Why ASMX web services are not an excuse anymore with WCF 4.0

ASXM web services has been the favorite choice for many developers for building soap web services in .NET during a long time because of its simplicity. With ASMX web services, you get a web service up and running in a matter of seconds, as it does not require any configuration. The only thing you need to do is to build the service implementation and the message contracts (xml serialization classes), and that’s all. However, when you build a system as a black box with most of the configuration hardcoded, and only a few extensibility points in mind, you will probably end up with something that is very easy to deploy and get running, but it can not be customized at all. That’s what an ASMX web service is after all, you don’t have a way easily change the protocol versions, encoders, security or even extend with custom functionality (SOAP extensions are the only entry point for extensibility, which work as message inspectors in WCF).

On the other hand, you have WCF, which is extensible beast for building services among other things. The number of extensibility points that you will find in WCF is extremely high, but the downside is that configuration also becomes extremely complex and a nightmare for most developers that only want to get their services up and running.

Fortunately, the WCF team has considerably improved the configuration experience in WCF 4.0, making possible to run a service with almost no configuration. The approach that they have taken for this version is to make everything work with no configuration, and give the chance to override what you actually need for a given scenario.

For instance, a WCF service that uses http as transport behaves a ASMX web service by default (it uses basicHttpBinding with SOAP 1.2, transport security, text encoding and Basic profile 1.1) unless you change that. So, how can you create a new WCF service as you did before with ASMX ?. That’s simple and you need to follow these steps,

1. Create a new WCF service in Visual Studio

visualstudio_newservice

2. Modify the service and data contract to expose the operations you actually need in the service.

 

// NOTE: You can use the "Rename" command on the "Refactor" menu to change the interface name "IService1" in both code and config file together.
[ServiceContract]
public interface IService1
{

[OperationContract]
string GetData(int value);

[OperationContract]
CompositeType GetDataUsingDataContract(CompositeType composite);

// TODO: Add your service operations here
}


// Use a data contract as illustrated in the sample below to add composite types to service operations.
[DataContract]
public class CompositeType
{
bool boolValue = true;
string stringValue = "Hello ";

[DataMember]
public bool BoolValue
{
get { return boolValue; }
set { boolValue = value; }
}

[DataMember]
public string StringValue
{
get { return stringValue; }
set { stringValue = value; }
}
}

3. Optionally, enable the service metadata page for the service, so any client application can use this to generate the proxies.

<system.serviceModel>
<behaviors>
<serviceBehaviors>
<behavior>
<serviceMetadata httpGetEnabled="true"/>
</behavior>
</serviceBehaviors>
</behaviors>
</system.serviceModel>

 

4. Optionally, enable the ASP.NET Compatibility mode to use the ASP.NET security context (Otherwise, the service will use the default security settings for the basicHttpBinding). That will require two additional steps, adding the “serviceHostingEnvironment” element in the existing service model configuration.

<system.serviceModel>
<serviceHostingEnvironment aspNetCompatibilityEnabled="true"/>

 

And adding an attribute in the service,

[AspNetCompatibilityRequirements(RequirementsMode=AspNetCompatibilityRequirementsMode.Allowed)]
public class Service1 : IService1

That’s all you need to implement a new WCF service that will behave as a traditional ASMX webservice. As you can see, no service or binding configurations were required for the service. In addition, the behavior element does not have any name, so it applies to all the services running in the same host.

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