Calling WCF service from iPhone

WCF changes way of communication between application-to-application and intra-application. This post will help you to call WCF from iPhone application. First we will see what we have to do on WCF to let iPhone application call service. And the sample code which call WCF from iPhone.

First let’s create simple WCF service.

[ServiceContract(Namespace = "")]
[DataContractFormat]
public class MultiEndPointsService
{
    [OperationContract]
    public string GetDictionary()
    {
        Dictionary<string, string> dict = new Dictionary<string, string>();
        dict.Add("IB", "Imran Bhadelia");
        dict.Add("DO", "David Oliver");
        dict.Add("NA", "Nick Althoff");
        dict.Add("JJ", "Jay Joshi");
        dict.Add("DL", "Dave Larson");
        dict.Add("BA", "Brenda Ayong-Chee");
        dict.Add("JP", "Jay Parikh");

        StringBuilder sbJson = new StringBuilder();
        new JavaScriptSerializer().Serialize(dict, sbJson);
        return sbJson.ToString();

    }
}

This is simple WCF Service. We need to add some decoration for enabling web script and handle POST method. We are going to send http post form iPhone application and send Json string as response. Doing so we also need to decorate our operation contract to set request and response format.

[ServiceContract(Namespace = "")]
[AspNetCompatibilityRequirements(RequirementsMode = AspNetCompatibilityRequirementsMode.Allowed)]
[ServiceBehaviorAttribute(IncludeExceptionDetailInFaults = true)]
[DataContractFormat(Style = OperationFormatStyle.Document)]
public class MultiEndPointsService
{
    [WebInvoke(Method = "POST", BodyStyle = WebMessageBodyStyle.WrappedRequest,
        RequestFormat = WebMessageFormat.Xml, ResponseFormat = WebMessageFormat.Json)]
    [OperationContract]
    public string GetDictionary()
    {
        Dictionary<string, string> dict = new Dictionary<string, string>();
        dict.Add("IB", "Imran Bhadelia");
        dict.Add("DO", "David Oliver");
        dict.Add("NA", "Nick Althoff");
        dict.Add("JJ", "Jay Joshi");
        dict.Add("DL", "Dave Larson");
        dict.Add("BA", "Brenda Ayong-Chee");
        dict.Add("JP", "Jay Parikh");
           
        StringBuilder sbJson = new StringBuilder();
        new JavaScriptSerializer().Serialize(dict, sbJson);
        return sbJson.ToString();
    }
}

And following are the configuration settings

<system.serviceModel>
    <services>
      <service name="Demo.Service.MultiEndPointsService" behaviorConfiguration="serviceBehaviour">
        <endpoint address="basic" binding="basicHttpBinding" bindingConfiguration="basicBinding" contract="Demo.Service.MultiEndPointsService" />
      </service>
    </services>
    <behaviors>
      <serviceBehaviors>
        <behavior name="serviceBehaviour">
          <serviceMetadata httpGetEnabled="true" />
          <serviceDebug includeExceptionDetailInFaults="false" />
        </behavior>
      </serviceBehaviors>
    </behaviors>
    <bindings>
      <basicHttpBinding>
        <binding name="basicBinding" maxBufferSize="2147483647" maxReceivedMessageSize="2147483647">
          <security mode="None"></security>
          <readerQuotas maxStringContentLength="2147483647" />
        </binding>
      </basicHttpBinding>    
    </bindings>
  </system.serviceModel>

We need to create basicHttpBinding so it get called form iPhone application, we haven’t sent security to call this method; and following is the Objective-C code which call WCF from iPhone.

NSString *soapMessage = [NSString stringWithFormat:@"<SOAP-ENV:Envelope xmlns:SOAP-ENV=\"http://schemas.xmlsoap.org/soap/envelope/\"><SOAP-ENV:Body><GetDictionary></GetDictionary></SOAP-ENV:Body></SOAP-ENV:Envelope>"];
   
NSURL *url = [NSURL URLWithString:@http://localhost/Demo.Service/MultiEndPointsService.svc/basic];
NSMutableURLRequest *theRequest = [NSMutableURLRequest requestWithURL:url];                        
NSString *msgLength = [NSString stringWithFormat:@"%d", [soapMessage length]];             
   
[theRequest addValue: @"text/xml; charset=utf-8" forHTTPHeaderField:@"Content-Type"];
[theRequest addValue: @"urn:MultiEndPointsService/GetDictionary" forHTTPHeaderField:@"SOAPAction"];
[theRequest addValue: msgLength forHTTPHeaderField:@"Content-Length"];
[theRequest setHTTPMethod:@"POST"];    
[theRequest setHTTPBody: [soapMessage dataUsingEncoding:NSUTF8StringEncoding]];

NSURLConnection *theConnection = [[NSURLConnection alloc] initWithRequest:theRequest delegate:self];

Once you parse the response it will look like following.

You can also call operation contract having parameters, for that need to create proper message and then add it in SOAP-BODY that will work.

WCF Service with webHttpBinding-basicHttpBinding-wsHttpBinding

WCF Services are designed to support distributed services where consumed client. Services are typically have WSDL interface which any of client can consumed regardless of platform on which WCF is hosted on.

WCF Services having three portions, Class having methods, host environment to host service, and one or more endpoints. Endpoints is place where WCF Client connects to WCF Service. In order to accommodate different communication scenario you just need to create more then one endpoints, for each endpoint you specify the address, a binding and a contract. Address is simple listener; contract specify the format of message which will arrive on specified address and binding is let you configure transport protocol, encoding and security. There are few built-in bindings represented by System.ServiceModel.Channels.Binding class to support HTTP, TCP and MSMQ protocols.

That was brief about WCF, now lets come to our business. We need to use wsHttpBinding + basicHttpBinding + webHttpBinding all together. That means we need to have multiple ends points to our service for different-different scenario. Here are the Service contract and operation contracts which we are going to use.

We will add one by one binding and check into WCF Test Client. First we will add basicHttpBinding which is designed for interoperability utmost important, its using SOAP 1.1.

You can see single endpoints having address and bindings, we have added binding configuration name basicBinding, which have property like security mode to None, readerQuotas having setting for client who is reading data from channel, also maxBufferSize which is parameter defined size which can be passed thru channel. We can see bindings in WCF Test Client it will show basic http bindings having one method. The value of maxBufferSize and maxReceivedMessgaeSize should be same for transfer mode is buffered. We have added behavior configuration for our service; serviceMetadata httpGetEnabled="true" allows simple HTTP Get request to succeed for metadata retrieval, by default WCF does not exposed metadata.

We can use WCF Test Client to check whether our setting are correct or not. So open WCF Test Client and add service url into service project.

It shows that we have exposed our service using basicHttpBinding. Now lets add wsHttpBinding binding, which is design for security, reliable messaging and transactions and its using SOAP 1.2 along with WS-Addressing 1.0 for message version which will carry additional protocol headers.

We have added binding configuration to set security and session reliability. The reliable session WCF provides ensures that messages sent between endpoints are transferred across SOAP or transport intermediaries and are delivered only once and, optionally, in the same order in which they were sent

Now let’s check on our WCF Test Client.

So, we can see two endpoints has been exposed, one is for basic binding and other is web script bindings. We already add basic and ws bindings lets add now web bindings.

One more endpoint, it’s now easy to expose more then one endpoint for single operation contract. If you need any security or additional settings then you can add binding configuration for this endpoint, but for now we don’t need any configurations. Let’s check our WCF Test Client.

We can see all these three binding for single operation contract! You can see wsdl file which will expose all these three bindings.

So we have exposed webHttpBinding + basicHttpBinding + wsHttpBinding endpoints in WCF service using same operation contract. We can use webHttpBinding for Silverlight application and also Json call.