Enabling Session in WCF

In web.config of your service application, aspnetcompatibility needs to be enabled

<system.sewerviceModel>

<serviceHostingEnvironment aspNetCompatibiltyEnabled="true"/>

</system.serviceModel>

2. Add the following line to the class that implements your service interface

[AspNetCompatibilityRequirements(RequirementsMode = AspNetCompatibilityRequirementsMode.Allowed)]

 AspNetCompatibilityRequirementsMode enum has three values, Allowed NotAllowed and Required.