My goal is to load an external class in a running application environment (like a plugin model). Creating an instances of the class in an running environment is not the problem (the classes using an Interface). The problem is to get the class which must be available from a central WCF services.
Is it possible to transport an class or assembly to the client by using WCF?
Something like this:
[ServiceContract]
public interface ISourceData
{
[OperationContract]
xxx GetClassData { get; set; } // <-- here to get data the class to app can create an instances of this
}
I hope that you understand my situation. Thanks.
First of all, the attribute in your sample above must be OperationContract, not DataContract. The DataContract attribute is for the class that you want to return in GetClassData.
The problem in your situation is that on the client side the class itself is not replicated when you add the service reference, but a stub is generated for the properties that you define in your DataContract. So you get the data, but not the logic.
You could now create an assembly which defines the data classes to be exchanged and add them to both the service and the client, but as I understand your question, you want to dynamically load assemblies in the service and send these "implementations" to the client without the client actually having access to the DLL that implements the class. This may not be possible in an easy way.
EDIT
Re-reading your question I now understand that you do not want to "transfer an instance", but you want to transfer the class definition. One way would be to actually transfer the source code for the class and try to use Reflection.Emit to create a dynamic assembly. A sample of this can be found here.
Yes , you can .
and also you must to define the type of your class like ↓
[ServiceKnownType(typeof(xxx))]
public interface IService
I think you need the assembly on the client so you need to transfer the dll containing the assembly to the client, then have the client save it in a plugins directory for the app and have the app and load it from there.
Although I image that this is going to be a permissions nightmare to get the app to be able to use the dlls downloaded from the service.
You would mark up the classes used in your interface like this:
[ServiceContract]
public interface ISourceData
{
[OperationContract]
MyClass GetClassData();
}
[DataContract]
public class MyClass
{
[DataMember]
public string MyMember1 {get; set;} // included in transport
public int MyMember2 {get; set;} // not included
}
Related
I'm consuming a SOAP web service. The web service designates a separate service URL for each of its customers. I don't know why they do that. All their functions and parameters are technically the same. But if I want to write a program for the service I have to know for each company is it intended. That means for a company called "apple" i have to use the following using statement:
using DMDelivery.apple;
and for the other called "orange"
using DMDelivery.orange;
But I would like to my program to work for all of them and have the name of the company or the service reference point as a parameter.
Update: If I have to write a separate application for each customer then I would have to keep all of them updated with each other with every small change and that would be one heck of an inefficient job as the number of customers increase.
Can anyone think of a solution? I'll be grateful.
If you have a base contract (interface) for all your services you can use a kind of factory to instantiate your concrete service and only have a reference to your interface in your client code (calling code).
//service interface
public interface IFruitService{
void SomeOperation();
}
//apple service
public class AppleService : IFruitService{
public void SomeOperation(){
//implementation
}
}
Having for example a kind of factory class (you can put your using statements here)
public static class ServiceFactory{
public static IFruitService CreateService(string kind){
if(kind == "apple")
return new AppleService();
else if(kind == "orange")
return new OrangeService();
else
return null;
}
}
And in your calling code (you just add an using statement for the namespace containing your interface):
string fruitKind = //get it from configuration
IFruitService service = ServiceFactory.CreateService( fruitKind );
service.SomeOperation();
You can also use the Dependency Injection principle.
If everything is the same and it's only the endpoint address that is different, maybe you can try changing only that before invoking the web service methods.
MyWebServiceObject ws= new MyWebServiceObject();
ws.Endpoint.Address = new System.ServiceModel.EndpointAddress("http://www.blah.com/apple.asmx");
Use any one client in your implementation. ex. Apple
Write a message inspector and attach this into the out going point
In message inspector replace the name space of the type with appropriate client name space.
EX:
Before Message inspector :MyClinet.Apple.Type
After Message Inspector : MyClient.Orange.Type, if the Provider is Orange.
I'm creating a study project using .net web services and I came across with this problem:
In order to provide for an opportunity to change the web server or even it's nature (it's the part of the task) I created an interface in a separate .dll that every possible (web)services must implement. Say,
public interface IDataAccess
{
// Group of methods which are used for login/logout
bool isUserRegistered(string username);
bool authorize(string username, string password);
//...
}
And I make the web service implement this interface:
[WebService(Namespace = "http://tempuri.org/")]
[WebServiceBinding(ConformsTo = WsiProfiles.BasicProfile1_1)]
[System.ComponentModel.ToolboxItem(false)]
public class Server : System.Web.Services.WebService, IDataAccess
{
//...
}
Then, in the client, I create a reference (namespace WebReference) to this service specifying to reuse type in all assemblies and try to do the following:
private IDataAccess webService = (IDataAccess)(new WebReference.Server());
but this assignment throws exception in runtime stating the convertion can't be done, and, indeed, in the Reference.cs (which is a part of what is created by adding reference to Web Service there is a redeclaration of Server class which doesn't declare IDataAccessImplementation:
public partial class Server : System.Web.Services.Protocols.SoapHttpClientProtocol {
//...
}
So, my question is how to make this reference implement that common interface IDataAccess without manually editting the file Reference.cs?
Firstly, you really don't need to implement the interface on the server side - that will do nothing for the generated code.
Next, note that the declaration is of a partial class. You can use that to your advantage.
All you need to do is create another C# file, which has:
public partial class Server : SoapHttpClientProtocol, IDataAccess {}
That's all you need (in the right namespace and with the right using directives). No code - that's all provided in the generated class. The C# compiler will blend the two declarations, and then you can just use:
private IDataAccess webService = new WebReference.Server();
... or better yet, inject it via a constructor so that you can write tests which don't need to use the real implementation at all!
I am using C# Visual Studio 2012 to create a wcf service.
I had the WSCF.blue tool generate the wsdl from the xsd-s. Then I generated the web service code using the same tool. WSCF.blue does not create a Service Contract and a Data Contract. It creates an interface and a .svc file that contains a class that implements the interface.
When generating the web service code I selected the option to create the abstract classes because I want to be able to keep the implementation of these classes in a separate file.
The abstract class looks like this:
[KnownType(typeof(WebMobileImplementation))]
public abstract class WebMobile : IWebMobile
{
public abstract PutLocationsResponse PutLocations(PutLocationsRequest request);
}
The implementing class (in a different file) looks like this (for now):
public class WebMobileImplementation : WebMobile
{
public override PutLocationsResponse PutLocations(PutLocationsRequest request)
{
PutLocationsResponse response = new PutLocationsResponse();
return response;
}
}
When trying to browse the service I get the message: "Service implementation type is an interface or abstract class and no implementation object was provided"
I thought that adding the knowntype to the implementing class will do the trick but it seems that the implementation is not 'seen' when running the service. What else can I do to 'connect' them?
In WCF 4.0, you can define virtual service activation endpoints that map to your service types in Web.config. This makes it possible to activate WCF services without having to maintain physical .svc files.
<serviceHostingEnvironment>
<serviceActivations>
<add relativeAddress="WebMobile.svc"
service="WebMobileNamespace.WebMobileImplementation"/>
</serviceActivations>
</serviceHostingEnvironment>
I have a WCF Host with something like this:
[ServiceContract]
public interface IMountToOs
{
[OperationContract]
char GetMountDriveLetter();
[OperationContract]
MyTestClass MyTest();
}
public class MyTestClass
{
public string A { get; set; }
public string B { get; set; }
}
Client
private IMountToOs _proxy;
public IMountToOs Proxy
{
get
{
if (_proxy == null)
{
NetTcpBinding binding = new NetTcpBinding();
binding.MaxReceivedMessageSize = 2147483647;
binding.OpenTimeout = TimeSpan.FromMilliseconds(50000);
EndpointAddress address = new EndpointAddress("net.tcp://localhost:1234/MountToOsHost");
//_proxy = new MountToOsClient(binding, address);
ChannelFactory<IMountToOs> factory = new ChannelFactory<IMountToOs>(binding);
_proxy = factory.CreateChannel(address);
}
return _proxy;
}
}
While I can access
MessageBox.Show("Okay - " + Proxy.GetMountDriveLetter());
I can't call this method:
MessageBox.Show("Okay - " + Proxy.MyTest().A);
The complete extension is not working. But only while using it in an extension. Even if I insert a Messagebox in the first line of the extension it is not hit. I don't know why. It seems to run a pre-check and find the call of the custom class which is refused or so...
If I use a winform or so there is no problem.
.net 3.5
curious is that I have a break-point and a message of the hosts side. So I see that the method is not called
Update
now I moved the wcf-call in the Load Method of the extension and get a exception:
System.MissingMethodException: method not found:
"Contracts.Interfaces.MyTestClass
Contracts.Interfaces.IMountToOs.MyTest()".
My winform test and this extension use the same interface so that the method should known from both. no contract or so is outdated
According to what I found here and in the comments of the post: "For creating dynamic service proxy using client channel factory method, you will need datacontracts of the service. If you don't have datacontracts but you have the service URL, then you could use reflection to create proxy at runtime and call the service method."
Seems that the MyTestClass type is not known on the client side, so I think you could use reflection, or share the class between the client and server or much more simple, use the datacontract attribute.
Also, found something on MSDN that says something like this:
"When to use a proxy?
We create proxy using svcutil.exe. The output of this tool gives a proxy class and makes corresponding changes to the application configuration file. If you have a service that you know is going to be used by several applications or is generic enough to be used in several places, you'll want to continue using the generated proxy classes. We use proxy in WCF to be able to share the service contract and entities with the client. Proxies have several restrictions like they need to have gets and sets , contructors can't be exposed , methods other than the service contract cannot be exposed, repetition of code, everytime that we add/modify a service contract/data contract/message contract we need to re-generate the proxy for the client.
When to use ChannelFactory
The other option is using the ChannelFactory class to construct a channel between the client and the service without the need of a proxy . In some cases, you may have a service that is tightly bound to the client application. In such a case, it makes sense to reference the Interface DLL directly and use ChannelFactory to call your methods using that. One significant advantage of the ChannelFactory route is that it gives you access to methods that wouldn't otherwise be available if you used svcutil.exe..
When to use a ChannelFactory vs Proxy class?
A DLL is helpful if the client code is under you control and you'd like to share more than just the service contract with the client -- such as some utility methods associated with entities and make the client & the service code more tightly bound. If you know that your entities will not change much and the client code is less, then a DLL would work better than a proxy. If the client to your service is external to the system, such as API, it makes sense to use a proxy, because it makes sharing the contract easier by giving a code file rather than a DLL."
We cant see the class
MountToOsClient: IMountToOs
So we can only assume it is ok.
[DataContract] // Missing
public class MyTestClass
{
[DataMember] // Missing
public string A { get; set; }
[DataMember] // Missing
public string B { get; set; }
}
MountToOsClient can not expose Mytestclass without these attributes.
I know when you create a service you can create a generic DataContract:
[DataContract(Name = "Get{0}Request")
public sealed class GetItemRequest<T>
where T : class, new() { ... }
[DataContract(Name = "Get{0}Response")
public sealed class GetItemResponse<T>
where T : class, new() { ... }
[ServiceContract]
public void MyService : IMyService
{
[OperationContract]
GetItemResponse<Foo> GetItem(GetItemRequest<Foo> request);
}
This generates a GetFooRequest and GetFooResponse definition for my WSDL. Now, what I'm curious about is if it is possible to go in the other direction?
Is it possible to create a client that uses the Generic DataContracts and pass those to the server as a concrete object? I attempted this after adding a Service Reference and it didn't really work out so well. So this is more of me wondering if there is any way (even if it means not adding a Service Reference) to do this?
Ultimately, WCF is going to look at the contract class. If that is generated from WSDL/MEX it won't have this (since this isn't how it is expressed in the metadata) - but if your client has the code as above, then sure it should work fine.
If you add a library reference (i.e. a dll / project reference) to your DTO dll from the client, and ensure WCF has shared-assemblies enabled, it should work. If it still baulks, then cheat: use a service reference just to get the config data. Then delete the service reference but keep the configuration (those config files are a pain otherwise). Then it should locate the type from the library.