I'm new to WCF, but not new to C# and .Net. and am using Visual Studio 2008 and .Net 3.5.
I'm trying to build a Web Service that can receive any inbound Request XML and any namespaces. It would behave like a transparent receiver and simply intake the inbound request XML.
Once I get the request I'm going to pass it to some custom .Net C# Project to invoke a MQPUT to IBM MQ Series.
Right now I have the WCF Web Service Application receiving a generic inbound operation called RunTest(). I consume the WSDL into SoapUI, build a sample request and breakpoint and it works. But, when I try to pass our company request XML it doesn't land on the breakpoint.
Here is the ServiceContract and Operation:
[ServiceContract(Name="IService1",Namespace="cfg-env=http://www.co.com/schemas/cfg- env/")]
//[ServiceContract]
public interface IService1
{
[OperationContract]
void RunTest();
[OperationContract]
void CFX();
Here is the Method for the Operation:
public void RunTest()
{ <<<it does break here using the request from the WSDL
string serviceName;
string queueManager;
string queue;
string requestMessage;
//Capture the Service Name
serviceName = "";
//Save the QueueManager
queueManager = "";
//Save the Request Queue
queue = "";
//Save the Message
requestMessage = "";
//Call MQ Put
Engine eng = new Engine();
try
{
eng.Put(serviceName, queue, requestMessage, queueManager);
}
The main thing I need to do is receive the inbound XML, interogate it for a few pieces of information and call this Method to do the MQPUT function on MQ.
The inbound namespace will look like the above but I'd like to ensure I can receive and interogate any XPATH that may be namespace qualified. If I have to I can work with the cfg-env namespace prefix exclusively as our services do use that as a standard.
What are my key hurdles in doing this in VS 2008 WCF? If you have any links please pass them along if you can.
I believe you specify the name property on the OperationContract attribute as "*" to accept all requests. To make the parameter itself schema agnostic, it should be of type System.ServiceModel.Channels.Message.
What you are building is a "WCF router".
Included in the latest .NET release is a configurable Routing Service.
If the routing service doesn't meet your needs, building your own router is possible but can get really complicated when secure messages are a requirement. This set of MSDN articles is the best resource. They answer your question of how to have a service accept any message, and then continue on into addressing and security issues.
Building a WCF Router, Part 1
Building a WCF Router, Part 2
Related
Just getting my head around message queues and Redis MQ, excellent framework.
I understand that you have to use .RegisterHandler(...) to determine which handler will process the type of message/event that is in the message queue.
So if I have EventA, EventB etc should I have one Service which handles each of those Events, like :
public class DomainService : Service {
public object Any(EventA eventA) {...}
public object Any(EventB eventA) {...}
}
So these should be only queue/redis list created?
Also, what If I want a chain of events to happen, so for example a message of type EventA also has a handler that sends an Email providing handlers earlier on the chain are successful?
ServiceStack has no distinction between services created for MQ's, REST, HTML or SOAP services, they're the same thing. i.e. they each accept a Request DTO and optionally return a Response DTO and the same service can handle calls from any endpoint or format, e.g HTML, REST, SOAP or MQ.
Refer to ServiceStack's Architecture diagram to see how MQ fits in.
Limitations
The only things you need to keep in mind are:
Like SOAP, MQ's only support 1 Verb so your methods need to be named Post or Any
Only Action Filters are executed (i.e. not Global or Attribute filters)
You get MqRequest and MqResponse stubs in place of IHttpRequest, IHttpResponse. You can still use .Items to pass data through the request pipeline but any HTTP actions like setting cookies or HTTP Headers are benign
Configuring a Redis MQ Host
The MQ Host itself is completely decoupled from the rest of the ServiceStack framework, who doesn't know the MQ exists until you pass the message into ServiceStack yourself, which is commonly done inside your registered handler, e.g:
var redisFactory = new PooledRedisClientManager("localhost:6379");
var mqHost = new RedisMqServer(redisFactory, retryCount:2);
mqHost.RegisterHandler<Hello>(m => {
return this.ServiceController.ExecuteMessage(m);
});
//shorter version:
//mqHost.RegisterHandler<Hello>(ServiceController.ExecuteMessage);
mqHost.Start(); //Starts listening for messages
In your RegisterHandler<T> you specify the type of Request you want it to listen for.
By default you can only Register a single handler for each message and in ServiceStack a Request is tied to a known Service implementation, in the case of MQ's it's looking for a method signature first matching: Post(Hello) and if that doesn't exist it looks for the fallback Any(Hello).
Can add multiple handlers per message yourself
If you want to invoke multiple handlers then you would just maintain your own List<Handler> and just go through and execute them all when a request comes in.
Calling different services
If you want to call a different service, just translate it to a different Request DTO and pass that to the ServiceController instead.
When a MQ Request is sent by anyone, e.g:
mqClient.Publish(new Hello { Name = "Client" });
Your handler is invoked with an instance of type IMessage where the Request DTO is contained in the Body property. At that point you can choose to discard the message, validate it or alter it.
MQ Requests are the same as any other Service requests
In most cases you would typically just forward the message on to the ServiceController to process, the implementation of which is:
public object ExecuteMessage<T>(IMessage<T> mqMsg)
{
return Execute(mqMsg.Body, new MqRequestContext(this.Resolver, mqMsg));
}
The implementation just extracts the Request DTO from the mqMsg.Body and processes that message as a normal service being passed a C# Request DTO from that point on, with a MqRequestContext that contains the MQ IHttpRequest, IHttpResponse stubs.
I'm putting together a WCF service using net.tcp and netTcpBinding to get duplex comms with my Silverlight client. I call into the service from the Silverlight app and the service calls out to another server, passing it a callback method in the WCF service class. The remote server calls back several times and each time it does, the WCF service uses the callbackchannel to send the data to the Silverlight client. It all works nicely most of the time.
If the user puts in a big request, I get a TimeoutException after a large number of callbacks have already worked. (Clearly, there's some work to do elsewhere to prevent this but I'd like to robustify the service, first.)
I was expecting to do some kind of 'if (client.ConnectionState == faulted)' check before trying to call back to the Silverlight client but I can't seem to find the object that holds the state of the connection. Is there one? Am I approaching this from the wrong side?
This is my first venture into a service net.tcp and duplex. I just moved house and my WCF bible is still in a box. Somewhere. :-) So, I can't do my usual background reading.
Any pointers would be gratefully received. Here's some bare code in case my description is too soupy:
private IActiveDirectoryClient client;
private AsyncSearchRunner runner;
public void Search(Request request)
{
this.client = OperationContext.Current.GetCallbackChannel<IActiveDirectoryClient>();
runner = new AsyncSearchRunner();
runner.Run(request.SearchRoot, request.SearchFilter, request.PageSize,
System.DirectoryServices.Protocols.SearchScope.Subtree, SendObjects);
}
private void SendObjects(List<DirectoryObject> items)
{
Response response = new Response();
response.DirectoryObjects = items.ToArray();
client.SendResponse(response);
}
Yes, there is a State property that is defined in the ClientBase<> class (all the proxy classes are derived from ClientBase<>).
There are some proxy wrappers out there that handle fault states of the connection and re-establish connections as needed. Google for "wcf proxy wrapper".
You can also home-brew something if you use some kind of ServiceLocator pattern.
Microsofts's WCF is easy to work with when you create Web services where each message has it's own Web method. WCF generates all of the WSDL and everything is easy.
What I want to do is have one Web method that accepts multiple different messages (I don't want to add a mew method every time I add a new message type). The messages themselves will have header information that identify the message type. Once I know the message type, I'll know the structure of the rest of the message.
The only way I've found to do this with WCF is to have the method accept a string, which I parse in as XML and and use. However, I can see no clear way to publish the various message types in the WSDL; so, the whole service is essentially undocumented.
Anyone know of a technique to use in WCF?
You can write an operation contract that accepts any message by setting the Action to * and having it take in a Message object:
[ServiceContract]
public interface IMessageContract
{
[OperationContract(Action = "*", ReplyAction = "*")]
Message ProcessRequest(Message request);
}
The Message object gives you access to the headers and has methods to deserialize the body.
To export your own WSDL, you will need to implement IWsdlExportExtension on a contract behavior or operation behavior and attach it to your service. This will give you access to a WsdlExporter, and you can create a ContractDescription yourself and call ExportContract to have it appear in the generated WSDL.
I created a WCF service that exposed a method that has one paramater:
public class Service1 : IService1
{
public string GetData(int value)
{
return string.Format("You entered: {0}", value);
}
}
The service has two endpoints defined (wsHttpBinding and basicHttpBinding) so that it would be compatable with older clients.
The service runs just fine in a .NET 3.0 and .NET 3.5 client app. However, when I create a .NET 2.0 client, the GetData method requires 2 parameters: an integer (expected) and a bool parameter called valueSpecified (unexpected). I never defined the second parameter. Why is this happening and how can I get rid of the second parameter?
Since value types can't be null (in latter versions of .net framework there is no Nullable<T>) VS besides to generate additional parameter to give you ability to not specify value type, you can call your service method like this.
service.GetData(val,true);
see this post, where John Saunders suggest to add [DataMember(Required = true)] attribute in the property.
The exact same question has been posted here.
Another way to avoid the extra boolean parameter to be generated on the client proxy when using .NET 2.0 is to switch to RPC-style enconding in the service contract (the default for both WCF and ASMX is Document Style).
This way the XmlSerializer on the client will make sure that the parameter always appears in the SOAP requests since it's part of the SOAP 1.1 specification, which is enforced when using the RPC-Style encoding.
In WCF you can specify the encoding style using the DataContractFormat attribute, either at the service or at the operation level.
[ServiceContract]
public interface IService
{
[OperationContract]
[DataContractFormat(Style = OperationFormatStyle.Rpc)]
string GetData(int value);
}
More information on the differences between RPC Style and Document Style encoding in SOAP can be found here.
In any case please consider carefully the implications of changing the contract of your services, since it can potentially break compatibility with any existing clients.
You could manually remove the valueSpecified property from GetData operation within your proxy class.
I am trying to design an Picture Upload feature into a web site.
I am using ASP.NET 3.5, C#, and WCF.
I have been asked to accomplish the following:
1) Make the Uploader a Web Service
2) Return progress updates to the user as files are uploaded.
3) Log other relevant user-selected options in the database.
So, I have started off by creating a WCF web client with the
below service contract:
IService.UploadPictures(HttpRequest request);
private UploadServiceClient upload;
protected void Page_Load(object sender, EventArgs e)
{
upload = new UploadServiceClient();
upload.UploadPictures(Request.Files);
}
When I compile, I get the below error:
Type 'System.Web.HttpRequest' cannot
be serialized. Consider marking it
with the DataContractAttribute, and
marking all of its members you want
serialized with the
DataMemberAttribute attribute.
So, I went back into my service contract and
changed [OperationContract] to [DataContract]
but the change produced the same error.
Can somebody kindly tell me what I am doing wrong
and provide examples as to how to best move forward?
Thanks for your time.
You cannot use something like a HttpRequest as a WCF parameter. The error messages says it all - the HttpRequest is not serializable, and in order to work with WCF, types have to be serializable.
Also, you need to remember: you're not just passing an object instance to a method here - what you're really doing is having the WCF runtime serialize your request (the method name to call plus all the parameters passed in) into a message (think: e-mail or xml file), sending it to the server, deserialising there and building up a new copy of the given datatype (as defined in your DataContract), and doing something with it.
Your WCF service could well be self-hosted, e.g. running in a NT Service or console app - no HttpRequest available in those circumstances!
You need to definitely rearchitect your solution - you need to either check into WCF streaming to upload files to WCF (google for it - you'll find plenty of hits) or you'll need to find another way to pass the relevant info (e.g. list of filenames) to the WCF service without use of a HttpRequest object.
Marc
You are submitting a request as a parameter to a request. This is not what you want to do. I'm assuming that "Request.Files" is an array of files. This is what you want to upload. So something like:
IService.UploadPictures(List<SomeFileType> request);