BizTalk Server 2009 : Using asynchronous services in WCF (part 1) - Creating the synchronous service

12/14/2010 4:44:44 PM

WCF has support for both client-side and server-side asynchronous programming scenarios. By "client-side" programming, I mean that a service built with a request/response operation can appear asynchronous to the client. For example, let's look at a simple sequence diagram that shows what I mean.

The WCF client proxy class is responsible for simulating the asynchronous communication, while the actual service still exposes only a synchronous operation. Let's look at an example of how we would physically create a client-side asynchronous experience in a WCF solution.

Creating the synchronous service

We start out by creating a new, empty Visual Studio.NET 2008 solution. Then we add a project of type WCF Service Library to the solution. This project type automatically adds an interface class, service class, and application configuration file. I've changed the interface class content so that it reflects the adverse event object that we'll be working with throughout this chapter. An adverse event is a patient experience with a drug that has caused them problems. My service interface (and corresponding data classes) now looks like this:

[ServiceContract(Namespace="http://Seroter.BizTalkSOA.Chapter6")]
public interface IAdverseEventSync
{
[OperationContract]
AdverseEventAction SubmitAdverseEvent(AdverseEvent NewAE);

}
[DataContract(Namespace="http://Seroter.BizTalkSOA.Chapter6")]
public class AdverseEvent
{
[DataMember]
public string Product { get; set; }
[DataMember]
public int PatientID { get; set; }
[DataMember]
public int PhysicianID { get; set; }
[DataMember]
public AECategoryType Category { get; set; }
[DataMember]
public DateTime DateStarted { get; set; }
[DataMember]
public ReportedByType ReportedBy { get; set; }
[DataMember]
public string Description { get; set; }
}
[DataContract(Namespace="http://Seroter.BizTalkSOA.Chapter6")]
asynchronous communicationusing, in WCFpublic class AdverseEventAction
asynchronous services, WCFsynchronous service, creating{
[DataMember]
public string SubmissionID { get; set; }
[DataMember]
public string Product { get; set; }
[DataMember]
public int PatientID { get; set; }
[DataMember]
public bool doCeaseMedication { get; set; }
[DataMember]
public bool doReduceDosage { get; set; }
[DataMember]
public bool doAdmitHospital { get; set; }
[DataMember]
public bool doScheduleFollowup { get; set; }
[DataMember]
WCFasynchronous services, usingpublic string AdditionalNotes { get; set; }
}
[DataContract]
public enum AECategoryType
{
[EnumMember]
InjectionSoreness = 0,
[EnumMember]
Swelling = 1,
[EnumMember]
Headache = 2,
[EnumMember]
Bleeding = 3,
[EnumMember]
Sickness = 4,
[EnumMember]
Rash = 5,
[EnumMember]
Other = 6
}
[DataContract]
public enum ReportedByType
{
[EnumMember]
Patient = 0,
[EnumMember]
Physician = 1,
[EnumMember]
SalesRep = 2,
[EnumMember]
Other = 3
}