OnBeginOfflineAnnouncement method is called when a Bye message is received by the Proxy
protected override IAsyncResult OnBeginOfflineAnnouncement(DiscoveryMessageSequence messageSequence, EndpointDiscoveryMetadata endpointDiscoveryMetadata, AsyncCallback callback, object state)
{
this.RemoveOnlineService(endpointDiscoveryMetadata);
return new OnOfflineAnnouncementAsyncResult(callback, state);
}
protected override void OnEndOfflineAnnouncement(IAsyncResult result)
{
OnOfflineAnnouncementAsyncResult.End(result);
}
// OnBeginFind method is called when a Probe request message is received by the Proxy
protected override IAsyncResult OnBeginFind(FindRequestContext findRequestContext, AsyncCallback callback, object state)
{
this.MatchFromOnlineService(findRequestContext);
return new OnFindAsyncResult(callback, state);
}
protected override void OnEndFind(IAsyncResult result)
{
OnFindAsyncResult.End(result);
}
// OnBeginFind method is called when a Resolve request message is received by the Proxy
protected override IAsyncResult OnBeginResolve(ResolveCriteria resolveCriteria, AsyncCallback callback, object state)
{
return new OnResolveAsyncResult(this.MatchFromOnlineService(resolveCriteria), callback, state);
}
protected override EndpointDiscoveryMetadata OnEndResolve(IAsyncResult result)
{
return OnResolveAsyncResult.End(result);
}
// The following are helper methods required by the Proxy implementation
void AddOnlineService(EndpointDiscoveryMetadata endpointDiscoveryMetadata)
{
lock (this.onlineServices)
{
this.onlineServices[endpointDiscoveryMetadata.Address] = endpointDiscoveryMetadata;
}
PrintDiscoveryMetadata(endpointDiscoveryMetadata, "Adding");
}
void RemoveOnlineService(EndpointDiscoveryMetadata endpointDiscoveryMetadata)
{
if (endpointDiscoveryMetadata != null)
{
lock (this.onlineServices)
{
this.onlineServices.Remove(endpointDiscoveryMetadata.Address);
}
PrintDiscoveryMetadata(endpointDiscoveryMetadata, "Removing");
}
}
void MatchFromOnlineService(FindRequestContext findRequestContext)
{
lock (this.onlineServices)
{
foreach (EndpointDiscoveryMetadata endpointDiscoveryMetadata in this.onlineServices.Values)
{
if (findRequestContext.Criteria.IsMatch(endpointDiscoveryMetadata))
{
findRequestContext.AddMatchingEndpoint(endpointDiscoveryMetadata);
}
}
}
}
EndpointDiscoveryMetadata MatchFromOnlineService(ResolveCriteria criteria)
{
EndpointDiscoveryMetadata matchingEndpoint = null;
lock (this.onlineServices)
{
foreach (EndpointDiscoveryMetadata endpointDiscoveryMetadata in this.onlineServices.Values)
{
if (criteria.Address == endpointDiscoveryMetadata.Address)
{
matchingEndpoint = endpointDiscoveryMetadata;
}
}
}
return matchingEndpoint;
}
void PrintDiscoveryMetadata(EndpointDiscoveryMetadata endpointDiscoveryMetadata, string verb)
{
Console.WriteLine("\n**** " + verb + " service of the following type from cache. ");
foreach (XmlQualifiedName contractName in endpointDiscoveryMetadata.ContractTypeNames)
{
Console.WriteLine("** " + contractName.ToString());
break;
}
Console.WriteLine("**** Operation Completed");
}
sealed class OnOnlineAnnouncementAsyncResult : AsyncResult
{
public OnOnlineAnnouncementAsyncResult(AsyncCallback callback, object state)
: base(callback, state)
{
this.Complete(true);
}
public static void End(IAsyncResult result)
{
AsyncResult.End<OnOnlineAnnouncementAsyncResult>(result);
}
}
sealed class OnOfflineAnnouncementAsyncResult : AsyncResult
{
public OnOfflineAnnouncementAsyncResult(AsyncCallback callback, object state)
: base(callback, state)
{
this.Complete(true);
}
public static void End(IAsyncResult result)
{
AsyncResult.End<OnOfflineAnnouncementAsyncResult>(result);
}
}
sealed class OnFindAsyncResult : AsyncResult
{
public OnFindAsyncResult(AsyncCallback callback, object state)
: base(callback, state)
{
this.Complete(true);
}
public static void End(IAsyncResult result)
{
AsyncResult.End<OnFindAsyncResult>(result);
}
}
sealed class OnResolveAsyncResult : AsyncResult
{
EndpointDiscoveryMetadata matchingEndpoint;
public OnResolveAsyncResult(EndpointDiscoveryMetadata matchingEndpoint, AsyncCallback callback, object state)
: base(callback, state)
{
this.matchingEndpoint = matchingEndpoint;
this.Complete(true);
}
public static EndpointDiscoveryMetadata End(IAsyncResult result)
{
OnResolveAsyncResult thisPtr = AsyncResult.End<OnResolveAsyncResult>(result);
return thisPtr.matchingEndpoint;
}
}
}
}
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