从c＃client调用ac＃wcf webservice

Question

i have ac# wcf web service and ac# client which makes calls to the web service which is working fine and have a scenario like below which i am unable to figure it out how to do it.

Here is the case, i have 2 methods in c# client as the 1st method will make more time and client doesn't know what going on as response from the wcf web service will take long time, so we implemented 2nd method which gives the status of the 1st method call(saying that the first method has a total of 10 tasks and is currently performing 1 or 2 or 3 etc). now i don't have any idea how the call goes to the 2nd method as the first method is not yet completed and as both the methods have to be in the same client. Can any one please help with this.

Answer 1

The very best way of solving this kind of issue is to split tasks across multiple different WCF methods, chaining the calls. Example:

instead of doing this (just a proof of concept):

serviceClient = new MyWCFClient();
serviceClient.TaskThatTakesForeverCompleted += (s,e) => { /*I'm done !*/ };
serviceClient.TaskThatTakesForeverAsync();

you'll end up doing this:

serviceClient = new MyWCFClient();
serviceClient.FirstTaskCompleted += (s,e) => { /*first task done!*/ serviceClient.SecondTaskAsync(); };
serviceClient.SecondTaskCompleted += (s,e) => { /*and so on... */ };
...
serviceClient.FirstTaskAsync();

while server-side you'd implement it like this:

[OperationContract]
public <return type> FirstTask() { /* code */}
[OperationContract]
public <return type> SecondTask() { /* more code */ }

Of course, this might not apply to your case, but very long tasks can be split up in this fashion.

WARNING : This kind of implementation is most definitely not best-practice since you'll find yourself with a bunch of methods which have to be invoked in a fixed order (FirstTask must be the first, then goes SecondTask, and so on) but in the end it would handle the issue of knowing what the service is doing.

It really is harder to explain than to understand, all it takes is a little fiddling around it's quite a straightforward logic.

NOTE : If you don't have the Async calls, enable them this way:

• Right click the service reference
• "Configure service reference"
• Check "generate asynchronous operations", leave "generate message contracts" unchecked and everything else as is
• Now you'll have the async calls at your disposal

Answer 2

If I have understand correctly... you need to implement asynchronous invocation . By default in WCF all calls are synchronous.

What you have now is a synchronous invocation.:

1. Method1 (Client) invokes Method2 (Server) to have tasks done.
2. Method1 waits a long time until Method2 finishes
3. Method1 receives a true (or whatever) from Method 2
4. Method 1can continue doing things.

What you need is:

1. Method1 (Client) calls Method2 (Server)

2. Method2

   2.1 Validate that request is correctly formed

   2.2 Creates a thread with working process

   2.3 Returns true (that means ok, I have queued your request)

   2.4 Method1 continue doing its stuff.

Then you have two options:

3A. When Method2 finishes it calls another method in Client to report that it has finished (Say Method 3 in Client)

3B. Method1 query another method in Server (Say Method4 in Server) to see progress of task every x seconds and show it on screen or do whatever it wants until it is finished.

You can check this MSDN link about how to implement asynchronous methods in WCF.