在 WCF C# 应用程序中模拟并发或多线程

Question

I am developing an Service-Oriented based application for Hotel Reservation System using WCF architecture. It has following 3 three components: 1. WCF Service that has Service and Data contracts for invoking moudules of room reservation. 2. WCF Host that keeps log of service access by client 3. WCF client that has UI for Hotel Reservation.

I am looking for guidelines to implement concurrency in my application having following features: 1. Only one request shall be entertained at the time. 2. If more than one requests are received, then these should be synchronized using locks/mutex/semaphores.

Coding guidelines shall be helpful.

Answer 1

I think this is the allocation issue of the external resources, such as the database access, the I/O for on the single file. WCF supports transaction and transmitting it on the client-side. We are capable of locking the access to the database by using transaction when another client attempt to access it.
https://docs.microsoft.com/en-us/dotnet/framework/wcf/feature-details/transactions-overview
Moreover, we can also use the shared lock which locks the service instance, occupying all the resource lest the other instance access the service, please refer to the below code.

    [ServiceBehavior(InstanceContextMode = InstanceContextMode.PerCall,
 ConcurrencyMode = ConcurrencyMode.Multiple)]
class MyService : IMyContract
{
 public void MyMethod()
 {
 lock(typeof(MyService))
 {
 ...
 MyResource.DoWork();
 ...
 }
 }
}
static class MyResource
{
 public static void DoWork()
 {
 lock(typeof(MyService))
 {
 ...
 }
 }
}

Please refer to the below link, Chaper8(concurrency management), resources and services, deadlock avoidance.
https://ashishmit99.files.wordpress.com/2013/01/oreilly-programming-wcf-services-3rd-edition-aug-2010.pdf
Here is an official document relates to Concurrency mode, aiming to solve access conflict from the multiple users.
https://docs.microsoft.com/en-us/dotnet/framework/wcf/feature-details/sessions-instancing-and-concurrency