instance management is the technique WCF uses to bind client requests to service instances, governing which service instance handles which client request, and when. WCF Supports 3 types of instance activation<\/p>\n
by and large the service instance mode is strictly a server side implementation detail, hat should not manifest itself on the client side in any way.<\/p>\n
now let’s define a service, that demonstrates the instance management in real life.<\/p>\n
let’s create a service, create a new project, take a Class Library template, name it InstanceLib<\/strong>, let’s do some house keeping with the newly created project.<\/p>\n to keep the things simple, let’s assume that each interface defines only one method, which simply adds a passed value, to its member variable.<\/p>\n so let’s define interface for each service.<\/p>\n \/\/ Listing of ISingleCallService.cs<\/strong><\/p>\n using System; namespace InstanceLib \/\/ Listing of ISessionService.cs<\/strong><\/p>\n using System; namespace InstanceLib \/\/ Listing of ISingletonService.cs<\/strong><\/p>\n using System; namespace InstanceLib Let’s implement each interface,as shown below.<\/p>\n \/\/ Listing of SingleCallService.cs<\/strong><\/p>\n using System; namespace InstanceLib public double AddValue(double dblVal) You can notice ServiceBehavior<\/strong> attribute of the class, which has been defined as InstanceContextMode.PerCall,<\/strong> it specifies that a new InstanceContext object is created prior to and recycled subsequent to each calll. if you omit this attribute or do not specify, then InstanceContextMode.PerCall<\/strong> is assumed by default.<\/p>\n \/\/ Listing of SessionService.cs<\/strong><\/p>\n using System; namespace InstanceLib public double AddValue(double dblVal) <\/strong><\/font><\/p>\n You can notice ServiceBehavior<\/strong> attribute of the class, which has been defined as InstanceContextMode.PerSession, <\/strong>it specifies that InstanceContext object is created for each session.<\/p>\n \/\/ Listing of SingletonService.cs<\/strong><\/p>\n using System; namespace InstanceLib public double AddValue(double dblVal) You can notice ServiceBehavior<\/strong> attribute of the class, which has been defined as InstanceContextMode.Singlel,<\/strong> it specifies that Only one InstanceContext<\/strong> object is used for all incoming calls and is not recycled to the calls. if the service object does not exist, one is created. <\/p>\n if you notice the all 3 service implementation, you will notice the difference in ServiceBehavior<\/strong> class attribute of each class, apart from that, all interfaces has been implemented has the same implementation. they simply add a passed value to a member variable of the class.<\/p>\n Build the project and your Class Library is ready. <\/p>\n for the sake of simplicity, i have have hosted this service as a self hosted service, to create the Host application, create a new Console based application<\/strong>.<\/p>\n Before we write any code for the Host application, let’s define the configuration file for the Service(s).<\/p>\n <?xml version="1.0" encoding="utf-8" ?> <!–************************ Single Call Service ************************ –> <endpoint address="<\/font>http:\/\/localhost:9011\/SingleCallService"<\/font><\/a> binding="wsHttpBinding" contract="InstanceLib.ISingleCallService"\/> <!\u2014************************ Single Session Service ************************–> <endpoint address="<\/font>http:\/\/localhost:9013\/SessionService"<\/font><\/a> binding="wsHttpBinding" contract="InstanceLib.ISessionService"\/> <!\u2014************************** Singleton Service **************************–> <endpoint address="<\/font>http:\/\/localhost:9015\/SingletonService"<\/font><\/a> binding="wsHttpBinding" contract="InstanceLib.ISingletonService"\/> <\/services><\/font><\/p>\n <!– **************************** behaviors ************************** –> <!– Single Call Service Behavior –> <!–Single Session Service Behavior –> <!–Singleton Service Behavior –> <serviceMetadata httpGetEnabled="true"\/> <\/serviceBehaviors> <\/system.serviceModel> Now let’s analyze the Configuration file.<\/p>\n <!–******************* Single Call Service ************************** –> <endpoint<\/font><\/strong> address="<\/font>http:\/\/localhost:9011\/SingleCallService"<\/font><\/a> binding="wsHttpBinding" contract="InstanceLib.ISingleCallService"\/> <!\u2014************************* Single Session Service ************************* –> <endpoint<\/font><\/strong> address="<\/font>http:\/\/localhost:9013\/SessionService"<\/font><\/a> binding="wsHttpBinding" contract="InstanceLib.ISessionService"\/> <!\u2014************************** Singleton Service **************************–> <\/strong> \n
Defining Interfaces<\/h4>\n
using System.Text;
using System.ServiceModel;<\/strong><\/font><\/p>\n
{
[ServiceContract]
interface ISingleCallService
{
[OperationContract]
double AddValue (double dblNum);
}
}
<\/font><\/strong><\/p>\n
using System.Text;
using System.ServiceModel;<\/strong><\/font><\/p>\n
{
[ServiceContract]
interface ISessionService
{
[OperationContract]
double AddValue (double dblNum);
}
}<\/strong><\/font><\/p>\n
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.ServiceModel;<\/strong><\/font><\/p>\n
{
[ServiceContract]
interface ISingletonService
{
[OperationContract]
double AddValue (double dblNum);
}
}<\/strong><\/font> <\/p>\n<\/ul>\n
Implementing Interfaces<\/h4>\n
using System.Text;
using System.ServiceModel ;<\/strong><\/font><\/p>\n
{
[ServiceBehavior(InstanceContextMode=InstanceContextMode.PerCall)]
public class SingleCallService : ISingleCallService
{
private double m_dblTotal = 0 ;<\/strong><\/font><\/p>\n
{
m_dblTotal += dblVal;
return m_dblTotal;
}
}
}<\/strong><\/font><\/p>\nImportant<\/h5>\n
using System.Text;
using System.ServiceModel;<\/strong><\/font><\/p>\n
{
[ServiceBehavior(InstanceContextMode = InstanceContextMode.PerSession)]
public class SessionService : ISessionService
{
private double m_dblTotal = 0 ;<\/strong><\/font><\/p>\n
{
m_dblTotal += dblVal;
return m_dblTotal;
}
}
}<\/strong><\/font> <\/p>\nImportant<\/h5>\n
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.ServiceModel;<\/strong><\/font><\/p>\n
{
[ServiceBehavior(InstanceContextMode = InstanceContextMode.Single)]
public class SingletonService : ISingletonService
{
private double m_dblTotal = 0 ;<\/strong><\/font><\/p>\n
{
m_dblTotal += dblVal;
return m_dblTotal;
}
}
}<\/strong><\/font> <\/p>\nImportant<\/h5>\n
Hosting the Service<\/h3>\n
<configuration>
<system.serviceModel>
<services><\/font><\/p>\n
<service name="InstanceLib.SingleCallService" behaviorConfiguration="SingleCallServiceBehavior<\/font>">
<\/strong> <host>
<baseAddresses>
<add baseAddress="<\/font>http:\/\/localhost:9011\/SingleCallService"\/<\/font><\/a>>
<add baseAddress="net.tcp:\/\/localhost:9012\/SingleCallService<\/strong>"\/>
<\/baseAddresses>
<\/host><\/font><\/p>\n
<endpoint address="net.tcp:\/\/localhost:9012\/SingleCallService<\/strong>" binding="netTcpBinding" contract="InstanceLib.ISingleCallService"\/>
<endpoint address="mex" binding="mexHttpBinding" contract="IMetadataExchange"\/>
<endpoint address="mex" binding="mexTcpBinding" contract="IMetadataExchange"\/>
<\/service><\/font><\/p>\n
<service name="InstanceLib.SessionService" behaviorConfiguration="SessionServiceBehavior<\/font>">
<\/strong> <host>
<baseAddresses>
<add baseAddress="<\/font>http:\/\/localhost:9013\/SessionService"\/<\/font><\/a>>
<add baseAddress="net.tcp:\/\/localhost:9014\/SessionService<\/strong>"\/>
<\/baseAddresses>
<\/host><\/font><\/p>\n
<endpoint address="net.tcp:\/\/localhost:9014\/SessionService<\/strong>" binding="netTcpBinding" contract="InstanceLib.ISessionService"\/>
<endpoint address="mex" binding="mexHttpBinding" contract="IMetadataExchange"\/>
<endpoint address="mex" binding="mexTcpBinding" contract="IMetadataExchange"\/>
<\/service><\/font><\/p>\n
<service name="InstanceLib.SingletonService" behaviorConfiguration="SingletonServiceBehavior<\/font>"><\/strong>
<host>
<baseAddresses>
<add baseAddress="<\/font>http:\/\/localhost:9015\/SingletonService"\/<\/font><\/a>>
<add baseAddress="net.tcp:\/\/localhost:9016\/SingletonService"\/>
<\/baseAddresses>
<\/host><\/font><\/p>\n
<endpoint address="net.tcp:\/\/localhost:9016\/SingletonService" binding="netTcpBinding" contract="InstanceLib.ISingletonService"\/>
<endpoint address="mex" binding="mexHttpBinding" contract="IMetadataExchange"\/>
<endpoint address="mex" binding="mexTcpBinding" contract="IMetadataExchange"\/>
<\/service><\/font><\/p>\n
<behaviors>
<serviceBehaviors><\/font><\/p>\n
<behavior name="SingleCallServiceBehavior<\/strong><\/font>">
<serviceMetadata httpGetEnabled="true"\/>
<\/behavior><\/font><\/p>\n
<behavior name="SessionServiceBehavior<\/strong><\/font>">
<serviceMetadata httpGetEnabled="true"\/>
<\/behavior><\/font><\/p>\n
<behavior name="SingletonServiceBehavior<\/strong><\/font>"><\/font><\/p>\n
<\/behavior><\/font><\/p>\n
<\/behaviors><\/font><\/p>\n
<\/configuration><\/font><\/p>\nSingle Call service. <\/h4>\n
<\/strong> <service name="InstanceLib.SingleCallService" behaviorConfiguration="SingleCallServiceBehavior">
<host>
<\/font><baseAddresses><\/font>
<add baseAddress<\/font>="<\/strong><\/font>http:\/\/localhost:9011\/SingleCallService"\/<\/font><\/a>>
<add baseAddress<\/font>="net.tcp:\/\/localhost:9012\/SingleCallService"\/>
<\/strong> <\/baseAddresses>
<\/font><\/strong> <\/host><\/font><\/p>\n
<endpoint<\/font><\/strong> address="net.tcp:\/\/localhost:9012\/SingleCallService<\/strong>" binding="netTcpBinding" contract="InstanceLib.ISingleCallService"\/>
<endpoint<\/font><\/strong> address="mex" binding="mexHttpBinding" contract="IMetadataExchange"\/>
<endpoint<\/font><\/strong> address="mex" binding="mexTcpBinding" contract="IMetadataExchange"\/>
<\/service><\/font><\/p>\nSession service. <\/h4>\n
<\/strong> <service name="InstanceLib.SessionService" behaviorConfiguration="SessionServiceBehavior">
<host>
<baseAddresses>
<\/strong><\/font> <add baseAddress<\/strong><\/font>="<\/font>http:\/\/localhost:9013\/SessionService"\/<\/font><\/a>>
<add baseAddress<\/strong><\/font>="net.tcp:\/\/localhost:9014\/SessionService<\/strong>"\/>
<\/baseAddresses><\/font><\/strong>
<\/host><\/font><\/p>\n
<endpoint<\/font><\/strong> address="net.tcp:\/\/localhost:9014\/SessionService" binding="netTcpBinding" contract="InstanceLib.ISessionService"\/>
<endpoint<\/font><\/strong> address="mex<\/strong>" binding="mexHttpBinding<\/strong>" contract="IMetadataExchange<\/strong>"\/>
<endpoint<\/font><\/strong> address="mex<\/strong>" binding="mexTcpBinding<\/strong>" contract="IMetadataExchange<\/strong>"\/>
<\/service><\/font><\/p>\nSingleton service. <\/h4>\n
<service name="InstanceLib.SingletonService" behaviorConfiguration="SingletonServiceBehavior<\/font>"><\/strong>
<host>
<baseAddresses><\/strong><\/font>
<add baseAddress<\/strong><\/font>="<\/font>http:\/\/localhost:9015\/SingletonService"\/<\/font><\/a>>
<add baseAddress<\/strong><\/font>="net.tcp:\/\/localhost:9016\/SingletonService<\/strong>"\/>