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WCF service Multiple Users at same time

I will be deploying my first application based on WCF and would like to know the best way to deploy. Here is my architecture. Please see the attached image.
We have a WCF written using 4.0 framework and has 3 methods. A front end ASP.NET website (www.site.com) calls the WCF to save data as well as read data. In figure method1 is saving to data and method2 and 3 are for reading the data from SQL server 2008 R2 database.
In my ASP.Net webstie...
I am calling the Method1 and closing the connection...like this..
ServiceClient client = new ServiceClient();
client.Method1(data to be saved)
client.close();
I am calling method 2 and 3 as follows
ServiceClient client = new ServiceClient();
dropDown1list.datasource = client.Method2()
dropDown2list.datasource = client.Method3()
client.close();
Multiple users could be using the website at the same time to submit the data. Considering this architecture..what would be the best way to deploy the WCF so that it could handle multiple users at same time?. I read the article http://www.codeproject.com/Articles/89858/WCF-Concurrency-Single-Multiple-and-Reentrant-and and http://www.codeproject.com/Articles/86007/ways-to-do-WCF-instance-management-Per-call-Per.
I now believe I need to have my WCF service as
[ServiceBehavior(ConcurrencyMode = ConcurrencyMode.Multiple , InstanceContextMode = InstanceContextMode.PerCall )]
public class Service : IService
{
public bool Method1(data to be saved)
{
}
public List<string> Method2()
{
}
public List<string> Method2()
{
}
}
Am I right ?. Any suggestions ?.

Just answered a similar question yesterday. Based on your description and the picture, I don't see a need to change your architecture. If you're using one of the main WCF bindings (webHttpBinding, wsHttpBinding or BasicHTTPBinding), the service you deploy should easily be able handle dozens of concurrent users, all saving and reading at the same time.
Each client request will generate its own connection and web service objects, each of which can communicate concurrently with your database, whether that request is to read data or write data. When the response is sent back to the client, your WCF service will destroy the objects and clean up the memory for you as long as you're not doing something strange.
I've spent the last two years working on WCF web services on and industrial scale. Lately I've been working on a load testing / benchmarking project that spins up hundreds of concurrent users, each of which is slamming our WCF test server with XML artifacts that get loaded into the database. We've managed to load up to 160 packages (about 110kb - each per client) per second. WCF is not perfect, but it's quick, clean and scales really well.
My experience has been that your database will be your bottleneck, not your WCF web service. If your client wants to scale this archtecture up to an Amazon size web service, then you bring in an F5 load balancer and scale it up that way.

WCF duplex: calling callback outside class of WCF-service

I develop WCF-service with duplex mode and use nettcpbinding. I use .NET 4.5. I have only one client and only one server and there is a lot of logic between its. The client always the first begins communication with the server. I want that server can call client functions outside WCF-service class. I try to use duplex mode for this purpose.
This is my WCF-service:
[ServiceBehavior(ConcurrencyMode = ConcurrencyMode.Single, InstanceContextMode = InstanceContextMode.Single)]
public class Service : IService
{
...
public IServiceCallback Callback
{
get
{
return OperationContext.Current.GetCallbackChannel<IServiceCallback>();
}
}
}
I have no problem when I call my callback within OperationContract functions of my service:
Callback.foo();
But when I try to call it outside class Service for example:
service = new Service();
service.Callback.foo();
I got NullReferenceException of OperationContext.Current. I found a lot of information about the similar problems on the SO and other resources but it can't help to decide my problem.
Are there any solutions of my issue or may be workarounds for calling of callback? At the moment I plan to create one more WCF-service for my purpose but I feel that this is bad solution. Thanks for attention.

OperationContext.Current has a meaning only when it runs from the same thread that handles the current client request. You did not specify where exactly you calls this from.

WCF - Determining when session ends on the server side

In the project I'm working on, we have several services implemented using WCF. The situation I'm facing is that some of the services need to know when a session ends, so that it can appropriately update the status of that client. Notifying the service when a client gracefully terminates (e.g. the user closes the application) is easy, however, there are cases where the application might crash, or the client machine might restart, in which case the client won't be able to notify the service about its status.
Initially, I was thinking about having a timer on the server side, which is triggered once a client connects, and changes the status of that client to "terminated" after, let's say, 1 minute. Now the client sends its status every 30 seconds to the service, and the service basically restarts its timer on every request from the client, which means it (hopefully) never changes the status of the client as long as the client is alive.
Even though this method is pretty reliable (not fully reliable; what if it takes the client more than 1 minute to send its status?) it's still not the best approach to solving this problem. Note that due to the original design of the system, I cannot implement a duplex service, which would probably make things a lot simpler. So my question is: Is there a way for the sevice to know when the session ends (i.e. the connection times out or the client closes the proxy)? I came accross this question: WCF: How to find out when a session is ending but the link on the answer seems to be broken.
Another thing that I'm worried about is; they way I'm currently creating my channel proxies is implemented like this:
internal static TResult ExecuteAndReturn<TProxy, TResult>(Func<TProxy, TResult> delegateToExecute)
{
string endpointUri = ServiceEndpoints.GetServiceEndpoint(typeof(TProxy));
var binding = new WSHttpBinding();
binding.Security.Mode = SecurityMode.Message;
binding.Security.Message.ClientCredentialType = MessageCredentialType.UserName;
TResult valueToReturn;
using (ChannelFactory<TProxy> factory = new ChannelFactory<TProxy>(binding,
new EndpointAddress(new Uri(endpointUri),
EndpointIdentity.CreateDnsIdentity(ServiceEndpoints.CertificateName))))
{
TProxy proxy = factory.CreateChannel();
valueToReturn = delegateToExecute(proxy);
}
return valueToReturn;
}
So the channel is closed immediately after the service call is made (since it's in a using block), is that, from a service standpoint, an indication that the session is terminated? If so, should I keep only one instance of each service during application runtime, by using a singleton maybe? I apologize if the questions seem a little vague, I figured there would be plenty of questions like these but wasn't able to find something similar.

Yes, closing the channel terminates the session, but if there is an error of some kind then you are subject to the timeout settings of the service, like this:
<binding name="tcpBinding" receiveTimeout="00:00:10" />
This introduces a ten second timeout if an error occurs.
Check out Managing WCF Session Lifetime with IsInitiating and IsTerminating

2 WCF Services and c# threading

I am trying to write code that imports a bunch of data as quickly and reliably as possible. Using threading I have been able to speed up the import code I wrote significantly on my local machine, but when I run it on our remote server it seems to have some WCF problems...
I have two WCF Service implementations: Service1 and Service2.
Basically this is the workflow:
Parallel.ForEach(objectData.Tables[0].Rows.Cast<DataRow>(), dataRow =>
{
...
Service1.ImportObjectFirstPart(ObjectToEnter);
...
Service2.ImportObjectSecondPart(ObjectToEnter);
}
Service1 call takes about 3 seconds, and service2 takes about 7 seconds both remotely and locally. However on my local machine, calls to service2 start after about 20 service1 calls. On the server, almost every service1 call finished before the first service2 call started. (Both services are implemented as PerCall).
The code to call the services uses 99% CPU as expected for awhile then slows to a crawl, then I have to exit it myself. Any idea what could be going wrong?
Thanks,

Have you tried
[ServiceBehavior(ConcurrencyMode = ConcurrencyMode.Multiple)]
you can read the details here
http://msdn.microsoft.com/en-us/library/system.servicemodel.servicebehaviorattribute.concurrencymode.aspx
The default is single so you should expect the behavior you are getting is pretty justified.

Can an WCF Service create his own host?

I have a client / server type of application and I'd like the server object to create his own host. It looks something like this:
public class Server : IServer {
private ServiceHost m_Host;
public Server() {
m_Host = new ServiceHost(this);
m_Host.Open();
}
}
It seems to work fine when there are few message transfers occurring. But when it starts to speed up (my application requires that data is transfered every 50 ms), the server hangs and and the transfers stop after a few seconds without throwing an exception.
So, is it possible for an object to create his own host? Or do I really have to create it in the main() or do something else?
EDIT: I think the problem in this case is that I want the object that implements the service itself to create his own ServiceHost.

There's nothing really stopping any object to create an instance of ServiceHost.
The big question then is - can you guarantee that your object containing the service host is "alive"? Or was it garbage collected by any chance?
We use Windows (NT) Services to host our own custom service host classes to provide around-the-clock availability for WCF services - works just fine.
Marc

To be a WCF service it simply needs to implement the service contract. There's nothing to stop you adding more methods to open and close an instance of itself as a service.

Check out the ServiceBehaviorAttribute which allows you to specify how your service ... behaves. ;) The ConcurrencyMode property defined the support for multithreading and defaults to single threaded mode, and the InstanceContextMode defines if the service object is per session, per call or singleton.
Quote from ConcurrencyMode:
Setting ConcurrencyMode to Single instructs the system to restrict instances of the service to one thread of execution at a time, which frees you from dealing with threading issues. A value of Multiple means that service objects can be executed by multiple threads at any one time. In this case, you must ensure thread safety.
Quote from InstanceContextMode:
If the InstanceContextMode value is set to Single the result is that your service can only process one message at a time unless you also set the ConcurrencyMode value to Multiple.
We could really use some code examples of your service to further debug the behavior you're describing. For example, is your service object expensive to construct (assuming non singleton implementation), or do the operation slow down? Do you know where the time is spent, is it code, or could it as well be some firewall that limits connection? What protocol do you use?