Monday, February 11, 2013

WCF Service Throttling




WCF Throttling provide provision to set Limit for number of  concurrent call, number of  instances and number of session is created by the application.
Performance can be improve by setting these properties according to the application uses.



Attribute
Description
maxConcurrentCalls
Limits the total number of calls that can currently be in progress across all service instances. The default is 16.
maxConcurrentInstances
The number of InstanceContext objects that execute at one time across a ServiceHost. The default is Int32.MaxValue.
maxConcurrentSessions
A positive integer that limits the number of sessions a ServiceHost object can accept. The default is 10.
Service Throttling can be configured either by service configuration file or Programmatically.


configuration file

Using <serviceThrottling> tag of the Service Behavior, you can configure the maxConcurrentCallsmaxConcurrentInstances ,maxConcurrentSessions property as shown below.
<system.serviceModel>
    <services >
      <service behaviorConfiguration="ServiceBehavior"  name="MyService">
        <endpoint address="" binding="wsHttpBinding" contract="IMyService">
          <identity>
            <dns value="localhost"/>
          </identity>
        </endpoint>
        <endpoint address="mex" binding="mexHttpBinding" contract="IMetadataExchange"/>
      </service>
    </services>
    <behaviors>
      <serviceBehaviors>
        <behavior name="ServiceBehavior">
          <serviceMetadata httpGetEnabled="true"/>
          <serviceDebug includeExceptionDetailInFaults="true "/>
          <serviceThrottling maxConcurrentCalls="500" maxConcurrentInstances ="100" maxConcurrentSessions ="200"/>
        </behavior>
      </serviceBehaviors>
    </behaviors>
  </system.serviceModel>


Programming Model
Use ServiceThrottlingBehavior object to set concurrent calls, session and instance property.
           ServiceHost host = new ServiceHost(typeof(MyService));
           ServiceThrottlingBehavior throttle  = host.Description.Behaviors.Find();
            if (throttle == null)            {
                throttle = new ServiceThrottlingBehavior();
                throttle.MaxConcurrentCalls = 500;
                throttle.MaxConcurrentSessions = 200;
                throttle.MaxConcurrentInstances = 100;
                host.Description.Behaviors.Add(throttle);
            }

            host.Open();
                      

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